Neonicotinoid-contaminated diet causes behavior changes in forager honey bees (Apis mellifera) that may reduce colony survival during late fall

Abstract

Neonicotinoid insecticides are often detected in pollen and nectar, which are the main food resources for honey bees. Sub-lethal and chronic exposure to these insecticides may have a prolonged effect on honey bees who are solely dependent on the stored food inside of the hive during cold weather. Our study investigated the effects of sub-lethal concentrations of imidacloprid on late fall forager honey bees’ behavior by accessing their activity levels and walking performance after being fed ad libitum with six different concentrations (2—125 μg/kg) of imidacloprid-dosed syrup for up to 48 h in the laboratory. Numbers of honey bees that walked after being released into a UV light illuminated tunnel decreased significantly as dosages of neonicotinoid in their diet increased. However, their walking speeds were not significantly affected by imidacloprid. The behavioral changes we observed in honey bees chronically exposed to neonicotinoid via diet could negatively affect individual honey bee performance of hive duties and consequently, colony survival during cold weather.