First picture of worldwide bee distribution fills knowledge gaps and may help protect species.
Bee diversity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg2NzM0My9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzNTY3NzgyMH0.sdzn0MenrQ85gIvjYM4rm-7oOVd3dO9gx7nqcm9QMwM/img.jpg?width=980" id="fe916" class="rm-shortcode" data-rm-shortcode-id="2961b6dac8da97fa083cb568b19bab10" data-rm-shortcode-name="rebelmouse-image" alt="\u200bTwelve different species of bees swarming a flowery meadow. Etching by J. Bishop, after J. Stewart." data-width="2996" data-height="1766" />
Twelve different species of bees swarming a flowery meadow. Etching by J. Bishop, after J. Stewart.
Credit: Wellcome Collection, CC BY 4.0<p>How many bee species are there? Wait a minute: honeybee, bumble bee, erhm… five? Five hundred? Five thousand? Not even close: the total is well over 20,000 – which means there are more species of bees than of birds and mammals combined. </p><p><span></span>There's no shame (nor surprise) for bee civilians like you or me in not knowing that. What is surprising, is that even scientists who specialise in bees didn't quite know how those species are distributed all over the world. Until now. </p><p><span></span>By combining and filtering more than 5.8 million public records of bee occurrences, a team of researchers from China, the U.S., and Singapore have built up the very first comprehensive picture of bee diversity worldwide. And that picture presents a few surprises, both for laypersons and specialists.</p><p>Bee ignoramuses will be surprised to learn that the United States is the throbbing heart of bee diversity. The U.S. has far more bee species than any other region on Earth. And by the fact that large tracts of Africa and the Middle East remain <em>terra incognita</em>, in terms of apiary diversity. <br></p>
Counter-intuitive distribution<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg2NzM0NS9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTYzNzQ3NTMwMX0.poqkJqPj6CPWWN9u_FOt7nBu1lrOc2aSnv1vRO4yOHY/img.png?width=980" id="2acb0" class="rm-shortcode" data-rm-shortcode-id="407b1e60d42246f6cdfd91cfc6ef7839" data-rm-shortcode-name="rebelmouse-image" alt="\u200bRelative bee species richness in the New World. Note the low density in the Amazon Basin." data-width="1586" data-height="1372" />
Relative bee species richness in the New World. Note the low density in the Amazon Basin.
Credit: Current Biology, open access<p>In general, there are more bee species in the Northern Hemisphere than the Southern and—confirming previous hypotheses–more in arid and temperate climates than in the tropics.</p><p>That goes against the common pattern in biology known as the 'latitudinal gradient', which predicts that species diversity (of most plants and animals) increases towards the tropics and decreases towards the poles. Bees are an exception, with a higher species concentration away from the poles (in what scientists call a 'bimodal latitudinal gradient').</p><p>To give that difference some visual immediacy, imagine a graph with one hump in the middle (i.e. the latitudinal gradient) versus one with two humps, one on either side of the middle (i.e. the bimodal latitudinal gradient). In other words: dromedary (one-hump) versus camel (two-hump). </p><p>It seems counter-intuitive that bees would thrive better in arid deserts than in lush tropical jungles; but that's because trees–the dominant vegetation type in the tropics–provide less bee food than the plants and flowers that grow elsewhere. <span></span></p>
Much-needed baseline<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDg2NzM0Ni9vcmlnaW4ucG5nIiwiZXhwaXJlc19hdCI6MTY1MzY5ODU4MX0.0B0Ixka9uJpMFDozhQ9YcJAX0a6LFuy1HZ0rWWvEA3A/img.png?width=980" id="c7b8b" class="rm-shortcode" data-rm-shortcode-id="5d8f1e55aeeda42ef836931ad0095101" data-rm-shortcode-name="rebelmouse-image" alt="Three ways of measuring species richness in the Americas: (A) richness of polygons, (B) sPCA and (c ) turnover. All suggest a large, distinct bee fauna in the southwestern U.S." data-width="1748" data-height="671" />
Three ways of measuring species richness in the Americas: (A) richness of polygons, (B) sPCA and (c ) turnover. All suggest a large, distinct bee fauna in the southwestern U.S.
Credit: Current Biology, open access<p>Also, bees don't like it too wet, unlike their cousins the ants, whose populations peak in the humid tropics. The researchers think humidity may play a role in limiting bee distribution by spoiling pollen resources.</p><p><span></span>The relative absence of bees from the tropics has consequences for pollination, which in those regions is performed by a wide variety of alternative species: wasps, moths, and even cockroaches.</p><p><span></span>Previous datasets of global bee distribution were either inaccurate, incomplete, or difficult to interpret. This world map clearly establishes that bees prefer dry and temperate zones to wet and tropical ones. For bee scientists, it provides a much-needed baseline to predict the geographic distribution of bees and interpret the relative richness of species. </p><p><span></span>While much work needs to be done to fill additional knowledge gaps, this baseline is an excellent starting point, not just for greater understanding, but also for better conservation. Because bees are not just for making honey. In many countries, they're the top pollinator species. And they typically visit 90 percent of the leading crop types. </p>
Carpenter bee (Xylocopa latipes) pollinating a flower in the Indian state of Kerala.
An active component of honeybee venom rapidly killed two particularly aggressive forms of breast cancer in a laboratory study.
- New laboratory studies by a team of scientists found that the active component of honeybee venom induced death in two forms of malignant breast cancer cells that are notoriously difficult to treat.
- The magic healing molecule in the honeybees' venom appears to be melittin, which rapidly killed cancer cells in under an hour.
- In the future, doctors could potentially use melittin alongside chemotherapy drugs to increase the efficacy of the treatment.
The magic molecule<p>Previously, honeybee venom has shown potential in treating other medical conditions such as <a href="https://www.sciencealert.com/mellitin-bee-venom-eczema-inflammation-treatment" target="_blank" rel="noopener noreferrer">eczema</a> and tumors, and it has been known to <a href="https://www.sciencedirect.com/science/article/abs/pii/S0041010108003796?via%3Dihub" target="_blank" rel="noopener noreferrer">have anticancer properties</a>. How the venom works against tumors on a molecular level hasn't been understood, but science just got a lot closer. </p><p>It seems that the magic healing ingredient in the honeybees' venom is melittin — the zingy molecule responsible for producing the painful sting of a bee. Scientists at the Harry Perkins Institute of Medical Research in Perth, Australia and the University of Western Australia found that the melittin induced cancer cell death. </p><p>Their lab study, reported in the journal <a href="https://www.nature.com/articles/s41698-020-00129-0" target="_blank" rel="noopener noreferrer">NPJ Precision Oncology</a>, is the first to have looked into the effect the ingredient has on a range of breast cancers, the most common cancer in women worldwide. The two most aggressive and hard-to-treat types are known as triple-negative breast cancer (TNBC) and HER2-enriched breast cancer, which tend to mutate to resist existing treatments. The researchers found that melittin rapidly kills these cancer types and, critically, does so with no negative effects on normal cells. </p><p>"The venom was extremely potent," <a href="https://www.perkins.org.au/honeybee-venom-kills-breast-cancer-cells/" target="_blank" rel="noopener noreferrer">said</a> research leader Ciara Duffy from The Harry Perkins Institute of Medical Research in a news release. "We found that melittin can completely destroy cancer cell membranes within 60 minutes."</p><p>The lab study also found that bumblebee venom (which does not contain melittin) did not kill those particular breast cancer cells.</p>
How it works<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="df37e6f56c59da163c4ed2df27444ee7"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/K3oMN1a_pdg?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>Melittin disarms cancer cells by puncturing holes in their outer membrane. Another stunning effect: within just 20 minutes of exposure to melittin, the chemical messages cancer cells need to grow and divide are disrupted.</p><p>"We looked at how honeybee venom and melittin affect the cancer signaling pathways, the chemical messages that are fundamental for cancer cell growth and reproduction, and we found that very quickly these signaling pathways were shut down," <a href="https://www.perkins.org.au/honeybee-venom-kills-breast-cancer-cells/" target="_blank" rel="noopener noreferrer">said Duffy</a>.</p><p>The molecule is able to do this by stopping the activation of receptors that signal growth factors in the cells' membranes. The large number of these receptors in HER2-enriched cancer cells and some TNBC cells is one reason for their uncontrollable growth. Melittin seems to halt the cell's proliferation by blocking those growth signals from getting through. </p><p>"Significantly, this study demonstrates how melittin interferes with signalling pathways within breast cancer cells to reduce cell replication," said Western Australia's Chief Scientist Professor Peter Klinken. "It provides another wonderful example of where compounds in nature can be used to treat human diseases."</p>
Enhancing current cancer treatments<p>The team also tested to see if melittin could be used with existing chemotherapy drugs, as the pores in the membranes that it creates may allow other treatments to faster penetrate and kill cancer cells. </p><p>They tested the idea on a lab mouse with triple-negative breast cancer. They injected it with a combination of melittin and docetaxel — a drug used to treat a number of cancers including breast cancer. The mixture proved to be more effective at shrinking the tumors than either melittin or docetaxel alone. </p><p>In the future, doctors could potentially use melittin alongside chemotherapy drugs to enhance the efficacy of the treatment. This may allow them to reduce the dosage of chemotherapy drugs, and the adverse side effects that come with it. </p><p>The authors in the study point out that honeybee venom is inexpensive and easy to obtain, thus making it a fantastic option for cancer treatment in regions and countries with poorly resourced health services and care.</p><p>"Honeybee venom is available globally and offers cost effective and easily accessible treatment options in remote or less developed regions," <a href="https://www.nature.com/articles/s41698-020-00129-0" target="_blank" rel="noopener noreferrer">the authors write.</a> "Further research will be required to assess whether the venom of some genotypes of bees has more potent or specific anticancer activities, which could then be exploited."</p><p>Though exciting, this research is still in early, lab testing stages. The researchers will still need to perform clinical trials to assess the safety and efficacy of melittin for treating breast cancer in humans.</p>
Declining bee populations could lead to increased food insecurity and economic losses in the billions.
From bee to farm to table<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUyOTUzOC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1NzM3MDkwNH0.coXBXgDBoRvXaZYIgKaH9fH_jhlUKp3O22-h2rY8jMQ/img.jpg?width=980" id="a317b" class="rm-shortcode" data-rm-shortcode-id="bd61c660c9d52353ba975145fab59625" data-rm-shortcode-name="rebelmouse-image" data-width="1569" data-height="628" />
A bar graph showing the percentage of pollination limitation for the seven crops studied.
Ecological and edible incentives<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUyOTUzMS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNTM4NzQwMX0.vclSktT0d_Mvns_QTZ7ZkFT_pWgIIpyb6ZNP1Tla2Qs/img.jpg?width=1245&coordinates=0%2C215%2C0%2C215&height=700" id="f15a3" class="rm-shortcode" data-rm-shortcode-id="b1e5b70e616daf5fcc0a63a041675e7a" data-rm-shortcode-name="rebelmouse-image" alt="hand holding dead bees" data-width="1245" data-height="700" />
A protester shows a handful of bees that died by pesticides. The protest was held during the Bayer AG shareholder meeting in 2019.
(PhooMaja Hitiji/Getty Images)<p>The concern extends beyond these seven. Crops such as coffee, avocados, lemons, limes, and oranges are also highly dependent on pollinators and may prove pollination limited. If declining bee populations are tied to such yields, it could mean barer supermarket shelves and increased prices. While that may only be an annoyance to some, to poor and vulnerable communities who already struggle to secure <a href="https://www.ers.usda.gov/amber-waves/2011/december/data-feature-mapping-food-deserts-in-the-us/" target="_blank">salubrious, affordable food</a>, such a deficit would present another barrier to the vital micronutrients necessary for a healthy life and diet.</p><p>Unfortunately, <a href="http://sro.sussex.ac.uk/id/eprint/54228/1/Science_1255957_Goulson_RV_revised_CA_edited.pdf" target="_blank">the threats to bees are numerous</a>. Parasites, agrochemicals, monoculture farming, and habitat degradation all play a role, and neither stressor works in isolation. Sublethal exposure to neonicotinoids, an insecticide, can cause <a href="https://bigthink.com/surprising-science/baby-bees-and-pesticides" target="_self">impairments in bees</a>, while monoculture farming serves up a monotonous and unhealthy floral buffet. Both impede bees' immune systems, rendering them vulnerable to parasites such as <a href="http://entnemdept.ufl.edu/creatures/misc/bees/varroa_mite.htm" target="_blank"><em>Varroa destructor</em></a>, a mite that can transmit debilitating viruses as it feeds on bees' fat bodies. And all of these stressors will likely be inflamed by climate change in the years to come. </p><p>Some have proffered mechanical solutions, such as Japan's National Institute of Advanced Industrial Science and Technology where technicians are developing <a href="https://www.newscientist.com/article/2120832-robotic-bee-could-help-pollinate-crops-as-real-bees-decline/" target="_blank">robotic bees</a>. These micro-drones are covered in gelled horsehair and have successfully cross-pollinated Japanese lilies. Other experiments include <a href="https://www.capitalpress.com/ag_sectors/orchards_nuts_vines/pollen-spray-could-replace-honeybees/article_f9a1c102-d5b3-519d-9dab-b0c44cfb99c5.html" target="_blank">pollen sprays</a>. However, the large-scale viability of tech-centric solutions seems questionable. After all, wild bees currently perform their ecological services pro bono and are as effective as managed honeybees. Any technological solution implemented in their absence would add to the agricultural costs and likely increase prices anyway.</p><p>Ecological amelioration will be necessary. To combat habitat fragmentation and strengthen biodiversity, many cities are implementing green-way strategies. For example, the Dutch city of Utrecht has decked its bus stop roofs with plants and grasses to <a href="https://bigthink.com/technology-innovation/urban-bees?rebelltitem=1#rebelltitem1" target="_self">create bee and butterfly shelters</a>, while other cities are looking to foster <a href="https://www.csmonitor.com/Environment/2020/0731/Can-roadsides-offer-a-beeline-for-pollinators" target="_blank">bee-friend roadsides</a>. And <a href="https://www.fsa.usda.gov/Assets/USDA-FSA-Public/usdafiles/FactSheets/2015/CRPProgramsandInitiatives/Honey_Bee_Habitat_Initiative.pdf" target="_blank">government initiatives</a> incentivize farmers and landowners to adopt bee-friendly management practices. These solutions aren't only a matter of ecological conservation but also food security and public health.</p>
Study finds that a colony's exposure to pesticides impairs offspring.
- Pesticide contamination in bee hives damages the learning capabilities of offspring, according to a recently published study.
- A key area of the affected bees' brains never correctly develops after pesticide exposure.
- Early impairment appears to be irreversible and is likely a factor in falling bee populations.
Broken learning<p>The study involved introducing neonicotinoids to the nectar consumed by members of 22 <a href="https://en.wikipedia.org/wiki/Bombus_terrestris" target="_blank"><em>Bombus terrestris audax</em></a> (buff-tailed honeybee) colonies. The learning abilities of their offspring were then measured against a control group of young bees from colonies whose food supply had not been contaminated.</p><p>The test assessed the extent to which a bee could learn to associate a specific smell with a reward, which was a sucrose solution. The bees from the neonicotinoid colony consistently fared more poorly than the control population.</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2ODE5Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0MTAyMzQzMn0.zxOo04Cq-7q4ClAydA0kLAwFMpj84Nr25DIVtR3EzAE/img.jpg?width=980" id="4967e" class="rm-shortcode" data-rm-shortcode-id="ba7b1c09f2daa90d686e7ee93ad0138a" data-rm-shortcode-name="rebelmouse-image" alt="a bumblebee on a purple flower" data-width="1440" data-height="1166" />
Image source: Mr. Meijer/Shutterstock
Tiny computed micrography (CT) scans<p>In hopes of identifying a structural explanation, the researchers stained the brain cells of 100 bees from the exposed colonies and took non-invasive <a href="https://www.imperial.ac.uk/news/171050/bee-brains-have-never-seen-them/" target="_blank">micro-CT</a> scans in a machine similar — albeit smaller — to those in which humans are medically imaged.</p><p>The researchers discovered a clear difference in brains of the young bees from pesticide-exposed colonies. A key brain area, the <a href="https://en.wikipedia.org/wiki/Mushroom_bodies" target="_blank">mushroom body</a>, was found to be much smaller in these bees' brains than it was in those from control colonies. This makes sense, since this region is believed to be involved in olfactory learning and memory.</p><p>The tests and scans were performed three days after pupal hatching and again after 12 days. The substandard learning capabilities and mushroom body sizes had not been resolved by the second test, indicating to the researchers that the damage caused by the neonicotinoids was irreversible.</p><p>(A honeybee's <a href="https://sciencing.com/life-span-honey-bee-6573678.html" target="_blank">life expectancy</a> depends on its role. Drones live roughly 8 weeks, while sterile workers live for about 6 weeks in the summer or 5 months in the winter. A queen can live for a few years.)</p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2ODIwMC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxODYyNDExNn0.oejYHpeBD1HdgT3ttnSOLyjBIMFcQ1GDYOv1UIl5s_Q/img.jpg?width=980" id="ace39" class="rm-shortcode" data-rm-shortcode-id="dfecbbebdef8988fd1c297e88ee1a7b5" data-rm-shortcode-name="rebelmouse-image" alt="Scans of the mushroom body area of the bees' brains" data-width="1934" data-height="746" />
Several views of the mushroom body
Image source: Gill, et al
Why this matters<p>The study's conclusion does not say definitively that the mushroom area is the only brain region impacted by pesticides. However, a smaller mushroom area is significant, explaining, as it does, the mechanism by which a bee's learning abilities and behavior may be impaired over the course of its life.</p><p>Gill says in a <a href="https://www.imperial.ac.uk/news/195793/pesticides-impair-baby-brain-development/" target="_blank">press release</a>, "Worryingly in this case, when young bees are fed on pesticide-contaminated food, this caused parts of the brain to grow less, leading to older adult bees possessing smaller and functionally impaired brains; an effect that appeared to be permanent and irreversible."</p><p>In fact, after the young bees were returned to their colonies, researchers saw lower-than-expected colony growth two to three weeks after the subjects' reintroduction.</p><p style="margin-left: 20px;"><em>"If future generations of workers are predisposed to be inefficient functioning cohorts, this could lead to a density-dependent build-up of colony-level impairment increasing the risk of colony collapse." — Gill, et al </em></p><img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjg2ODIwNC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzMTUxMDAyN30.jOBiSfYKhVGP0nYZf-oWGEFqeCqL7AFwirgMDGpnDzc/img.jpg?width=980" id="f916f" class="rm-shortcode" data-rm-shortcode-id="93579968ab98750c4a8b349ef692a14f" data-rm-shortcode-name="rebelmouse-image" alt="Illustration of Bombus terrestris audax bee" data-width="1440" data-height="1440" />
Illustration of *Bombus terrestris audax*
Image source: Duda Vasilii/Shutterstock
And then there’s the adult bees<p>In addition to the problems caused by the behavior of bees hatched with pesticide damage, it's not as if pesticide exposure necessarily abates later on. As lead author of the study <a href="https://www.researchgate.net/profile/Dylan_Smith8" target="_blank">Dylan Smith</a> explains, "There has been growing evidence that pesticides can build up inside bee colonies. Our study reveals the risks to individuals being reared in such an environment, and that a colony's future workforce can be affected weeks after they are first exposed."</p><p>The study concludes that simply looking at the damaging effect of pesticide on adult bee population misses a significant, and more far-reaching, part of the story:</p><p style="margin-left: 20px;"><em>"Bees' direct exposure to pesticides through residues on flowers should not be the only consideration when determining potential harm to the colony. The amount of pesticide residue present inside colonies following exposure appears to be an important measure for assessing the impact on a colony's health in the future. " — Gill, et al</em></p>
2018's winter was particularly harsh on U.S. honeybees. What's causing bee populations to plummet, and what can we do about it?
- Since 2006, the Bee Informed Partnership has conducted a survey on U.S. beekeepers. The most recent survey shows that the 2018 winter resulted in the biggest die-off since the survey began, with a loss of 37.7 percent.
- This die-off is part of a larger trend. Bee populations have been falling for decades.
- The reasons why are multifaceted and compound on one another.