A recent study from Purdue University has found that bees collect the vast majority of their pollen from uncultivated crops, but that they still come into contact with a lot of pesticides and herbicides which pose a threat to them. While bees do collect pollen from corn or soybeans, they spend more of their time collecting it from plants related to clover and alfalfa. While these generally aren’t the kinds of plants that are subject to agricultural pesticide use, they could be impacted by that use as rainwater or wind moves particles off of the intended crops and onto other plants.
The bulk of the chemicals found in tested pollen actually came from pesticides used by landscapers and homeowners, intended to get rid of mosquitos, wasps, and other insects seen as a nuisance. Neonicotinoids, the kind of pesticides primarily used on crops, are more poisonous to bees than pyrethroids, which are more commonly used where those bees are spending most of their time. These are the class of pesticides used by homeowners, who often have gardens with diverse flowering plants which attract bees in the first place.
All of these pesticides are long term stress factors for bees, and may be contributing to colony collapse disorder, which takes out entire beehives. There is also a question of just how these various chemicals interact with each other. Herbicides, also found in pollen collected by bees, normally isn’t dangerous to insects, but it is commonly used alongside pesticides. The researchers are concerned that these chemicals, upon coming into contact with each other, could elicit chemical reactions that do make them dangerous, or which make pesticides more dangerous to bees.
The study poses many new questions, but it has also told us a great deal about bee habits and what kinds of dangers face them. Future studies might be able to hone in the impact of specific types of pesticides, and help us figure out how to prevent them from damaging bees.