Jeffrey Pettis, lead researcher at the USDA’s very own Bee Research Laboratory, completed research two years ago suggesting that even extremely low levels of exposure to neonicotinoids makes bees more vulnerable to harm from common pathogens.
Pettis’s study focuses on imidacloprid, which like clothianidin is a neonicotinoid pesticide marketed by Bayer as a seed treatment. The study demonstrates that the insects’ vulnerability to infection is increased by the presence of imidacloprid, even at the most microscopic doses.
Pettis says he and his research team exposed two sets of honey bees to Nosema, a fungal pathogen toxic to honey bees. One set was also exposed to a neonicotinoid pesticide; the other not. “And we saw an increase, even if we fed the pesticide at very low levels—an increase in Nosema levels—in direct response to the low level feeding of neonicotinoids, as compared with the ones which were fed normal protein,”
Scientists have been focusing on the interaction between the Nosema fungus and the Iridoviridae virus [invertebrate iridescent virus type 6 (IIV-6)] as the culprit. Pettis’ research seems to suggest that neonicotinoids play a role, too—and at levels so low that researchers may be overlooking them.