Chronic, field-relevant imidacloprid exposure alters learning acquisition in honey bees

Honey bees are crucial to human survival in their role as generalist pollinators. However, humans also impact honey bees through the use of agricultural chemicals, typically aimed at increasing crop yield. Pesticide exposure to honey bees has been associated with a decrease in colony growth and fewer queens being born. However, the safety of pesticides is derived from acute feeding studies that focus on mortality. Pesticides are now ubiquitous in the environment and honey bees are constantly exposed. Studies utilizing long-term exposure better represent the lifetime experience of a typical honey bee. Here we measured changes in associative learning following 1 week of exposure to one of two sub-lethal, field-relevant doses of imidacloprid. While neither concentration of pesticide altered mortality relative to control, learning acquisition decreased in the high compared to control groups. These data demonstrate that chronic exposure to field-relevant doses of imidacloprid impact the ability for honey bees to form memories. The foraging success of honey bees relies on remembering the location of the hive and potential forage locations.