tag:theconversation.com,2011:/global/topics/aphids-10013/articlesAphids – The Conversation2020-12-15T13:20:28Ztag:theconversation.com,2011:article/1504962020-12-15T13:20:28Z2020-12-15T13:20:28ZVirgin births from parthenogenesis: How females from some species can reproduce without males<figure><img src="https://images.theconversation.com/files/374837/original/file-20201214-17-2nde3j.png?ixlib=rb-1.1.0&rect=0%2C0%2C5463%2C3006&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Getting the job done. A female Asian water dragon (Physignathus cocincinus) produced a daughter (left) without the assistance of a male. </span> <span class="attribution"><a class="source" href="https://nationalzoo.si.edu/news/scientists-confirm-facultative-parthenogenesis-smithsonians-national-zoos-asian-water-dragon">Skip Brown/Smithsonian’s National Zoo</a></span></figcaption></figure><p>An Asian water dragon hatched from an egg at the Smithsonian National Zoo, and her keepers were shocked. Why? Her mother had never been with a male water dragon. Through genetic testing, zoo scientists discovered the newly hatched female, born on Aug. 24, 2016, had been produced through a <a href="https://doi.org/10.1371/journal.pone.0217489">reproductive mode called parthenogenesis</a>.</p>
<p>Parthenogenesis is a Greek word meaning “virgin creation,” but specifically refers to female asexual reproduction. While many people may assume this behavior is the domain of science fiction or religious texts, parthenogenesis is <a href="https://doi.org/10.1038/sdata.2014.15">surprisingly common throughout the tree of life</a> and is found in a variety of organisms, including plants, insects, fish, reptiles and even birds. Because mammals, including human beings, require certain genes to come from sperm, <a href="https://doi.org/10.1159/000090812">mammals are incapable of parthenogenesis</a>.</p>
<h2>Creating offspring without sperm</h2>
<p>Sexual reproduction involves a female and a male, each contributing genetic material in the form of eggs or sperm, to create a unique offspring. The vast majority of animal species reproduce sexually, but females of some species are able to produce eggs <a href="https://www.britannica.com/science/parthenogenesis">containing all the genetic material required for reproduction</a>.</p>
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<a href="https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A microscopic view of a translucent water flea show four round eggs inside." src="https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=526&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=526&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373966/original/file-20201209-19-1x4523.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=526&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">A female freshwater water flea (<em>Daphnia magna</em>) carrying parthenogenetic eggs.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/microscopic-view-of-freshwater-water-flea-royalty-free-image/841300586">buccaneership/iStock via Getty Images Plus</a></span>
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<p>Females of these species, which include <a href="https://doi.org/10.1002/evl3.30">some wasps</a>, <a href="https://doi.org/10.1086/283761">crustaceans</a> and <a href="https://www.scientificamerican.com/article/asexual-lizards/">lizards</a>, reproduce only through parthenogenesis and are called obligate parthenogens.</p>
<p>A larger number of species experience spontaneous parthenogenesis, best documented in animals kept in zoo settings, like the Asian water dragon at the National Zoo or a <a href="https://doi.org/10.1111/j.1095-8649.2008.02018.x">blacktip shark at the Virginia Aquarium</a>. Spontaneous parthenogens typically reproduce sexually, but may have occasional cycles that produce developmentally ready eggs.</p>
<p>Scientists have learned <a href="https://doi.org/10.1098/rspb.2009.2113">spontaneous parthenogenesis may be a heritable trait</a>, meaning females that suddenly experience parthenogenesis might be more likely to have daughters that can do the same.</p>
<h2>How can females fertilize their own eggs?</h2>
<p>For parthenogenesis to happen, <a href="https://doi.org/10.1534/g3.112.005421">a chain of cellular events must successfully unfold</a>. First, females must be able to create egg cells (oogenesis) without stimulation from sperm or mating. Second, the eggs produced by females need to begin to develop on their own, forming an early stage embryo. Finally, the eggs must successfully hatch. </p>
<p>Each step of this process can easily fail, particularly step two, which requires the chromosomes of DNA inside the egg to double, ensuring a full complement of genes for the developing offspring. Alternatively, the egg can be “faux fertilized” by leftover cells from the egg production process known as <a href="https://doi.org/10.1002/mrd.21266">polar bodies</a>. Whichever method kicks off the development of the embryo <a href="https://doi.org/10.1525/bio.2009.59.7.3">will ultimately determine the level of genetic similarity</a> between the mother and her offspring.</p>
<p>The events that trigger parthenogenesis are not fully understood, but appear to include environmental change. In species that are capable of both sexual reproduction and parthenogenesis, such as <a href="https://doi.org/10.1371/journal.pone.0115099">aphids</a>, stressors like <a href="https://doi.org/10.1111/een.12080">crowding and predation</a> may cause females to switch from parthenogenesis to sexual reproduction, but not the other way around. In at least one <a href="https://doi.org/10.1007/978-90-481-2770-2_15">type of freshwater plankton</a>, <a href="https://doi.org/10.5762/KAIS.2016.17.4.692">high salinity</a> appears to cause the switch.</p>
<h2>Advantages of self-reproduction</h2>
<p>Though spontaneous parthenogenesis appears to be rare, it does provide some benefits to the female who can achieve it. In some cases, it can allow females to generate their own mating partners. </p>
<p>The sex of parthenogenetic offspring is determined by the same method sex is determined in the species itself. For organisms where sex is determined by chromosomes, like the XX female and XY male chromosomes in some insects, fish and reptiles, a parthenogenetic female can produce offspring only with the sex chromosomes she has at hand – which means she will always produce XX female offspring. But for organisms where females have ZW sex chromosomes (such as in snakes and birds), all living offspring produced will either be ZZ, and therefore male, or <a href="https://doi.org/10.1098/rsbl.2010.0793">much more rarely, WW, and female</a>.</p>
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<p>Between 1997 and 1999, <a href="https://doi.org/10.1111/j.1095-8312.2012.01954.x">a checkered gartersnake kept at the Phoenix Zoo</a> gave birth to two male offspring that ultimately survived to adulthood. If a female mated with her parthenogenetically produced son, it would constitute inbreeding. While inbreeding can result in a host of genetic problems, from an evolutionary perspective it’s better than having no offspring at all. The ability of females to produce male offspring through parthenogenesis also suggests that asexual reproduction in nature may be more common than scientists ever realized before. </p>
<p>Biologists have observed, over long periods of time, that <a href="https://doi.org/10.1016/0022-5193(71)90058-0">species that are obligate parthenogens frequently die out</a> from <a href="https://doi.org/10.1038/s41514-018-0025-3">disease</a>, <a href="https://doi.org/10.1073/pnas.87.9.3566">parasitism</a> or <a href="https://doi.org/10.1002/evl3.30">changes in habitat</a>. The inbreeding inherent in parthenogenetic species appears to contribute to their short evolutionary timelines. </p>
<p>Current research on parthenogenesis seeks to understand why some species are capable of both sex and parthenogenesis, and whether occasional sexual reproduction might be enough for a species to survive.</p><img src="https://counter.theconversation.com/content/150496/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mercedes Burns has previously received funding from the National Science Foundation. </span></em></p>Parthenogenesis, a form of reproduction in which an egg develops into an embryo without being fertilized by sperm, might be more common than you realized.Mercedes Burns, Assistant Professor of Biological Sciences, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1028382018-09-07T05:13:42Z2018-09-07T05:13:42ZWasps, aphids and ants: the other honey makers<figure><img src="https://images.theconversation.com/files/235349/original/file-20180907-190639-1nvjzhk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Myrmecocystus honeypot ants, showing the repletes, their abdomens swollen to store honey, above ordinary workers.</span> <span class="attribution"><span class="source"> Greg Hume via Wikimedia Commons</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>There are seven species of <em>Apis</em> honey bee in the world, all of them native to Asia, Europe and Africa. <em>Apis mellifera</em>, the western honey bee, is the species recognised globally as “the honey bee”. But it’s not the only insect that makes honey. </p>
<p>Many other bee, ant and wasp species make and store honey. Many of these insects have been used as a natural sugar source for centuries by indigenous cultures around the world.</p>
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Read more:
<a href="https://theconversation.com/what-is-fake-honey-and-why-didnt-the-official-tests-pick-it-up-102573">What is fake honey and why didn’t the official tests pick it up?</a>
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<p>By definition, honey is a sweet, sticky substance that insects make by collecting and processing flower nectar. The commercial association between honey and honey bees has mostly developed alongside the long-term relationship between humans and domesticated honey bees. </p>
<p>This association is also supported by the <a href="http://www.fao.org/fao-who-codexalimentarius/codex-texts/list-standards/en/">Codex Alimentarius</a>, the international food standards established by the United Nations and the World Health Organisation. The Honey Codex mentions only “honey bees” and states that honey sold as such should not have any food additives or other ingredients added.</p>
<h2>Oh honey, honey</h2>
<p>Biologically, there are other insect sources of honey. Stingless bees (Meliponini) are a group of about 500 bee species that are excellent honey producers and are also managed as efficient crop pollinators in some regions. Stingless bees are mostly found in tropical and subtropical regions of Australia, Africa, Southeast Asia and the Americas. </p>
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Read more:
<a href="https://theconversation.com/a-bee-economist-explains-honey-bees-vital-role-in-growing-tasty-almonds-101421">A bee economist explains honey bees' vital role in growing tasty almonds</a>
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<p>Their honey is <a href="http://www.redalyc.org/html/339/33901206/">different in taste and consistency</a> to honey bee honey. It has a higher water content, so it’s a lot runnier and tastes quite tangy. Stingless bee honey is an important food and income source for many traditional communities around the world. </p>
<p>Harvesting “sugarbag”, as it’s known in Australia, is an <a href="http://www.abc.net.au/news/2018-01-21/native-honeybees-provide-popular-bush-tucker/9333278">important cultural tradition for indigenous communities</a> in northern and eastern regions.</p>
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<span class="caption">A sugarbag bee.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/25027666@N02/6363058903">James Niland/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Stingless bee honey production hasn’t reached the commercial success of honey bee honey, mostly because stingless bee colonies produce a lot less honey than an Apis honey bee hive and are more complicated to harvest. But keeping stingless bees in their native range for honey, pollination services and human well-being is <a href="https://www.apidologie.org/articles/apido/abs/2006/02/m6035sp/m6035sp.html">an increasing trend</a>. </p>
<p>Bumblebees also make honey, albeit on a very small scale. The nectar they store in wax honey pots is mostly for the queen’s consumption, to maintain her energy during reproduction. Because very few bumblebee colonies establish permanently, they don’t need to store large quantities of honey. This makes it almost impossible to manage these bees for honey production.</p>
<p>Bees aren’t the only <a href="https://www.britannica.com/animal/hymenopteran">hymenopterans</a> that make honey. Some species of paper wasps, particularly the Mexican honey wasps (<em>Brachygastra</em> spp.), also store excess nectar in their cardboard nests. Local indigenous communities value these wasps as a source of food, income and traditional medicine.</p>
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<a href="https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/235354/original/file-20180907-190639-1v4u7ib.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"></a>
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<span class="caption">Mexican honey wasp.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
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<p>Ants have similar lifestyles to their bee and wasp cousins and are common nectar foragers. Some species also make honey. </p>
<p>“Honeypot ant” is a common name for the many species of ant with workers that store honey in their abdomen. These individuals, called repletes, can swell their abdomens many times the normal size with the nectar they gorge. They act as food reservoirs for their colony, but are also harvested by humans, particularly by <a href="https://search.informit.com.au/documentSummary;dn=108392124224680;res=IELHSS">indigenous communities in arid regions</a>. </p>
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<span class="caption">Close-up of three large replete honeypot ants (<em>Myrmecocystus mimicus</em>) at Oakland Zoo.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/Category:Honeypot_ants#/media/File:Closeup_on_honeypot_ants_(Myrmecocystus_mimicus)_at_Oakland_Zoo.jpg">via Wikimedia Commons</a></span>
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<p>These ants don’t just collect nectar from flowers, but also sap leaks on plant stems (called extrafloral nectaries) and honeydew produced by hemipteran sap-suckers like aphids and scale insects.</p>
<p>Aphids and scale insects aren’t all bad – they produce a delicious sugary syrup called honeydew. We mostly know these insects as garden and crop pests: warty lumps huddled on plant stems, often coated in sticky honeydew and the black sooty mould that thrives on the sugar. </p>
<p>Males of these insect species are usually short-lived, but females can live for months, sucking plant sap and releasing sweet sticky honeydew as waste from their rears. The sugar composition varies greatly depending on <a href="https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1046/j.0269-8463.2001.00550.x">both the plant and the sap-sucking species</a>. </p>
<p>Honeydew has long been a valuable sugar source for indigenous cultures in many parts of the world where native honey-producing bees are scarce. Many other animals that seek out floral nectar, like bees, flies, butterflies, moths and ants, also feed on honeydew. It’s an especially valuable resource over winter or when floral resources are scarce, and not just for other insects; <a href="https://www.tandfonline.com/doi/abs/10.1080/00222930150215378">geckoes</a>, <a href="http://www.publish.csiro.au/mu/MU9800213">honeyeaters</a>, other small birds, <a href="http://www.publish.csiro.au/WR/WR9840265">possums</a> and <a href="http://www.publish.csiro.au/wr/WR97037">gliders</a> are all known to feed on honeydew.</p>
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<span class="caption">Honeydew on a leaf.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Honeydew_on_the_leafs_(cropped).jpeg">Dmitri Don/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>It’s also an indirect source of honey bee honey: plant sap that has been recycled through two different insect species! Honey bees are well-known honeydew collectors. In some parts of Europe, honeydew is <a href="https://www.tandfonline.com/doi/abs/10.1080/0005772X.1985.11098832">an important forage resource for bee colonies</a>. </p>
<p>Honeydew honeys have a unique flavour, depending on the host tree the scale insects were feeding on. Famous examples of this specialty honey are the German Black Forest honey and New Zealand’s Honeydew honey.</p>
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Read more:
<a href="https://theconversation.com/unique-pollen-signatures-in-australian-honey-could-help-tackle-a-counterfeit-industry-97859">Unique pollen signatures in Australian honey could help tackle a counterfeit industry</a>
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<p>So why not find out a bit more about what insects are producing honey in your local region?</p><img src="https://counter.theconversation.com/content/102838/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Manu Saunders 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>Honey might be synonymous with bees, but they’re not the only insects that come up with the goods.Manu Saunders, Research fellow, University of New EnglandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/989982018-07-10T10:38:06Z2018-07-10T10:38:06ZRock ‘n’ roll is noise pollution – with ecological implications that can spread through a food web<figure><img src="https://images.theconversation.com/files/226364/original/file-20180705-122250-eoerm5.jpg?ixlib=rb-1.1.0&rect=274%2C203%2C2514%2C1735&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Not interested in your new favorite band.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/tjgehling/33349047406">TJ Gehling</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Despite being <a href="https://www.riaa.com/gold-platinum/?tab_active=top_tallies&ttt=T1A#search_section">one of the best-selling albums of all time</a>, ideology from AC/DC’s “Back in Black” album has gone unchallenged for nearly 40 years. The album’s closing track posited a testable hypothesis, asserting with rock-star confidence that “Rock ‘n’ roll ain’t noise pollution.” Opinions may vary from person to person, but little scientific evidence has been evaluated to determine if rock music is noise pollution … until now. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/X_IWlPHMziU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">AC/DC – ‘Rock And Roll Ain’t Noise Pollution’</span></figcaption>
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<p>My research group <a href="https://doi.org/10.1002/ece3.4273">recently tested the “AC/DC hypothesis.”</a> Sadly, we report that, at least in some situations, rock ‘n’ roll in fact is noise pollution. </p>
<p>OK, yes, our experiment may sound silly or frivolous. But our hope is to focus a little more attention on how sounds – whether Angus Young’s guitar licks or the steady drone from a busy highway – can affect ecosystems. Our work demonstrates that the effects of noise pollution are not restricted just to the animals directly affected by the sounds, but can alter their behaviors and interactions with other animals and plants, spreading the effects throughout an ecosystem.</p>
<h2>Noise and nature</h2>
<p>Noise pollution has been recognized as an <a href="https://theconversation.com/human-noise-pollution-is-disrupting-parks-and-wild-places-78074">increasing threat for wildlife</a>. For instance, scientists have shown that the sounds of <a href="https://doi.org/10.2981/wlb.00225">mining can affect deer behavior</a>. Noise from <a href="https://e360.yale.edu/features/how_ocean_noise_pollution_wreaks_havoc_on_marine_life">ocean drilling affects marine life</a>. And sounds from recreational vehicles are a particular <a href="https://home.nps.gov/subjects/sound/noise-sources.htm">concern in natural places</a> – spawning an <a href="https://electrek.co/2018/03/03/tesla-inspired-taiga-electric-snowmobile/">industry of quieter electric alternatives</a>.</p>
<p>Most existing studies focus largely on the direct effects of noise – an animal hears the noise in its environment and is affected. But of course, animals don’t live in isolation. They’re embedded within a tangle of food web interactions with other species. So by affecting even one species, noise pollution – or any other environmental change – may generate indirect effects that spread from individual to individual, and eventually may affect entire communities.</p>
<p>Studying noise pollution and its cascading indirect effects is difficult, especially on large free-roaming animals. To test these interactions, <a href="https://scholar.google.com/citations?user=NuXykqQAAAAJ&hl=en&oi=ao">my</a> <a href="https://www.bartonlab.net">research group</a> will often scale-down our experiments and use smaller model systems.</p>
<p>Specifically, we study lady beetles, including <em><a href="https://biocontrol.entomology.cornell.edu/predators/Harmonia.php">Harmonia axyridis</a></em>, the multi-colored Asian lady beetle. Unknown to many, lady beetles are among the most <a href="https://www.nytimes.com/2018/06/01/science/ladybugs-aphids-toxic.html">important predators of agricultural pests</a> such as soybean aphids. By voraciously consuming aphids in soybean fields, lady beetles provide natural <a href="https://theconversation.com/us/topics/biological-control-7766">biological control</a> of pests and minimize the amount of pesticides needed on crops. Lady beetles provide an important ecosystem service – anything that disrupts their ability to attack aphids could be perceived as having a negative effect on society.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/226395/original/file-20180705-122277-hm38fq.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=460&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 plants in their listening setup.</span>
<span class="attribution"><span class="source">Brandon Barton</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Firing up the hi-fi in the ecology lab</h2>
<p>With the help of colleagues – and fellow AC/DC fans – <a href="https://www.biology.msstate.edu/people/staff.php?id=vk85">Vince Klink</a> and <a href="https://scholar.google.com/citations?user=G84D9fQAAAAJ&hl=en&oi=ao">Marcus Lashley</a>, my team of undergraduate and graduate students sought to determine if noise pollution would decrease lady beetle effectiveness at controlling aphids. Further, we suspected that reducing predation rates on aphids would allow the pest population to explode, which would in turn reduce soybean yield. </p>
<p>First we wanted to figure out what sounds affected lady beetle feeding rates. We placed lady beetle larvae within small enclosures with a known number of aphids to eat, and allowed them to forage either in silence or under loud conditions. We played sounds through computer speakers at maximum volume: 95-100 decibels, approximately equal to a lawn mower or outboard motor.</p>
<p>In addition to AC/DC, we queued up one of our favorite country music albums – “Wanted! The Outlaws” featuring Willie Nelson, Waylon Jennings and others. We DJ’d a mix of rock music, including Lynyrd Skynyrd, Guns ‘n’ Roses, The Supersuckers, the British folk band Warblefly, and a mix of city sounds such as jackhammers, car horns, and so on.</p>
<p>Our results were good news for country and folk fans – lady beetles agreed that those songs were not noise pollution and continued to attack aphids with the same vigor when serenaded by these genres as they did in silence. However, lady beetles were not fans of AC/DC, the rock mix or city noises, even when played at the same volume as the country and folk treatments. In fact, listening to the “Back in Black” album cut the amount of aphids being eaten during a 16 to 18 hour period almost in half.</p>
<p>At least according to lady beetles, it seemed that rock ‘n’ roll was noise pollution and indirectly benefited agricultural pests. But could it have an effect on soybean plants?</p>
<p>Many researchers have investigated <a href="https://doi.org/10.1016/S2095-3119(13)60492-X">how music affects plant growth</a> with mixed results. However, when we blasted soybean plants with two weeks of nonstop “Back in Black,” we didn’t see any effect on growth. Similarly, we found no effect of continuous AC/DC on pest abundance when we grew aphids on plants without their predators.</p>
<p>But we were interested in whether there was an interactive effect of rock music and predators on pest and plants. So for two weeks, we watched lady beetles attack aphids, while aphids reproduced and plants grew.</p>
<p>When the plants were grown without music, the predators reduced aphid density to nearly zero. As a consequence, the plants grew strong and healthy in the absence of their pest. In contrast, when plants were grown with “Back in Black” blaring, the lady beetles did not control aphids and the pests’ population size was more than 40 times larger than in the silent condition – from an average of about 4 aphids per plant to more than 180. As a consequences of high pest abundance, the plants in music treatments were 25 percent smaller. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/226388/original/file-20180705-122265-1611ax7.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">Without predators to keep pests in check, crops like soybeans would need to be sprayed more.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/unitedsoybean/10060153913">United Soybean Board</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Cascading effects of noise pollution</h2>
<p>While others have shown that noise pollution can have <a href="https://theconversation.com/how-noise-pollution-is-changing-animal-behaviour-52339">direct effects on organisms and alter their predation rates</a>, our study uniquely demonstrates that these <a href="https://doi.org/10.1002/ece3.4273">effects can cascade throughout a food web</a>.</p>
<p>We also showed that insects are affected by noise pollution, too. Most previous work in this area focused on large, “sexy” megafauna. But insects provide many ecosystem services that are essential for the healthy functioning of our planet. Disrupting insect behaviors such as pollination or predation can have drastic consequences.</p>
<p>Finally, our work empirically evaluated the AC/DC hypothesis for the first time since its inception in 1980. As fans of AC/DC and rock music, we sadly must disagree with the band and concede that rock ‘n’ roll is noise pollution, at least for lady beetles. Of course, rock music is not really a threat to ecosystems. But because loud music is similar to other real-world instances of noise pollution such as the hum of snowmobiles and the <a href="https://www.npr.org/sections/alltechconsidered/2015/08/13/431982136/drones-increase-heart-rates-of-wild-bears-too-much-stress">buzz of drones overhead</a>, our results serve as a proof-of-concept that sound pollution can have pervasive effects throughout an ecosystem.</p>
<p>What about AC/DC’s other hypothesis, that “rock n roll ain’t gonna die?” As rock lovers, we’re happy to report there’s no evidence to contradict that one.</p><img src="https://counter.theconversation.com/content/98998/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brandon Barton does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>An AC/DC-loving biologist tests the band’s 1980 assertion that “rock ‘n’ roll ain’t noise pollution.” Turns out it can be – and the negative effects of noise can ripple through an ecosystem.Brandon Barton, Assistant Professor of Biological Sciences, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/968792018-05-22T11:09:41Z2018-05-22T11:09:41ZAphid explosion: why are the skies filled with greenfly and how can you get rid of them?<figure><img src="https://images.theconversation.com/files/219774/original/file-20180521-14978-4cmjh8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/extreme-magnification-green-aphids-on-plant-693228553?src=ME2eUjy21S2Qrqk_A67whw-1-3">Shutterstock</a></span></figcaption></figure><p>The warm, still weather of May is great for us and for many plants and animals, but some of these creatures are a nuisance. Around this time every year in many parts of the northern hemisphere, people begin complaining about a plague of tiny green insects filling the air. But really, these aphids or greenfly shouldn’t be seen a problem, just a sign of spring.</p>
<p>Each year aphids and other insects are poised, ready to start feeding on plants as soon as the leaf buds open and they start to grow. The aphids that fly in May are sycamore aphids (<em>Drepanosiphum platanoidis</em>) and, as their name suggests, <a href="http://influentialpoints.com/Gallery/Drepanosiphum_platanoidis_common_sycamore_aphids.htm">they feed on</a> sycamore trees and a few other tree species. They don’t attack garden plants or crops, but if a large group develop on a tree they can reduce its growth. A full-sized tree can host an estimated <a href="https://www.tandfonline.com/doi/abs/10.1080/03071375.1980.10590586">2.5m aphids</a>.</p>
<h2>Why do aphids appear in swarms?</h2>
<p>Sycamore aphids and other insects often grow quickly in the spring as the plants at this time of year are highly nutritious and have fewer defences. You can see evidence of aphid feeding in honeydew, the sugary waste of their feeding, which covers lower leaves (and cars) and provides food for flies and other insects. Eventually the honeydew will become covered with sooty mould.</p>
<p>The rapid growth of aphid numbers is because the species doesn’t rely on sex for reproduction. The all-female aphids reproduce “parthenogenetically”, meaning without the need for their eggs to be fertilised by males. Unlike most insects, aphids also give birth to live (all female) young. In fact, you can dissect an aphid and find her unborn daughters within her body and her unborn granddaughters within them, something known as the <a href="https://www.jstor.org/stable/2389567?seq=1#page_scan_tab_contents">telescoping of generations</a>.</p>
<p>If all these offspring stayed in the same place they would get overcrowded so, when a group begins to get too large, the aphids take flight, dispersing to other leaves, trees or even further afield. They are not strong fliers and are very much at the mercy of the wind, so many probably perish.</p>
<p>In the UK there is an aphid-forecasting scheme run at <a href="https://www.rothamsted.ac.uk/insect-survey">Rothamsted Research in Harpenden</a>. The survey monitors airborne aphids and provides an early warning system for crops that are at risk. In May 2018, the sycamore aphid was the most abundant type found, but in previous years we have seen mass flights of other species that have <a href="https://issuu.com/suffolknaturalistssociety/docs/tsns18_2_g">stopped factories</a> and other workplaces for a time and, worse still, even caused cricket matches to be abandoned.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219775/original/file-20180521-14957-1hovdjv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219775/original/file-20180521-14957-1hovdjv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=471&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219775/original/file-20180521-14957-1hovdjv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=471&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219775/original/file-20180521-14957-1hovdjv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=471&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219775/original/file-20180521-14957-1hovdjv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=592&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219775/original/file-20180521-14957-1hovdjv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=592&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219775/original/file-20180521-14957-1hovdjv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=592&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ladybirds are one of the best defences against aphids.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/ladybug-eating-greenfly-aphid-germany-149806715?src=1P20IG5TpDX29Iva6R-jKg-1-4">Shutterstock</a></span>
</figcaption>
</figure>
<h2>How to deal with them</h2>
<p>Most species of aphids have a similar life-history. While the sycamore aphid does not usually cause any serious harm, other species attack garden plants and crops. This is only really a problem when aphid numbers get too large. Usually, weather and natural enemies such as ladybirds, hoverflies, lacewings and many species of parasitic wasp keep the aphid numbers in check.</p>
<p>In some crops, the aphids can also cause damage by spreading plant viruses such as <a href="https://www.apsnet.org/edcenter/intropp/lessons/viruses/Pages/BarleyYelDwarf.aspx">barley yellow dwarf virus</a> or <a href="https://apsjournals.apsnet.org/doi/10.1094/PDIS-12-16-1811-RE">potato leafroll virus</a>. Gardeners worried about their plants need to keep a watch for aphid infestations and can reduce the chances of attack, by encouraging ladybirds and other natural enemies.</p>
<p>Natural enemies of aphids and other plant pests usually prefer habitats with flowers (for nectar and pollen) and permanent vegetation (for passing the winter). If the aphids get out of hand, they can often be removed from plants by washing them with soapy water. There is also a range of insecticides available if wanted, but unless they are used carefully according to the label instructions these can have an effect on other species as well as aphids.</p><img src="https://counter.theconversation.com/content/96879/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gordon Port 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>Aphids often appear in swarms around May and June but what risk do they pose to plants?Gordon Port, Senior Lecturer in Ecology, Newcastle UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/257652014-04-22T12:59:29Z2014-04-22T12:59:29ZSpying on plant communication with tiny bugs<figure><img src="https://images.theconversation.com/files/46709/original/z8k9ts93-1397751836.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">I'm catching some signals, fellow aphid. Are you?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/drriss/8999852104">drriss</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>Internal communications in plants share striking similarities with those in animals, <a href="http://onlinelibrary.wiley.com/doi/10.1111/nph.12807/abstract">new research reveals</a>. With the help of tiny insects, scientists were able to tap into this communication system. Their results reveal the importance of these communications in enabling plants to protect themselves from attack by insect pests.</p>
<p>Like any organism, plants need to transport essential nutrients from one part to another. This is achieved by two parts of the plant: the xylem and the phloem. Xylem, which is largely made of dead cells, transports water and dissolved nutrients obtained by roots up to the aerial tissues of the plants. By contrast, the phloem is made up of living cells – active tubes that transport a syrupy sap, rich in sugars made by photosynthesis in the leaves.</p>
<p>In the 1980s, scientists discovered that phloem cells also function as a communication system through which electrical signals travel. This is similar to the electrical signals transmitted through the neurons in your nervous system.</p>
<p>In both plants and animals, electrical signals function in an analogous manner. They transmit information from one location to another. If someone wounded your hand, an electrical signal travels through neurons from your skin, up your arm, to your brain, to let you know you have been wounded, and to draw your hand away. Similarly, when a herbivore wounds a plant, an electrical signal is generated which, instead of travelling to a centralised brain, travels through the phloem to other parts of the plant, informing them that wounding has occurred.</p>
<h2>Tapping into defence</h2>
<p>Wounding means danger in plants because it normally happens when the plant is becoming some herbivore’s meal. The ability of a wounded part of the plant to let other parts know that wounding has occurred can help prepare against the attack. Plants have a suite of <a href="https://theconversation.com/plants-release-chemical-weapons-and-deploy-insect-armies-in-their-defence-24853">sophisticated defences</a> that they can bring to bear to protect themselves from herbivores.</p>
<p>Some herbivores don’t wound plants as much as they nibble. Nibbling may escape the detection of the plant, but could have dire consequences—a lot of nibbling can be as fatal as a big bite. But it has been difficult to determine if plants are able to detect nibbling and transmit a warning signal, in the same manner as they do when wounded.</p>
<p><a href="http://www.researchgate.net/profile/Vicenta_Salvador_Recatala">Vicenta Salvador-Recatalà</a> of the University of Lausanne and her colleagues used aphids – specialised insects that feed on plants – to find out how the phloem network responds to nibbling by caterpillars. Their results have been published in the journal <a href="http://onlinelibrary.wiley.com/doi/10.1111/nph.12807/abstract">New Phytologist</a>.</p>
<p>Aphids feed by using their straw-like mouths, which penetrate deep into the plant. As long as there aren’t too many aphids, it doesn’t harm the plant much. In fact, it is in the aphid’s interest to ensure that the plant remains healthy, so that there is still plenty of its sugary syrup to be had.</p>
<p>Aphids don’t just connect themselves to the internal plumbing; they’re also tapped in to the plant’s internal communication system. The aphid’s mouth drills into the phloem, is not easily dislodged, and doesn’t break. This means that aphids that are attached to the plant’s phloem can then be converted into living electrodes. A living-aphid-electrode system can be used to detect electrical signals transmitted through the plant body without causing additional damage to the plant – damage that can set off the plants’ warning system and confuse the results.</p>
<p>Using this aphid phloem-tapping system, Salvador-Recatalà and colleagues investigated the transmission of electrical signals in response to caterpillar feeding. They found that even the nibbling of caterpillars could induce electrical signals, on a smaller scale, but akin to those transmitted by wounding.</p>
<p>The electrical signals travelled like waves, spreading most rapidly to leaves that were closest to the site of caterpillar feeding, and more slowly to other regions of the plant. When the waves were rapid, a wound response was activated on surrounding leaves – beyond the one that the caterpillar was nibbling on.</p>
<h2>Behaving like animals</h2>
<p>In neurons in animals, electrical waves are transmitted by virtue of changes in the way charged atoms flow into and out of the cell. The flow of these charged atoms is controlled by protein channels embedded in the membrane of neurons. In the absence of a signal, the channels are closed. When a neuron receives the right signal, these channels open, allowing the ions to flow out through the channel. This induces a change in ion concentrations inside the cell, and thereby creates the electrical wave.</p>
<p>Plants make protein channels that are similar to those found in neurons. They also open and close in response to appropriate signals, and, when open, allow ions, especially calcium, to flow. When Salvador-Recatalà and colleagues looked at plants where the function of some of these channels was impaired, they found that caterpillar feeding no long produced electrical waves.</p>
<p>These findings suggest that plants respond to caterpillar nibbling using an electrical signalling network that functions through the same mechanics that neurons rely on. Clearly, plants don’t have neurons, but they make use of similar molecular building blocks to construct a response network.</p>
<p>While aphid spies do have their drawbacks – after all, they are also feeding on the plant – these little parasites are inadvertently providing us with profound insights into how their host plants function. The “wiretapping capabilities” they provide are likely to uncover other secrets encoded in plant responses to a variety of threats, including those of the aphids’ relatives: insect pests.</p><img src="https://counter.theconversation.com/content/25765/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Malcolm Campbell receives funding from the Natural Sciences and Engineering Research Council of Canada, and Genome Canada.</span></em></p>Internal communications in plants share striking similarities with those in animals, new research reveals. With the help of tiny insects, scientists were able to tap into this communication system. Their…Malcolm Campbell, Professor & Vice-Principal Research, University of TorontoLicensed as Creative Commons – attribution, no derivatives.