Bee populations have been declining in recent years. Not only have honey bee colonies declined around the world; wild bees are disappearing, too. A global survey from 2017 indicates that over half (749) of extant bee species are at serious risk of extinction due to human activity. These wild bees are incredibly diverse, from the near-microscopic, shiny sweat bee, to lovingly clumsy, fuzzy bumblebees. They serve distinct roles in their ecosystem and represent a fantastic, beautiful family of animals.

     Compared to wild species, understanding honey bee threats comes with an advantage. Honey bees are managed by beekeepers so their hives can be counted and colony health monitored. Honey bees are easy to come by for experimental or commercial purposes. Most bees we see buzzing around us are indeed honey bees! 

     Wild bees, on the other hand, are not closely monitored or kept by humans. We can’t raise them in large groups or harvest their products to consume or sell. Most live solitary lives, and cannot be traced back to large nests. This makes it difficult for scientists to measure wild bee species diversity and numbers of individuals within a habitat.. However, this information is important because wild bees are essential pollinators, and their conservation is crucial to the functioning of ecosystems, as well as pollinating our food, worldwide.

     Since wild bees are so difficult to monitor, can honey bees provide proxy data for wild bee survival? T.J. Wood, a scientist in Belgium, and his team sought to answer this question by comparing managed and wild bee data across Europe. Honey bees and wild bees are influenced by similar factors, so, therefore, they might yield similar results. Both honey and wild bees will forage (collect nectar and pollen from various sources) from the same plants. Because of this, lack of available flowers or pesticide contamination may affect both types of bees. Other factors, such as weather, would potentially have an impact on all bees, as well. 

     When I worked in my first bee lab, I aided a Ph.D. candidate in measuring wild bee populations in a large botanical garden. The process is painstaking. I had to quickly find bees, perched on flowers often several feet away. Then, I crept up to them and quickly captured them in a small vial. Many attempts were unsuccessful and could’ve led to stings (although I was spared!). Lugging dozens of bees in my pockets, I’d return to the lab. There I killed and pinned them in order to properly identify them. This methodology is laborious and doesn’t give a 100% accurate picture of the local populations. Imagine if wild bee scientists, and the sacrificed bees, were spared this process!

A gorgeous brown-belted bumble bee I caught while surveying native bee populations.

     Wood and his fellow researchers approached their question by comparing existing datasets on wild bees and managed honey bees across Europe. The biggest challenge was a severe lack of data for most wild bees. For example, the genus Apis, honey bees, is the least threatened bee genus, but the leading genus in data collected. Data on the most threatened genera is sparse. This paradox makes it difficult to understand the relationship between wild and managed bee populations.

     There is another reason why researchers determined that honey bees can’t simply be a surrogate for monitoring their wild counterparts. Even though many factors influence both, some wild bee species are very different from honey bees. 

     Some wild bees specialize in pollinating a very small range of plants, meaning that is their only source of food. If those plants decrease in availability, honey bees can find others to forage from. However, wild specialists are left in the dust. For example, 28 species of mason and carpenter bees strictly visit flowers in the Aster family, such as daisies. They cannot survive if Asters disappear from their habitat. We depend on specialists as well. Vanilla, native to the island of Madagascar, is now mostly grown and harvested in South America, lacking Madagascar’s orchid bees. These bees are the only ones capable of pollinating the vanilla orchid. Therefore, in South America, humans must hand pollinate each blossom with a toothpick. That’s why vanilla is so expensive! 

     Honey bees also have an upper hand because they are managed, receiving extra protection from threats such as pathogens and parasites. Beekeepers can intervene to help affected honey bee colonies, while wild bees have no human helpers.

     While Wood’s research doesn’t offer shortcuts for monitoring wild bee populations, it provides insightful direction for the future of wild bee conservation. Research and surveys should focus on the most vulnerable genera that lack robust information. After all, shouldn’t science be trying to answer our unanswered questions?. 

     In the future, the grueling work of monitoring tiny wild bees could pay off, and that data may support an efficient monitoring system, helping us better understand the vital roles these insects play in ecosystems.