A
U.S. Department of Agriculture (USDA) scientist is trying to learn what is
causing the decline in bumblebee populations and also is searching for a
species that can serve as the next generation of greenhouse pollinators.
Bumblebees, like honeybees, 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
companies stopped rearing them. Populations of other bumblebee species also are
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.
ARS is USDA’s chief intramural scientific research agency, and this research
supports the USDA priority of improving agricultural sustainability.
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. Evidence gathered so far shows that the range and
populations of B. occidentalis have
declined, that it is not as genetically diverse as it used to be, and that it
has higher pathogen prevalence than other bee species with stable populations.
The results were recently published in the Proceedings of the National Academy of Sciences.
The
researchers also have assembled a large database with information on more than
80,000 Bombus specimens representing
10 species throughout the country, including B. occidentalis. With Geographic Information System (GIS) modeling
technology, they were able to construct historic and current range maps of
several bumblebee species. The mapping process is described in the Uludag Bee Journal.
Read
more about this research in the August 2011 issue of Agricultural Research magazine.