Return of the Bumblebee?

Bombus occidenatlis is back! And it’s living on Zumwalt Prairie.

Since the mid-1990s, the western bumblebee (Bombus occidentalis) declined from being one of the most common to one of the rarest bumblebee species in the Pacific Northwest. This large, plain-looking black and yellow pollinator has become so rare that it was recently petitioned for U.S. Fish and Wildlife Service listing as threatened or endangered—the first insect species ever petitioned for listing.

But recent surveys of bees by Paul Rhoades of the University of Idaho and, Sujaya Rao of Oregon State University found small but growing populations of this vanishing bee in widely separated locations—Zumwalt Prairie, the Washington Palouse and the Olympic Mountains.

western bumblebee.jpgThere are 40 species of bumblebee in the western U.S. These animals have large, furry bodies that allow them to fly and work in colder temperatures when other bees are inactive. They are the premier pollinators in alpine and arctic environments. Like honeybees, bumblebees are social insects that live in colonies headed by one queen who is the mother off all the bees in the colony. Colonies usually inhabit abandoned rodent burrows, and prefer open meadows and grassland landscapes.

Native bees and native pollinators are in decline across the globe. The reasons are unresolved, but likely include disease and competition with non-native and commercially introduced species—which are also in trouble. Rhoades suggests that PNW native bumblebee decline is related to competition and diseases related to introduction of non-native bees (Nosema bombi) to pollinate greenhouses in the early 1990s.

Only 2.4 percent of bumblebees collected on the Washington Palouse were the western bumblebee (Bombus occidenatlis) Still, the news that populations may be on the increase, however slight, is heartening. The western bumblebee is especially important because it is a general pollinator, serving wildflowers, fruit trees, and crops that include tomatoes and eggplants.

On Zumwalt, Rhoades and his colleagues documented the presence of the bee. It is a fragile population, constituting only 2% of the 200 bumblebees counted over the two years (2012 and 2014) of the study. In 2011, Sujaya Rao and colleagues from Oregon State University, collected 49 western bumblebees on Zumwalt—the highest number of this species found in one area since its population collapse in the 1990’s.

So this important wildflower pollinator, once-common and now rare, seems to persist on Zumwalt. Researchers note that undisturbed habitat is important to this bee. With its abundance of open space and native grasslands, Zumwalt should provide an inviting habitat for recovery for a native son.

To read the original papers:

Rao: https://www.conservationgateway.org/ConservationByGeography/NorthAmerica/UnitedStates/oregon/Documents/2011-Rao_et_al-NWSci.pdf

 

Rhoades: http://jinsectscience.oxfordjournals.org/content/16/1/20

 

Guide to Bumblebees: http://www.fs.fed.us/wildflowers/pollinators/documents/BumbleBeeGuideWestern2012.pdf

 

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