Honey bees (Apis mellifera) have been experiencing an ongoing decline in population over the last half century despite their tremendous importance to agriculture. A variety of environmental pressures have been implicated in this decline including pesticides commonly found within the hive and foraging environments. To assess the potential effect of exposure to in-hive pesticides on drone spermatozoa viability, we compared the viability of spermatozoa collected from drones reared in pesticide-free wax to that of drones reared in wax contaminated with field-relevant doses of several common agrochemicals, including chlorothalonil and chlorpyrifos, and miticides, including fluvalinate, coumaphos and amitraz. Our results suggest a significant negative effect of in-hive pesticide exposure during development on spermatozoa viability.
The greatest risk of exposure to pesticides, however, is faced by a subset of workers, foragers, that function in food collection from floral resources. The activity of honey bee foragers contributes approximately $17 billion annually in pollination services for several major crops in the United States including almond, which is completely dependent on honey bees for pollination. To assess the effects of pesticides commonly used during almond bloom on honey bee forager survival, foragers were exposed to label dose variants of the fungicides iprodione, boscalid/pyraclostrobin formulation and azoxystrobin alone and in combination. Label dose variants of two insect growth regulators, methoxyfenozide and pyriproxyfen, as well as an acaricide, bifenazate, were also assessed for their effects on forager survival. We utilized a wind tunnel and atomizer set up (wind-speed: 2.9 m/s) to simulate field-relevant exposure of honey bees to these chemicals during aerial application in almond orchards. Our results indicate a significant decrease in forager survival resulting from exposure to pesticides commonly applied during almond bloom. To assess the effects of commonly used mosquito control insecticides on honey bee forager mortality, foragers were exposed using a wind tunnel-atomizer assembly simulating exposure from ultra-low volume spray truck application (wind-speed: 1.8 m/s). Significant acute forager mortality resulted from exposure to the mosquito control insecticides when applied above and below the manufacturer application rate
