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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Bee Research Laboratory » Research » Publications at this Location » Publication #320557

Research Project: Managing Honey Bees against Disease and Colony Stress

Location: Bee Research Laboratory

Title: Sperm viability and gene expression in honey bee queens (Apis mellifera) following exposure to the neonicotinoid insecticide Imidacloprid and the organophosphate Acaricide Coumaphos

Author
item Chaimanee, Veeranan - Maejo University
item Evans, Jay
item Chen, Yanping - Judy
item Jackson, Caitlin - University Of Maryland
item Pettis, Jeffery

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2016
Publication Date: 3/12/2016
Citation: Chaimanee, V., Evans, J.D., Chen, Y., Jackson, C., Pettis, J.S. 2016. Sperm viability and gene expression in honey bee queens (Apis mellifera) following exposure to the neonicotinoid insecticide Imidacloprid and the organophosphate Acaricide Coumaphos. Journal of Insect Physiology. 89:1-8. doi: 10.1016/j.jinsphys.2016.03.004.

Interpretive Summary: Honey bee population declines are a global concern. Numerous factors appear to cause the decline including parasites, pathogens, malnutrition and pesticides. Here, we assess the effects of different doses on the viability of sperm stored in the honey bee queens. Our results demonstrate that sub-lethal doses of imidacloprid decreased sperm viability by 50%, 7 days after treatment. Sperm viability was also reduced about 33% in queens treated with high doses of coumaphos. This research clearly demonstrates that chemical exposure can affect sperm viability in queen honey bees. This information will be useful to queen breeders and beekeepers to better manage their colonies and produce healthy long-lived queens.

Technical Abstract: Honey bee population declines are a global concern. Numerous factors appear to cause the decline including parasites, pathogens, malnutrition and pesticides. Residues of the organophosphate acaricide coumaphos and the neonicotinoid insecticide imidacloprid, widely used to combat Varroa mites and for crop protection in agriculture, respectively, have been detected in wax, pollen and comb samples. Here, we assess the effects of these compounds at different doses on the viability of sperm stored in the honey bee queens’ spermatheca. Our results demonstrate that sub-lethal doses of imidacloprid (0.02 ppm) decreased sperm viability by 50%, 7 days after treatment. Sperm viability was also reduced about 33% in queens treated with high doses of coumaphos (100 ppm). The expression of genes that are involved in development, immune responses and detoxification in honey bee queens and workers exposed to chemicals was measured by qPCR analysis. The data showed that expression levels of specific genes were triggered 1 day after treatment. Gene responses between honey bee queens and workers were quite different. Cytochrome P450 monooxygenases (P450s) were decreased in honey bee queens treated with low doses of coumaphos (5 ppm) and imidacloprid (0.02 ppm). Moreover, these two compounds suppressed the expression of genes related to antioxidation, immunity and development in queens at day 1. However, eater showed up-regulation in pesticide-treated queens, suggesting that low doses had negative effects on gene expression in queens. Up-regulation of antioxidants by these compounds in worker bees was observed at day 1. Coumaphos also caused a repression of detoxification enzymes in workers. Antioxidants appear to prevent chemical damage to honey bees. Surprisingly, detoxification enzymes did not appear to mediate these compounds in queens or workers. We also found that the promotion of DWV replication in workers treated with imidacloprid varied between colonies. Genetic variation between colonies and/or other factors might have contributed to DWV replication in workers. This research clearly demonstrates that chemical exposure can affect sperm viability in queen honey bees.