By Tracey Baute ‐ Field Crop Entomologist and Greg Stewart ‐ Corn Specialist, Ontario Ministry of Agriculture, Food and Rural Affairs.
A high level of concern was raised last spring regarding bee kills and corn planting. Many growers are asking what actions they can take to help reduce the risk of bee kills this spring during planting. We will try to clarify the situation, and give the best recommendations we can provide at this time.
In the spring of 2012, coinciding with corn planting, there were approximately 200 incidences of what was likely acute poisoning of honey bees in Ontario. Representatives from the Ministry of
Environment (MOE), Pest Management Regulatory Agency (PMRA), and OMAFRA investigated
affected bee hives, taking bee samples for residue analysis by PMRA. Though final results have not been released, PMRA’s initial lab results indicate “that pesticides used on treated corn seeds may have contributed to at least some of the 2012 spring bee losses that occurred in Ontario, however, there is still additional information being collected”. It is important to note that they have found no cases of off‐label use by growers. It is also important to note that, though the analysis indicates the presence of clothianidin (active ingredient in Poncho), thiamethoxam (active ingredient in Cruiser) breaks down to metabolites that include clothianidin.Virtually all corn seed sold in Ontario is treated with some form of the insecticides in question.
Many factors may have contributed to these incidences. Environmental conditions and planting practices during the 2012 planting season may play a significant role. Unfortunately, without being present in each field at the time of planting to collect data, there may never be conclusive evidence as to route(s) of exposure to bees. However, results indicate that honey bees were somehow exposed to corn seed insecticides. So how can a bee come into contact with a seed insecticide during planting? Read more