Non-cultivated plants present a season-long route of pesticide exposure for honey bees

This study found that pollen collected by honey bees in agricultural landscapes were contaminated throughout the growing season with multiple pesticides. Approximately 30 pesticides were found at each of the three sites evaluated (an open meadow, a treated maize field margin, and an untreated maize field margin). The chemical makeup between the sites was similar but residue levels were highest at an agricultural site where treated maize had been planted. The pesticides that were ranked as high risk (when compared to lethal doses) were two pyrethroids used in mosquito abatement and other public health pest management, as well as the neonicotinoids clothianidin and thiamethoxam. These two neonicotinoids still triggered high risk even though the researchers purposefully started the study after coated seeds were planted to exclude the risk from neonicotinoid dust-off caused during planting.

Researchers noted that the toxicity of the pesticides didn’t drive whether there was a high risk. In other words, high toxicity did not always lead to a high risk determination. Researchers also noted that the majority of pollen gathered by the honey bees was from wildflowers (although it is worth noting that the agricultural fields were maize, which is not considered attractive to honey bees).