Multiple Factors Impact Decline in Honey Bee Colonies

Open cotton bolls.

Multiple factors – including parasites and disease, genetics, poor nutrition and pesticide exposure – are playing a role in the decline of honey bee colonies, according to a comprehensive scientific report on honey bee health released May 2 by the United States Department of Agriculture (USDA) and the Environmental Protection Agency (EPA).

The report evolved from a 2012 National Stakeholders Conference on Honey Bee Health led by federal researchers and managers, along with Penn State University, to synthesize the current base of knowledge regarding the primary factors that have the greatest impact on managed bee health.

Among the key findings:

• The parasitic Varroa mite continues to be the major factor underlying colony loss in the U.S. and other countries, and they are now showing widespread resistance to the chemicals used to control them within the hive. New virus species – several of which have been associated with Colony Collapse Disorder (CDD) – have also been found in the U.S.

• U.S. honeybee colonies need increased genetic diversity to help improve thermoregulation (the ability to keep body temperature steady even if the surrounding environment is different), disease resistance and worker productivity. Honey bee breeding should emphasize traits such as hygienic behavior to help improve resistance to Varroa mites and diseases such as American foulbrood.

• A nutrition-poor diet can make bees more susceptible to harm from disease and parasites. Bees need better forage and a variety of plants to support colony health and longevity. Land management actions are needed to maximize available nutritional forage to promote and enhance good bee health and protect bees by keeping them away from pesticide-treated fields.

• Best Management Practices associated with bees and pesticide use are not widely followed within the crop-producing industry. More informed and coordinated communication and collaboration is needed between growers, beekeepers and other stakeholders regarding ways to protect bees from pesticides. Accurate and timely bee kill incident reporting, monitoring and enforcement is also needed.

• Additional research is needed to determine actual pesticide risks to bees in the field and colony productivity.

An estimated one-third of all food and beverages are made possible by pollination, mainly by honey bees. In the United States, pollination contributes to crop production worth $20-30 billion in agricultural production annually. A decline in managed bee colonies increases pressure on those sectors of agriculture reliant on commercial pollination services.

Agencies involved in developing the report include USDA’s Office of Pest Management Policy (OPMP), National Institute of Food and Agriculture (NIFA), Agricultural Research Services (ARS), Animal and Plant Health Inspection Service (APHIS), and National Resource Conversation Service (NRCS), as well as the EPA and Penn State University.

The report provides important input to the Colony Collapse Disorder Steering Committee, led by the USDA, EPA and the National Agricultural Statistics Service (NASS). This Committee will consider the report’s recommendations and update the CCD Action Plan which will outline major priorities to be addressed in the next 5-10 years and serve as a reference document for policy makers, legislators and the public, and will help coordinate the federal strategy in response to honey bee losses.

To view the report, visit

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