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UNH research: Dramatic decline in NH bumble bees

December 25. 2017 9:31PM
Molly Jacobson, a recent graduate of UNH's undergraduate wildlife and conservation biology program, was one of four researchers who studied the status of the state's bumble bee population. (Jeremy Gasowski/UNH)

DURHAM — In the first long-term study of the state’s bumble bee population, researchers with the New Hampshire Agricultural Experiment Station at the University of New Hampshire have found three of the state’s most important bumble bee species have experienced drastic declines and range constriction over the last 150 years, with a fourth bee also in significant decline.

The goal, UNH researchers said in a news release, is to prevent “vulnerable pollinators from going extinct with far-reaching ramifications within ecosystems.”

The value of pollination to agriculture is estimated at more than $200 billion a year worldwide.

“The abundance of and diversity of pollinators are declining in many agricultural landscapes across the United States,” the news release states. “Given this importance, widespread declines in pollinator diversity have led to concern about a global pollinator crisis.”

To conduct their research, scientists analyzed 3,333 bumble bee specimens comprising 16 Bombus species dating to 1867.

Bombus specimens for this study were made available from the UNH Insect Collection, as well as from field collections performed during the summers of 2014–2016. This allowed researchers to track over time changes in abundance and distribution, with focus on species designated of greatest conservation need by the New Hampshire Department of Fish and Game.

Floral records also provided insight into the diet breadth of these species, which may affect their vulnerability.

Scientists found drastic decline in Bombus affinis, Bombus fervidus, and Bombus terricola, as well as significant decline in Bombus vagans, with data suggesting it has been ecologically replaced by Bombus impatiens over time.

The rusty patch bumble bee, Bombus affinis, was the first bee listed as an endangered species in the continental United States earlier this year. This species is thought to be locally extinct in New Hampshire and was last collected in 1993, according to the UNH news release.

Among other species of greatest conservation need, Bombus fervidus has declined by 96 percent over the past 150 years, and Bombus terricola has declined by 71 percent.

Bombus vagans has also experienced a significant decline of 42 percent in New Hampshire. The researchers suggest Bombus vagans receive future conservation consideration.

“Wild bees, particularly bumble bees, are highly important pollinators for both agriculture and unmanaged ecosystems,” said Sandra Rehan, assistant professor of biological sciences at the University of New Hampshire. “They have experienced alarming declines in recent decades, and in order to effectively work toward their protection, information about their life histories, ecological roles, and distributional changes on a more local scale is needed.”

The research was conducted by Rehan along with Erika Tucker, USDA research fellow and a postdoctoral researcher with the experiment station; Minna Mathiasson, a graduate student in biology; and Molly Jacobson, a recent graduate of UNH’s undergraduate wildlife and conservation biology program.

Their analyses also found a severe constriction of the geographic range of Bombus terricola to high elevation regions in the latter half of the 20th century, and its role as pollinator of several alpine plants necessitates immediate conservation action, the UNH news release states.

More information on the native bees of New Hampshire can be found on the bee lab’s educational website. This material is based upon work supported by the NH Agricultural Experiment Station, through joint funding of the National Institute of Food and Agriculture, U.S. Department of Agriculture and the state of New Hampshire. The research also is supported by the UNH Hamel Center for Undergraduate Research.

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