tag:theconversation.com,2011:/us/topics/midges-25136/articlesMidges – The Conversation2023-04-05T13:53:51Ztag:theconversation.com,2011:article/2030962023-04-05T13:53:51Z2023-04-05T13:53:51ZEaster bunnies, cacao beans and pollinating bugs: A basket of 6 essential reads about chocolate<figure><img src="https://images.theconversation.com/files/519391/original/file-20230404-14-reloqo.jpg?ixlib=rb-1.1.0&rect=422%2C0%2C4914%2C3173&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Easter has its bunnies, but chocolate comes out for every holiday.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/chocolate-bunny-family-royalty-free-image/177875356">garytog/iStock via Getty Images Plus</a></span></figcaption></figure><p><a href="https://www.insider.com/surprising-easter-fun-facts-stats-2019-4#as-many-as-91-million-chocolate-bunnies-are-sold-in-the-us-for-easter-annually-8">Tens of millions of chocolate bunnies</a> get sold in the U.S. every Easter. Here are six articles about chocolate from The Conversation’s archive – great reading while you’re nibbling the ears off your own bunny (if you’re one of the <a href="https://www.insider.com/surprising-easter-fun-facts-stats-2019-4#as-many-as-78-of-americans-eat-the-ears-of-their-chocolate-bunny-first-11">three-quarters of Americans who start</a> at the top).</p>
<h2>1. Food scientist on cocoa chemistry</h2>
<p>Chocolate bunnies don’t grow on trees – but cacao pods do. It takes a lot of processing to get from the raw agricultural input to the finished output.</p>
<p>Food scientist <a href="https://scholar.google.com/citations?user=5iZjEckAAAAJ&hl=en&oi=ao">Sheryl Barringer</a> from The Ohio State University wrote about various chemical reactions that are part of the transformation of beans into chocolate. One is the Maillard reaction, the same thing that gives the browned bits on roasted meats or a bread’s golden crust their flavor. <a href="https://theconversation.com/chocolate-chemistry-a-food-scientist-explains-how-the-beloved-treat-gets-its-flavor-texture-and-tricky-reputation-as-an-ingredient-198222">Barringer also explains that weird white stuff</a> – known as bloom – that might appear on your Easter chocolates if they hang around for a while. (Don’t worry, it’s still edible.)</p>
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<a href="https://theconversation.com/chocolate-chemistry-a-food-scientist-explains-how-the-beloved-treat-gets-its-flavor-texture-and-tricky-reputation-as-an-ingredient-198222">Chocolate chemistry – a food scientist explains how the beloved treat gets its flavor, texture and tricky reputation as an ingredient</a>
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<h2>2. Chocolate is a fermented food</h2>
<p>Food science Ph.D. candidate <a href="https://scholar.google.com/citations?user=QjIM6yUAAAAJ&hl=en&oi=ao">Caitlin Clark</a> from Colorado State University focuses her research on the microbes responsible for much of chocolate’s flavor. As a fermented food, chocolate depends on yeast and bacteria to help turn a raw ingredient into the treat you can recognize.</p>
<p>Clark described how the microorganisms that occur naturally in a given geographical location can give high-end chocolates their “terroir” – “<a href="https://theconversation.com/chocolates-secret-ingredient-is-the-fermenting-microbes-that-make-it-taste-so-good-155552">the characteristic flair imparted by a place</a>” you might be more used to thinking about with regard to wine.</p>
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Read more:
<a href="https://theconversation.com/chocolates-secret-ingredient-is-the-fermenting-microbes-that-make-it-taste-so-good-155552">Chocolate's secret ingredient is the fermenting microbes that make it taste so good</a>
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<a href="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cacao pods and flowers on branch tree close up" src="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.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">Tiny flies spread pollen from one cacao tree to another.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cacao-pods-and-flower-on-branch-royalty-free-image/1165785501">dimarik/iStock via Getty Images Plus</a></span>
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<h2>3. Pollinators are important part of process</h2>
<p>Cacao growers rely on another tiny ally to pollinate their crop. Entomologist <a href="https://scholar.google.com/citations?hl=en&user=qvmWZYwAAAAJ">DeWayne Shoemaker</a> from the University of Tennessee described the mini flies – particularly biting midges and gall midges – that get the job done. “Pollinators must pick up pollen from the male parts of a flower of one tree and deposit it on the female parts of a flower on another tree,” Shoemaker wrote.</p>
<p>But up to <a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">90% of cacao flowers don’t get pollinated</a> at all. People can hand-pollinate the little flowers, but it remains a mystery which other insects might do the job in the wild.</p>
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Read more:
<a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">Tiny cacao flowers and fickle midges are part of a pollination puzzle that limits chocolate production</a>
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<h2>4. Child labor is chocolate’s bitter secret</h2>
<p>Harvesting and processing cacao is labor-intensive. To meet this need, some farmers turn to child labor. Cultural anthropologist <a href="https://scholar.google.com/citations?user=1ErMxzgAAAAJ&hl=en&oi=ao">Robert Ulin</a> from the Rochester Institute of Technology described how the global chocolate industry is tied to inequality via exploitative labor practices.</p>
<p>“The largest chocolate companies signed a protocol in 2001 that <a href="https://theconversation.com/some-chocolate-has-a-dark-side-to-it-child-labor-179271">condemned child labor and childhood slavery</a>,” Ulin wrote. But he noted that consumers may want more information to make sure their purchase power supports “fair labor practices in the chocolate sector.” </p>
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Read more:
<a href="https://theconversation.com/some-chocolate-has-a-dark-side-to-it-child-labor-179271">Some chocolate has a dark side to it – child labor</a>
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<a href="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dog and woman, both with Easter bunny ears on" src="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.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>
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<span class="caption">Do not share your chocolates with your pooch.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/dog-and-woman-with-costume-and-easter-decorations-royalty-free-image/1359250422">F.J. Jimenez/Moment via Getty Images</a></span>
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<h2>5. Not safe for furry family members</h2>
<p>Eating a ton of chocolate is probably not a healthy choice for anyone. But even a little bit of chocolate can be deadly for dogs and cats. </p>
<p>In an article about all kinds of holiday foods that are unsafe for pets, veterinarian and researcher <a href="https://experts.okstate.edu/le.fanucchi">Leticia Fanucchi</a> from Oklahoma State University explained the chemicals in this human delicacy that can cause fatal “<a href="https://theconversation.com/holiday-foods-can-be-toxic-to-pets-a-veterinarian-explains-which-and-what-to-do-if-rover-or-kitty-eats-them-196453">chocolate intoxication</a>.” Don’t delay getting veterinary help if your pet does raid your Easter basket.</p>
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Read more:
<a href="https://theconversation.com/holiday-foods-can-be-toxic-to-pets-a-veterinarian-explains-which-and-what-to-do-if-rover-or-kitty-eats-them-196453">Holiday foods can be toxic to pets – a veterinarian explains which, and what to do if Rover or Kitty eats them</a>
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<h2>6. An enslaved chocolatier in colonial America</h2>
<p>An enslaved cook named Caesar, born in 1732, was one of the first chocolatiers in the American colonies. Historical archaeologist <a href="https://berkeley.academia.edu/KelleyFantoDeetz">Kelley Fanto Deetz</a> from the University of California, Berkeley described how Caesar “would have had to <a href="https://theconversation.com/oppression-in-the-kitchen-delight-in-the-dining-room-the-story-of-caesar-an-enslaved-chef-and-chocolatier-in-colonial-virginia-151356">roast the cocoa beans on the open hearth</a>, shell them by hand, grind the nibs on a heated chocolate stone, and then scrape the raw cocoa, add milk or water, cinnamon, nutmeg or vanilla, and serve it piping hot.”</p>
<p>Cocoa was a hot commodity for Virginia’s white elite during this period, when it was a culinary component – along with pineapples, Madeira wine, port, champagne, coffee and sugar – of the Columbian Exchange.</p>
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Read more:
<a href="https://theconversation.com/oppression-in-the-kitchen-delight-in-the-dining-room-the-story-of-caesar-an-enslaved-chef-and-chocolatier-in-colonial-virginia-151356">Oppression in the kitchen, delight in the dining room: The story of Caesar, an enslaved chef and chocolatier in Colonial Virginia</a>
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<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/203096/count.gif" alt="The Conversation" width="1" height="1" />
Two food scientists, an entomologist, an anthropologist, a veterinarian and a historian walk into a bar (of chocolate) and tell bitter and sweet stories of this favorite treat.Maggie Villiger, Senior Science + Technology EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1543342021-02-10T13:14:11Z2021-02-10T13:14:11ZTiny cacao flowers and fickle midges are part of a pollination puzzle that limits chocolate production<figure><img src="https://images.theconversation.com/files/382043/original/file-20210202-23-1me4d8a.jpg?ixlib=rb-1.1.0&rect=18%2C9%2C6211%2C4138&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Only 10%-20% of cacao flowers are pollinated.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/chocolate-bar-cocoa-powder-cocoa-beans-and-cocoa-royalty-free-image/1193489803">carlosgaw/E+ via Getty Images</a></span></figcaption></figure><p>It’s almost impossible to imagine a world without chocolate. Yet cacao trees, which are the source of chocolate, are vulnerable. </p>
<p>I am a passionate chocolate lover <a href="https://scholar.google.com/citations?hl=en&user=qvmWZYwAAAAJ">and an entomologist</a> who studies cacao pollination. The crop’s sustainability currently appears to depend on several species of tiny fly pollinators, who are frankly struggling to get the job done. </p>
<h2>Thousands of flowers</h2>
<p>Chocolate is derived from the seeds of the cacao tree, <em>Theobroma cacao L.</em>, which literally means “food of the gods.” The plant <a href="https://doi.org/10.1038/s42003-018-0168-6">originated in the Western Amazon region of South America</a> and has been cultivated for more than 3,000 years in many parts of Central and South America. Today it’s grown in equatorial regions around the world, including western Africa and several tropical regions in Asia. </p>
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<a href="https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Trunk and branches of cacao tree covered in tiny flowers." src="https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.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">Cacao blossoms are unusual for a tree.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cacao-flowers-on-tree-royalty-free-image/1137440314">dimarik/iStock via Getty Images Plus</a></span>
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<p>A mature cacao tree can produce many thousands of flowers each year. These flowers are tiny, only a half inch or so in diameter (1-2 cm). The flowers typically grow in clusters <a href="https://upf.com/book.asp?id=9780813030449">directly from the trunk of the tree or off large branches</a>. </p>
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<img alt="Close-up of cacao pod on a tree." src="https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Pods can be green, white, yellow, purplish or red in color.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-cacao-fruit-on-tree-royalty-free-image/1205928514">Neilstha Firman/EyeEm via Getty Images</a></span>
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<p>Each flower requires pollination to successfully produce a nearly football-sized fruit – a pod containing 30-60 seeds, which can be processed to make chocolate. </p>
<p>It sounds straightforward but, in fact, successful <a href="https://doi.org/10.1016/j.ppees.2010.02.005">cacao pollination is problematic</a> in many regions. Only around 10%-20% of the flowers produced by a cacao tree are successfully pollinated. The rest, <a href="https://doi.org/10.1016/j.agee.2017.05.021">up to 90%, never receive pollen</a> – or do not receive enough pollen to create fruits.</p>
<p>Scientists don’t fully understand cacao pollination, which is surprising given that over 50 million people worldwide currently <a href="https://www.iisd.org/ssi/commodities/cocoa-coverage/">depend on chocolate for their livelihood</a>. </p>
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<a href="https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A midge on human skin." src="https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.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">In the U.S., some midges are better known as ‘no-see-ums.’</span>
<span class="attribution"><a class="source" href="https://eol.org/media/7472715">tompiast</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<h2>A big job for a tiny fly</h2>
<p>The insects responsible for pollinating cacao’s tiny flowers are, themselves, also tiny, in order to access the flower’s reproductive structures. <a href="https://doi.org/10.1016/j.agee.2017.05.021">Biting midges from the <em>Ceratopogonidae</em> family and gall midges from the <em>Cecidomyiidae</em> family</a> are among the most important known cacao pollinators worldwide. </p>
<p>The majority of cacao trees are what are known as <a href="https://doi.org/10.1093/jxb/erx293">self-incompatible</a>, meaning they cannot pollinate themselves. Successful pollinators must pick up pollen from the male parts of a flower of one tree and deposit it on the female parts of a flower on another tree. </p>
<p>Cacao flowers are also short-lived, typically receptive to pollen for only one or two days. Flowers that do not receive ample pollen <a href="https://doi.org/10.1016/j.agee.2017.05.021">die and fall within 36 hours</a> of opening.</p>
<p>Evidence suggests <a href="https://doi.org/10.1002/eap.1491">improving midge habitat</a> can increase fruit yield. So, in some cacao-growing areas, current farming practices include developing and maintaining suitable ground habitat within and near cacao orchards in an effort to increase the number of midges capable of pollen transmission.</p>
<h2>Lingering mysteries</h2>
<p>The <a href="https://doi.org/10.21273/HORTSCI12852-18">success of artificial or hand pollination</a>, which can more than double yields, shows cacao trees are capable of producing many more pods than they currently do.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/lXe-xptz2Nk?wmode=transparent&start=272" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Workers at a cacao farm in Ghana demonstrate how they hand-pollinate the tree’s flowers.</span></figcaption>
</figure>
<p>It’s hard not to wonder: Why aren’t midges doing a better job of pollinating cacao flowers? Scientists think part of the answer might be that midges <a href="https://doi.org/10.1007/s10886-019-01118-9">don’t solely depend upon cacao flowers for their life cycle</a>. Because they can get sugar from other plant sources, they are likely passive rather than active pollinators of cacao. Scientists also wonder if they are up to the task of flying the significant distances between wild trees.</p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>All of which begs the question: Are there insects better designed for the job? And, if so, where did they go?</p>
<p>Most studies linking midges to cacao pollination were conducted in orchards, while the biology of wild cacao pollination is almost completely unstudied. </p>
<p>One exception is a study that looked at <a href="https://doi.org/10.1007/s10457-016-0019-8">both cultivated and wild cacao in Bolivia</a>. It found that midges represented only 2% of all insect visitors to wild trees. Other flies and tiny wasps were more common there. </p>
<p>These results are intriguing and raise the possibility that one or more unknown insects are the primary pollinators of cacao in the wild. Only additional study of wild cacao may reveal if this is the case. Such information could have far-reaching implications for the chocolate industry.</p><img src="https://counter.theconversation.com/content/154334/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>DeWayne Shoemaker works for the University of Tennessee Institute of Agriculture</span></em></p>Entomologists wonder if the insects currently pollinating farmed cacao are the right ones for the task.DeWayne Shoemaker, Professor and Department Head, Entomology and Plant Pathology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/985862018-06-20T10:16:21Z2018-06-20T10:16:21ZIn praise of the midges pestering footballers in the World Cup<p>England’s opening match in World Cup 2018 was a dramatic clash between Gareth Southgate’s Young Lions and <a href="https://www.bbc.co.uk/sport/football/44519710">several million gnats</a>, not to mention Tunisia’s wrestling footballers. England pulled a win out of the bag <a href="https://www.bbc.co.uk/sport/football/44533213">at the last minute</a> – but only after a gruelling fight with some determined insects. Those plucky gnats also had to fight off the insecticide treatments of nearby swamps and insect repellent sprays deployed by the team and the media. </p>
<p>I suppose this could open up new possibilities for product endorsement – in addition to the usual shampoo and shaving adverts – if you need to <a href="https://www.youtube.com/watch?v=GmLNoHMnvEA">shave your chest</a> and remove any unsightly insect life that might have got stuck to you during a game.</p>
<p>But, despite the bad press, these swarms of midges are a very heartening sight. The last year has seen a series of reports spotlighting the grim decline of insect abundance in Europe (notably <a href="https://www.researchgate.net/profile/Theo_Zeegers/publication/325206013_Analysis_of_insect_monitoring_data_from_De_Kaaistoep_and_Drenthe/links/5afdcf30aca272b5d80f3ae0/Analysis-of-insect-monitoring-data-from-De-Kaaistoep-and-Drenthe.pdf">long-term data from Germany</a>) which has provoked headlines of ecological Armageddon and a fond nostalgia for the days of <a href="https://theconversation.com/the-moth-snowstorm-an-environmental-call-to-arms-as-powerful-as-silent-spring-67576">bug-filled countryside jaunts</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1008714393868218368"}"></div></p>
<p>The trouble is that while bees and butterflies readily gain our sympathy, other vital groups that do much of the pollinating and other crucial work that helps keep the planet turning have a dodgier reputation. Of all the bugs, it is flies that may be the hardest to like. The ones that generally attract our attention sit around on poo, vomit on our food or bite us for blood. </p>
<p>Flies can take little solace from their place in high culture. Shakespeare points out their appetite for public casual sex (King Lear, Act 4), while the Old Testament threatens plagues on multiple occasion in Exodus, or the Book of Isiah where they are summoned from the furthest rivers (which at least shows an appreciation of the powers of gnat dispersal).</p>
<p>But we dismiss flying “pests” at our peril – and the Volgograd pitch invaders may be a particularly important group for our welfare – if we can work out what they are.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1008877657159884802"}"></div></p>
<p>The precise identification of the pesky Volgograd Diptera (fly) is uncertain: are they mosquitoes, midges or gnats? The general abundance and behaviour suggests midges – but midges come in many forms. In much of the northern temperate world the biting midges of the family Ceratopogondiae are notorious. The UK version – the Highland Midge – is credited with <a href="https://must-see-scotland.com/midges-in-scotland/">scaring away tourists</a> from Scotland. They are tiny but determined females in search of a blood meal. They get in ears, eyes and noses and make them a tickling mess. </p>
<p>However the Volgograd midges seem bigger, almost beautiful as they sparkled in the setting sun, much more like Chironomidae – so called non-biting midges. Lacking the bloodthirsty reputation of their biting cousins, it is easy to take the Chironomidae for granted – but they deserve our thanks. </p>
<h2>Fighting pollution</h2>
<p>In countries with sewage treatment works it is Chironomidae larvae that do much of the sewage processing, preventing the gross pollution of waterways. Sewage treatment commonly involves filtering out the larger debris we flush away, then dribbling the resulting liquid slowly through large gravel beds. In these gravel beds, billions of midge larvae feast on the organic soup, turning much of our waste in midge biomass. This is why sewage plants are often prized by bird watchers as the sheer quantity of flies that eventually emerge make a great food source, attracting all sorts of avian visitors.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A non-biting Chironomidae on a pine needle.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/nonbiting-midget-chironomidae-on-pine-needle-285316016?src=nrw4rY3MY0hwClZjodK-_g-1-20">Shutterstock/HenrikLarsson</a></span>
</figcaption>
</figure>
<p>The midge’s larvae are tough. Some species hang on in severely degraded rivers, familiar as “blood worms” – vivid red because of haemoglobin in their bodies to glean the limited oxygen from the mud. Each midge may be tiny but hatching numbers are colossal. East African rift valley lakes may seem to smoke <a href="https://www.bbc.co.uk/programmes/p0065wmb">as rising clouds of Chironomidae</a> emerge. </p>
<p>The massive swarms can be harvested, squished into midge-balls and eaten by lakeside villagers. Midge swarms seem to show <a href="http://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1003697">remarkable collective manoeuvres</a>, individual midges adjusting velocity and direction response to their immediate neighbours, detecting shifts up to at least a centimetre away (although studies do not account for the impact of footballers waving their hands about).</p>
<p>Evening is prime time for swarms as males dance in the hope of attracting a mate, so the Volgograd kick-off was perfectly timed to attract midge trouble as millions of males, newly emerged and looking their best, hit the town. Let’s not be too down on midges. The 2-1 scoreline will encourage England fans. For those who appreciate flies, the dancing swarms will also gladden the heart.</p>
<hr>
<p><em>More evidence-based articles about football and the <a href="https://theconversation.com/uk/topics/world-cup-2018-11490?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">World Cup</a>:</em></p>
<ul>
<li><p><em><a href="https://theconversation.com/how-to-keep-footballers-fit-and-fuelled-for-a-world-cup-97803?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">How to keep footballers fit and fuelled for a World Cup</a></em></p></li>
<li><p><em><a href="https://theconversation.com/world-cup-all-the-ways-footballers-and-fans-can-be-hacked-97572?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">World Cup: All the ways footballers and fans can be hacked</a></em></p></li>
<li><p><em><a href="https://theconversation.com/world-cup-var-technology-is-transforming-the-beautiful-game-97907?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">World Cup VAR: technology is transforming the beautiful game</a></em></p></li>
</ul><img src="https://counter.theconversation.com/content/98586/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Jeffries 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>Footballers came under attack from a swarm of flies on the Volgograd pitch. But there’s more to midges and gnats than meets the eye.Mike Jeffries, Associate Professor, Ecology, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/818442017-07-31T15:27:37Z2017-07-31T15:27:37ZAaargh midges: but Scotland’s bitey critters may hold the key to malaria<figure><img src="https://images.theconversation.com/files/180364/original/file-20170731-18350-1r6botc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bonnie Scotland. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/swarm-midges-culicoides-impunctatus-scotland-560352292?src=FiD3wFGKZ7QWxxA3jQOSZQ-1-1">Malago</a></span></figcaption></figure><p>Even among the greatest enthusiasts for visiting Scotland in the summertime, few would miss the ravenous midge. <em>Culicoides impunctatus</em> is a persistent biter of outdoor types, occurring in vast numbers in some of the most beautiful parts of the countryside. </p>
<p>But if midges make it harder to enjoy the Scottish outdoors, there may soon be an important consolation. Work began by researchers several decades ago to help understand why they prefer certain types of people is informing new research into another bloodsucker whose feeding habits can be deadly: the mosquito. If it succeeds, the results could make a big difference in the battle against malaria. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=640&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=640&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=640&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=804&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=804&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180365/original/file-20170731-29992-1n3czhw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=804&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 bloody chamber.</span>
<span class="attribution"><span class="source">Steve Archibald/Institute for Animal Health</span></span>
</figcaption>
</figure>
<p>Midges are in their element in the Scottish Highlands in wet <a href="http://www.wildlifetrusts.org/wildlife/habitats/lowland-dry-acid-grassland">acid grassland</a> among rushes, sphagnum mosses and silver birch, where rainfall is more than 125cm a year. The minute worm-like larvae live in the soil over winter, emerging as adults in June. </p>
<p>The blood-sucking females spend the months until October attacking people and animals voraciously to gain protein to grow their eggs. They are particularly active at dawn and dusk <a href="http://connection.ebscohost.com/c/articles/10746498/biting-midge-chemical-ecology">and also</a> on damp still days when cloud levels are low, since this favours their flight activity. As many as 40,000 could land on one forearm in a single hour, we <a href="http://connection.ebscohost.com/c/articles/10746498/biting-midge-chemical-ecology">have estimated</a>. </p>
<p>Little wonder that complaining about itchy red bites from midges is a Scottish literary tradition. One particularly good example was penned by Edward Burt, a civil engineer during military road construction in the 1730s. <a href="https://www.birlinn.co.uk/Midges-in-Scotland-9781841589381.html">He wrote</a>: </p>
<blockquote>
<p>I have been vexed with a plague of Malhoulakins that bore with their little augers turning the face to red and causing great wrath and curses of the little vermin.</p>
</blockquote>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180360/original/file-20170731-15340-1m518wl.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">It sucks!</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/45535917@N07/4850264643/in/photolist-8oASGt-Tvk6nD-Wg9AeK-Fwr7Gh-9S7DH7-TFcGAb-oCCJQe-SJiiBF-opkj5y-cnP2dj-VMEnkN-aZXjic-oKcDks-adWxUV-aZXiLk-aZXjFK-q8tvbn-pyZH4K-7gFdvD-pxfvwm-39e9k-qFKmXa-nMmnLU-byyavi-dZW24C-7gqVzx-byybeT-4TcPF8-qSg8Qw-d17HsU-9V8k8K-k5j91-89RjFe-F9kwg-isjyy-5i8EWL-aoY1vj-fv2JDC-77YDmM-fDYfmG-bEUFi4-rMoy8V-eGwcdH-89RhUH-dH9ipT-ngJBaj-oJRZuG-a3To4f-dge5KG-SJiizg">Anja Jonsson</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Rules of attraction</h2>
<p>One persistent question about midges over the years has been why some people are attacked by them more than others. This fascinating phenomenon was the subject of a study around 15 years ago by University of Aberdeen, Rothamsted Research and the London School of Hygiene and Tropical Medicine. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=570&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=570&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=570&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=716&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=716&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180351/original/file-20170731-16085-kgn07w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=716&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chemical collection.</span>
<span class="attribution"><span class="source">Mordue/Logan</span></span>
</figcaption>
</figure>
<p>Volunteers were asked to bare their flesh on the west coast of Scotland to separate the “midge magnets” from the people who get left alone. Next, their body odour was collected by putting the volunteers inside large bags and extracting the air through filters to trap the chemicals (see right). </p>
<p>Finally, an experiment was done where the human odour extracts were blown over midge antennae, connected to mini-electrodes, to identify the compounds the insects could detect in human odour. It was <a href="https://www.ncbi.nlm.nih.gov/pubmed/19351071">found that</a> the people who don’t attract midges produce natural repellents. It’s <a href="https://theconversation.com/chemical-attraction-why-mosquitos-zone-in-on-some-people-but-not-others-40705">as though</a> their bodies have a natural defence. </p>
<p>As a result of this discovery, a new generation of products with natural human-derived repellents is under development. But most importantly, it also helped inform <a href="https://malariajournal.biomedcentral.com/articles/10.1186/1475-2875-9-239">work on mosquitoes</a>. As with midges, it was discovered that some people produce compounds which give them a natural defence against these carriers of malaria, dengue and Zika. Malaria alone <a href="http://www.who.int/features/factfiles/malaria/en/">kills</a> hundreds of thousands of people every year. </p>
<h2>Repulsive families</h2>
<p>But these findings still left many unanswered questions about the genetics of such compounds. <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/1471-2458-10-275">Another study</a> conducted on the shores of Loch Ness revealed that attractiveness to midges runs in families. And through <a href="https://www.lshtm.ac.uk/newsevents/news/2015/twins_mosquito_study.html">work on</a> identical and non-identical twins, it was shown that the trait for being unattractive to biting insects was highly heritable. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180367/original/file-20170731-20214-1e3cd2n.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">Shore thing.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/simonvarwell/2699920142/in/photolist-fvicE3-fv3Ub2-fv3TRM-fws9sS-fwcSS8-fvibn5-fvib4f-fws8Cw-fwsa6E-fwcTHi-ajdtbr-6o3dTY-6nY1qB-KP7M3s-57zNch">Simon Varwell</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The London School of Hygiene and Tropical Medicine <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0122716">has now</a> received a grant from the Medical Research Council to work on identifying the genes that control the production of natural repellents in people in the UK and also in The Gambia. The hope is that in the next few years, this will unlock new ways of controlling diseases like malaria, including a pill that would cause the body to release natural repellents. </p>
<p>If so, it might be time for Scots and others to learn to love the irksome midge. It might have annoyed people since time immemorial. But if it helps to solve one of the world’s greatest public health problems, maybe all those bites will have been worth it after all.</p><img src="https://counter.theconversation.com/content/81844/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Logan receives funding from the Medical Research Council. </span></em></p><p class="fine-print"><em><span>A. Jennifer Mordue 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>Wondering why the Good Lord gave Culicoides impunctatus to Scotland? This might be the best answer yet.A. Jennifer Mordue, Emeritus Professor of Zoology, University of AberdeenJames Logan, Professor of Disease Control, London School of Hygiene & Tropical MedicineLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/641382016-08-19T15:22:16Z2016-08-19T15:22:16Z‘Canary species’ can sing songs that warn of ecosystem collapse<figure><img src="https://images.theconversation.com/files/134784/original/image-20160819-30383-191n1f1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some midge species can act as an early warning system.</span> <span class="attribution"><span class="source">simak</span></span></figcaption></figure><p>Too big to fail. That expression could often be heard in 2008. The meltdown in the international banking system was choking off the supply of cash to finance and industry. The US, the UK and other nations rushed through moves to shore up teetering corporations. General Motors was <a href="http://www.reuters.com/article/us-autos-gm-treasury-idUSBREA3T0MR20140430">bailed out</a> while the British bank Northern Rock <a href="https://www.nao.org.uk/report/hm-treasury-the-nationalisation-of-northern-rock">was nationalised</a> and brought under control by the government. To not act would have been to risk large sections of our globalised economy <a href="https://www.theguardian.com/business/2015/aug/03/rbs-sale-fred-goodwin-bailout-years-of-losses">going to the wall</a>. </p>
<p>We can think of these large corporations as “keystone species” in an economic ecosystem. Remove them and the entire system can come crashing down. This may support the view that the affairs of smaller corporations can be safely ignored. Businesses go bust every day. However, there may be vital information about the state of entire economies lurking in data about seemingly inconsequential businesses. </p>
<p>The natural world is subject to the same sort of process. If we are to avoid a collapse in ecosystems then we may be best served by monitoring the presence and absence of species great and small, as they all give important information as to the underlying health or resilience of a system. This is the conclusion of new research we conducted as part of an international team, and <a href="http://onlinelibrary.wiley.com/doi/10.1002/ecy.1558/abstract">published in Ecology</a>.</p>
<h2>Detecting trouble ahead</h2>
<p>Given humanity’s continual <a href="https://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432">assault on biodiversity</a>, we risk producing rapid changes that can sweep through an entire ecosystem. Such changes are called <a href="https://theconversation.com/understanding-transitions-may-be-critical-to-our-survival-28378">critical transitions</a> and have been observed in kelp forests, drylands, shallow lakes or even in the <a href="https://www.theguardian.com/environment/2016/jul/21/sections-of-great-barrier-reef-suffering-from-complete-ecosystem-collapse">total ecosystem collapse</a> of portions of the Great Barrier Reef. Very few ecosystems are not being affected in some way. </p>
<p>If we could get an early warning of critical transitions, then we may be able to put in place changes to avoid future collapse. Searching for these warning signals has become a <a href="http://www.nature.com/nature/journal/v461/n7260/full/nature08227.html">hot research topic</a>. </p>
<p>The theory underlying much of this work is that ecosystems can take multiple stable states. For example, a freshwater lake can have clear water, and an abundance of plants and fish species. It can also be a cloudy, dark green algal soup with very few plants and fish. Lakes can flip from clear to cloudy water state in a matter of weeks – a classic critical transition, which powerful feedback loops make very hard to reverse.</p>
<p><a href="http://water.usgs.gov/edu/phosphorus.html">Phosphorus-rich fertiliser</a> used in surrounding fields often drives such critical transitions in lakes by promoting plant growth. Up to a point. Very high phosphorus levels lead to an increase in algae which can suddenly erupt in large blooms that block out light. This initiates a die back of plants which, along with a number of other chemical changes in the water and lake sediment, increases phosphorus even further. New feedback loops keep high concentrations of phosphorus, dense algae colonies and very little else. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/134782/original/image-20160819-30363-mzgw3a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/134782/original/image-20160819-30363-mzgw3a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=323&fit=crop&dpr=1 600w, https://images.theconversation.com/files/134782/original/image-20160819-30363-mzgw3a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=323&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/134782/original/image-20160819-30363-mzgw3a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=323&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/134782/original/image-20160819-30363-mzgw3a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=406&fit=crop&dpr=1 754w, https://images.theconversation.com/files/134782/original/image-20160819-30363-mzgw3a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=406&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/134782/original/image-20160819-30363-mzgw3a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=406&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Once a lake looks like this, there’s often no going back.</span>
<span class="attribution"><span class="source">Nagel Photography/Shutterstock</span></span>
</figcaption>
</figure>
<p>This matters because lakes provide a wide range of ecosystem services that support surrounding communities. Lakes such as <a href="http://www.resalliance.org/tdb-database/105">Erhai in China</a> have witnessed very rapid increases in population around it, agriculture and farming. This produces algae blooms that can decimate fishing and so threaten livelihoods. Tourism can also be affected given that clear waters and a wide range of species bring many people to the region.</p>
<p>Early warning signals have been <a href="http://www.nature.com/nature/journal/v492/n7429/full/nature11655.html">detected in lakes</a> that have experienced critical transitions. As the system is being driven from the clear water to the cloudy water stable state, statistical analysis of variables such as the concentration of phosphorus in the water can show that the system is approaching a <a href="http://www.early-warning-signals.org/tag/critical-slowing-down">tipping point between the two states</a>. A recent study <a href="http://link.springer.com/article/10.1007/s12080-013-0186-4">detected early warning signals</a> in lake Erhai. The key challenge of course is to detect the earliest signal, so as to have the best chance of taking action to avoid a collapse, while also minimising the chance of false alarms.</p>
<h2>Diving deeper into lake behaviour</h2>
<p>We wanted to see if changes in algae and non-biting midges could predict a critical transition. Why these species? Because their remains are well persevered in sediment found on the bed of the lake. Along with traces of pollen and indicators of water chemistry, these remains allow us to read the history of the lake.</p>
<p>Using sediment cores from lake Erhai and other Chinese lakes, some of which have undergone critical transitions in the past 50 years, we were able to reconstruct algae and midge communities. From these data we identified three key types: strongly competitive but slowly reproducing “keystone” species; weakly competitive but fast reproducing “weedy” species; and slowly reproducing and weakly competitive “canary” species. Like canaries <a href="http://news.bbc.co.uk/onthisday/hi/dates/stories/december/30/newsid_2547000/2547587.stm">that coal miners used to check for poisonous gasses</a> deep underground, ecosystem canaries are often the first to disappear. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/134785/original/image-20160819-30400-1v26x40.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&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 study looked at a major group of algae known as diatoms. Some species are canaries, others keystones.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:Diatom2.jpg">wipeter</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>But we cannot rely on just looking for their removal from the population, because these canary species are continually appearing then disappearing. We need to link their presence or absence to changes in the competitive interactions between the three types of algae and midge communities. </p>
<p>Low phosphorus lakes have a healthy turnover of keystones, weedy and canary species. As phosphorus levels rise, strongly competitive algae keystone species proliferate at the expense of canary species until the keystones eventually collapse themselves. This is followed by a bloom of weedy species in the absence of competition: the critical transition is complete.</p>
<p>To wait for reductions in the keystones would be to miss the window of opportunity of avoiding the collapse. Our early warning signal was able to detect an impending critical transition much sooner than other techniques that monitor phosphorus levels in the lake water, because we are looking directly at some of the ecological mechanisms that are involved in the critical transition itself. </p>
<p>As fascinating as these ecological dynamics are, ultimately our study will have worth if it can produce useful early warning techniques that can be used to monitor ecosystems in real time. And that these warnings are heeded.</p><img src="https://counter.theconversation.com/content/64138/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Dyke received funding for this research from the UK Engineering and Physical Sciences Research Council.</span></em></p><p class="fine-print"><em><span>Patrick Doncaster received funding for this work from the UK Engineering and Physical Sciences Research Council. </span></em></p>Populations of certain species collapse long before a wider ecological disaster, says new research.James Dyke, Lecturer in Sustainability Science, University of SouthamptonPatrick Doncaster, Professor of Ecology, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/551772016-02-24T11:21:41Z2016-02-24T11:21:41ZLatest threat to British livestock? Bluetongue-infected midges blown over from France<figure><img src="https://images.theconversation.com/files/112583/original/image-20160223-16459-a7t6wa.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">robbinsbox / shutterstock</span></span></figcaption></figure><p>Bluetongue disease, a virus which attacks sheep and cattle, has broken out in France, leading to fears that some time this year infected midges are likely to be blown across the channel and bring the disease to the UK, according to a recent <a href="https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/499882/qra-BTV8-UK-160212.pdf">government report</a>. </p>
<p>By mid-February <a href="http://www.oie.int/wahis_2/public%5C..%5Ctemp%5Creports/en_fup_0000019722_20160215_165159.pdf">184 farms had been infected</a> throughout France. A 150km restriction zone has been thrown up around them in an attempt to control the disease. It’s easy to see why – northern Europe’s most recent outbreak between 2006 and 2010 caused an economic loss of <a href="http://openaccess.sruc.ac.uk/handle/11262/10648">hundreds of millions of pounds</a> while more than <a href="http://www.theoneclickgroup.co.uk/documents/louping_ill/Climate%20Change%20-%20Infectious%20Diseases%20of%20Animals.pdf">2m sheep</a> across Europe have died since 1998 as a direct or indirect consequence of bluetongue. </p>
<p>Just as malaria is carried from human to human by infected mosquitoes, bluetongue is transmitted from animal to animal by female <a href="http://rstb.royalsocietypublishing.org/content/364/1530/2669">biting midges</a>. The virus mainly affects sheep, goats, cattle and deer – it doesn’t do anything to humans. </p>
<p>The name bluetongue was given for the characteristic swollen and blue-purple coloured tongue in infected animals, especially sheep. However, this is a rare feature and most don’t actually get a blue tongue at all. More common symptoms include fever, low milk production, haemorrhages, mouth and nasal ulcers and problems with reproduction. In previous European outbreaks nearly half of the infected sheep died from the disease, while mortality rates in some sheep breeds can be <a href="http://www.ncbi.nlm.nih.gov/pubmed/18620768">up to 70%</a>.</p>
<p>Meanwhile cattle often carry the virus without actually suffering from any of the symptoms. Cows can be the perfect invisible source of a bluetongue outbreak within a farm.</p>
<h2>Many-faced disease</h2>
<p>Bluetongue virus is widespread in the Americas, southern Asia, northern Australia, Africa and Europe. As with all other viruses, bluetongue is constantly mutating. Of the <a href="http://www.ncbi.nlm.nih.gov/pubmed/26129785">27 different genetic forms</a> (called serotypes) only one has caused large outbreaks in northern Europe: bluetongue serotype 8. </p>
<p>Serotype 8 emerged across northern Europe from France to Germany in 2006, 550km from <a href="http://www.ncbi.nlm.nih.gov/pubmed/18819670">previous outbreaks</a> in Italy and Spain, and reached the UK <a href="http://rstb.royalsocietypublishing.org/content/364/1530/2669">the following year</a>. A large <a href="http://www.ncbi.nlm.nih.gov/pubmed/21309456">vaccination programme</a> eventually got things under control and by 2012 northern Europe was once again declared <a href="http://eubtnet.izs.it/btnet/reports/Outbreaks.html">free of bluetongue</a>.</p>
<p>It remained that way until August 2015. The latest outbreak was first reported around Louroux-de-Bouble, a village in one of the major cattle areas in the centre of France. In total 27 cattle and 6 sheep were <a href="http://www.oie.int/wahis_2/public%5C..%5Ctemp%5Creports/en_fup_0000019722_20160215_165159.pdf">found to be infected</a>. French authorities deployed a 150km control zone around the infected farm and started <a href="http://veterinaryrecord.bmj.com/content/177/23/585.extract">localised vaccinations</a>. </p>
<p>It’s thought unlikely that this will stop the spread of bluetongue. While the majority of today’s infected farms are concentrated to the south of the first infection, the latest – reported on February 10 – was found 200km to the north.</p>
<h2>What happens next</h2>
<p>If bluetongue keeps spreading northwards, aided by the mild midge-friendly winter, and arrives in the farms along France’s north coast later this year then there is a very good chance it will jump across the English channel and British livestock will become infected. A <a href="https://www.gov.uk/government/publications/qualitative-risk-assessment-bluetongue-virus-btv-8-entry-into-the-uk">UK government report</a> says there’s a 60-80% likelihood this will happen by the end of summer.</p>
<p>Midges can be carried downwind for long distances – comfortably far enough to cross the channel, which narrows to just 30km (20 miles) at the strait of Dover. Infected midge-blowing is probably what caused the UK’s 2007 <a href="http://www.ncbi.nlm.nih.gov/pubmed/22672434">bluetongue outbreak</a> and the 2012 outbreak of <a href="http://www.nature.com/articles/srep03361">Schmallenbertg</a>, another livestock disease transmitted in the same way. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/112616/original/image-20160223-16425-xi8cco.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/112616/original/image-20160223-16425-xi8cco.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/112616/original/image-20160223-16425-xi8cco.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/112616/original/image-20160223-16425-xi8cco.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/112616/original/image-20160223-16425-xi8cco.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/112616/original/image-20160223-16425-xi8cco.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/112616/original/image-20160223-16425-xi8cco.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An advanced case of bluetongue. Foot pain can cause the sheep to stand in a hunched position.</span>
<span class="attribution"><span class="source">CSIRO</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Bluetongue can also be introduced through the movement of live animals or through infected semen and embryos, but these are legally restricted and therefore <a href="https://www.gov.uk/government/publications/qualitative-risk-assessment-bluetongue-virus-btv-8-entry-into-the-uk">the risk is very low</a>. Wild boar, deer and other wildlife act as “reservoirs” for the disease, periodically passing it on to midges, and thus back into livestock. The most dangerous and unpredictable way for the disease to spread uncontrollably remains the combination of <a href="http://www.sciencedirect.com/science/article/pii/S092144881500111X">midges and infected wildlife</a>. </p>
<p>The <a href="http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2002:031:0001:0024:en:PDF">control zones</a> we currently have aren’t enough. They’re supposed to contain bluetongue outbreaks through restricting animal movements, vaccination and surveillance – yet the effectiveness of these zones has never been evaluated, so <a href="http://veterinaryrecord.bmj.com/content/early/2015/04/03/vr.102979.full">each country</a> responds in <a href="http://www.sciencedirect.com/science/article/pii/S1090023315003238">different ways</a>.</p>
<h2>Stopping the spread</h2>
<p>The exact source of this latest infection is unknown – often the case with bluetongue outbreaks – which makes it more difficult to predict the development of the disease. In the UK, vaccine production was stopped after northern Europe was declared bluetongue-free in 2012, so supplies are very limited. </p>
<p>Yet vaccination is the only way to stop the spread of the disease. Models <a href="http://www.ncbi.nlm.nih.gov/pubmed/21945148">show</a> that to prevent an outbreak, at least two-thirds of the farms at risk <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0009353">must be vaccinated</a> in a relatively short time. At the moment negotiations are in place to <a href="https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/499882/qra-BTV8-UK-160212.pdf">produce enough vaccine</a> for Britain’s sheep and cows.</p>
<p>This is going to be expensive. Farmers need <a href="http://www.ncbi.nlm.nih.gov/pubmed/26783200">more support</a> and EU or national governments should subsidise part of the cost where necessary. Environmental and animal agencies should also look out for infected midges and infected wild animals along the south coast – catching a British bluetongue outbreak as soon as possible will determine how quickly and successfully it can be controlled.</p><img src="https://counter.theconversation.com/content/55177/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Luigi Sedda received EU funding in 2011-2014 for a project on emerging and introduction of vector-borne diseases in Europe. </span></em></p>French farms have seen a major outbreak of bluetongue virus, which can be fatal for sheep.Luigi Sedda, Lecturer in Spatial Epidemiology, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.