By Ron Hammond and Andy Michel, Ohio State University Extension entomologists
Over the past decade we have discussed the need for growers to be careful when applying foliar insecticides to their crops because of the potential for harming bees that might be foraging for nectar if the crop or nearby plants are in bloom, and to manage their applications carefully to reduce the possibility of drift.
Recent articles in the popular press and newspapers, including Saturday in the Columbus Dispatch, bring up another possible concern, that being the use of a relatively new class of insecticides, neonicotinoids, which are related to nicotine found in tobacco. In field crops, their main use is as seed treatments, and includes the insecticides clothianidin (Poncho), thiamethoxam (Cruiser), and imidacloprid. Recent studies out of Purdue and labs in Europe suggest that the use of clothianidin as a seed treatment might impact bees, either by causing mortality or more likely affecting their behavior and preventing bees from returning to their hives. There is also the possibility that they might interact with various pathogens that attack bees, making the bees more susceptible to various diseases. The neonicotinoids, when applied to the seed, apparently can get mixed with the talc that is often used to allow seeds to flow more easily in the planters, and then the insecticides and/or talc enter the environment during planting or when the seed boxes are cleaned.
At this time, this issue is an on-going story, with much more work to be done. Currently there are numerous groups calling for a ban on these seed treatments in the U.S, especially clothianidin. A petition submitted to EPA can be read at http://www.panna.org/sites/default/files/CFS-Clothianidin-Petition-3-20-12.pdf.