A survey of managed honey bee colony losses in the USA, fall 2009 to winter 2010

Authors: VANENGELSDORP, DENNIS - Pennsylvania State University; HAYES, JERRY - Florida Department Of Agriculture; UNDERWOOD, ROBYN - Kutztown University; CARON, DEWEY - Oregon State University; Pettis, Jeffery

Submitted to: Journal of Apicultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2010
Publication Date: 11/19/2010
Citation: Vanengelsdorp, D., Hayes, J., Underwood, R.M., Caron, D., Pettis, J.S. 2010. A survey of managed honey bee colony losses in the USA, fall 2009 to winter 2010. Journal of Apicultural Research. 50(1):1-10.

Interpretive Summary: Honey bee colony losses continue to be a major issue in the U.S. A survey was conducted for the fourth straight year to try and determine the extent and reason for honey bee colony losses. This survey found that over the winter of 2009 – 2010 for the fourth consecutive year U.S. beekeepers experienced high winter loss of managed honey bee (Apis mellifera) colonies. On average U.S. beekeepers reported a 42.2% loss of their colonies, for a total loss of 34.4%. Sideline and backyard beekeepers reported a higher colony loss than commercial beekeepers (those operating more than 500 colonies). Similarly, beekeepers who managed colonies in more than one state and beekeepers whose colonies pollinated almond orchards had a lower total loss than beekeepers who managed colonies in one state or whose colonies were not pollinating almonds. Responding beekeepers self-identified manageable conditions such as starvations and weak conditions in the fall as the leading causes of colony loss. Commercial beekeepers reported poor queens, Varroa mites and pesticides as the leading cause of colony loss. This survey compared the 2009-2010 responses to 2008 – 2009 responses. This survey benefits beekeepers worldwide.

Technical Abstract: This study records the fourth consecutive year of high winter losses in managed honey bee (Apis mellifera) colonies in the USA. Over the winter of 2009-2010, US beekeepers responding to this survey lost an average of 42.2% of their colonies, for a total loss of 34.4%. Commercial beekeepers (those operating more than 500 colonies) experienced lower total losses as compared to sideline and backyard beekeepers. Similarly, operations that maintained colonies in more than one state and operations that pollinated almond orchards over the survey period had lower total losses than operations either managing colonies in one state exclusively or those not pollinating almonds. On average beekeepers consider acceptable losses to be 14.5%, and 65% of all responding beekeepers suffered losses in excess of what they considered acceptable. The proportion of operations that experienced losses and reported having no dead bees in their colonies or apiaries was comparable to that reported in the winter of 2008-2009. Manageable conditions, such as starvation and a weak condition in the fall were the leading self-identified causes of mortality as reported by all beekeepers. Commercial beekeepers were, however, less likely to list such manageable causes, instead listing poor queens, mites, and pesticides most frequently as the self-identified causes of mortality in their operations.