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Why bumblebees are disappearing

August 12, 2011 - Washington

A U.S. Department of Agriculture (USDA) scientist is tracking the cause of the decline in bumblebee populations and also searching for a species that can serve as the next generation of greenhouse pollinators.

Bumblebees, like honey bees, are important pollinators of native plants and are used to pollinate greenhouse crops like peppers and tomatoes.

But colonies of Bombus occidentalis used for greenhouse pollination began to suffer from disease problems in the late 1990s and companies stopped rearing them. Populations of other bumblebee species are also believed to be in decline.

Entomologist James Strange is searching for solutions at the Agricultural Research Service (ARS) Pollinating Insects-Biology, Management and Systematics Research Unit in Logan, Utah.

Many greenhouse growers now use commercially produced Bombus impatiens, a generalist pollinator native to the Midwest and Eastern United States and Canada.

But scientists are concerned about using a bee outside its native range, and some western states restrict the import and use of non-native bees.

If B. impatiens were to escape and form wild colonies in the western United States, they could compete with native bees for food and resources and expose native bumblebees to pathogens they are ill equipped to combat.

Strange has been studying a pretty, orange-striped generalist named Bombus huntii, native to the western half of the country that could be used in greenhouses in the western United States.

He is determining how to best rear B. huntii in a laboratory setting, a vital step in commercializing it.

To understand the decline of B. occidentalis, Strange and his colleagues also have been tracking its habitat range and population trends.

The results were recently published in the Proceedings of the National Academy of Sciences.


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