Effects of neonicotinoids on honey bee and bumble bee queens and impacts on colony development

Monday, March 27, 2017 - 4:10pm
Event Type: 

Dr. Judy Wu-Smart from the University of Nebraska Department of Entomology will be presenting a seminar as part of the Department of Entomology's spring semester seminar series.  This event is co-sponsored by EEB and EEOB.

Abstract: Systemic neonicotinoid insecticides can translocate to nectar and pollen of treated plants where foraging bees may become exposed, leading to impaired foraging and memory, and possibly to bee decline. Little studied are the potential effects of exposure within a colony, particularly on the reproductive queens. To assess the effects of neonicotinoids on honey bee (Apis mellifera L.) queen fecundity, small colonies of varying sizes were fed imidacloprid (0, 20, 50, 100ppb) in 50% sucrose for 3-weeks.  We found dose-dependent effects where higher concentrations resulted in greater reductions in queen egg-laying, brood production, and pollen stores in all treated colonies. Some negative effects were not as evident in larger colonies, possibly because honey bee queens are indirectly exposed to neonicotinoids through trophallaxis. In contrast, bumble bee queens are vulnerable to direct exposure while foraging for nectar and pollen during solitary nest initiation. To assess the effects on bumble bee (Bombus impatiens Cresson) queen survival and nest founding we fed imidacloprid (1, 5, 10, 25ppb) in 50% syrup for 18-days. Treated bumble bee queens exhibited reduced survival, even as low as 1 ppb, compared to untreated queens. Queens that survived initial exposure exhibited dose-dependent delay in nest initiation, suggesting some recovery, however, the delay led to slower worker brood emergence.  This study improves our understanding of how neonicotinoids may impact colony development and identifies risk mitigation options in early spring to better protect honey bee and bumble bee queens.

The ENT seminar series is coordinated by Greg Courtney (gwcourt@iastate.edu) and Rick Hellmich (richard.hellmich@ars.usda.gov). Please feel free to contact them with questions.