tag:theconversation.com,2011:/fr/topics/dung-beetles-20298/articlesDung beetles – The Conversation2023-06-29T14:35:32Ztag:theconversation.com,2011:article/2071452023-06-29T14:35:32Z2023-06-29T14:35:32ZDung beetles: expedition unearths new species on Mozambique’s Mount Mabu<figure><img src="https://images.theconversation.com/files/533691/original/file-20230623-22-6mwktq.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A landscape view of Mabu Forest, Zambezia, Mozambique. </span> <span class="attribution"><span class="source">Gimo Daniel/Author.</span></span></figcaption></figure><p>Mount Mabu in north central Mozambique supports the <a href="https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A1CD0A42708C5C2287FB8ABD808F36AC/S0030605313000720a.pdf/discovery_biodiversity_and_conservation_of_mabu_forestthe_largest_mediumaltitude_rainforest_in_southern_africa.pdf;">largest continuous block of rainforest</a> in southern Africa.</p>
<p>The Mabu Forest was originally inhabited by hunters of the Manhawa ethnic group. Its name refers to “beekeeping” in the eManhawa language. </p>
<p>The area contains exceptional levels of biodiversity. But its extremely diverse wildlife was unknown to scientists until 2005. Since then biodiversity surveys have <a href="https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A1CD0A42708C5C2287FB8ABD808F36AC/S0030605313000720a.pdf/discovery_biodiversity_and_conservation_of_mabu_forestthe_largest_mediumaltitude_rainforest_in_southern_africa.pdf;">recorded</a> more than 20 species new to science. These include several species of plants, a new species of bat, a new species of forest viper and two species of chameleons, as well as several new species of butterflies. </p>
<p>In a recent <a href="http://biotaxa.org/Zootaxa/article/view/zootaxa.5258.4.4">paper</a> we set out our findings from the first dung beetle survey on Mount Mabu. Within 15 days of exploration, we collected over 4,000 specimens of dung beetles, classified into 30 species. Of these species, half are new to science, and several are new country records.</p>
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<p>Our findings are exciting because we live in a world where the danger of losing species is more imminent than the chances of describing them. New discoveries provide vital ammunition in the battle against biodiversity loss.</p>
<p>The discovery of new dung beetle species should be seen as a call to national and international authorities to protect Mount Mabu and its rare and distinctive biodiversity, as it remains unprotected by law.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/533697/original/file-20230623-19-7cjr30.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/533697/original/file-20230623-19-7cjr30.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=736&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533697/original/file-20230623-19-7cjr30.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=736&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533697/original/file-20230623-19-7cjr30.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=736&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533697/original/file-20230623-19-7cjr30.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=925&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533697/original/file-20230623-19-7cjr30.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=925&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533697/original/file-20230623-19-7cjr30.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=925&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Onthophagus mabuensis, a new dung beetle species.</span>
<span class="attribution"><span class="source">Werner Strumpher.</span></span>
</figcaption>
</figure>
<h2>Why dung beetles matter</h2>
<p>There are over <a href="https://www.catalogueoflife.org/data/dataset/1027">7,000 dung beetle species worldwide</a>. They are among the most dominant invertebrates in tropical forests and are essential to a well-functioning ecosystem.</p>
<p>Dung beetles feed mainly on the faeces of mammals. During the feeding process, they <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320708001420">perform</a> a series of ecological processes and environmental services. These include: </p>
<ul>
<li><p>dung removal and nutrient recycling in ecosystems, which increases soil fertility </p></li>
<li><p>secondary seed dispersal </p></li>
<li><p>reduction of survival rates of nematodes and flies. </p></li>
</ul>
<p>For example, manure is the breeding ground and incubator for horn flies and face flies, two economically important pests of cattle.</p>
<p>We surveyed dung beetles using pitfall traps. These consisted of a two-litre plastic bucket baited with mammal faeces. The traps were left in the field for 48 hours, and then the catch of each individual trap was labelled and stored separately in alcohol. The collected specimens were processed and identified in the laboratory at the National Museum in Bloemfontein, South Africa.</p>
<h2>Dung beetles must be protected from extinction</h2>
<p>Our research results increase the number of currently valid dung beetle species recorded from Mozambique to 326. We believe this is still way below the country’s actual diversity. </p>
<p>The research uncovered an unknown community of dung beetles; previous dung beetle surveys in the country were centred in southern Mozambique (especially its coastal areas) and Gorongosa National Park. In contrast, other areas of the country are poorly studied.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man stands in front of a log of wood in a forest" src="https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1006&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1006&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534305/original/file-20230627-15-qqkpi7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1006&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author, standing by a sweep net during the expedition. Isildo Nganhane.:</span>
</figcaption>
</figure>
<p>Interestingly, the species composition of dung beetles from Mabu Forest suggests ancient linkages and evidence of a significant influence of dung beetle fauna from mountains to the north (Tanzania) and to the west (Malawi), the Eastern Arc Mountains, and Moreau’s Tanganyika–Nyasa Montane Chain, respectively. </p>
<p>Several dung beetle species collected in our expedition seem to be endemic (restricted to a certain location) to the region of Mabu. Endemic dung beetle species are key to their ecosystems and become a thermometer when it comes to measuring the state of a territory’s health. For that reason, their protection from extinction threats is critical.</p>
<h2>Next steps</h2>
<p>We are living in an era where land use, habitat fragmentation, global climate change, direct over-exploitation and co-extinction of species dependent on other species are all threats to biodiversity. Insects – including dung beetles – are declining globally. Thus, it is critical that biodiversity surveys are expanded to remote and unsampled areas, especially unprotected “sky-island forests”, such as Mount Mabu and others in northern Mozambique. </p>
<p>Our findings and others from previous surveys should be translated into biodiversity conservation policies to change people’s uncaring attitude to biodiversity loss and to avert a sixth mass extinction.</p><img src="https://counter.theconversation.com/content/207145/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gimo Mazembe Daniel receives funding from the National Geographic Society through a research grant (EC-83071R-21).</span></em></p>The forests around Mount Mabu in Mozambique are rich in biodiversity, including some newly discovered species.Gimo Mazembe Daniel, Principal Museum Scientist, National Museum, BloemfonteinLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1917712023-01-23T00:06:24Z2023-01-23T00:06:24ZDon’t kill the curl grubs in your garden – they could be native beetle babies<figure><img src="https://images.theconversation.com/files/501433/original/file-20221215-19-5mtmdl.jpg?ixlib=rb-1.1.0&rect=6%2C165%2C4594%2C3283&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Have you ever been in the garden and found a large, white, C-shaped grub with a distinctive brown head and six legs clustered near the head? </p>
<p>If so, you’ve had an encounter with the larva of a scarab beetle (family: <em>Scarabaeidae</em>) also known as a “curl grub”. </p>
<p>Many gardeners worry these large larvae might damage plants. </p>
<p>So what are curl grubs? And should you be concerned if you discover them in your garden?</p>
<h2>What are curl grubs?</h2>
<p>Curl grubs turn into scarab beetles.</p>
<p>There are more than 30,000 species of scarab beetles worldwide. Australia is home to at least 2,300 of these species, including iridescent Christmas beetles (<a href="https://australian.museum/learn/animals/insects/christmas-beetle/"><em>Anoplognathus</em></a>), spectacularly horned rhinoceros beetles (<em>Dynastinae</em>), and the beautifully patterned flower chafers (<a href="https://keys.lucidcentral.org/keys/v3/aus_museum/flower_chafers/key/Cetoniinae/Media/Html/key.htm"><em>Cetoniinae</em></a>). </p>
<p>While the adults might be the most conspicuous life stage, scarabs spend most of their lives as larvae, living underground or in rotting wood. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bird holds a curl grub in its beak." src="https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499922/original/file-20221209-25133-p3m533.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Curl grubs make an excellent meal for hungry birds.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Scarab larvae can help the environment</h2>
<p>Soil-dwelling scarab larvae can aerate soils and help <a href="https://www-sciencedirect-com.ezproxy.library.sydney.edu.au/science/article/pii/S0006320708001420">disperse</a> seeds. </p>
<p>Species that eat decaying matter help recycle nutrients and keep soils healthy. </p>
<p>Most scarab larvae are large and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4684676/">full of protein and fat</a>. They make an excellent meal for <a href="https://deepgreenpermaculture.com/2018/08/12/organic-control-of-curl-grubs-in-lawn/#:%7E:text=The%20most%20useful%20natural%20enemies,digging%20them%20out%20of%20lawns.">hungry birds</a>.</p>
<p>Besides being important for ecosystems, scarabs also play a role in <a href="https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1093&context=entomologypapers">cultural celebrations</a>.</p>
<p>For example, the ancient Egyptians famously worshipped the sun through the symbol of the ball-rolling dung beetle. </p>
<p>In Australia, colourful Christmas beetles traditionally heralded the arrival of the holiday season. </p>
<p>Sadly, Christmas beetle numbers have <a href="https://australian.museum/learn/animals/insects/christmas-beetles/">declined</a> over the last few decades, likely due to habitat loss. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1332262556560453632"}"></div></p>
<h2>Are the curl grubs in my garden harming my plants?</h2>
<p>Most scarab larvae feed on grass roots, and this can cause damage to plants when there’s a lot of them.</p>
<p>In Australia, the <a href="https://inaturalist.ala.org.au/taxa/517487-Cyclocephala-signaticollis">Argentine lawn scarab</a> and the <a href="https://www.agric.wa.gov.au/olives/african-black-beetle-horticulture">African black beetle</a> are invasive pest species that cause significant damage to pastures and lawns. </p>
<p>Native scarab species can also be pests under the right circumstances.</p>
<p>For example, when Europeans began planting sugar cane (a type of grass) and converting native grasslands to pastures, many native Australian scarab species found an abundant new food source and were subsequently classified as <a href="https://www.mdpi.com/2075-4450/11/1/54/htm">pests</a>.</p>
<p>Unfortunately, we know little about the feeding habits of many native scarab larvae, including those found in gardens.</p>
<p>Some common garden species, like the beautifully patterned <a href="https://australian.museum/learn/animals/insects/fiddler-beetle/">fiddler beetle</a> (<em>Eupoecila australasiae</em>), feed on decaying wood and are unlikely to harm garden plants. </p>
<p>Even species that consume roots are likely not a problem under normal conditions. </p>
<p>Plants are surprisingly <a href="https://link.springer.com/article/10.1007/s00442-011-2210-y">resilient</a>, and most can handle losing a small number of their roots to beetle larvae. Even while damaging plants, curl grubs may be helping keep soil healthy by providing aeration and nutrient mixing.</p>
<hr>
<p>
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<hr>
<figure class="align-center ">
<img alt="manicured grass and garden" src="https://images.theconversation.com/files/502386/original/file-20221221-18-bs2txf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/502386/original/file-20221221-18-bs2txf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/502386/original/file-20221221-18-bs2txf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/502386/original/file-20221221-18-bs2txf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/502386/original/file-20221221-18-bs2txf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/502386/original/file-20221221-18-bs2txf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/502386/original/file-20221221-18-bs2txf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Most plants can handle losing a small number of their roots to beetle larvae.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>How do I know if I have ‘good’ or ‘bad’ beetle larvae in my garden?</h2>
<p>Unfortunately, identifying scarab larvae species is challenging. Many of the features we use to tell groups apart are difficult to see without magnification.
While there are identification guides for scarabs larvae found in <a href="https://cesaraustralia.com/pestfacts/scarabs-and-cockchafers-identification/">pastures</a>, there are currently no such identification resources for the scarabs found in household gardens. </p>
<p>Since identification may not be possible, the best guide to whether or not scarab larvae are a problem in your garden is the health of your plants. Plants with damaged roots may wilt or turn yellow. </p>
<p>Since most root-feeding scarabs prefer grass roots, lawn turf is most at risk and damage is usually caused by exotic scarab species.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501443/original/file-20221215-14-rbzlz0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Unfortunately, identifying scarab larvae species is challenging.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What should I do if I find curl grubs in my garden?</h2>
<p>Seeing suspiciously plump curl grubs amongst the roots of prized garden plants can be alarming, but please don’t automatically reach for insecticides. </p>
<p>The chemicals used to control curl grubs will harm all scarab larvae, regardless of whether or not they are pests. </p>
<p>Many of the most common treatments for curl grubs contain chemicals called “anthranilic diamides”, which are also <a href="http://npic.orst.edu/factsheets/chlorantraniliprole.html#howwork">toxic</a> to butterflies, moths and aquatic invertebrates.</p>
<p>And by disrupting soil ecosystems, using insecticides might do more harm than good and could kill harmless native beetle larvae.</p>
<hr>
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Read more:
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<hr>
<p>So what to do instead? </p>
<p>Larvae found in decaying wood or mulch are wood feeders and are useful composters; they will not harm your plants and should be left where they are. </p>
<p>Larvae found in compost bins are helping to break down wastes and should also be left alone.</p>
<p>If you find larvae in your garden soil, use your plant’s health as a guide. If your plants appear otherwise healthy, consider simply leaving curl grubs where they are. Scarab larvae are part of the soil ecosystem and are unlikely to do damage if they are not present in high numbers. </p>
<p>If your plants appear yellow or wilted and you’ve ruled out other causes, such as under-watering or nutrient deficiencies, consider feeding grubs to the birds or squishing them. It’s not nice, but it’s better than insecticides.</p>
<p>Lawns are particularly susceptible to attack by the larvae of non-native scarabs.
Consider replacing lawns with <a href="https://www.sgaonline.org.au/lawn-alternatives/">native</a> ground covers. This increases biodiversity and lowers the chances of damage from non-native scarab larvae.</p>
<p>Scarab beetles are beautiful and fascinating insects that help keep our soils healthy and our wildlife well fed.</p><img src="https://counter.theconversation.com/content/191771/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya Latty volunteers for and is affiliated with Invertebrates Australia, a not for profit conservation organisation. She is also affiliated with the Australian Entomological Society and the Australasian Society for the Study of Animal Behaviour. She receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Chris Reid has received funding from a federal Australian Biological Resources Study grant and the NSW Department of Education.</span></em></p>Many gardeners worry these large larvae might damage plants. But before you squish them, read this.Tanya Latty, Associate professor, University of SydneyChris Reid, Adjunct Associate Professor in Zoology, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1919832022-11-09T13:39:42Z2022-11-09T13:39:42ZDung beetle mothers protect their offspring from a warming world by digging deeper<figure><img src="https://images.theconversation.com/files/493591/original/file-20221104-11-c5yawz.jpg?ixlib=rb-1.1.0&rect=15%2C15%2C5028%2C3362&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A road sign in Bursa, Turkey, warns drivers of the presence of dung beetles, stating 'Attention! It may come out, don't crush it please!' </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/protection-measures-are-taken-for-the-dung-beetles-which-news-photo/1241220698">Ugur Ulu/Anadolu Agency via Getty Images</a></span></figcaption></figure><p>If the TV series “<a href="https://www.discovery.com/shows/dirty-jobs">Dirty Jobs</a>” covered animals as well as humans, it would probably start with <a href="https://www.britannica.com/animal/dung-beetle">dung beetles</a>. These hardworking critters are among the insect world’s most important recyclers. They eat and bury manure from many other species, recycling nutrients and improving soil as they go. </p>
<p>Dung beetles are found on <a href="https://animals.sandiegozoo.org/animals/dung-beetle">every continent except Antarctica</a>, in forests, grasslands, prairies and deserts. And now, like many other species, they are coping with the effects of climate change.</p>
<p>I am an <a href="https://scholar.google.com/citations?hl=en&user=XBb0FNQAAAAJ&view_op=list_works&sortby=pubdate">ecologist</a> who has spent nearly 20 years studying dung beetles. My research spans tropical and temperate ecosystems, and focuses on how these beneficial animals respond to temperature changes. </p>
<p>Insects don’t use internally generated heat to maintain their body temperature. Adults can take actions such as moving to warmer or colder areas. However, earlier life stages such as larvae are often less mobile, so they can be strongly affected by changing temperatures. </p>
<p>But dung beetles appear to have a defense: I have found that adult dung beetles modify their nesting behaviors in response to temperature changes by burying their brood balls deeper in the soil, which protects their developing offspring.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/I1RHmSm36aE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Without dung beetles, the world would be messier and smellier.</span></figcaption>
</figure>
<h2>Champion recyclers</h2>
<p>It’s easy to joke about these busy insects, but by collecting and burying manure, dung beetles provide many ecological benefits. They recycle nutrients, aerate soil, <a href="https://doi.org/10.1038/srep18140">lessen greenhouse gas emissions from cattle farming</a> and reduce pest and parasite populations that harm livestock. </p>
<p>Dung beetles are also important secondary seed dispersers. Dung from other animals, such as bears and monkeys, contains seeds that the beetles bury underground. This protects the seeds from being eaten, makes them more likely to germinate and improves plant growth.</p>
<p>There are roughly <a href="https://www.smithsonianmag.com/science-nature/the-humble-dung-beetle-180967781/">6,000 species of dung beetles around the world</a>. Most feed exclusively on dung, though some will feed on dead animals, decaying fruit and fungi. </p>
<p>Some species use stars and even <a href="https://doi.org/10.1016/j.cub.2012.12.034">the Milky Way to navigate along straight paths</a>. One species, the bull-headed dung beetle (<em>Onthophagus taurus</em>), is the <a href="https://www.science.org/content/article/scienceshot-worlds-strongest-insect">world’s strongest insect</a>, able to pull over 1,000 times its own body weight. </p>
<p>That strength comes in handy for dung beetles’ best-known behavior: gathering manure. </p>
<h2>Rolling and tunneling</h2>
<p>Most popular images of dung beetles show them collecting manure and rolling it into balls to spirit away. In fact, some species are rollers and others are <a href="https://kids.frontiersin.org/articles/10.3389/frym.2021.583675">tunnelers</a> that dig into the ground under a dung pat, bring dung down into the tunnel and pack it into a clump or sphere, called a brood ball. The female then lays an egg in each brood ball and backfills the tunnel with soil. Rollers do the same once they get their dung ball safely away from the competition.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two human fingers grasp a pingpong ball-size dung ball with a fingernail-size egg embedded in the surface" src="https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/493590/original/file-20221104-14-7dvawf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An egg is visible in the center of a brood ball from a female rainbow scarab beetle (<em>Phanaeus vindex</em>).</span>
<span class="attribution"><span class="source">Kimberly Sheldon</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>When the egg hatches, the larva feeds on dung from the brood ball, <a href="https://www.merriam-webster.com/dictionary/pupate">pupates</a> and emerges as an adult. It thus goes through <a href="https://nhmlac.org/marvelous-metamorphosis#">complete metamorphosis</a> – from egg to larva to pupa to adult – inside the brood ball. </p>
<h2>Warmer temperatures produce smaller beetles</h2>
<p>Dung beetle parents don’t provide care for their offspring, but their nesting behaviors affect the next generation. If a female places a brood ball deeper underground, the larva in the brood ball experiences cooler, less variable temperatures than it would nearer the surface. </p>
<p>This matters because temperatures during development can affect offspring survival and other traits, such as adult body size. If temperatures are too hot, offspring perish. Below that point, warmer, more variable temperatures lead to <a href="https://doi.org/10.1016/j.jinsphys.2021.104215">smaller-bodied beetles</a>, which can affect the next generation’s reproductive success. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1168955226063351810"}"></div></p>
<p>Smaller males can’t compete as well as larger males, and smaller females have lower reproductive output than larger females. In addition, smaller-bodied beetles <a href="https://doi.org/10.1111/1365-2656.13798">remove less dung</a>, so they provide fewer benefits to humans and ecosystems, such as nutrient cycling.</p>
<h2>Beetles in the greenhouse</h2>
<p>Climate change is <a href="https://doi.org/10.1038/nclimate2378">making temperatures more variable</a> in many parts of the world. This means that insects and other species have to handle not just warmer temperatures, but greater changes in temperature day to day. </p>
<p>To examine how adult dung beetles responded to the types of temperature shifts associated with climate change, I designed cone-shaped mini-greenhouses that would fit over 7-gallon buckets buried in the ground to their brims. Will Kirkpatrick, an undergraduate student in my lab, led the field trials. </p>
<p>We randomly placed a fertilized female rainbow scarab, <em><a href="https://en.wikipedia.org/wiki/Phanaeus_vindex">Phanaeus vindex</a></em>, in each greenhouse bucket and in the same number of uncovered buckets to serve as controls. Using temperature data loggers placed at four depths in the buckets, we verified that soil temperatures in “greenhouse” buckets were warmer and more variable than soil temperatures in uncovered buckets.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large round beetle with red, green and gold shading" src="https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/493588/original/file-20221104-24-pcsfqh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A male rainbow scarab dung beetle (<em>Phanaeus vindex</em>).</span>
<span class="attribution"><span class="source">Dan Mele</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>We gave the beetles fresh cow dung every other day for 10 days and allowed them to make brood balls. Then we carefully dug through the buckets and recorded the number, depth and size of brood balls in each bucket. </p>
<h2>Digging deeper</h2>
<p>We found that beetle mothers in greenhouse environments created more brood balls overall, that these brood balls were smaller, and that these females <a href="https://doi.org/10.1098/rsbl.2022.0109">buried their brood balls deeper in the soil</a> than beetle mothers in control buckets. Brood balls in the greenhouses still ended up in areas that were slightly warmer than those in the control buckets – but not nearly as warm as if the beetle mothers had not altered their nesting behaviors. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cone-shaped cover placed in a patch of dirt" src="https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=563&fit=crop&dpr=1 600w, https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=563&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=563&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=708&fit=crop&dpr=1 754w, https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=708&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/493912/original/file-20221107-23-ksn05u.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=708&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A dung beetle greenhouse placed over a buried bucket of soil in the author’s field trial.</span>
<span class="attribution"><span class="source">Kimberly Sheldon</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>However, by digging deeper, the adults fully compensated for temperature variation. There was no difference in the temperature variation experienced by brood balls in greenhouse buckets and control buckets. This reflects the fact that soil temperatures <a href="https://www.chicagotribune.com/news/ct-xpm-2011-09-24-ct-wea-0924-asktom-20110924-story.html">become increasingly stable with depth</a> as the soil becomes more and more insulated from the changing air temperatures above it. </p>
<p>Our findings also hint at a possible trade-off between burial depth and brood ball size. Beetle mothers that dug deeper protected their offspring from temperature changes but provided less dung in their brood balls. This meant less nutrition for developing offspring. </p>
<p>Climate change could still affect adult dung beetles in ways we did not test, with consequences for the next generation. In future work, we plan to place brood balls of <em>Phanaeus vindex</em> and other species of dung beetles back into the greenhouse and control buckets at the depths at which they were buried so that we can see how the beetle offspring develop and survive. </p>
<p>So far, though, my colleagues and are encouraged to find that these industrious beetles can alter their behavior in ways that may help them survive in a changing world.</p><img src="https://counter.theconversation.com/content/191983/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kimberly S. Sheldon receives funding from the US National Science Foundation. </span></em></p>Everyone is feeling the heat these days – even species that develop underground.Kimberly S. Sheldon, Associate Professor of Ecology and Evolutionary Biology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1668362021-09-06T10:27:18Z2021-09-06T10:27:18ZDung beetle experiment suggests carbon dioxide is bad for insects too<figure><img src="https://images.theconversation.com/files/419062/original/file-20210902-15-1gj4xku.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dung beetles</span> <span class="attribution"><span class="source">Marcus Byrne</span></span></figcaption></figure><p>Insects are a vital cog in the great wheel of nature. They outnumber humans a billion to one and make up more than <a href="https://youtu.be/2ivZ6GSaK1M">75% of animals on earth</a>. It’s no wonder that they are the primary providers of essential ecosystem services such as pollination and waste recycling. </p>
<p>But, by many accounts, their numbers are falling in what has been called an “<a href="https://theconversation.com/weaving-insect-wildlife-back-into-the-tapestry-of-life-132535">insect apocalypse</a>”. It’s not clear yet what mechanism – if there is only one – is responsible for reports of plummeting insect numbers. <a href="https://theconversation.com/skyglow-forces-dung-beetles-in-the-city-to-abandon-the-milky-way-as-their-compass-165110">Light pollution</a>, insecticide use, habitat loss and changing weather are all implicated, but these effects are patchy in terms of their occurrence across the planet. </p>
<p>Elevated atmospheric carbon dioxide (eCO₂), however, <a href="https://public.wmo.int/en/media/press-release/carbon-dioxide-levels-continue-record-levels-despite-covid-19-lockdown">is global</a>. It permeates every inch of our biosphere, including the soil. We wanted to know how that might be affecting insects, given that more than half of the known species of insects spend a substantial portion of their life cycle underground. This is where they are potentially under the influence of eCO₂. </p>
<p>For air breathing animals, increases in atmospheric CO₂ are trivial. For example, CO₂ levels in human lungs are <a href="https://ethanolrfa.org/wp-content/uploads/2016/02/Module-2-Handout-How-Inhaled-CO2-Affects-the-Body-%E2%80%93-Fact-Sheet.pdf">100 times greater</a> than those in the air, and can be rapidly returned to atmospheric levels by hyperventilating, with no ill effects. Soil microbes, on the other hand, increase in biomass under eCO₂. This allows them to consume more organic material in the soil and compete with other organisms for oxygen. </p>
<p>Our latest research used dung beetles as a model “<a href="https://idioms.thefreedictionary.com/canary+in+a+coal+mine">canary in the mine</a>” to test the effect of eCO₂ on soil-dwelling insects. <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15804">We found</a> that beetles exposed to eCO₂ emerged later and smaller, and had a reduced chance of making it to adulthood. This additional effect of eCO₂ on the biosphere adds to the growing list of problems caused by eCO₂ released from unfettered human activity.</p>
<h2>Creatures of the soil</h2>
<p>Dung beetles are creatures of the soil. There, they bury dung and recycle it by feeding on it, both as larvae and as adults. </p>
<p>As a representative of the numerous insect species living in the soil, dung beetles are an ideal organism on which to test the effects of eCO₂. We know that some dung dwelling beetles can tolerate extreme levels of CO₂, accompanied by low levels of O₂. These exposures are only for short periods (minutes to hours), such as those experienced when tunnelling through oxygen-depleted dung. </p>
<p>However, immature dung beetles developing inside their brood balls, buried deep in the soil, will be exposed to eCO₂ for weeks or even months.</p>
<p>Dung beetle larvae develop <a href="https://theconversation.com/five-things-dung-beetles-do-with-a-piece-of-poo-47367">inside a ball of dung</a>, where they eat the inner walls, digest the dung and defecate the remains back onto the wall, to be eaten again. Although scientists have some understanding of how adult dung beetles turn this low nutrient food source into a <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/phen.12336">hearty meal</a>, it’s not clear how their larvae subsist on such unsavoury leftovers. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Beetle standing on its front legs, with its back legs on a ball of dung" src="https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/419065/original/file-20210902-15-my5fab.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dung beetle rolling a food ball.</span>
<span class="attribution"><span class="source">Marcus Byrne</span></span>
</figcaption>
</figure>
<p>Unlike the adults, they consume all the big bits with the help of strong jaws, which the adults lack. Microbes, both within their gut and on the inner wall of the ball, probably assist in the breakdown of tough plant remains containing what would be otherwise undigestible lignin (the compound that makes plants woody) and cellulose. Microbes may even fix valuable nitrogen from the atmosphere, which would contribute to <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/mec.13901">proteins in the growing larvae</a>.</p>
<p>Elevated CO₂ could be interfering with this symbiotic relationship in the dung ball, either by promoting the growth of unwanted microorganisms which consume what the dung beetle larva should be eating, or by changing the physical conditions inside the larval ball – or both. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/yWt_8meQ20k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Humans add more than <a href="https://www.statista.com/statistics/276629/global-co2-emissions/">35 billion metric tons of CO₂</a> to the atmosphere every year. This CO₂ is <a href="https://theconversation.com/deep-but-not-dead-how-tropical-subsoil-microbes-could-affect-the-carbon-cycle-35295">stimulating microbial activity in the soil</a>, which we think leads to a contest for food and oxygen with developing insects, while altering their underground habitat. </p>
<h2>Experiments</h2>
<p>In <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15804">our study</a> we reared dung beetles in walk-in chambers, where we could set all the climatic parameters, including levels of CO₂. This allowed us to go back into the past, before industry had changed our atmosphere, and to project into the future humans are creating if we continue our current carbon emissions. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two beetles" src="https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/418910/original/file-20210901-21-ug8kfq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The dung beetles tested under eCO₂, <em>Euoniticellus intermedius</em>. Female (left), male (right).</span>
<span class="attribution"><span class="source">Marcus Byrne</span></span>
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</figure>
<p>We used pre-industrial <a href="https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide">levels</a> of CO₂ (250 parts per million, or ppm), current levels (400 ppm), and levels predicted by 2050 (600 ppm), and 2070 (800 ppm) in our experiments. Even the current eCO₂ reduced beetle size and slowed their development compared to their “pre-industrial” relatives. It appears therefore that the soil insects are already taking strain. </p>
<p>The balls in which the beetles were growing was changed by the atmosphere in the chambers. We noted an increase in brood ball pH (increased alkalinity), associated with eCO₂, along with 10 times eCO₂ in the ball in our most extreme treatment. </p>
<p>Many insects developing inside wet burrows or plant galls can tolerate 100 times greater CO₂ levels. This leads us to suspect microorganisms in the soil or the dung as the agents of change.</p>
<p>We now intend to turn our attention to the microbes in the soil and dung to pin down the precise cause of this effect. But whatever we discover in the future, clearly the best policy now is for humans to curtail our CO₂ output <a href="https://theconversation.com/infantile-climate-discussion-rages-while-the-atmosphere-chokes-557">sooner rather than later</a>. This will safeguard not only ourselves, but the little things that run our world, too.</p><img src="https://counter.theconversation.com/content/166836/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcus Byrne receives funding from The National Research Foundation, South Africa.</span></em></p><p class="fine-print"><em><span>Claudia Tocco does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Beetles exposed to elevated carbon dioxide emerged later and smaller and had a reduced chance of making it to adulthood.Marcus Byrne, Professor of Zoology and Entomology, University of the WitwatersrandClaudia Tocco, Postdoctoral fellow, Lund UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1651102021-07-29T15:12:38Z2021-07-29T15:12:38ZSkyglow forces dung beetles in the city to abandon the Milky Way as their compass<figure><img src="https://images.theconversation.com/files/413110/original/file-20210726-17-7nasuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A dung beetle climbs atop its precious ball to orient itself using the night skies.</span> <span class="attribution"><span class="source">Chris Collingridge</span></span></figcaption></figure><p>Globally, nights are <a href="https://www.nationalgeographic.com/science/article/nights-are-getting-brighter-earth-paying-the-price-light-pollution-dark-skies">becoming ever brighter</a>. Increasing urbanisation and the installation of new streetlights, security floodlights and outdoor ornamental lighting all contribute to growing light pollution. </p>
<p>This light floods directly into the eyes of animals that are active at night and also into the skies. There a proportion of it is redirected back downwards towards an earthbound observer. This is known as “<a href="https://www.lrc.rpi.edu/programs/nlpip/lightinganswers/lightpollution/skyglow.asp">skyglow</a>”, an omnipresent sheet of light across the night sky in and around cities that can block all but the very brightest stars from view.</p>
<p>We wanted to understand how this change in night brightness would affect animals that rely on the sky as their compass. Would their sensitive eyes be blinded by bright city lights? Would the disappearance of stars from the night sky cause them to lose their way? So we used the well-studied “sky compass” of the nocturnal dung beetle, <em>Scarabaeus satyrus</em>, to <a href="https://doi.org/10.1016/j.cub.2021.06.038">compare orientation</a> under pristine and light polluted skies.</p>
<p><a href="https://doi.org/10.1016/j.cub.2021.06.038">Our study</a> compared the dung-rolling performance of beetles in a rural part of Limpopo province with that of beetles at the University of Witwatersrand in inner city Johannesburg, both in South Africa. Our findings confirm that beetles exposed to light pollution – both directly through the glare of bright artificial lights and indirectly via skyglow that obscures the stars – are forced to change strategy. They abandon their sky compass and rely instead on earthbound artificial lights as beacons.</p>
<p>This change in strategy comes at a cost. </p>
<h2>Light pollution</h2>
<p>These beetles, found across southern Africa, collect dung from various animals, fashioning it into a ball. By rolling this ball away from the dung pile they need not share it with other insects. But even when rolling their ball they are not safe from competition. Their best option is to leave the dung pile as quickly as possible, by using their internal compass to travel in a straight line away from it.</p>
<p>Before rolling the dung away to an area where it can safely dig into the ground, rest and feed, each beetle climbs on top of its ball and performs a brief pirouette termed the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3261170/">orientation “dance”</a>. It scans the scene for features it can use to hold its course. Since it starts each night in unfamiliar territory, the most reliable references are those in the sky that stay stable while the beetle maintains the same heading. On starlit nights, the Milky Way acts as these beetles’ primary reference. </p>
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Read more:
<a href="https://theconversation.com/theres-still-so-much-we-dont-know-about-the-star-gazing-beetle-with-a-tiny-brain-117709">There's still so much we don't know about the star-gazing beetle with a tiny brain</a>
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<p>When the beetles relied on artificial lights to navigate, they all rolled towards them – numerous beetles rolling in the same direction. Under natural conditions, they almost always roll in different directions. Rolling towards artificial lights makes them more likely to encounter one another and fights may break out as the beetles try to steal each other’s dung balls. </p>
<p>Artificial light is also more likely to guide beetles into the concrete and asphalt regions of their immediate environment, where they may find themselves unable to dig into the ground and bury their ball. </p>
<p>It’s not just dung beetles that could be affected by light pollution in this way. Even species that can rely on other compass references may still suffer from the loss of the stars. <a href="https://journals.biologists.com/jeb/article/220/9/1578/19610/Compass-cues-used-by-a-nocturnal-bull-ant-Myrmecia">Nocturnal ants</a> use landmarks for outbound journeys, but need their sky compass when returning home. Migratory birds have a magnetic compass, with which they check latitude and magnetic North, but use their sky compass to calibrate their magnetic compass to geographic North. </p>
<p>In the worst case, animals that need the stars to find their home or breeding site may never make it. But even with their backup systems, starless skies may cause them to gradually deviate off course, wasting energy and risking predator encounters. </p>
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Read more:
<a href="https://theconversation.com/monarch-butterflies-navigate-using-magnetism-28440">Monarch butterflies navigate using magnetism</a>
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<h2>Country beetle and city beetle</h2>
<p>We collected two sets of ten beetles at the same site, then transported them to our chosen locations.</p>
<p>When the skies were clear at both locations, beetles rolled their ball to the edge of a circular arena. Each beetle could be collected with its ball at the arena’s edge and replaced at the centre ten times in row, without losing its focus. This allowed us to record ten exit bearings for each beetle, to measure the accuracy of their compass under both pristine and light-polluted skies.</p>
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<a href="https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two people, both in dark clothing, are standing alongside two cameras. One is squatting, one is standing. The sky is full of stars, and the people are gazing at a small object on a lit-up pink circle on the ground" src="https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/413118/original/file-20210726-13-hz2kca.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Dr James Foster and Prof. Marie Dacke performing orientation experiments at a dark-sky site in rural Limpopo.</span>
<span class="attribution"><span class="source">Chris Collingridge</span></span>
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</figure>
<p>We also recorded the experimental conditions using a camera with a fisheye lens pointed up towards the sky. By post-processing these images, we could estimate what compass information should be available to a beetle when it performs its orientation dance. These images revealed that Johannesburg skies were between ten and 100 times brighter than those in rural Limpopo. The Milky Way and most other star patterns were almost completely obscured by skyglow in Johannesburg.</p>
<p>In spite of this dramatic loss of sky compass references, the beetles in Johannesburg performed at least as well as those in rural Limpopo. They maintained the same heading direction across sequential trials with remarkable accuracy. But on closer inspection it appeared that they were using different strategies to hold their course. </p>
<p>Beetles under pristine skies were relying on the Milky Way, as evidenced by a slight tendency to choose headings towards its brightest region. Those under light-polluted skies rolled towards brightly lit buildings. </p>
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Read more:
<a href="https://theconversation.com/the-moon-and-stars-are-a-compass-for-nocturnal-animals-but-light-pollution-is-leading-them-astray-142301">The Moon and stars are a compass for nocturnal animals – but light pollution is leading them astray</a>
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<p>In our follow-up experiments, the same set of beetles changed their behaviour when exposed to a single floodlight under pristine skies. They rolled towards the floodlight when it was switched on but dispersed away from one another when the light was switched off. </p>
<p>We also confirmed our worst fears about light-polluted skies. When bright lights were blocked from view, beetles in Johannesburg became completely disoriented. The light-polluted sky was of no use to them. Those viewing pristine skies remained comparatively better oriented. </p>
<h2>Solutions exist</h2>
<p>There is a remarkably simple solution to reducing animals’ experience of direct and indirect light pollution: turning off unnecessary lights at night. Where lights cannot be turned off, they can be shielded so that they do not shed light into the surrounding environment and sky.</p>
<p>The International Dark-Skies Association has certified more than 130 “<a href="http://www.darksky.org/our-work/conservation/idsp">International Dark Sky Places</a>”, where artificial lighting has been adjusted to reduce skyglow and light trespass. However, nearly all are in developed countries in the northern hemisphere. </p>
<p>This gap should be addressed. Less-developed regions are often both species-rich and, currently, less light-polluted, presenting an opportunity to invest in lighting solutions before animals there are seriously affected.</p><img src="https://counter.theconversation.com/content/165110/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Foster received funding from the Wallenberg Foundation, the Swedish Science Foundation (VR 2014-4623), the European Research Council (817535-UltimateCOMPASS), National Geographic (NGS-56504R-19), and travel grants to from the Royal Physiographic Society of Lund and Royal Swedish Academy of Sciences to support this work. He is currently supported by the German Science Foundation (DFG).</span></em></p>On starlit nights, the Milky Way acts as these beetles’ primary reference. But light pollution gets in the way.James Foster, Research Fellow, Julius Maximilian University of WürzburgLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1627102021-06-15T17:10:49Z2021-06-15T17:10:49ZCounting mammals, birds and dung beetles could be vital for saving the Amazon<p>The Amazon rainforest holds around <a href="https://rainforests.mongabay.com/amazon/">50% of all remaining rainforests</a> on the planet, while hosting more than <a href="https://conbio.onlinelibrary.wiley.com/doi/abs/10.1111/j.1523-1739.2005.00705.x">400 species of mammal, 1700 species of bird</a> and an unknown number of insect species numbering in the millions. It is also vital for maintaining life on Earth. Amazonian forests mitigate climate change by <a href="https://iopscience.iop.org/article/10.1088/1748-9326/aabc61">soaking up</a> around 560 million tons of carbon per year and support agriculture by <a href="https://www.nature.com/articles/s41558-018-0177-y">stimulating rainfall</a> at both local and continental scales.</p>
<p>Amazonian forests and their immense biodiversity are disappearing at an alarming rate, which has been linked to <a href="https://www.sciencedirect.com/science/article/abs/pii/S0264837720325333?dgcid=author">increased livestock production and exports</a> in Brazil. Those forests that still stand are under continual threat from destructive human-caused activities including <a href="https://www.sciencedirect.com/science/article/pii/S0006320717311709">logging</a>, <a href="https://theconversation.com/amazon-fires-explained-what-are-they-why-are-they-so-damaging-and-how-can-we-stop-them-122340">fires</a> and <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rstb.2019.0116">climatic disturbances</a> such as extreme droughts and floods.</p>
<p>To date, research on climate and biodiversity issues in tropical forests are mostly based on short-term investigations that focus on plant and carbon responses. As a result, most of us are aware of the importance of forest trees for climate regulation. For example, our research in the Amazon found high <a href="https://royalsocietypublishing.org/doi/10.1098/rstb.2018.0043">tree mortality and carbon loss</a> still occurring many years after drought-induced forest fires.</p>
<p>Yet to fully understand the resilience of tropical forests we also need long-term research that considers the impacts of climate disturbances on fauna, and evaluates their role in post-disturbance forest recovery.</p>
<p>Animals are key to understanding the resilience of tropical forests. Birds, for example, are seed dispersers and their loss can drive <a href="https://science.sciencemag.org/content/340/6136/1086">reductions in seed size</a> of tropical palm trees, making <a href="https://theconversation.com/without-birds-tropical-forests-wont-bounce-back-from-deforestation-68094">vegetation recovery unlikely or impossible</a>. Similarly, large fruit-eating animals, including howler and spider monkeys, ingest and disperse seeds, so any reduction in their abundance can alter the pathways of <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/ele.12102">forest regeneration</a>.</p>
<p>Even though it has become a commonplace observation that creepy crawlies are <a href="https://www.jstor.org/stable/2386020?seq=1">the little things that run the world</a>, our understanding of the role of invertebrates is in its infancy. Within tropical forests, <a href="https://science.sciencemag.org/content/363/6423/174">termites</a> have been shown to enhance drought resilience, while dung beetles can help rainforests regrow.</p>
<h2>Counting fauna</h2>
<p>While we know that fauna and their functions are important for understanding forest recovery, it’s not easy to measure them.</p>
<p>Though trees are very diverse and can be hard to identify, they are nonetheless relatively straightforward to monitor; they don’t move, can be measured year to year, their structural and chemical features can be sampled and assessed, and their physiological responses can be evaluated in the ground. Of course, all of this requires hard work in the field, but there is no doubt that our understanding of tropical forest vegetation’s <a href="https://science.sciencemag.org/content/368/6493/869">sensitivity to climate</a> has been enabled by its immobile nature.</p>
<p>Animals, on the other hand, are much harder. A single hectare of forest can hold up to 160 species of bird alone, and 100 hectares – an area considerably smaller than Hyde Park in London – can contain <a href="https://esajournals.onlinelibrary.wiley.com/doi/abs/10.2307/1943045">up to 245</a>.</p>
<p>Listen to the <a href="https://macaulaylibrary.org/asset/336869191">following avian chorus</a>. How many species can you hear? A specialist could name 12 species in this simple 32-second snippet, but there are very few people in the world with that ability.</p>
<iframe width="100%" height="360" src="https://macaulaylibrary.org/asset/336869191/embed/640" frameborder="0" allowfullscreen="" style="width:640px;"></iframe>
<p>It is hard enough to make a snapshot assessment of what species are present, let alone assess changes over time – the species that call at any given moment vary through the year, from day to day, throughout the day, and even with lunar cycles.</p>
<p>What about invertebrates? Most species have not yet even been formally classified by taxonomists, and identification relies on a few specialists with access to comprehensive reference collections. They also vary in abundance <a href="https://link.springer.com/article/10.1007/s00442-020-04831-5">throughout the year</a>, <a href="https://www.sciencedirect.com/science/article/abs/pii/S1470160X18305958">from year to year</a>, in response to variations in climate, <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/btp.12756">extreme climatic events</a>, and other factors that are poorly understood.</p>
<h2>What are some of the solutions?</h2>
<p>Fortunately, some solutions exist to monitor forest fauna. Our project, Bioclimate, is adopting both novel and well-established methods to evaluate how large and small animals can help tropical forests bounce back after disturbances like logging, droughts or fires.</p>
<p>For insects, we can use some groups that indicate the forest health. Dung beetles are ideal as they perform <a href="https://www.sciencedirect.com/science/article/pii/S0006320708001420?via%3Dihub">many activities</a> that benefit forests, are easy and cheap to collect, and can <a href="https://www.biorxiv.org/content/10.1101/2021.02.10.430568v1.full">represent the impacts of disturbances</a> for other animals whose faeces they use for feeding and nesting.</p>
<p>We can analyse the DNA from the faeces dung beetles eat to assess the mammals that are present in Amazonian forests. This knowledge is useful in helping us understand how environmental change affects <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2018.2002">dung beetle-mammal relationships</a>.</p>
<p>For birds, using <a href="https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/2041-210X.13521">autonomous audio recorders</a> allows us to constantly monitor populations and help us understand the dynamics of occupancy in different locations – many forest birds are rare with large territories and can easily be missed in one-off visits.</p>
<p>Having numerous audio recorders running at the same time for long periods makes it possible to multiply the number of sites and animals monitored at the same time. To overcome humans’ difficulty in hearing multiple bird calls, we are also developing <a href="https://openresearchsoftware.metajnl.com/articles/10.5334/jors.154/">machine-learning algorithms</a> to help identify the vocalisations of certain species.</p>
<p>If we want to secure the future of the Amazon, we need to move from research focused on short-term and species-specific responses toward analysing precisely how the many different insects, birds and other animals that live there contribute to the health of the forest.</p>
<p>Bioclimate will integrate long-term datasets and this new experimental data to advance our understanding of the relationship between biodiversity and climate in tropical forests. With this knowledge, we aim to provide a better picture of how the Amazon responds to human activities, and how we might preserve it in future.</p>
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<img alt="" src="https://images.theconversation.com/files/213123/original/file-20180404-189798-1dksj9k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/213123/original/file-20180404-189798-1dksj9k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=129&fit=crop&dpr=1 600w, https://images.theconversation.com/files/213123/original/file-20180404-189798-1dksj9k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=129&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/213123/original/file-20180404-189798-1dksj9k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=129&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/213123/original/file-20180404-189798-1dksj9k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=163&fit=crop&dpr=1 754w, https://images.theconversation.com/files/213123/original/file-20180404-189798-1dksj9k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=163&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/213123/original/file-20180404-189798-1dksj9k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=163&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>The research project “Bioclimate” is supported by the <a href="https://group.bnpparibas/en/group/bnp-paribas-foundation">BNP Paribas Foundation</a> as part of the <a href="https://group.bnpparibas/en/hottopics/climate-biodiversity-initiative">Climate and Biodiversity Initiative</a> program</em>.</p><img src="https://counter.theconversation.com/content/162710/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Filipe França has received research funding from the BNP Paribas Foundation (Climate and Biodiversity) and the Brazilian National Council for Scientific and Technological Development (CNPq). He is the co-coordinator of Synergize and PELD-RAS projects and, currently, a Visiting Academic at the University of Canterbury, New Zealand.</span></em></p><p class="fine-print"><em><span>Alexander C. Lees has received research funding from the BNP Paribas Foundation (Climate and Biodiversity) and the National Environment Research Council (NERC).</span></em></p><p class="fine-print"><em><span>Jos Barlow has received research funding from the BNP Paribas Foundation (Climate and Biodiversity) and the National Environment Research Council (NERC).</span></em></p><p class="fine-print"><em><span>Yves Bas has received research funding from the BNP Paribas Foundation (Climate and Biodiversity).</span></em></p>We know surprisingly little about the millions of animals, plants and birds that live in the Amazon – here’s how we can understand them better.Filipe França, Senior research associate, Lancaster UniversityAlexander C. Lees, Senior Lecturer in Conservation Biology, Manchester Metropolitan UniversityJos Barlow, Professor of Conservation Science, Lancaster UniversityYves Bas, Post-doctorant, Muséum national d’histoire naturelle (MNHN)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1019752020-03-11T02:50:48Z2020-03-11T02:50:48ZHow the humble dung beetle engineers better ecosystems in Australia<p>Dung beetles play an important role helping clear up all the dung left by other animals in an environment.</p>
<p>In Australia there are approximately 475 native species of dung beetle.</p>
<p>But there’s a problem. Most of them are adapted to deal with marsupial dung. When British colonisers brought livestock down under, they introduced an entirely new type of dung that the native dung beetles were ill-equipped to handle.</p>
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Read more:
<a href="https://theconversation.com/french-beetles-flown-in-to-clean-up-australias-cattle-dung-30367">French beetles flown in to clean up Australia's cattle dung</a>
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</p>
<hr>
<h2>Not touching <em>that</em> dung</h2>
<p>Cattle dung is wet and bulky. It is very unlike marsupial dung – which is typically small, dry pellets – and so the native dung beetles largely left it alone. As a result, large deposits of cattle dung accumulated in the Australian agricultural landscape.</p>
<p>Besides fouling the land, the dung was an excellent breeding site for bush flies and other nuisance insects, as well as internal parasites that plague the digestive tracts of livestock.</p>
<p>So CSIRO embarked on an ambitious plan to introduce into Australia many dung beetles that were adapted to livestock dung. Starting in 1966, it imported and released 43 species of dung beetles over 25 years.</p>
<p>The beetles came from places such as South Africa, France, Spain and Turkey. The chosen beetles had similar climate requirements and were adapted to wild and domestic livestock, so they could live in Australia and process livestock dung.</p>
<h2>What do dung beetles do?</h2>
<p>When people think of dung beetles, the popular image that comes to mind is that of an industrious beetle labouring to roll a large ball of dung across the landscape.</p>
<p>These little engineers are actually trying to find a suitable spot to situate the ball, on which they will lay an egg. Their offspring will have food and a safe place to grow up, and generate more dung beetles.</p>
<p>Most species of dung beetles actually tunnel beneath piles of dung and drag bits of it into subterranean chambers, where they then lay their eggs.</p>
<p>The larvae develop over the following weeks to months, eventually emerging as adults and crawling to the surface in search of a mate and another pile of dung to colonise.</p>
<h2>The introduced dung beetles</h2>
<p>Of the 43 species introduced to Australia by CSIRO, 23 have become established and many are having a positive impact.</p>
<p>The activities of dung beetles helped remove dung from pastures and with it, the breeding site for nuisance flies and internal parasites.</p>
<p>They also improved pasture fertility. They increased the permeability of pasture soils to rainwater which decreased runoff of rainwater laden with nutrients that can pollute waterways.</p>
<p>But it is not known just how widely each of the introduced species has spread. There might be geographical and seasonal gaps in dung beetle activity that could be filled by other species yet to be introduced to Australia.</p>
<h2>Working with farming</h2>
<p>Dung beetles have been around for tens of millions of years, but their ability to survive in modern agricultural environments may be jeopardised by some farming practices.</p>
<p>Tilling paddocks used in cropping and livestock rotation systems may destroy the developing dung beetle larvae. </p>
<p>Some deworming agents, used by livestock producers to control intestinal parasites, may pass through the livestock and out in their faeces, and might poison the dung beetles colonising the dung.</p>
<p>It should be possible to manage tillage and deworming to minimise harm to the dung beetles, and so maximise their positive impact on the land. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/five-things-dung-beetles-do-with-a-piece-of-poo-47367">Five things dung beetles do with a piece of poo</a>
</strong>
</em>
</p>
<hr>
<p>That’s where <a href="https://www.dungbeetles.com.au/">Dung Beetle Ecosystem Engineers</a> (DBEE) comes in.</p>
<p>In this project, a group of research institutions, producer groups, land management groups and dung beetle entrepreneurs are working together. </p>
<p>The project, now in its second year, is supported by Meat and Livestock Australia and funded by the Rural Research and Development for Profit Program of the Australian Department of Agriculture, Water and the Environment. Charles Sturt University leads the project, with cooperators at CSIRO, University of Western Australia, University of New England, Mingenew-Irwin Group, Warren Catchment Council, Dung Beetle Solutions International, and LandCare Research NZ.</p>
<p>Dung Beetle Ecosystem Engineers aims to:</p>
<ol>
<li><p>understand the distribution of dung beetle species previously introduced to Australia, and predict their ultimate spread</p></li>
<li><p>evaluate new species of dung beetle for importation and release into Australia</p></li>
<li><p>estimate the economic impact of dung beetles on farming systems</p></li>
<li><p>develop a database of information on dung beetles in Australasia and educational materials for use by a range of users</p></li>
<li><p>work with farming and land management groups to engage landholders in detecting dung beetles and modifying agricultural practices to enhance the success of dung beetles.</p></li>
</ol>
<p>At the end of the DBEE project, we will have a better understanding of the role of dung beetles as a farming tool, helping farmers choose agricultural practices that will improve their bottom line.</p>
<p>New dung beetle species will be ready to work for Australia and New Zealand, and a distribution network will enhance their spread to new geographic areas.</p>
<p>DBEE aims bring economic and ecological benefits to the agricultural sector and wider Australian and New Zealand community.</p><img src="https://counter.theconversation.com/content/101975/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The Dung Beetle Ecosystem Engineers project is supported by Meat and Livestock Australia and funded by the Rural Research and Development for Profit Program of the Australian Department of Agriculture. Charles Sturt University leads the project, with CSIRO, University of Western Australia, University of New England, Mingenew-Irwin Group, Warren Catchment Council, Dung Beetle Solutions International, and LandCare Research NZ.</span></em></p>Wet and bulky cattle dung is very unlike marsupial dung that Australian dung beetles are adapted to deal with, meaning native dung beetles tend to leave it alone. But help from abroad is at hand.Paul Weston, Senior Research Fellow / EH Graham Centre for Agricultural Innovation, Charles Sturt UniversityTheo Evans, Associate Professor , The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1304442020-03-09T12:22:47Z2020-03-09T12:22:47ZDung beetles help rainforests regrow – but extreme drought and wildfires in the Amazon are killing them off<figure><img src="https://images.theconversation.com/files/316508/original/file-20200220-92526-w5ecx2.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2385%2C1588&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An Amazon forest in Brazil's Para state after deforestation and wildfires March 9, 2019. Unlike in some tropical forests, the animals of the Amazon are not adapted to survive fire.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/members-of-the-ibama-forest-fire-brigade-fight-burning-in-news-photo/1167455725?adppopup=true">Gustavo Basso/NurPhoto via Getty Images</a></span></figcaption></figure><p>The dung beetle may <a href="https://theconversation.com/five-things-dung-beetles-do-with-a-piece-of-poo-47367">eat and nest in poop</a>, but its role in nature is anything but humble. </p>
<p>These hardshelled scarabs live on every continent except Antarctica, <a href="https://www.youtube.com/watch?v=uSTNyHkde08">recycling feces</a> and <a href="https://doi.org/10.1111/1365-2664.12821">suppressing parasites</a> that could otherwise harm people and animals. Dung beetles also <a href="https://doi.org/10.1098/rspb.2016.1634">spread both seeds and nutrients</a> into the soil, helping to maintain a healthy ecosystem.</p>
<p>Conversely, dung beetles suffer when an ecological system is struggling. In tropical forests, for example, stress caused by environmental disturbances causes dung beetles to <a href="https://doi.org/10.1002/ece3.2488">gain body fat</a> and <a href="https://doi.org/10.1016/j.foreco.2017.12.027">work less</a>. <a href="https://doi.org/10.1111/1365-2664.12657">Species diversity</a> declines.</p>
<p>That’s why, as <a href="https://scholar.google.com/citations?user=5srODa8AAAAJ&hl=da">Amazon</a> <a href="https://scholar.google.com/citations?hl=da&user=HYNoVoUAAAAJ&view_op=list_works&sortby=pubdate">researchers</a>, we use the marvelous, hard-working dung beetle to measure the ecological health of the world’s largest rainforest. Since 2010, we have collected and studied over 14,000 dung beetles from 98 different species in the vast and still wild interior of Brazil’s Santarém region, a remote corner of the Amazon forest – part of a long-term project with the <a href="https://www.rasnetwork.org/">Sustainable Amazon Network</a>.</p>
<p>Most recently, we studied dung beetles to assess the Amazon’s recovery from the intense drought and forest fires of 2015 and 2016, extreme climatic events brought on by <a href="https://theconversation.com/el-nino-is-over-but-has-left-its-mark-across-the-world-59823">the most severe El Niño on record</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/316506/original/file-20200220-92512-1vqs5at.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/316506/original/file-20200220-92512-1vqs5at.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/316506/original/file-20200220-92512-1vqs5at.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/316506/original/file-20200220-92512-1vqs5at.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/316506/original/file-20200220-92512-1vqs5at.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/316506/original/file-20200220-92512-1vqs5at.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/316506/original/file-20200220-92512-1vqs5at.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The hard-working Amazonian dung beetle.</span>
<span class="attribution"><span class="source">Filipe França</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Stressed beetles take less crap</h2>
<p>Some forests in our 10,586-square-mile research area were burned in the El Niño fires, which scorched <a href="https://doi.org/10.1098/rstb.2017.0312">4,000 square miles of the Amazon</a>. These climate-triggered fires are not to be confused with last year’s <a href="https://doi.org/10.1111/gcb.14872">Amazon fire crisis</a>, which was deforestation-related. Other Amazonian forests in our study experienced extreme drought but not fire. </p>
<p>We knew going into this project that Amazonian fauna are particularly sensitive to fire – unlike animals in Australia, which <a href="https://theconversation.com/animal-response-to-a-bushfire-is-astounding-these-are-the-tricks-they-use-to-survive-129327">have a long history of fire adaptation</a>. But our <a href="https://doi.org/10.1111/btp.12756">study</a>, which was published in the scientific journal <a href="https://onlinelibrary.wiley.com/journal/17447429">Biotropica</a> in February 2020, reveals that both forest fires and drought are far more damaging than previously thought. </p>
<p>Dung beetles are captured in traps baited with – what else? – human and pig poop. There we count and physically examine them. To assess their activity level, we trick dung beetles into dispersing seeds by building a small arena filled with a mix of dung and artificial seeds on the forest floor. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/316507/original/file-20200220-92502-11md6ap.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers measuring beetles’ dung-removal and seed-dispersal services.</span>
<span class="attribution"><span class="source">Marizilda Cuppre/ RAS Network</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Comparing our catches before and after the El Niño forest fires, we learned that almost 70% of dung beetles had disappeared. We believe that’s because most dung beetles <a href="https://doi.org/10.1890/14-1211.1">nest in shallow soil depths</a> of between zero to 6 inches, so <a href="https://doi.org/10.2307/2256168">fire heat</a> is likely to kill them. </p>
<p>The El Niño droughts likewise decimated the Amazonian dung beetle populations. Their populations dropped by about 60% in forests affected only by drought, not fire. </p>
<p>Together, extreme drought and forest fires in the Amazon had severely diminished the beetles’ ability to remove dung and spread seeds, which declined by 67% and 22%, respectively, in comparison to data recorded in 2010 – before El Niño. This reduced haul is probably the result of population loss. </p>
<p>Both the reduction in the number of dung beetles captured and their diminished waste disposal functions persisted even two years after El Niño. While dung beetle populations recover quickly in <a href="https://doi.org/10.1111/een.12705">fire-dependent ecosystems</a>, insect recovery from fire disturbance <a href="https://doi.org/10.1111/j.1466-882X.2004.00074.x">in tropical forests can take many years</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/316504/original/file-20200220-92533-hm3meo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Author Filipe França with an Amazonian dung beetle.</span>
<span class="attribution"><span class="source">Marizilda Cuppre/RAS Network</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Tropical beetles</h2>
<p>If both drought and fire kill off dung beetles, the Amazon forests are in serious trouble. </p>
<p>In damaged forests, <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2745.13358">most regrowth depends on seed dispersal</a> by animals. Dung beetles disperse the seeds that promote revegetation and spread nutrients in the soil, <a href="https://doi.org/10.1098/rspb.2016.1634">helping seedlings survive</a>.</p>
<p>They aren’t the only animals that play this critical ecological function. <a href="https://doi.org/10.1111/btp.12627">Tapirs</a>, <a href="https://doi.org/10.1111/j.1744-7429.1999.tb00125.x">monkeys</a>, <a href="https://doi.org/10.1080/12538078.1999.10515813">ants, bee beetles and even wasps</a> also spread the seeds that aid vegetation regrowth. </p>
<p>But many <a href="https://doi.org/10.1038/s41558-018-0225-7">studies</a> show that dung beetle responses to environmental stress are similar to those suffered by other seed-spreading animals necessary to tropical forest health. And climate change is likewise causing the <a href="https://theconversation.com/climate-change-is-killing-off-earths-little-creatures-109719">collapse of these insect populations</a>, killing off <a href="https://doi.org/10.1073/pnas.1722477115">ants, bees, butterflies and wasps</a>.</p>
<p>Without these important tropical animals, forests damaged by fire and drought will recover much more slowly. That means they may barely begin their regrowth before the next disaster. And with climate change projected to bring the tropics more intense and frequent droughts, along with <a href="http://dx.doi.org/10.1098/rstb.2019.0116">hotter and dry global temperatures</a>, such disasters will likely come ever more quickly.</p>
<p>From our field sites deep in the Amazon, we are rooting for all the little creeping and crawling creatures that <a href="https://www.jstor.org/stable/2386020?seq=1">keep the world running</a> – with, admittedly, some particular affection and concern for the humble dung beetle. </p>
<p>[<em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>.]</p><img src="https://counter.theconversation.com/content/130444/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Filipe França is also affiliated with Lancaster University and the Empresa Brasileira de Pesquisa Agropecuária, in Brazil. He receives funding from BNP Paribas Foundation and the Brazilian National Council for Scientific and Technological Development. His fieldwork was funded by the Natural Environment Research Council. </span></em></p><p class="fine-print"><em><span>Joice Ferreira receives funding from the Brazilian Research Council CNPq. She works for the Brazilian government research organization Empresa Brasileira de Pesquisa Agropecuária, or Embrapa.</span></em></p>A new study finds 70% of Amazonian dung beetles were killed by the severe fire and droughts of 2015 to 2016. By spreading seeds and poop, dung beetles fertilize forests and aid regrowth of vegetation.Filipe França, Researcher, Tropical Ecology, Universidade Federal do Pará (UFPA)Joice Ferreira, Researcher in Ecology, Universidade Federal do Pará (UFPA)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1210722019-07-29T15:48:33Z2019-07-29T15:48:33ZBelligerent beetles show that fighting for mates could help animals survive habitat loss<figure><img src="https://images.theconversation.com/files/286026/original/file-20190729-43145-1p8sarc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">En garde!</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/rhinoceros-beetle-on-wood-forest-243404500?src=x3wJuQTOXK6isXUv-_Gwog-1-1&studio=1">BaLL LunLa/Shutterstock</a></span></figcaption></figure><p>Animals around the world are seeing their environments change. <a href="https://theconversation.com/animals-will-struggle-to-adapt-fast-enough-to-cope-with-climate-change-study-finds-120857">Climate change</a> is causing heating and changes to weather patterns, the oceans are becoming <a href="https://theconversation.com/the-worlds-shellfish-are-under-threat-as-our-oceans-become-more-acidic-103868">more acidic</a>, and previously undisturbed habitats are being <a href="https://theconversation.com/habitat-loss-doesnt-just-affect-species-it-impacts-networks-of-ecological-relationships-117687">altered and degraded</a> by human activities.</p>
<p>If we want to understand how these changes will affect animals around the world, we need a better understanding of how their biology might determine how well they survive these changes. My colleagues and I have just <a href="https://doi.org/10.1111/ele.13358">published research</a> that demonstrates how important an animal’s mating system is to this. We found that species whose males compete for mates are more likely to survive damaging changes to their environment.</p>
<p>In many species, males try to woo females <a href="https://theconversation.com/strut-your-stuff-how-rockstars-and-peacocks-attract-the-ladies-29045">with signals</a> like calls, colouration or long tails, or they try to monopolise access to females by fighting other males with weaponry like horns or antlers. This competition for mates helps drive the evolution of these species, in a process called <a href="https://theconversation.com/why-men-are-not-biologically-useless-after-all-42012">sexual selection</a>. The most attractive or most aggressive mates are more likely to pass on their genes to the next generation and produce more offspring with their attractive features or aggressive nature. </p>
<p>There are many reasons to think competitive mating could affect the resilience of a species to environmental change. First, the signals and weapons that often evolve in those species where competition is more intensive are costly to grow and to carry. They can make animals more conspicuous to predators, and both contests with rival males and extravagant displays to females can use enormous amounts of energy. So these strongly sexually selected species could be less able to cope with environmental change because of these costs.</p>
<p>On the flip side, strong competition between males for mates means that only a few particularly strong, healthy or energetic males “win” and father the majority of the next generation. If the environment is changing, then males that are genetically best suited to the new environment are likely to be in the best condition. If these males end up as the winners in the competition for mating then their well-adapted genes will spread very rapidly. So strong sexual selection could make animal populations <a href="https://mast.queensu.ca/%7Etday/pdf/Lorchetal03.pdf">adapt faster to new environments</a>, making them more resilient in the face of it changing.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/286032/original/file-20190729-43136-166fkp8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Peacocking is a costly mating strategy.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/indian-male-peacock-1147396844?src=8jEkBHVkTbTf6jxsFJXBGw-1-4&studio=1">Kandarp/Shutterstock</a></span>
</figcaption>
</figure>
<p>So which process is more important in influencing species survival? A <a href="https://www.nature.com/articles/s41467-019-10074-7">series of lab studies</a> have consistently found that strong sexual selection improves outcomes for animal species when the environment shifts from their optimum. But studies of animals in the field have often found either no effect of sexual selection or the opposite. For example, when birds have been introduced to islands <a href="https://besjournals.onlinelibrary.wiley.com/doi/10.1046/j.1365-2656.1998.00199.x">such as New Zealand</a>, then the species that are more sexually selected are less likely to become established.</p>
<p>One possible reason for this disparity is that the field studies have often concentrated on very small populations of animals. It’s possible that the effects of sexual selection on a population’s resilience vary with its size. </p>
<p>Very small populations living in a certain location might not have enough genetic variety to produce individuals that are very well adapted to its particular environment. In which case, the costs of sexual selection could make them more likely to go extinct. Whereas large populations are more likely to have the genetic variety that will produce “winning” males even when the environment is unfriendly.</p>
<p>What was needed was a field study of sexual selection and persistence in larger populations. To that end, my colleagues and I conducted a study, published in <a href="https://doi.org/10.1111/ele.13358">Ecology Letters</a>, of how dung beetles respond to environmental change in the rainforest of Sabah in Malaysian Borneo.</p>
<h2>Horny beetles</h2>
<p>Dung beetles are fascinating animals for many reasons, one of which is the diversity of their sex lives. Males from the familiar ball-rolling species do compete for matings. But there are also many species of dung beetle that don’t roll, instead burying dung directly under where they find it, and these species show much greater variability. Some species have <a href="https://www.sciencenewsforstudents.org/article/little-beetle-big-horns">males with horns</a>, which they use in <a href="http://hs.umt.edu/dbs/labs/emlen/documents/Emlen%20Publications/BRCLososEmlenFINALlowres.pdf">fights with other males</a>, whereas others are less strongly sexually selected, with hornless males who are less aggressive in their pursuit of mates.</p>
<p>Using an existing large-scale study called the <a href="https://www.safeproject.net/">SAFE Project</a>, we followed 34 species of beetle found in untouched “old growth” forest. We looked at how they fared in lightly-logged and heavily logged forest and then oilpalm plantation where the original forest was largely removed. </p>
<p>We found that those species with horns were more likely to survive in all these cases. Strikingly, all 11 remaining species in the most disturbed plantation environment carried horns. </p>
<p>We also compared species with relatively small horns against those with big horns for their size. We found that beetle species with big horns are not only more likely to survive in disturbed environments, but they also tend to have larger remaining population sizes.</p>
<p>This tells us that – in some particular cases at least – we should think about sexual selection as well as other aspects of an animal’s biology if we want to predict or to manage population sizes in the face of environmental change. Sexual selection is a ubiquitous and powerful force driving evolution in the animal kingdom and has been intensively studied by behavioural and evolutionary biologists. Maybe now it’s time ecologists and wildlife management specialists started to think about it as well.</p><img src="https://counter.theconversation.com/content/121072/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rob Knell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New evidence boosts the idea that species with males who compete for mates adapt faster to changing circumstances.Rob Knell, Reader in Evolutionary Ecology, Queen Mary University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1177092019-05-26T09:05:19Z2019-05-26T09:05:19ZThere’s still so much we don’t know about the star-gazing beetle with a tiny brain<figure><img src="https://images.theconversation.com/files/276296/original/file-20190524-187179-frjxy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A dung beetle wearing silicon boots to protect its feet from the hot soil, as part of an experiment.
</span> <span class="attribution"><span class="source">Courtesy of Adrian Bailey/baileyphotos.com</span></span></figcaption></figure><p><em>Edited extract from <a href="http://witspress.co.za/catalogue/dance-of-the-dung-beetles/">“The Dance of the Dung Beetles</a>” published by Wits University Press.</em></p>
<p>Dung beetles have been ever-present in the history of the West – but oddly, less so elsewhere – in religion, art, literature, science and the environment. What we understand about them now mirrors our greater understanding of the important role they play in keeping our planet healthy.</p>
<p>The story of these beetles, which we tell in our new book “The Dance of the Dung Beetles”, comes with a few unexpected twists. It moves from the tombs of the pharaohs to the drawing rooms of directors of the Dutch East India Company to the remote forests of Madagascar. It is a big story carried on the back of a family of small creatures who seldom diverge from their dogged pursuit of dung in its infinite variety and abundant supply. </p>
<p>Like the housemaids of Victorian Britain, who tended fires and households in the small hours while the Empire swept across the globe, they remain largely unseen and ignored. Yet without those housemaids, the world would have a lot more dirt in it. In the same way, dung beetles are largely invisible. And yet without their vital activities, the world would have a lot more faeces in it.</p>
<h2>More than “dung-grubbers”</h2>
<p>Dung beetles have relatively minuscule brains, much of which is devoted to analysing smells. But they also process visual information that even humans with their vast brains struggle to comprehend. This was shown in <a href="https://theconversation.com/scientists-have-worked-out-how-dung-beetles-use-the-milky-way-to-hold-their-course-75666">a study</a> we conducted with other scientists that revealed how dung beetles use the light of the Milky Way to orientate.</p>
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<a href="https://theconversation.com/scientists-have-worked-out-how-dung-beetles-use-the-milky-way-to-hold-their-course-75666">Scientists have worked out how dung beetles use the Milky Way to hold their course</a>
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<p>The original story was picked up way beyond the scientific literature and spread rapidly <a href="http://www.sci-news.com/biology/article00844.html">around the world</a>. We were struck by how the tale of a lowly beetle and the distant Milky Way engaged popular imagination when so much other information about dung beetles is equally impressive, if not even more fascinating. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/276125/original/file-20190523-187169-1x2vr5b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/276125/original/file-20190523-187169-1x2vr5b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=273&fit=crop&dpr=1 600w, https://images.theconversation.com/files/276125/original/file-20190523-187169-1x2vr5b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=273&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/276125/original/file-20190523-187169-1x2vr5b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=273&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/276125/original/file-20190523-187169-1x2vr5b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=343&fit=crop&dpr=1 754w, https://images.theconversation.com/files/276125/original/file-20190523-187169-1x2vr5b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=343&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/276125/original/file-20190523-187169-1x2vr5b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=343&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Wearing a cap prevents this beetle seeing orientation cues in the sky. As a consequence it rolls its ball around in circles, like a human lost in a featureless desert.</span>
<span class="attribution"><span class="source">Courtesy Marcus Byrne</span></span>
</figcaption>
</figure>
<p>This realisation prompted us to respond on behalf of these little creatures, which can be found on every continent except Antarctica, to show that they deserve better press than to be seen as mere dung-grubbers – some of whom happen to orientate by the stars.</p>
<p>Together with earthworms and ants, dung beetles represent a trinity of earth transformers. They literally change the earth beneath us, and they do so at absolutely no cost to us. Dung beetles play a largely unexplored role in soil health, which is increasingly important in a hungry world full of people. There is still so much we do not know about the <a href="https://www.smithsonianmag.com/science-nature/the-humble-dung-beetle-180967781/">6,000 species</a> that clean our world. </p>
<p>We do not know, for example, exactly what they eat. Most eat dung, some eat carrion (dead animals). But getting by on low nutrient waste requires careful selective feeding performed by specialised mouth parts. Microorganisms in the dung and soil might also have a role, fixing nitrogen from the atmosphere to increase food quality and soil health. </p>
<p>We know how dung beetles use celestial cues to orientate, but it’s not clear how a brain so small can <a href="http://jeb.biologists.org/content/222/Suppl_1/jeb192450">process or remember such information</a>. We know they are attracted to the smell of dung, but we do not really understand how that works, or if that sense switches off when they turn their attention to the visual task of rolling a dung ball. Does their neural limitation preclude parallel processing of disparate information?</p>
<h2>Evolution of science</h2>
<p>In our history of the development of contemporary science, we have seen the evolution of belief in magic, to one of stocktaking and empirical observation, to interpretation and deepening levels of sophisticated tunnelling into the smallest known particles. We have gone from myth, symbols, vague observation and interpretation of a world run by the gods, to a world with one God, and then a world in which the boundaries of religion no longer act as the limit to our knowledge.</p>
<p>The quest for money rather than scientific or natural interests drove much early exploration. <a href="https://www.metmuseum.org/toah/hd/gold/hd_gold.htm">Gold</a>, and then <a href="https://www.nytimes.com/2008/04/30/books/30gord.html">trade</a>, became the vehicles for global expansion and settlement. The knowledge we now have of how the world works comes with the recognition that so much of what there is, is threatened by the very pursuits that opened up our world. </p>
<p>It is an irony that cannot be lost on us as we look at the growing list of flora and fauna <a href="https://www.ipbes.net/news/Media-Release-Global-Assessment">on the brink of destruction and extinction</a>. The relevance to what we still do not know about creatures as small and seemingly insignificant as dung beetles is that we are beginning to understand what German naturalist and artist <a href="https://www.britannica.com/biography/Maria-Sibylla-Merian">Maria Sibylla Merian</a> showed in her paintings: that the world is deeply and fundamentally interconnected.</p>
<p>Biological evolution represents the history of a dynamic process – but evolution has its own timetable. So, even though many creatures can adapt relatively rapidly to the environmental changes we have induced, there are hundreds of thousands of species that cannot. Dung beetles are however, excellent models of rapid evolution and speciation. </p>
<p>The development of the magnificent horn of many dung beetles can be switched on or off in the <em>same</em> gene carried by males and female dung beetles, allowing natural selection – that is, chances of survival – to be balanced against sexual selection (chances of reproducing) <a href="https://theconversation.com/what-dung-beetles-are-teaching-us-about-the-genetics-of-sex-differences-73827">in different habitats</a>. The export of dung beetles to different continents, for control of dung-breeding flies, has created a massive natural experiment which will eventually reveal which way evolution will drive those species.</p>
<p>If we need a reminder of how much we do not know, then the study of one little sub-family of unseemly beetles is instructive. Their endless complexity and variety has absorbed the energies of so many researchers across the globe since the Egyptian <a href="https://warburg.sas.ac.uk/pdf/noh%2050b2331470.pdf">Horapollo</a> recorded the first observation of them rolling their ball “from East to West, looking himself towards the East” 3,000 years ago.</p>
<p><em>Dr Helen Lunn co-authored <a href="http://witspress.co.za/catalogue/dance-of-the-dung-beetles/">“The Dance of the Dung Beetles</a>”, which is published by Wits University Press.</em></p><img src="https://counter.theconversation.com/content/117709/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcus Byrne receives funding from the South African National Research Foundation.</span></em></p>Dung beetles are largely invisible. And yet without their vital activities, the world would have a lot more faeces in it.Marcus Byrne, Professor of Zoology and Entomology, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/756662017-04-21T11:59:44Z2017-04-21T11:59:44ZScientists have worked out how dung beetles use the Milky Way to hold their course<figure><img src="https://images.theconversation.com/files/164673/original/image-20170410-8855-epopod.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Insects navigate in much the same way that ancient humans did: using the sky. Their primary cue is the position of the sun, but insects can <a href="dx.doi.org/10.1007/s00114-004-0525-9">also detect properties of skylight</a> (the blue light scattered by the upper atmosphere) that give them indirect information about the sun’s position. Skylight cues include gradients in brightness and colour across the sky and the way light is polarised by the atmosphere. Together, these sky “compass cues” allow many insect species to hold a stable course.</p>
<p>At night, as visual cues become harder to detect, this process becomes more challenging. Some can use the light of the moon but one insect, the nocturnal dung beetle <em>Scarabaeus satyrus</em>, uses light from the Milky Way to orient itself. To find out exactly how this process works, my colleagues and I constructed an artificial Milky Way, using LEDs, to test the beetles’ abilities. <a href="http://rstb.royalsocietypublishing.org/content/372/1717/20160079">We found</a> that they rely on the difference in brightness between different parts of the Milky Way to work out which way to go.</p>
<p><em>Scarabaeus satyrus</em> holds its course with apparent ease every night. They take to the air at dusk in the African Savanna, in search of the fresh animal droppings on which they feed. But they are not alone and, to escape competition from other dung beetles, they construct a piece of <a href="https://books.google.com/books?isbn=1444341987">dung into a ball and roll it</a> a few meters away from the dung pile before burying and consuming it.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/165831/original/image-20170419-6395-1dtpf5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/165831/original/image-20170419-6395-1dtpf5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165831/original/image-20170419-6395-1dtpf5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165831/original/image-20170419-6395-1dtpf5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165831/original/image-20170419-6395-1dtpf5k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165831/original/image-20170419-6395-1dtpf5k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165831/original/image-20170419-6395-1dtpf5k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Where am I supposed to take this thing?</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>To avoid returning to their starting point, they maintain a straight path while rolling their ball. Scientists discovered that the beetles could do this even on moonless clear nights. So in 2009, a group of researchers took some beetles on a trip to the <a href="http://www.planetarium.co.za">planetarium in Johannesburg</a>, and watched them try to orient themselves under different star patterns.</p>
<p><a href="http://bit.ly/2otpafg">They found</a> the beetles could hold their course well when the planetarium displayed just the Milky Way, the streak of light across the night sky produced by the disc-shaped arrangement of the stars in our galaxy. But the beetles became disoriented when only the brightest stars in the sky were shown.</p>
<p>What was still unclear was exactly what kind of compass cue the beetles extracted from the Milky Way. We knew, for example, that <a href="http://www.sandiegocounty.gov/content/dam/sdc/pds/ceqa/Soitec-Documents/Final-EIR-Files/references/rtcref/ch9.0/rtcrefaletters/F1%202014-12-19_Emlen1975.pdf">night-migrating birds learn the constellations</a> surrounding the sky’s northern centre of rotation, much as sailors did before the advent of modern navigation systems. These constellations remain in the northern part of the sky as the Earth rotates, and so are a reliable reference for north–south journeys.</p>
<p>The planetarium experiments had shown that the beetles don’t use constellations of bright stars, but perhaps they could learn patterns within the Milky Way instead. My colleagues and I then proposed that the beetles might perform a brightness comparison, identifying either the brightest point in the Milky Way or a brightness gradient across the sky that is influenced by the Milky Way.</p>
<h2>Artificial Milky Way</h2>
<p>We used our artificial night sky to test this theory, constructing <a href="dx.doi.org/10.1098/rstb.2016.0079">a simplified Milky Way streak</a> that simulated different patterns of stars and brightness gradients. We found that the beetles became lost when given a pattern of stars within the artificial Milky Way. The beetles only maintained their heading when the two sides of the streak differed in brightness. </p>
<p>This suggests nocturnal beetles do not use the intricate star patterns within the Milky Way as their compass cue, but instead identify a brightness difference across the night sky to set their heading. This is similar to what their <a href="dx.doi.org/10.1242/jeb.101154">day-active relatives</a> do when the sun is not visible but instead orient themselves using the brightness gradient of the daytime sky.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/164663/original/image-20170410-8846-n7u3of.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/164663/original/image-20170410-8846-n7u3of.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164663/original/image-20170410-8846-n7u3of.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164663/original/image-20170410-8846-n7u3of.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164663/original/image-20170410-8846-n7u3of.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164663/original/image-20170410-8846-n7u3of.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164663/original/image-20170410-8846-n7u3of.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Night-time compass.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>This brightness-comparison strategy may be less sophisticated than the way <a href="dx.doi.org/10.%202307/4083330">birds</a> and human sailors identify specific constellations, but it’s an efficient solution to interpreting the complex information present in the starry sky—given how small the beetles’ eyes and brains are. In this way, they overcome the limited bandwidth of their information processing systems and do more with less, just as humans have learnt to do with technology.</p>
<p>This straightforward brightness comparison strategy is particularly effective over short distances. So although <em>Scarabaeus satyrus</em> is the only species known to hold its course in this way, the technique may also be used by many other nocturnal animals that perform short journeys at night.</p><img src="https://counter.theconversation.com/content/75666/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Foster receives funding from the Swedish Research Council, the Knut and Alice Wallenberg foundation, Carl Trygger's foundation for Scientific Research, the Lars Hierta Memorial foundation and the Royal Physiographic Society of Lund. </span></em></p>New research shows the insects use the brightness of different stars to work out which direction to go.James Foster, Postdoctoral fellow in functional zoology, Lund UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/738272017-03-21T01:02:56Z2017-03-21T01:02:56ZWhat dung beetles are teaching us about the genetics of sex differences<p>Picture a lion: The male has a luxuriant mane, the female doesn’t. This is a classic example of what biologists call sexual dimorphism – the two sexes of the same species exhibit differences in form or behavior. Male and female lions pretty much share the same genetic information, but look quite different.</p>
<p>We’re used to thinking of genes as responsible for the traits an organism develops. But different forms of a trait – mane or no mane – can arise from practically identical genetic information. Further, traits are not all equally sexually dimorphic. While the tails of peacocks and peahens are extremely different, their feet, for example, are pretty much the same.</p>
<p>Understanding how this variation of form – what geneticists call phenotypic variation – arises is crucial to answering several scientific questions, including how novel traits appear during evolution and how complex diseases emerge during a lifetime.</p>
<p>So researchers have taken a closer look at the genome, looking for the genes responsible for differences between sexes and between traits within one sex. The key to these sexually dimorphic traits appears to be a kind of protein called a <a href="https://www.khanacademy.org/science/biology/gene-regulation/gene-regulation-in-eukaryotes/a/eukaryotic-transcription-factors">transcription factor</a>, whose job it is to turn genes “on” and “off.”</p>
<p><a href="http://dx.doi.org/10.1038/ncomms14593">In our own work with dung beetles</a>, my colleagues and I are untangling how these transcription factors actually lead to the different traits we see in males and females. A lot of it has to do with something called “alternative gene splicing” – a phenomenon that allows a single gene to encode for different proteins, depending on how the building blocks are joined together.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/161596/original/image-20170320-9132-112g2nz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The gene <em>doublesex</em> produces visually obvious sexual dimorphism in the butterfly <em>Papilio polytes</em>, the common Mormon. Female (top), male (bottom).</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Papilio_polytes_mating_in_Kadavoor.jpg">Jeevan Jose, Kerala, India</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>On/off, male/female</h2>
<p>Over the years, different groups of scientists independently worked with various animals to identify genes that shape sexual identity; they realized that many of these genes share a specific region. This gene region was found in both the worm gene <em>mab-3</em> and the insect gene <em>doublesex</em>, so they named similar genes containing this region DMRT genes, for “<a href="http://dx.doi.org/10.1038/35618">doublesex mab-related transcription factors</a>.” </p>
<p>These genes code for DMRT proteins that turn on or off the reading, or expression, of other genes. To do this, they seek out genes in DNA, bind to those genes, and make it <a href="https://www.khanacademy.org/science/biology/gene-expression-central-dogma/transcription-of-dna-into-rna/a/stages-of-transcription">either easier or harder to access the genetic information</a>. By controlling what parts of the genome are expressed, DMRT proteins lead to products characteristic of maleness or femaleness. They match the expression of genes to the right sex and trait. </p>
<p>DMRTs almost always confer maleness. For instance, without DMRT, <a href="http://dx.doi.org/10.1038/nature10239">testicular tissue in male mice deteriorates</a>. When DMRT is experimentally produced in female mice, they <a href="http://dx.doi.org/10.1242/dev.122184">develop testicular tissue</a>. This job of promoting testis development is common to most animals, from fish and birds to worms and <a href="http://dx.doi.org/10.1016/j.tig.2012.02.002">clams</a>. </p>
<p>DMRTs even confer maleness in animals where individuals develop both testes and ovaries. In fish that exhibit sequential hermaphroditism – where gonads change from female to male, or vice versa, within the same individual – the waxing and waning of DMRT expression results in the <a href="http://dx.doi.org/10.1111/j.1742-4658.2011.08030.x">appearance and regression of testicular tissue</a>, respectively. Likewise, in turtles that become male or female based on temperatures experienced in the egg, DMRT is produced in the genital tissue of <a href="http://dx.doi.org/10.1002/(SICI)1526-968X(200003)26:3%3C174::AID-GENE2%3E3.0.CO;2-J">embryos exposed to male-promoting temperatures</a>.</p>
<p>The situation is a little different in insects. First, the role of DMRT (<em>doublesex</em>) in generating sexual dimorphism has extended beyond gonads to other parts of the body, including <a href="http://dx.doi.org/10.1371/journal.pgen.1004098">mouthparts</a>, <a href="http://dx.doi.org/10.1038/nature13112">wingspots</a> and mating bristles aptly named “<a href="http://dx.doi.org/10.1371/journal.pbio.1001131">sex combs</a>.” </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/161588/original/image-20170320-9121-z0fsyj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Depending on how the pieces are put together, one gene can result in a number of different proteins.</span>
<span class="attribution"><span class="source">Cris Ledón-Rettig</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Secondly, male and female insects generate their own versions of the <em>doublesex</em> protein through what’s called “<a href="https://www.khanacademy.org/science/biology/gene-expression-central-dogma/transcription-of-dna-into-rna/a/eukaryotic-pre-mrna-processing">alternative gene splicing</a>.” This is a way for a single gene to code for multiple proteins. Before genes are turned into proteins, they must be turned “on”; that is, transcribed into instructions for how to build the protein.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=831&fit=crop&dpr=1 600w, https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=831&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=831&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1045&fit=crop&dpr=1 754w, https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1045&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/161602/original/image-20170320-9127-1d7sk76.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1045&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Thanks to the <em>doublesex</em> gene, in the stag beetle <em>Cyclommatus metallifer</em>, mandibles of males (right) are much larger than those of females (left).</span>
<span class="attribution"><a class="source" href="http://dx.doi.org/10.1371/journal.pgen.1004098">http://dx.doi.org/10.1371/journal.pgen.1004098</a></span>
</figcaption>
</figure>
<p>But the instructions contain both useful and extraneous regions of information, so the useful parts must be stitched together to create the final protein instructions. By combining the useful regions in different ways, a single gene can produce multiple proteins. In male and female insects, it’s this alternative gene splicing that results in the <em>doublesex</em> proteins <a href="http://dx.doi.org/10.1016/0092-8674(89)90633-8">behaving differently in each sex</a>.</p>
<p>So in a female, instructions from the <em>doublesex</em> gene might include sections 1, 2 and 3, while in a male the same instruction might include only 2 and 3. The different resulting proteins would each have their own effect on what parts of the genetic code are turned on or off – leading to a male with huge mouthparts and a female without, for instance.</p>
<h2><em>Doublesex</em> in dung beetles</h2>
<p>How do male and female forms of <em>doublesex</em> regulate genes to produce male and female traits? <a href="http://ecoevodevo.com/">Our research group</a> answered this question using dung beetles, which are exceptionally numerous in species (over 2,000), widespread (inhabiting every continent except Antarctica), versatile (consuming about every type of dung) and show amazing diversity in a sexually dimorphic trait: <a href="https://en.wikipedia.org/wiki/Dung_beetle">horns</a>.</p>
<p>We focused on the bull-headed dung beetle <em>Onthophagus taurus</em>, a species in which males produce large, bull-like head horns but females remain hornless. We found that <em>doublesex</em> proteins can <a href="http://dx.doi.org/10.1038/ncomms14593">regulate genes in two ways</a>.</p>
<p>In most traits, it regulates different genes in each sex. Here, <em>doublesex</em> is not acting as a “switch” between two possible sexual outcomes, but instead bestowing maleness and femaleness to each sex independently. Put another way, these traits don’t face a binary decision between becoming male or female, they are simply asexual and poised for further instruction.</p>
<p>The story is different for the dung beetles’ head horns. In this case, <em>doublesex</em> acts more like a switch, regulating the same genes in both sexes but in opposite directions. The female protein suppressed genes in females that would otherwise be promoted by the male protein in males. Why would there be an evolutionary incentive to do this?</p>
<p>Our data hinted that the female <em>doublesex</em> protein does this to avoid what is known as “sexual antagonism.” In nature, fitness is sculpted by both natural and sexual selection. Natural selection favors traits increasing survival, whereas sexual selection favors traits increasing access to mates. </p>
<p>Sometimes these forces are in agreement, but not always. The large head horns of male <em>O. taurus</em> increase their access to mates, but the same horns would be a hassle for females who have to tunnel underground to raise their offspring. This creates a tension between the sexes, or sexual antagonism, that limits the overall fitness of the species. However, if the female <em>doublesex</em> protein turns “off” genes that in males are responsible for horn growth, the whole species does better. </p>
<h2>Beyond beetle sex</h2>
<p>Our ongoing research is addressing how <em>doublesex</em> has evolved to generate the vast diversity in sexual dimorphism in dung beetles. Across species, horns are found in different body regions, grow differently in response to different quality diets, and can even occur in females rather than males.</p>
<p>In <em>Onthophagus sagittarius</em>, for instance, it’s the female that grows substantial horns while males remain hornless. This species is only five million years diverged from <em>O. taurus</em>, a mere drop of time in the evolutionary bucket for insects. For perspective, beetles diverged from flies about 225 million years ago. This suggests that <em>doublesex</em> can evolve quickly to acquire, switch, or modify the regulation of genes underlying horn development. </p>
<p>How will understanding the role of <em>doublesex</em> in sexually dimorphic insect traits help us understand phenotypic variation in other animals, even humans?</p>
<p>Despite the fact that DMRTs are spliced as only one form in mammals and act primarily in males, the <a href="http://dx.doi.org/10.1038/nature07509">majority of other human genes are alternatively spliced</a>; just like insects’ <em>doublesex</em> gene, most human genes have various regions that can be spliced together in different orders with varying results. Alternatively spliced genes can have distinct or opposing effects based on which sex or trait they’re expressed in. Understanding how proteins that are produced by alternatively spliced genes behave in different tissues, sexes and environments will reveal how one genome can produce a multitude of forms depending on context.</p>
<p>In the end, the humble dung beetle’s horns can give us a peek into the mechanisms underlying the vast complexity of animal forms, humans included.</p><img src="https://counter.theconversation.com/content/73827/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cris Ledón-Rettig is affiliated with Indiana University, Bloomington. </span></em></p>How can the same basic genome produce such different forms in the two sexes of a single species? It turns out one gene can encode for various things, depending on the order its instructions are read.Cris Ledón-Rettig, Postdoctoral Fellow of Biology, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/666922016-10-17T04:10:38Z2016-10-17T04:10:38ZHow dung beetles are duped into rolling and burying seeds<figure><img src="https://images.theconversation.com/files/141771/original/image-20161014-30269-12qsfnj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jeremy Midgley</span></span></figcaption></figure><p>Dung beetles find their food - which is dung - by its pungent smell. Once found, dung beetles then roll and bury dung balls or dung pellets to later eat or to lay eggs in. But in the De Hoop Nature Reserve of the southern Cape plants called <em>Ceratocaryum argenteum</em> have managed to dupe dung beetles into rolling and burying their seeds. These seeds look and smell like dung pellets, so this is a classic case of plants deceiving animals.</p>
<p><em>Ceratocaryum argenteum</em> is a tall grass-like plant in the <a href="http://redlist.sanbi.org/species.php?species=2555-1">Restionaceae family</a> and is a part of sand plain fynbos. Fynbos is the local name for Cape shrublands, a biome that regularly experiences natural fires. These seeds are the same rounded shape and brown colour as a dung pellet from local antelope like bontebok and eland. Fresh seeds are really stinky and the scent profile of the dung of these herbivores and that of the seeds is remarkably complex, yet similar. </p>
<p>Given the right weather conditions, such as after rain, within minutes of putting seeds out, dung beetles arrive and rapidly roll and bury the seeds. Dung beetles typically eat soft dung, mostly as developing larvae inside a dung ball but also, to a lesser degree, as adults. The hard seeds of <em>Ceratocaryum argenteum</em> are therefore inedible to dung beetles and thus there is no reward for the dung beetles that disperse these seeds.</p>
<p>Our <a href="http://sajs.co.za/two-dung-beetle-species-disperse-mimetic-seeds-both-feed-eland-dung/jeremy-j-midgley-joseph-d-m-white">research</a> shows the deception is not that costly to the beetles as they do not lay eggs on the seeds. When they try to lay eggs in the hard seeds, they realise something is wrong and they leave.</p>
<h2>Small mammals shy away</h2>
<p>Originally, we thought that these large seeds would be dispersed and buried by small mammals in a process known as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2830248/">scatter-hoarding</a>. Scatter-hoarders bury seeds and then later return to find their stash when they are <a href="https://emammal.wordpress.com/2013/09/24/gray-squirrels-and-scatter-hoarding/">hungry</a>. Their memory is less than perfect and some buried seeds eventually escape seed predation, germinate and establish. </p>
<p>Two species of Cape small mammals are scatter-hoarders; the <a href="http://www.proteaatlas.org.za/p54spiny.htm">spiny mouse and the hairy footed-gerbil</a>. But neither of these two species occurs in southern Cape sandy fynbos where <em>Ceratocaryum argenteum</em> grows. </p>
<p>Here the most common small mammal, the four-striped mouse, seems to be repelled by the seed coat. Interestingly, if the hard seed coats are cracked open, this rodent avidly consumes the inner nutritious part <a href="http://www.nature.com/article-assets/npg/nplants/2015/nplants2015141/extref/nplants2015141-s2.mp4">of the seed</a>.</p>
<p>The benefit to the plant of being buried by dung beetles is very significant because large seeds do not easily get buried passively. Large seeds left on the soil surface would then be prone to incineration. This is through natural, mainly <a href="http://workingonfire.org/fire-in-the-south-african-landscape/">lightning-caused fires</a>, that typically burn through fynbos about every 10 to 20 years. The seeds would also be prone to desiccation as they wait for post-fire conditions in which to germinate and establish. So burial is crucial.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ugxRx7alXb4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Dung beetles rolling and burying seeds.</span></figcaption>
</figure>
<h2>Implications</h2>
<p>This discovery has several implications. This is probably the best example globally of deception in plant seed dispersal. The only realistic previous example of deception of animal dispersers by plants, concerned red and black hard seeds, the so-called “lucky-beans”. The idea was that these mimic red fleshy fruits and deceive birds into eating and <a href="http://www.plantzafrica.com/plantefg/erythrinlysist.htm">dispersing them</a>. </p>
<p>But often these seeds are poisonous and birds hardly ever take them. So, this is not deception but <a href="http://www.merriam-webster.com/dictionary/aposematism">aposematism</a> or warning colouration. Many animals use red and black colouration to warn predators that they are harmful. </p>
<p>The evolution of dung beetle deception in a fynbos plant implies the long term presence of dung and thus the presence of large herbivores. Fynbos is generally considered to be unpalatable and therefore that large herbivores <a href="https://books.google.co.za/books?id=JgcIBgAAQBAJ&pg=PT1&dq=fynbos+ecology+evolution+and+conservation&hl=en&sa=X&ved=0ahUKEwiE5rzOiNrPAhVEDcAKHQRbBZUQ6AEIJTAA#v=onepage&q=most%20authors%20suggest%20these%20megaherbivores&f=false">would be absent</a>. </p>
<p>In contrast, our results suggest the sustained presence of dung. It also raises the question of why dung beetle deception has not evolved in the herbivore rich savannas of Africa. I guess that this system works best in ecosystems where dung is in limited supply because the plant is so dependent on burial. </p>
<p>The final point regarding the significance of this work is that many novel natural history observations can still be made in the Western Cape and elsewhere. Although this is hardly big science emerging from big labs or big computers, I have been amazed at the enormous public and scientific <a href="http://www.sciencemag.org/news/2015/10/plant-seeds-look-smell-poop-fooling-dung-beetles-planting-them,">interest</a> this paper has <a href="https://whyevolutionistrue.wordpress.com/2015/10/07/a-new-and-bizarre-form-of-mimicry-plant-seeds-mimic-shape-and-smell-of-animal-feces-to-facilitate-dispersal-by-dung-beetles/">had</a>. </p>
<p>There certainly is large public interest in natural history and since the public often funds science, its great to have had public impact. I suspect that much of the public interest is because deception is the “dark” side of evolution, it is unexpected that plants can deceive animals. Also dung beetles are such interesting, hardworking and charismatic beasts; they attract public attention.</p><img src="https://counter.theconversation.com/content/66692/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jeremy Midgley receives funding from UCT and NRF. </span></em></p>A tall grass-like plant in the Western Cape has managed to dupe dung beetles into rolling and spreading its seeds.Jeremy Midgley, Professor at Department of Biological Sciences, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/473672015-09-14T04:43:50Z2015-09-14T04:43:50ZFive things dung beetles do with a piece of poo<figure><img src="https://images.theconversation.com/files/94474/original/image-20150911-1559-1wgfrb0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dung beetle rolling in the shade.</span> <span class="attribution"><span class="source">Marcus Byrne</span></span></figcaption></figure><p>Dung beetle behaviour has fascinated humans for thousands of years – including the ancient Egyptians, who incorrectly believed the beetles reproduced only from males. But Egyptian observations that the beetles’ ball rolling is influenced by the sun is accurate and could be the first recorded accounts of animal behaviour. </p>
<p>Dung beetles evolved at least 65 million years ago, as the dinosaurs were in decline, and the mammals (and their droppings) were getting bigger. There are about 6000 species worldwide, concentrated in the tropics where they feed mainly on the dung of terrestrial vertebrates. </p>
<p>Dung beetles have been cleaning up the planet ever since; but what on earth do they do with all that poo? Here are the top five most interesting.</p>
<h2>Eat it</h2>
<p>Vulgar and aggressive, but true. Dung beetles eat dung. But they are fussy eaters, picking out the big bits and concentrating on the tiniest particles, 2-70 microns big (1 micron = 1/1000 of a millimetre), which is where most of the nitrogen in dung is to be <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2311.2007.00915.x/abstract">found</a>. </p>
<p>All organisms need nitrogen to build proteins, such as muscle. Dung beetles get theirs from dung. By eating poo, dung beetles may be selecting the cells from the gut wall of the herbivore which made it. These are a protein-rich nitrogen source. </p>
<p>The latest studies show that obesity and diabetes in humans might be linked to our individual gut <a href="http://care.diabetesjournals.org/content/33/10/2277.full">microbiomes</a>. Dung beetles might be using their gut microbiome to help them digest the difficult components of dung.</p>
<h2>Roll it – although only a minority do</h2>
<p>90% of dung beetles tunnel directly beneath the dung pat and make an underground nest of brood balls in which they lay eggs. You’ll never see them unless you are prepared to poke around in the stuff.</p>
<p>On the other hand, the rollers transport their prize on the soil surface. They use celestial cues such as the sun or the moon to keep to a straight track away from competitors that might steal their <a href="http://link.springer.com/article/10.1007%2Fs00359-003-0415-1#page-1">ball</a>. </p>
<p>There is one species which has been shown how to use the stars of the Milky Way as its celestial compass, allowing it to dominate the midnight market in dung <a href="http://www.cell.com/current-biology/abstract/S0960-9822(12)01507-2">transport</a>.</p>
<h2>Make a packed lunch</h2>
<p>This is what the brood ball represents to the larval dung beetle. Hatching from a single egg inside each brood ball, the larva eats its way around the interior of the ball.</p>
<p>This dung is coarse and crunchy, so the larva has chewing mouthparts not found in the adult beetle, and doesn’t have the luxury of selecting what it can eat or discard, so it eats everything – several times. Therefore, its microbiome is different from their parents’, and might contain symbiotic microorganisms living in a mutually beneficial relationship with the host <a href="http://onlinelibrary.wiley.com/doi/10.1111/een.12011/abstract">larva</a>. </p>
<p>That gives the larva access to sugars in otherwise indigestible cellulose, and may even “fix” nitrogen from the atmosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=452&fit=crop&dpr=1 600w, https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=452&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=452&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=568&fit=crop&dpr=1 754w, https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=568&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/94475/original/image-20150911-1559-rxq9c8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=568&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dung beetle making a packed lunch.</span>
<span class="attribution"><span class="source">Marcus Byrne</span></span>
</figcaption>
</figure>
<h2>Woo girlfriends</h2>
<p>All that is needed is a small ball of poo. Place the poo at the base of a short tunnel, then retreat to the entrance where you stick your bum in to the air and release a pheromone which alerts nearby female beetles that you have a juicy prize for them. This is in return for sexual <a href="https://books.google.co.za/books?id=ibZ8Y74XIwcC&pg=PA94&lpg=PA94&dq=Pheromone+release+by+dung+beetles+GD+Tribe&source=bl&ots=gO2CVlPir6&sig=QZ5giQ28Sryqr9MuADtr5r32upk&hl=en&sa=X&ved=0CCMQ6AEwAWoVChMI6feJtKXsxwIVCTsUCh0bJA25#v=onepage&q=Pheromone%20release%20by%20dung%20beetles%20GD%20Tribe&f=false">favours</a>. </p>
<p>Pheromones are chemical messengers, which leave the body and are often associated with sexual attraction. </p>
<p>But sometimes the males cheat. They make the tunnel, do the head-standing trick to lure a naïve female, who after succumbing to his wiles discovers that males are not to be trusted – even the six-legged versions.</p>
<h2>Chill on it</h2>
<p>On a hot day in the <a href="http://www.kalaharidesert.net/">Kalahari</a> the soil surface can reach 60°C, which is death to any animal that can’t control its body temperature. </p>
<p>Dung beetles are small, and so is their thermal inertia. Consequently they heat up very rapidly. To avoid overheating while rolling their balls in the blazing midday sun, they climb on top of the ball to momentarily cool off, before hot-footing across the sand looking for shade. Giving them chilled dung balls from the fridge allows them to roll further before going back onto the ball.</p>
<p>Heated balls have the opposite effect. And giving them insulating silicon boots lets them tolerate high temperatures for <a href="http://www.cell.com/current-biology/abstract/S0960-9822(12)01061-5">longer</a>, showing that the dung ball is used as a thermal refuge from the heat.</p>
<p>Each example shows how evolution has co-opted a single, seemingly odd behaviour of eating dung into a more sophisticated use of the same material in different roles, each of which have enhanced the animal’s survival. This ranges from making nuptial gifts to thermal refuges. </p>
<p>Those beetles that discovered these new behaviours by accident had more offspring, bearing their slightly different genes and behaviour into the next generation. This is where they became entrenched as an evolutionary adaptation to a successful way of life at the back-end of the food chain.</p><img src="https://counter.theconversation.com/content/47367/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcus Byrne receives funding from Wits University and the National Research Foundation.</span></em></p>Dung beetles have been cleaning up the planet for at least 65 million years. The 6000 species across the world have adapted to a life at the back end of the food chain in the most remarkable ways.Marcus Byrne, Professor of Zoology and Entomology, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.