Review of Bee Health

By Jeffrey Hahn, Extension Entomologist, May 23, 2014

New research about bees and pesticides from Harvard University was recently published by Lu et al. in the Bulletin of Insectology. This research examined honey bee colonies that were fed high fructose corn syrup (HFCS) contaminated with two common neonicotinoids (imidacloprid or clothianidin) during late summer and then observed in the following spring. Both the control colonies and the insecticide exposed colonies did well going into fall. While both sets of colonies then declined, the control colony numbers rebounded while the insecticide exposed colonies suffered large losses. The authors’ conclusions are that insecticides are the leading explanation for colony collapse disorder (CCD).

While this seems like compelling information on the surface, there are a number of concerns and flaws about this research that should cause readers to examine it very cautiously. The biggest concern for many is the concentration of insecticides which was fed to bees at a rate of 135.8 parts per billion (ppb), in a volume of 1.9 liters of sucrose water per colony per week, for 13 consecutive weeks. This is considered an extremely high concentration and does not represent a realistic rate of pesticide exposure to bees.

Interestingly, Dr Lu’s own data in his 2012 research paper, also published in the Journal of Insectology, showed that at field-relevant dosages, neonicotinoids did not appear to harm bees (halfway through his research, he abruptly increased the dosage being fed to bees after it appeared that there was greater numbers of capped brood cells occurring when exposed to lower dosages).