Detrimental interactions of neonicotinoid pesticide exposure and bumblebee immunity

This study assessed how exposure to neonicotinoids combined with an immune challenge affected bumble bees. Adult bumble bees (Bombus impatiens) received 6-day pulse exposures to either low (0.7 ppb) or high (7.0 ppb) field realistic doses of the neonicotinoid imidacloprid. The bees also received a nonpathogenic immune challenge. Then their survival and immunity were assessed. Researchers found that at the high-end dose, imidacloprid negatively affected bumble bee immune response. Furthermore, at both exposure levels researchers noted a decreased probability of survival when imidacloprid exposure was combined with an immune challenge. When tested individually, neither the immune challenge nor the imidacloprid decreased the probability of survival. The researchers theorized that detoxification, an energy intensive activity, could be at the expense of investing energy into immunity.

This study did not attempt to reproduce a worst-case scenario. The imidacloprid doses given are orders of magnitude lower than some imidacloprid levels found in the field but are representative of levels found in the crops grown with neonicotinoid treated seed. Furthermore, the 6-day pulse is considered shorter than the expected duration of exposure.

Authors: 
Czerwinski, M. A. and B. M. Sadd
Journal: 
Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
Year published: 
2017