Non-insecticide pesticide impacts on bees: A review of methods and reported outcomes

Losses of honey bees have been repeatedly reported from many places worldwide. The widespread use of synthetic pesticides have led to concerns regarding their environmental fate and their effects on pollinators. While the impact of insecticides on bees has received substantial attention, relatively little is known about the consequences of the use of non-insecticidal pesticides for bee health, and no comprehensive review is available. Here, we used a standardized method to review scientific papers with classifiable outcomes on bee health of noninsecticidal applications (i.e., fungicides, herbicides, and other non-specific pesticides) and their interactive effect on bee health. We comprehensively summarize for the first-time overall outcomes and outcomes per bee species, as well as the individual and combinatory outcomes for specific chemicals, types, and classes. The available information indicates minimal impact for nearly all fungicides and fungicide combinations, confirming that, with some exceptions, fungicides are not as harmful as insecticides. However, when interactions were found, fungicide-fungicide combinations were just as harmful as fungicide-insecticide interactions. Herbicide and other groups were more harmful than fungicides and showed similar interactive effects. Because exposure to multiple chemicals is likely to be common in most agricultural landscapes, we recommend that the detrimental interactive effects through co-application be made available on pesticide labels.

Automated summary

The study found that most fungicides and fungicide combinations have minimal impact on bees, compared to insecticides. However, when interactions occur, fungicide-fungicide combinations are just as harmful as fungicide-insecticide interactions. Herbicides and other groups are more harmful to bees and show similar interactive effects.