tag:theconversation.com,2011:/global/topics/bee-disease-19034/articlesBee disease – The Conversation2023-01-20T13:37:37Ztag:theconversation.com,2011:article/1976712023-01-20T13:37:37Z2023-01-20T13:37:37ZHow do you vaccinate a honeybee? 6 questions answered about a new tool for protecting pollinators<figure><img src="https://images.theconversation.com/files/505433/original/file-20230119-14-78gogp.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C4759%2C3216&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A new vaccine promises better protection against a virulent honeybee infection. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/BeeHealth/dec03c6d562c457fa83f50032ab8a6f1/photo">AP Photo/Elise Amendola</a></span></figcaption></figure><p><em>Honeybees, which pollinate <a href="https://www.fda.gov/animal-veterinary/animal-health-literacy/helping-agricultures-helpful-honey-bees">one-third of the crops Americans eat</a>, face many threats, including infectious diseases. On Jan. 4, 2023, a Georgia biotechnology company called <a href="https://www.dalan.com/">Dalan Animal Health</a> announced that it had <a href="https://www.businesswire.com/news/home/20230104005262/en/First-in-Class-Honeybee-Vaccine-Receives-Conditional-License-from-the-USDA-Center-for-Veterinary-Biologics">received a conditional license</a> from the U.S. Department of Agriculture for a vaccine designed to protect honeybees against American foulbrood, a highly destructive infection.</em> </p>
<p><em>To receive a conditional license, which usually lasts for one year and is subject to further evaluation by the USDA, veterinary biological products must be shown to be <a href="https://www.aphis.usda.gov/animal_health/vet_biologics/publications/pel_2_2.pdf">pure, safe and reasonably likely to be effective</a>. Dr. Jennie Durant, an <a href="https://scholar.google.com/citations?user=B1qAtjIAAAAJ&hl=en">agriculture researcher</a> at the University of California, Davis, who specializes in honeybee health, explains why this vaccine is potentially an important step in ongoing efforts to protect pollinators.</em></p>
<h2>1. What threat does this vaccine address?</h2>
<p>The new bee vaccine, <a href="https://www.dalan.com/product">Paenibacillus Larvae Bacterin</a>, aims to protect honeybees from <a href="https://www.ars.usda.gov/northeast-area/beltsville-md-barc/beltsville-agricultural-research-center/bee-research-laboratory/docs/american-foulbrood-disease/">American foulbrood</a>. This highly destructive bacterial disease gets its name from the foul scent honeybee larvae exude when infected. </p>
<p>An outbreak of American foulbrood is effectively a death sentence for a bee colony and can economically devastate a beekeeping operation. The spores from the bacteria, <em>Paenibacillus larvae</em>, are highly transmissible and can remain <a href="https://pollinators.msu.edu/resources/beekeepers/diagnosing-and-treating-american-foulbrood-in-honey-bee-colonies/">virulent for decades</a> after infection. </p>
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<figcaption><span class="caption">How American foulbrood affects honeybee colonies.</span></figcaption>
</figure>
<p>Once an outbreak occurs, beekeepers typically have to <a href="https://extension.psu.edu/honey-bee-diseases-american-foulbrood#:%7E:text=American%20foulbrood%20(AFB)%20is%20a,death%20in%20only%20three%20weeks.">destroy any bee colonies</a> that they know were infected to avoid spreading the disease. They also have to destroy the hive boxes the colonies were stored in and any equipment that may have touched infected colonies. </p>
<p>Beekeepers have used antibiotics preventively for decades to keep foulbrood in check and treat infected colonies. Often they mix the antibiotics with powdered sugar and sprinkle it inside the colony box. As often happens when antibiotics are overused, scientists and beekeepers are seeing <a href="https://doi.org/10.1016/j.vetmic.2007.05.018">antibiotic resistance</a> and <a href="https://doi.org/10.1371/journal.pbio.2001861">negative impacts on hive health</a>, such as disruption of the helpful microbes that live in bees’ guts.</p>
<p>In 2017, the U.S. Food and Drug Administration began <a href="https://www.fda.gov/animal-veterinary/development-approval-process/using-medically-important-antimicrobials-bees-questions-and-answers">requiring a veterinarian’s prescription or feed directive</a> to use antibiotics for foulbrood. While this regulatory change <a href="https://www.fda.gov/animal-veterinary/animal-health-literacy/helping-agricultures-helpful-honey-bees">sought to address antibiotic resistance</a>, it limited beekeepers’ access to antibiotics and their ability to treat foulbrood preventively. The vaccine would ideally provide a more sustainable solution. </p>
<h2>2. How effectively does the vaccine prevent infection?</h2>
<p>Studies are still analyzing its effectiveness. One <a href="https://doi.org/10.3389/fvets.2022.946237">published study</a> demonstrated a 30% to 50% increase in resistance to American foulbrood in a vaccinated queen’s offspring. </p>
<p>While this might seem low, it’s important to put the results in context. Given how deadly and contagious American foulbrood is, researchers did not want to directly expose an outdoor hive to foulbrood with an unproven vaccine. Instead, they conducted lab studies where they exposed test hives to around 1,000 times the number of American foulbrood spores a colony would typically be exposed to in the field. Dalan, the manufacturer, has field trials planned for 2023. </p>
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<h2>3. How do you vaccinate honeybees?</h2>
<p>It’s not done with tiny needles – beekeepers mix the vaccine <a href="https://www.dalan.com/science">into bee food</a>. This approach exposes queen bees to inactive <em>Paenibacillus larvae</em> bacteria, which helps larvae hatched in the hive to resist infection. </p>
<p>This is not a <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html">mRNA vaccine</a>, like the Pfizer and Moderna COVID vaccines. It’s a more traditional <a href="https://www.news-medical.net/health/What-is-an-Inactivated-Vaccine.aspx">inactive vaccine</a> like the one we use against polio. To understand how the vaccine works, it’s helpful to know what queen bees eat: a protein-rich substance called “<a href="https://www.beeculture.com/royal-jelly-worker-bee-produced-protein-rich-mothers-milk/">royal jelly</a>” that is secreted from glands on the heads of young worker bees. </p>
<p>When queen bees are shipped to a beekeeper, they are typically placed in a small cage with 50 to 200 worker bees that have been fed something called queen candy. This substance is often made with powdered sugar and corn syrup and has the consistency of sugar cookie dough or modeling clay. Worker bees consume the candy, produce royal jelly and feed it to the queen.</p>
<p>The vaccine’s delivery method uses this unique system. A beekeeper can mix the vaccine with the queen candy, which is then digested by worker bees. They produce royal jelly and feed it to the queen, who digests it and then transfers the vaccine to her ovaries. Once she is transferred to the hive and begins laying eggs, the larvae that hatch from those eggs have a heightened immunity to American foulbrood.</p>
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<figcaption><span class="caption">The new vaccine takes advantage of the queen’s central role in the hive.</span></figcaption>
</figure>
<h2>4. Who will use the vaccine?</h2>
<p>According to representatives at Dalan, limited quantities of the vaccine should be available starting in spring 2023 to commercial beekeepers and bee producers, with the aim of supplying smaller-scale beekeepers and hobbyists in the future. </p>
<h2>5. How long will a dose last?</h2>
<p>Dalan is still researching the specifics. Its current understanding is that it will last as long as the queen bee can lay eggs. If she dies, is killed or is replaced, the beekeeper will have to purchase a new vaccinated queen. </p>
<h2>6. Is this a big scientific advance?</h2>
<p>Yes – it is the <a href="https://www.nytimes.com/2023/01/07/science/honeybee-vaccine.html">first vaccine for any insect in the U.S.</a> and could help pave the way for new vaccines to treat other issues that have plagued the beekeeping industry for decades. Honeybees face many urgent threats, including <a href="https://beelab.umn.edu/varroa-mites"><em>Varroa</em> mites</a>, <a href="https://theconversation.com/bees-face-many-challenges-and-climate-change-is-ratcheting-up-the-pressure-190296">climate change</a> and <a href="https://theconversation.com/poor-nutrition-may-be-another-reason-for-the-declining-honey-bee-population-48684">poor nutrition</a>, which makes this vaccine an exciting new development. </p>
<p>Dalan is also working on a vaccine to protect bees against <a href="https://www.ars.usda.gov/northeast-area/beltsville-md-barc/beltsville-agricultural-research-center/bee-research-laboratory/docs/european-foulbrood-disease/">European foulbrood</a>. This disease is less fatal than American foulbrood, but is still highly infectious. Beekeepers have been able to treat it with antibiotics but, as with American foulbrood, they are seeing signs of resistance.</p><img src="https://counter.theconversation.com/content/197671/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennie L. Durant 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>A vaccine for bees may evoke images of teeny hypodermic needles, but this product works in a sophisticated way that reflects the social structure of honeybee colonies.Jennie L. Durant, Research Affiliate in Human Ecology, University of California, DavisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1217922019-09-09T12:22:28Z2019-09-09T12:22:28ZTo save honey bees we need to design them new hives<figure><img src="https://images.theconversation.com/files/291507/original/file-20190909-109952-ngkno6.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/close-flying-bees-wooden-beehive-plenty-1399101203?src=AsbFqAb3cDNMZwdD4SoXdA-3-27">Aleksandr Gavrilychev/Shutterstock</a></span></figcaption></figure><p>Honey bees are under extreme pressure. Beekeepers in the US have been losing and then replacing an <a href="https://beeinformed.org/results/2018-2019/">average of 40%</a> of their honey bee colonies every year since 2010, a rate that is probably unsustainable and would be unacceptable in other kinds of husbandry. The biggest contributor to this decline is viruses spread by a parasite, <em>Varroa Destructor</em>. But this isn’t a natural situation. The parasite is spread by beekeeping practices, including keeping the bees in conditions that are very different from their natural abode of tree hollows.</p>
<p>A few years ago, <a href="http://dx.doi.org/10.1007/s00484-015-1057-z">I demonstrated</a> that the heat losses in man-made honey bee hives are many times greater than those in natural nests. Now, using engineering techniques more commonly found probing industrial problems, <a href="http://dx.doi.org/10.1098/rsif.2019.0048">I’ve shown</a> that the current design of man-made hives also creates lower humidity levels that favour the <em>Varroa</em> parasite.</p>
<p>Natural nests inside tree cavities create high humidity levels in which honey bees thrive and which prevent <em>Varroa</em> from breeding. So if we can redesign beekeeper hives to recreate these conditions, we could help stop the parasite and give honey bees a chance to recover. </p>
<p>The life of the honey bee colony is intimately entwined with its home. We can see this from the <a href="https://press.princeton.edu/titles/9267.html">sophisticated way</a> honey bees choose nests of the correct sizes and properties, and how hard they work to modify them. In fact, the nest can be seen as part of the honey bee itself, a concept that in biology is known as an “<a href="http://wallace.genetics.uga.edu/groups/evol3000/wiki/94a1a/Extended_Phenotype.html">extended phenotype</a>”, which refers to all the ways a creature’s genes affect the world.</p>
<p>Perhaps the most common example of an extended phenotype is that of the beaver, which shapes its environment by controlling the flow of water with dams. Nests enable honey bees to similarly adjust their environment by controlling the flow of two fluids – air and water vapour – plus something that acts like a fluid – heat.</p>
<p>The honey bees select a tree hollow with an entrance at the bottom that makes rising hot air inside the nest less likely to escape. They then modify it by applying an antibacterial vapour-retarding sealant of tree resin over the inside walls and any small holes or cracks. This further prevents any warm air leaks and helps maintain the right level of water vapour. Inside the nest, the bees build a honeycomb containing thousands of cells, each of which provides an insulated microclimate for growing larvae (baby bees) or making honey.</p>
<h2>Unnatural designs</h2>
<p>Despite the importance of nests to honey bees, the hives we build them bear little resemblance and have few of the properties of the natural tree nests European honey bees evolved with. In the 21st century, we’re still using hives designed in the 1930s and 1940s, based on ideas from the 1850s. Natural nests were only scientifically <a href="http://dx.doi.org/10.1007/BF02223477">surveyed as recently as 1974</a> and research into their <a href="http://dx.doi.org/10.1007/s00484-015-1057-z">physical properties only began in 2012</a>.</p>
<p>Man-made hives are squat and squarish (for example 45cm high), constructed from thin wood (under 2cm thick) with large entrances (around 60cm²) and often large openings of wire mesh underneath. They were designed to be cheap and for beekeepers to easily access the bees and remove the honey. In contrast, European honey bees evolved with natural tree nests that are on average tall (around 150cm), narrow (20cm) with thick walls (15cm) and small entrances (7cm²).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/288425/original/file-20190818-192258-1qv9g1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/288425/original/file-20190818-192258-1qv9g1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/288425/original/file-20190818-192258-1qv9g1b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/288425/original/file-20190818-192258-1qv9g1b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/288425/original/file-20190818-192258-1qv9g1b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/288425/original/file-20190818-192258-1qv9g1b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/288425/original/file-20190818-192258-1qv9g1b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Man-made hives versus natural nests.</span>
<span class="attribution"><span class="source">Derek Mitchell</span></span>
</figcaption>
</figure>
<p>In order to assess how well man-made hives recreate the conditions of natural nests, I needed to measure the flow of fluids (air, water vapour and heat) around them. To do that, I turned to an aspect of physical science and engineering called <a href="https://www.sciencedirect.com/topics/engineering/thermofluids">thermofluids</a>, the study of liquids, gases and solids of combustion, and changes of state, mass and energy movement.</p>
<p>In the honey bee nest, this means the “combustion” of sugars in honey and nectar, the evaporation and condensation of water, and air flow through the nest. It also includes everything being transported by the honey bees through the entrance or leaking through the walls.</p>
<p>The various barriers that honey bee nests create can be used as convenient boundaries in mathematical models of the energy needed and humidity produced inside the nest. My new study combines these models with data from <a href="http://dx.doi.org/10.1007/s00484-015-1057-z">experimental research</a> on the thermal properties of honey bee nests and hives and <a href="http://dx.doi.org/10.1016/j.jinsphys.2008.08.011">behavioural studies</a> on how honey bees ventilate their nest.</p>
<p>This enabled me to compare the average humidity in man-made hives and tree nests with that needed by honey bees and their parasites. I found that most man-made hives have seven times higher heat loss and eight times bigger entrance size than tree nests. This creates the lower humidity levels that favour the parasite.</p>
<p>My research shows the role of the honey bee nest is clearly far more sophisticated than just simple shelter. Simple changes to hive design in order to lower heat loss and increase humidity, for example using smaller entrances and thicker walls, could reduce the stress on the honey bee colonies caused by <em>Varroa Destructor</em>. <a href="http://dx.doi.org/10.1098/rsif.2018.0879">We already know</a> that simply building hives from polystyrene instead of wood can significantly increase the survival rate and honey yield of the bees. More research into the thermofluidic complexity of nests would allow us to design the optimal hives that balance the needs of honey bees with their human keepers.</p>
<p><em>This article has been amended to make clear that the average 40% of US honey bee colonies lost each year are replaced.</em></p><img src="https://counter.theconversation.com/content/121792/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Derek Mitchell is affiliated with Institute of Thermofluids, School of Mechanical Engineering, University of Leeds</span></em></p>Beehive designs haven’t changed since the 1940s.Derek Mitchell, PhD Candidate in Mechanical Engineering, University of LeedsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/924642018-02-28T05:18:20Z2018-02-28T05:18:20ZEmbattled bees face yet another potential threat – virus-carrying hoverflies<figure><img src="https://images.theconversation.com/files/208072/original/file-20180227-36686-187s74g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Bees have had a tough time for decades. The number of bee species has seen a <a href="https://www.ipbes.net/sites/default/files/downloads/pdf/individual_chapters_pollination_20170305.pdf">long-term decline</a> across Europe and North America, and <a href="https://www.theguardian.com/environment/2015/mar/19/nearly-one-in-ten-of-europes-wild-bee-species-face-extinction-says-study">many species</a> of wild bees have seen <a href="https://www.theguardian.com/us-news/2015/dec/21/wild-bees-population-decline-agriculture-farming-california-midwest">their total numbers decline</a>. And although the global population of commercially managed honeybees <a href="http://www.cell.com/current-biology/abstract/S0960-9822(09)00982-8">has long been increasing</a> as honey farming expands, the last ten years have seen individual honeybee colonies collapsing <a href="https://www.epa.gov/pollinator-protection/colony-collapse-disorder">in significant numbers</a> in the US, and to a lesser degree in <a href="https://wedocs.unep.org/rest/bitstreams/14378/retrieve">other parts of the world</a>.</p>
<p><a href="http://www.cbc.ca/news/canada/montreal/quebec-pesticides-honeybees-1.4541996">Many countries</a> have banned or restricted the use of pesticides <a href="https://www.nature.com/articles/ncomms12459">such as neonicotinoids</a> in farming because of their <a href="https://theconversation.com/new-study-pesticides-increase-extinction-risk-for-bumblebee-populations-82406">links to bee decline</a>. But this may not be enough to stem the decline, as habitat loss, disease <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0029639">and parasites</a> are also <a href="https://www.sussex.ac.uk/webteam/gateway/file.php?name=goulson-et-al-science-2015.pdf&site=411">major threats to bees</a>.</p>
<p>My colleagues and I <a href="http://dx.doi.org/10.1098/rsbl.2018.0001">have discovered</a> evidence that suggests bee viruses are being spread much more widely than previously thought thanks to another pollinating insect, the hoverfly. Urgent research is now needed to work out to what degree hoverflies are exposing bees to disease, and if the hoverfly population is also threatened.</p>
<p>Bee viruses are not uncommon. For example, they can be found in about <a href="http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12345/abstract">20% to 25% of wild bumblebee foragers</a>. From studies of <a href="http://www.caes.uga.edu/departments/entomology/research/honey-bee-program/bees-beekeeping-pollination/honey-bee-disorders/honey-bee-disorders-viral-diseases.html">honey bees</a>, we know that bee viruses can have substantial effects on the insects’ health. Some cause symptoms such as paralysis, deformities such as crippled wings, and many result in an early death. Wild bees are also affected by these viruses. For example, deformed wing virus shortens the life of a bumblebee by an <a href="https://pure.royalholloway.ac.uk/portal/en/publications/disease-associations-between-honeybees-and-bumblebees-as-a-threat-to-wild-pollinators%20(6e119009-90eb-4507-a0b7-8343be2fec0e).html">average of six days</a> (down from around six weeks in the lab).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/208081/original/file-20180227-36686-d5lkhx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/208081/original/file-20180227-36686-d5lkhx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/208081/original/file-20180227-36686-d5lkhx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/208081/original/file-20180227-36686-d5lkhx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/208081/original/file-20180227-36686-d5lkhx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/208081/original/file-20180227-36686-d5lkhx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/208081/original/file-20180227-36686-d5lkhx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Honey bee with deformed wings.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/worker-honey-bee-apis-mellifera-deformed-107151209?src=09kgicyB0oBR6Pey7FSejg-1-0">Shutterstock</a></span>
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<p>It is easy to see how humans have changed the environment for bees over the past few decades, using more pesticides and removing wildflowers from the landscape as farming has becoming more intense. But bee diseases are invisible to the casual observer, and it’s much less obvious how we could combat them. </p>
<p>Viruses are particularly important because they can evolve very quickly. This allows them to infect new species relatively easily while still affecting previously infected species. We see this every winter with new flu strains that can infect people who’ve had the disease before.</p>
<h2>Virus spreading</h2>
<p><a href="https://pure.royalholloway.ac.uk/portal/en/publications/disease-associations-between-honeybees-and-bumblebees-as-a-threat-to-wild-pollinators(6e119009-90eb-4507-a0b7-8343be2fec0e).html">Recent research</a> has shown that bee viruses can spread between commercially managed honey bees and other wild species such as bumble bees. The most likely way this happens is that infected bees contaminate flowers with their viruses, which then infect other bees that come to feed. <a href="https://doi.org/10.1098/rspb.2015.1371">We already know</a> that other bee parasites can be spread in this way.</p>
<p>Our new research shows that bees face another disease risk from hoverflies that feed at and pollinate the same flowers. Hoverflies are often mistaken for bees because of their black and yellow stripes, although they have no stings. The <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0030641">one previous study</a> that looked at this topic found no evidence for bee viruses in hoverflies. But <a href="http://dx.doi.org/10.1098/rsbl.2018.0001">new data</a> collected by Kaitlin Deutsch, formerly of Oxford University, and analysed by myself and colleagues at Royal Holloway, suggests hoverflies do indeed harbour bee viruses and that they move freely between the species.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/208077/original/file-20180227-36671-18xtxf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/208077/original/file-20180227-36671-18xtxf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/208077/original/file-20180227-36671-18xtxf7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/208077/original/file-20180227-36671-18xtxf7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/208077/original/file-20180227-36671-18xtxf7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/208077/original/file-20180227-36671-18xtxf7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/208077/original/file-20180227-36671-18xtxf7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hoverfly: copycat colour scheme.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/hoverfly-on-yellow-dandelion-flower-391744516?src=BXq2a1Ep2rvZSZAjRm6AwA-1-4">Shutterstock</a></span>
</figcaption>
</figure>
<p>Many hoverflies, including one of the species that we found bee viruses in (both drone flies), undertake <a href="https://blogs.tcv.org.uk/natural-talent/2009/09/21/the_flight_of_the_hoverfly/">large annual migrations</a> across Europe. This means hoverflies could easily spread new strains of viruses that local bees haven’t adapted to, putting them at particular risk.</p>
<p>Given that many wild bee species are already in long-term decline, it’s important that we now try to learn how much of a threat viruses pose to them, and exactly what role the hoverfly plays in spreading bee diseases. But because hoverflies are important pollinators in their own right, with some species facing <a href="https://www.theguardian.com/environment/2015/dec/08/wildlife-decline-threatens-uks-biodiversity-study-finds">their own decline</a>, we also need to find out how they are being affected by the viruses.</p>
<p>It may be possible to reduce the spread of these viruses by stopping them being so readily transferred between bees and hoverflies, perhaps by planting more flowers that attract only one or the other. </p>
<p>But for now, this discovery reminds us that bee decline is much more complex than the idea that pesticides are driving all pollinators to extinction.</p><img src="https://counter.theconversation.com/content/92464/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Bailes receives funding from the BBSRC and is a member of the British Ecological Society. The study reported here was funded by the Biotechnology and Biological Sciences Research Council and John Fell OUP Research Fund.</span></em></p>Hoverflies are helping spread disease among the already declining bee population.Emily Bailes, Post doctoral researcher, School of Biological Sciences, Royal Holloway University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/486842015-10-20T03:35:40Z2015-10-20T03:35:40ZPoor nutrition may be another reason for the declining honey bee population<figure><img src="https://images.theconversation.com/files/98260/original/image-20151013-31126-3mupea.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sunflowers contain less protein than aloe plants and bees need more of this. </span> <span class="attribution"><span class="source">Chamanti Laing</span></span></figcaption></figure><p>Honey bees are essential for pollination of wild and cultivated plants, and honey production. As a result honeybee colonies are managed all over the world. Bees and other pollinators are in the <a href="http://news.nationalgeographic.com/news/2013/13/130510-honeybee-bee-science-european-union-pesticides-colony-collapse-epa-science/">news</a> a lot more recently because they are declining in numbers, while the demand for crop production increases.</p>
<p><a href="http://www.economist.com/node/21551451">Pesticides</a> and bee <a href="http://www.dpi.nsw.gov.au/agriculture/livestock/honey-bees/pests-diseases">diseases</a> seem to draw the most attention as the cause of declining bee numbers. But nutritional stress could be another. Habitat loss and intensified agriculture lead to diminishing food resources for bees. This additional stress lowers their resistance to pesticides and diseases.</p>
<h2>Nutritional requirements of bees</h2>
<p>Adult bees need mainly carbohydrates, and sugars in nectar provide energy for foraging and thermoregulation. Their larvae need protein, fats, vitamins and minerals for growth. These nutrients come from <a href="http://health.howstuffworks.com/diseases-conditions/allergies/outdoor-allergies/what-is-pollen.htm">pollen</a>. Among solitary bees, larvae are the main pollen consumers. Honey bees differ in that the main consumers are nurse bees, young workers who digest pollen and produce jelly that they feed to the larvae, also known as brood.</p>
<p>We need to distinguish between the quality and quantity of bee food. Mass-flowering crops such as sunflower or canola provide superabundant food. But this has disadvantages: it’s for a limited period only, it increases exposure to pesticides and it is unlikely to be nutritionally balanced. Sunflower pollen for example, contains much less protein than <a href="http://www.honeybadger.co.za/sabj_7401.html">aloe pollen</a>.</p>
<p>In addition to the total amount of protein, amino acids are important. Some pollen lacks essential amino acids, or the proportions may be wrong for developing larvae. A mixed pollen diet is much better than a single pollen source.</p>
<p>In a recent <a href="https://honeymedic.files.wordpress.com/2015/03/science-2015-goulson.pdf">review</a> of bee problems, bees feeding on monoculture crops were likened to humans eating only sardines, chocolate or parsnips for a month!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98664/original/image-20151016-25152-1wgvn7d.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">Bee on an aloe plant.</span>
<span class="attribution"><span class="source">Massimo Nepi</span></span>
</figcaption>
</figure>
<h2>Nectar and pollen</h2>
<p>Nectar is mainly a solution of simple sugars; sucrose, glucose and fructose in varying proportions. It also contains amino acids but in much smaller amounts. Water has to be removed from the nectar before storage as honey. This is achieved by repeated regurgitation and evaporation in the hive.</p>
<p>Pollen is much more complex. Much of its nutritional value is in the protein - this can be more than half the dry mass. When bees collect pollen they add nectar to stick the grains together for transport on their legs, so pollen brought into the hive contains extra sugar.</p>
<p>This stored pollen is known as bee bread. It’s been assumed that microbes in stored pollen improve its nutritional value through fermentation, but recent <a href="http://www.nzbees.net/threads/pollen-nutrition-research.6009/">research</a> has shown that microbes are essentially absent. In fact the added nectar has a preservative function. This confirms our analyses of sunflower and aloe pollens, which do not change in composition during storage.</p>
<p>Social existence makes nutrient regulation more complex. Does a bee forage for herself or the colony? Foraging bees tend to specialise in either nectar or pollen collection, but they forage for the whole colony. Its protein requirements depend on the worker/brood ratio. More brood means a greater need for pollen protein. Storage of food resources as honey or bee bread can buffer nutritional imbalances to some extent.</p>
<h2>Interacting effects of disease, pesticides and nutrition</h2>
<p>Honey bees are plagued by many parasites and pathogens that can affect their health. Multiple pathogen infections are common, often associated with the parasitic mite <a href="http://entnemdept.ufl.edu/creatures/misc/bees/varroa_mite.htm">Varroa destructor</a>. This infects most managed colonies world-wide and also transmits viral diseases. </p>
<p>Some pathogens have a direct influence on nutrition. The gut parasite Nosema competes with host bees for carbohydrates, placing them under energetic stress, and interferes with digestion. Poor nutrition in honey bees, as when consuming a single pollen type compared to a mixture, reduces their immunity to infection.</p>
<p>Malnourished honey bees may also be less efficient at detoxifying pesticides. The widely used neonicotinoids are systemic pesticides that spread throughout plant tissues and into <a href="http://www.npr.org/sections/thesalt/2013/03/27/175278607/are-agricultures-most-popular-insecticides-killing-our-bees">nectar and pollen</a>. Apart from direct toxicity, they have been shown to have subtle, sublethal effects on flight, navigation and learning in bees. This behaviour is important for food collection. A recent study showing that bees can’t taste neonicotinoid pesticides is especially <a href="http://www.bbc.com/news/science-environment-32399907">worrying</a>.</p>
<p>Even without going out to forage, honey bees are exposed to multiple pesticides at home. Many toxic chemicals end up in stored pollen in the <a href="http://www.honeycolony.com/article/honeybee-pollen-contaminated-cocktail-pesticides/">hive</a>, including the miticides that are used by beekeepers to combat Varroa.</p>
<p>These complex interactions between poor nutrition and other stress factors contribute to poor health of both wild and managed honey bees. But there are ways to improve bee nutrition. An obvious one is preserving semi-natural habitat in farmland, so that wild flowers sustain the bees and add variety to their diet.</p><img src="https://counter.theconversation.com/content/48684/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sue Nicolson receives funding from the National Research Foundation of South Africa.</span></em></p>Nutrition is another factor - in addition to pesticides and bee disease - that has led to the dwindling of the global bee population.Sue Nicolson, Professor of Zoology, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/479542015-10-08T03:39:27Z2015-10-08T03:39:27ZHow African honey bees can help mitigate global colony losses<figure><img src="https://images.theconversation.com/files/97397/original/image-20151006-7349-1d1ub7l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The African honeybee is more resistant to pests and pathogens than its European counterparts.</span> <span class="attribution"><span class="source">Jon Hrusa/EPA</span></span></figcaption></figure><p>Managed honeybee population stocks are declining in many <a href="http://www.ibra.org.uk/articles/Guest-Editorial-Honey-bee-colony-losses">countries</a>, worrying scientists, the public and politicians. This decline affects us all, as it poses a risk to food security. </p>
<p>Honeybees can be moved where needed and are not picky about the flower they visit to collect pollen and nectar which they feed on. Thanks to these qualities, they are the major crop pollinators relied on by humans. The honeybee equals and sometimes surpasses all other wild pollinators for this task. </p>
<p>In the last decade, many studies focused on honeybee health to identify the causes of unusually high colony losses. Most of this work has been performed in <a href="http://www.ibrabee.org.uk/index.php/component/k2/item/3131">Europe</a> and <a href="http://www.ibra.org.uk/articles/US-honey-bee-colony-mortality-2012-13">North America</a> where bees are exploited in large scale commercial operations. Scientists observe interactions of many factors affecting honeybee <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0043562">health</a>. </p>
<p>But these results are so far not sufficiently clear to understand the causes of the declines and implement adapted mitigation measures. Scientists and beekeepers will first need to understand the reasons for deaths amongst bees before they can adjust their practices to ensure the stocks’ survival.</p>
<p>Honeybee health status or even basic data of population sizes in the wild before the modern beekeeping area is unknown. We lack important information to evaluate the severity of the current problem. Understanding how bees deal with pests, pathogens and other environmental factors in Africa, where beekeeping has not been as intrusive, could help scientists understand more about why the bees of Europe and North America struggle. </p>
<h2>How can African honeybees help?</h2>
<p>The honeybee, <em>Apis mellifera</em>, is also present in <a href="http://entnemdept.ufl.edu/creatures/misc/bees/ahb.htm">Africa</a>. In contrast to the docile European honeybees, African honeybees are more <a href="http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Apis_mellifera_scutellata.htm">aggressive</a> to beekeepers and are rarely confined to man-made hives. The majority of their estimated 310 million colonies strong <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2009.01331.x/suppinfo">population</a> is <a href="http://edis.ifas.ufl.edu/mg113">wild</a> and lives in natural cavities in trees or ground. </p>
<p>A lack of data on the health status of African honeybees has prompted several international teams to investigate this issue in recent years. In attempting to deal with the problem of colony losses, beekeepers and scientists throughout the world posed the following questions:</p>
<ol>
<li><p>Is it possible that by developing beekeeping to the current industrial level, we pushed the honeybees to their biological limits? When managing these pollinators, do we place them in such unnatural situations that they are weakened?</p></li>
<li><p>Was the selective breeding used to improve desirable traits such as honey production or docility done at the expense of their defence mechanisms? </p></li>
<li><p>Does the wide scale honeybee trade result in the spread of damaging pathogens to which the honeybees are not adapted? </p></li>
</ol>
<p>By studying African honeybees in their unique <a href="http://www.apidologie.org/articles/apido/abs/2009/03/m08180/m08180.html">context</a>, we could obtain the answers.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/97425/original/image-20151006-7375-1akj0fi.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">Bee with deformed wings caused by a virus transmitted by the varroa mite.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Increased knowledge on African honey bee health</h2>
<p>Recent health surveys indicated that honeybee populations in <a href="http://www.sciencedirect.com/science/article/pii/S0022201113000748">South Africa</a>, <a href="http://www.sciencedirect.com/science/article/pii/S0022201110000571">Uganda</a>, <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0094459">Kenya</a> and <a href="http://link.springer.com/article/10.1007%2Fs13592-015-0372-z">Benin</a> are indeed healthy. Pathogens, either endemic or imported, are present but do not at this time seem to generate unusual and widespread mortality. A notable exception is the damage done by a certain <a href="http://www.ibra.org.uk/articles/Colony-losses-in-South-Africa-2009-11">honeybee</a>. A particular honeybee lineage originating in the Cape region in South Africa functions as a social <a href="http://www.americanscientist.org/issues/pub/2002/9/attack-of-the-pseudo-clones">parasite</a>.</p>
<p>To promote its own reproduction, this parasitic honeybee invades colonies of other subspecies and exhausts their resources until they dwindle to death. Tens of thousands of managed colonies in the hands of the beekeepers have been lost to this parasite, while the wild populations still living in natural nests fortunately seem spared. This means that beekeepers are seen as the vectors of the parasitic bee as it largely affects managed <a href="http://www.apidologie.org/articles/apido/abs/2006/04/M6021/M6021.html">honeybees</a>. </p>
<p>This phenomenon is one example of an unexpected and negative consequence of trade involving the displacement of a subspecies of bees from their natural distribution range. The huge numbers of bees being traded all over the word exposes them to numerous <a href="http://web.oie.int/boutique/index.php?page=ficprod&id_prec=945&id_produit=1062&lang=en&fichrech=1">diseases</a>.</p>
<p>In contrast, the invasion by the most damaging honeybee parasite, the well named mite <em>Varroa destructor</em>, does not show the same long term devastating effect on some African honeybee <a href="http://link.springer.com/article/10.1007%2Fs10493-014-9842-7">populations</a>. </p>
<p>Researchers are very interested in identifying the tolerance mechanisms of the honeybee populations able to survive infestation without treatments. Selective breeding of the responsible behavioural or physiological traits could help the currently susceptible populations survive in presence of the parasite. Control efforts of the past decades have not resulted in parasite eradication and new methods are required. Honeybees that can live in the presence of this mite without human intervention are the Holy Grail for many scientists and beekeepers.</p>
<h2>Learning from past mistakes</h2>
<p>The African honeybee populations have so far largely coped with the arrival of new parasites and <a href="http://www.apidologie.org/articles/apido/abs/2009/03/m08180/m08180.html">pathogens</a>. But measures should be put in place to maintain their apparently healthy status. Beekeepers should work with local honeybee populations and refrain from importing colonies from distant places. </p>
<p>Despite the general positive situation, worrying signs of declining populations have recently been <a href="http://www.bioone.org/doi/abs/10.4001/003.022.0313?journalCode=afen">reported</a> in Madagascar, Kenya and South Africa. This is where colonies succumb to the newly arrived varroa mite or where beekeepers have increasing difficulty trapping wild swarms to build their stocks.</p>
<p>Africa would benefit from the mistakes made elsewhere by preventing such problems through the protection of honeybee populations. Before the states establish rules and restrictions, better information for the primary stakeholders are needed. Beekeepers play a vital role. They can help keep African honeybees healthy. The African honeybee could be a major tool for researchers and beekeepers if they want to learn about conserving the western honeybee.</p><img src="https://counter.theconversation.com/content/47954/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vincent Dietemann receives funding from the government and other foundations for his research. He is also part of part of the COLOSS (Preventing Honeybee Colony Losses) network.</span></em></p>The way the Africa honeybee’s deal with parasites and pathogens can teach western beekeepers and researchers how to adapt their bees to fight diseases.Vincent Dietemann, Extraordinary lecturer in Zoology and Entomology, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/448042015-07-31T04:04:43Z2015-07-31T04:04:43ZAmerican disease that’s wreaking havoc on the Cape’s honeybee population<figure><img src="https://images.theconversation.com/files/90128/original/image-20150729-30851-1s3nz7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A honeybee in the Cape region where the American Foulbrood disease is having devastating effects.</span> <span class="attribution"><span class="source">EPA/Nic Bothma</span></span></figcaption></figure><p>Until recently, sub-Saharan Africa was thought to be free from the American foulbrood disease, which afflicts its honeybee population. This was believed to be due to the African honeybees’ biology, and possibly that American foulbrood strains in Africa have a low virulence and rarely generate outbreaks. However, it is not the <a href="http://mg.co.za/article/2015-04-16-honeybee-crisis-catches-sa-off-guard">case</a>.</p>
<p>The first Cape honeybee colonies with heavy clinical symptoms of American foulbrood disease were <a href="http://www.sabio.org.za/?page_id=14">found</a> in South Africa’s Western Cape in December 2008 and confirmed with laboratory tests in February 2009. To date, an estimated 40% of the Western Cape bee population has been <a href="http://www.bioone.org/doi/abs/10.4001/003.019.0301">wiped out</a> by the disease.</p>
<h2>Just how bad is it?</h2>
<p>Insect pollinators, especially solitary and social bees, play the major role in providing pollination <a href="http://nativeplants.msu.edu/about/pollination">services</a>. Besides pollinating wild plants, managed honeybees are the most economically valuable pollinators of crop and fruit monocultures <a href="http://rspb.royalsocietypublishing.org/content/274/1608/303">worldwide</a>. </p>
<p>The value of honeybees to the agricultural industry - of pollination, honey, and beeswax - is <a href="http://mg.co.za/article/2015-04-16-honeybee-crisis-catches-sa-off-guard">estimated</a> at R20 billion. A continued loss of honeybee colonies thus poses a <a href="http://scholar.sun.ac.za/handle/10019.1/2578">crisis</a> not only to the industry, but also potentially to the <a href="http://www.southafrica.info/about/animals/capefloralregion.htm">Cape Floristic Region</a>, an area of high distinctive biological diversity and endemism. It is <a href="http://www.sajs.co.za/sites/default/files/%20publications/pdf/%20Melin_%20Review%20Article.pdf">globally recognised</a> as a significant centre of diversity for plants. </p>
<p>American foulbrood in South Africa will cause a collapse in pollination services. It will negatively affect species richness and biodiversity, as well as potentially drive the Cape honeybee to <a href="http://beekind.co.za/index.php/2015/06/18/our-bee-crisis-in-the-western-cape-one-workable-solution/">extinction</a>.</p>
<h2>What is the disease?</h2>
<p>American foulbrood presumably dates back to <a href="http://www.ct.gov/caes/lib/caes/documents/plant_science_day/2009/dingman_psd_2009.pdf">Aristotle</a> (384–322 BC). In one of his books, he described a diseased condition that was:</p>
<blockquote>
<p>… smelling unpleasant and leaving the bees sluggish. </p>
</blockquote>
<p>Even though Aristotle’s description is not sufficient to identify American foulbrood with certainty, it <a href="http://link.springer.com/article/10.1007/s00003-008-0379-8">suggests</a> that bees then suffered similar diseases to those we refer to today as foulbrood.</p>
<ul>
<li><p>American foulbrood is a larval disease of honeybees. The causative agent of American foulbrood is a bacterium known as <em>Paenibacillus larvae</em>. </p></li>
<li><p>The bacterium produces infected spores which contaminate larval food. Adult bees transmit the disease to uninfected larvae during larval feeding. The bacterium enters the larva’s digestive tract. </p></li>
<li><p>The disease is highly contagious and produces very high numbers of spores. Ten spores or fewer is <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1462-2920.2008.01579.x/pdf">sufficient</a> to cause infections in honeybee larvae, as has been shown for bees originating from Europe. </p></li>
<li><p>The spores germinate in the larval midgut and multiply with the bacteria, finally penetrating the intestinal epithelium. At this time it enters the larval body cavity, killing the larva.</p></li>
<li><p>In dead larvae the bacterium continues to grow and form spores. The larval body turns brown and decomposes to a semi-fluid glue-like remain with a specific smell. This is American foulbrood’s most characteristic clinical symptom.</p></li>
</ul>
<p>As disease progresses within the colony, the number of young bees drops drastically. The foulbrood-infected bee colony collapses and eventually dies.</p>
<p>American foulbrood is highly contagious and the extremely high numbers of spores produced – about 2500 million spores in just one individual – are exceptionally environmentally stable. They retain their infectivity for more than 35 years. The disease is easily transmitted between colonies, apiaries and even countries. </p>
<p>Within a colony, spores are transmitted to larvae via feeding. Transmission between colonies is through bees robbing other colonies for resources. Long-distance transmission occurs through the importation of infected queens, colonies and contaminated honeybee products. </p>
<p>American foulbrood is among the most <a href="http://www.bijenhouders.nl/files/Bijengezondheid/graaf/3.-avb-art-genersch-2009.pdf">lethal and severe</a> bee diseases. It is distributed worldwide and causes significant losses in honeybee populations and considerable damage to the beekeeping industry.</p>
<h2>What can be done about it?</h2>
<p>There is still no <a href="http://entomology.ucdavis.edu/files/147615.pdf">cure</a> for American foulbrood. Because of the production of extremely high numbers of long-lived spores in diseased colonies, the control of American Foulbrood is very difficult. </p>
<p>The disease is often treated with the registered antibiotic, oxytetracycline (OTC). While this may seem to “solve” the problem in the short term, unfortunately the over-use of OTC has <a href="http://naldc.nal.usda.gov/download/17023/PDF">led to</a> widespread resistance of honeybees to OTC. </p>
<p>Therefore, the best way to treat American foulbrood is to destroy all colonies and equipment by burning – known as the eradication method – once diagnosed. This is considered to be the only effective measure.</p><img src="https://counter.theconversation.com/content/44804/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Theresa C. Wossler 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>American Foulbrood is causing serious damage to the bee population in the Western Cape.Theresa C. Wossler, Associate Professor in Behavioural Ecology, Stellenbosch UniversityLicensed as Creative Commons – attribution, no derivatives.