The U.S. Department of Agriculture and the EPA released a comprehensive scientific report on honey bee health in May 2013. The Report on the National Stakeholders Conference on Honey Bee Health (PDF) (72 pp, 1.2 MB, PDF) states that there are multiple factors playing a role in honey bee colony declines, including parasites and disease, genetics, poor nutrition and pesticide exposure.

With regard to pesticide exposure, acute and sublethal effects of pesticides on honey bees have been increasingly documented and are a concern, but it is not clear, based on current research, whether pesticide exposure is a major factor associated with U.S. honey bee health declines. The most pressing research questions relate to determining actual pesticide exposures bees receive in the field.