Kimberly A. Stoner
Department of Entomology, Connecticut Agricultural Experiment Station, New Haven, CT, USA
Man spraying something from two cannisters, one in each hand


Bumble bees and honey bees have different life-cycles. Honey bees live in a social colony that is protective of the queen bee and overwinters each year. The queen honey bee does not forage for food. Additionally, the honey bee queen only leaves the colony once for her mating flight. Bumble bees are different because they live in colonies for part of the year and only the queen bee overwinters each year. Bumble bee queens also forage for pollen and nectar so they are at a higher risk of being exposed to direct pesticides than honey bee queens. Dr Kim Stoner studied what amount of imidacloprid would negatively impact bee colonies and their queens.

Assessing the sub-lethal effects of systemic insecticides on bees must be addressed differently for honey bees and bumble bees because their life-cycles differ. To study the effects at a colony level is acceptable for honey bees but erroneous for bumble bees because the approach addresses only part of the honey bee’s life-cycle. Bumble bees live in colonies for only a few months of the year and their queens are at a higher risk of being exposed to pesticides because bumble bee queens forage for nectar and pollen. Dr. Kim Stoner’s research in this article determined the toxic effects various doses of imidacloprid had on bees and colonies.


Recent research has demonstrated colony-level sublethal effects of imidacloprid on bumble bees affecting foraging and food consumption, and thus colony growth and reproduction, at lower pesticide concentrations than for honey bee colonies. However, these studies may not reflect the full effects of neonicotinoids on bumble bees because bumble bee life cycles are different from those of honey bees. Unlike honey bees, bumble bees live in colonies for only a few months each year. Assessing the sublethal effects of systemic insecticides only on the colony level is appropriate for honey bees, but for bumble bees, this approach addresses just part of their annual life cycle. Queens are solitary from the time they leave their home colonies in fall until they produce their first workers the following year. Queens forage for pollen and nectar, and are thus exposed to more risk of direct pesticide exposure than honey bee queens. Almost no research has been done on pesticide exposure to and effects on bumble bee queens. Additional research should focus on critical periods in a bumble bee queen’s life which have the greatest nutritional demands, foraging requirements, and potential for exposure to pesticides, particularly the period during and after nest establishment in the spring when the queen must forage for the nutritional needs of her brood and for her own needs while she maintains an elevated body temperature in order to incubate the brood.

Download Current Pesticide Risk Assessment Protocols Do Not Adequately Address Differences between Honey and Bumble Bees