The Lonely Plight of Solitary Bees

Are you thinking of dressing up as a bee this Halloween? Then you’d better read this post before finalizing the details of your costume. If not, it could still enlighten you to whole families of insects you may not have known about!

The diversity of colors, shapes, and life cycles across the superfamily Apoidea (the bees) is remarkable and unfairly underestimated by their stereotypical portrayal in popular media. The cartoon image of a yellow and black striped honey bee, likely fending off some bear pillaging their home for honey, is no doubt a depiction of the European honey bee (Apis mellifera). This species of bee has enjoyed a special relationship with humans since we first discovered the delicious and nutritious honey held in their hives. Early explorers of the New World brought with them beekeeping and spread feral colonies of A. mellifera throughout North and South America.

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Image 1. Apis mellifera. “Bee on Aster” by John Flannery is licensed under CC BY 2.0

Although frequently overlooked, there is a lonelier, less often recognized group of bees that live equally busy, solitary lives. They produce little to no honey or beeswax. But these bees are of special conservation concern in light of recent increases in global bee mortality. Unlike the invasive honeybees, these bees often pollinate native flowers with a high level of species specificity, meaning the plants require a specific interaction with one bee species for reproduction. Wildflowers that would not be otherwise pollinated by feral colonies are pollinated by these native bee populations. These bees specificity also makes them efficient pollinators, since they can focus on one flowering species instead of wasting time and pollen at flowers of many species.

Native bees often employ extraordinary techniques for completing their reproductive life cycle without the support of a hive and a queen. Some bees are carpenters, who carve small holes in tree branches where they lay their eggs. These mothers leave a nutritional store of pollen for the hatched larvae to feed on before pupating and emerging as adult bees. Others are masons or leaf-cutters and find hollow cavities to furnish partitioned nests for their eggs with leaves or mud. Some are kleptoparasites, who steal the nests of other bees like cuckoo birds (hence their name, cuckoo bees). (Native bees pictured below)

Image 2. “Osmia cornuta” by Gilles San Martin is licensed under CC BY 2.0

Image 3. “Native bee” by James Niland is licensed under CC BY 2.0

Keeping these unique bees around in the face of global bee population decline is a serious concern to conservation biologists. The surefire way to ensure their continued survival seems to be the inclusion of a wide variety of flowering plant species near their habitat. A recent study done by Thomas J. Wood et. al. from the University of Essex and published in the Journal of Applied Ecology found that sowing an environment rich in flower species increased resource availability and could aid in the conservation of a richer bee community (Wood et al., 2016). The study focused on solitary bees living on farmland in England. Farmland is of special significance since agricultural expansion can decrease the floral diversity in a given area of land by establishing a monoculture of a given crop (Wood et al., 2016). Native bees generally do not pollinate sown crops, preferring flowers that grow wild in the surrounding areas. Foraging for pollen on agricultural crops can also hurt bees by exposing them to pesticides like neonicotinoids, which have been suspected to be one of the primary causes of colony collapse disorder. This only gives more reason to promote rich communities of wild flowers for bees to pollinate since they are safer to collect pollen from.

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Image 4. “Megachilid” by Michael Saucedo

img_0702Image 5. “Bombus” by Michael Saucedo

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Image 6. “Megachilid” by Michael Saucedo

So what should we do? Bees promote flowers and flowers promote bees. Everything should be fine, right? No, because the anthropogenic stressors facing these overlooked bees are   the same stressors that have contributed to colony collapse disorder. Habitat fragmentation, agricultural development, and the use of pesticides all could negatively affect the populations of native bees, which could in turn affect the populations of flowers. Perhaps you can see how this positive feedback loop could be disastrous for preserving ecosystem function.

Although some squeamish or allergic people might not care for the conservation of bees on a personal level, we can all agree on a scientific level that bee populations carry out one of the more important ecosystem functions, pollination, and should therefore be protected and their depleted populations nurtured back to health. According to the same article mentioned earlier, “maintaining pollinator species diversity is crucial for providing ecosystem resilience in the face of future environmental change,” (Wood et al., 2016). No one wants to live in a world without flowering plants unless they also want to live in a world without fruits and vegetables and other plant products.

To appreciate the value of solitary bees it is best to observe them either in photographs or in person. If you want, I advise everyone to help support solitary bee populations by encouraging the growth of native “bee-friendly’ plants in places near your home or on campus. Get out there and do some guerrilla gardening if you’re crazy enough! Your actions could save a lonely bee raising a family all her own.

 

Works Cited

Wood, T. J., Holland, J. M. and Goulson, D. (2016), Providing foraging resources for solitary bees on farmland: current schemes for pollinators benefit a limited suite of species. J Appl Ecol. doi:10.1111/1365-2664.12718

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This entry was posted in Conservation Biology Posts, Conservation Editorials 2016. Bookmark the permalink.

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