Planting of neonicotinoid-treated maize poses risks for honey bees and other non-target organisms over a wide area without consistent crop yield benefit

This study evaluated both the potential for honey bees to be exposed to neonicotinoids during the planting of corn as well as the benefits of neonicotinoid seed coatings for crop yield. Neonicotinoid deposition is estimated to occur across 42% of the state of Indiana during the time when corn seed is planted. Plus, they estimated that more than 94% of foraging honey bees are at risk of exposure to neonicotinoids during corn planting season. Estimated exposure levels varied but it was found that some bees would be exposed to lethal levels. Worth noting is that researchers found neonicotinoid deposition in all directions, not only downwind of planting. Furthermore, research over three cropping seasons documented no crop yield benefit from neonicotinoid seed coatings on corn. Researchers describe their study design as conservative (likely to underestimate exposure) for a number of reasons including that they only looked at corn (while other crops are also treated with neonicotinoids) and they did not consider deposition beyond 90 meters from a field margin even though their own data suggest that deposition upwards of 100 meters is highly likely. In conclusion, the researchers suggest that the risk to honey bees and other non-target organisms could be greatly reduced if the use of neonicotinoid seed coatings were better aligned with pest incidence.

Krupke, C.H., J.D. Holland, E.Y. Long, and B.D. Eitzer
Journal of Applied Ecology
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