Stress indicator gene expression profiles, colony dynamics and tissue development of honey bees exposed to sub-lethal doses of imidacloprid in laboratory and field experiments

摘要

In this study, different context-dependent effects of imidacloprid exposure on the honey beeresponse were studied. Honey bees were exposed to different concentrations of imidaclopridduring a time period of 40 days. Next to these variables, a laboratory-field comparisonwas conducted. The influence of the chronic exposure on gene expression levels was determinedusing an in-house developed microarray targeting different immunity-related anddetoxification genes to determine stress-related gene expression changes. Increased levelsof the detoxification genes encoding, CYP9Q3 and CYT P450, were detected in imidacloprid-exposed honey bees. The different context-dependent effects of imidacloprid exposureon honey bees were confirmed physiologically by decreased hypopharyngeal gland sizes.Honey bees exposed to imidacloprid in laboratory cages showed a general immunosuppressionand no detoxification mechanisms were triggered significantly, while honey bees infieldshowed a resilient response with an immune stimulation at later time points. However,the treated colonies had a brood and population decline tendency after the first brood cyclein the field. In conclusion, this study highlighted the different context-dependent effects ofimidacloprid exposure on the honey bee response. These findings warn for possible pitfallsconcerning the generalization of results based on specific experiments with short exposuretimes. The increased levels of CYT P450 and CYP9Q3 combined with an immune responsereaction can be used as markers for bees which are exposed to pesticides in the field.