Neonicotinoid insecticides have been the target of much scrutiny as possible causes of recent declines observed in pollinator populations. Although neonicotinoids have been implicated in honey bee pesticide incidents, there has been little examination of incident report data. Here we summarize honey bee incident report data obtained from the Canadian Pest Management Regulatory Agency (PMRA).



In Canada, there were very few honey bee incidents reported 2007-2011 and data were not collected prior to 2007. In 2012, a significant number of incidents were reported in the province of Ontario, where exposure to neonicotinoid dust during planting of corn was suspected to have caused the incident in up to 70% of cases. Most of these incidents were classified as "minor" by PMRA, and only six cases were considered "moderate" or "major". In that same year, there were over three times as many moderate or major incidents due to older non-neonicotinoid pesticides, involving numbers of hives or bees far greater than those suspected to be due to neonicotinoid poisoning.



These data emphasize that, while exposure of honey bees to neonicotinoid-contaminated dust during corn planting needs to be mitigated, other pesticides also pose a risk. That neonicotinoids are toxic to bees has never been debated. What is disputed is whether or not exposure to these compounds in the field poses an unacceptable risk to pollinators.



Based on the number of colonies showing mortality or loss as listed in the report, 402 suffered moderate or major effects from neonicotinoids, all of which were reported from the provinces of Ontario and Quebec. Moderate or major effects from other pesticides were observed in at least 3855 colonies. Over half of these incidents were in the province of Saskatchewan and were thought to be due to exposure to dimethoate or chlorpyrifos during foliar sprays on alfalfa or other crops. From multiple provinces, a large number of incidents, including lethal effects on queen bees and brood, were also attributed to formic acid used by beekeepers during treatments for Varroa mite



Cutler, G. C., Scott‐Dupree, C. D., & Drexler, D. M. (2013). Honey bees, neonicotinoids, and bee incident reports: the Canadian situation. Pest Management Science.



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