Study: Greenhouse Bees Infecting Wild Bees With Pathogen

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Main Category: Water - Air Quality / Agriculture
Article Date: 26 Jul 2008 - 0:00 PDT

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A study published in the open-access journal PLoS ONE reports an alarming spread of disease from commercial bees to wild pollinators that may explain a decline in the wild bee population.

Almost 33% of the human diet is derived from plants pollinated by insects, and bees are an important link in the pollination process for several of these crops. However, researchers have noticed that in North America, these pollinating bees are suffering widespread declines, and this could have a devastating impact on agriculture and food supplies. In their analysis of the situation, Michael Otterstatter and James Thomson (University of Toronto) provide a body of evidence suggesting that the wild bees are being infected by commercially produced bumble bees used in greenhouses. They posit that the reduction in wild bees can be largely explained by this phenomenon.

The scientists conducted their field research - analyzing the occurrence of disease in wild bumble bees - in southern Ontario, Canada in areas close to industrial greenhouse operations. Laboratory experiments and mathematical models assisted in understanding the spread, or "spillover," of disease into the wild population. They also predicted the extent and severity of this disease spread from commercial to wild bees.

Crithidia bombi is a harmful and highly contagious pathogen carried by the commercial bumble bees - bees tat regularly escape from greenhouses and meet with wild bees at flowers. There was a clear correlation between pathogen infection and proximity to greenhouses. About one half of wild bumble bees who were near greenhouses were found to be infected with C. bombi, while no bees carried the pathogen if they were located away from greenhouses. The researchers also found that as they moved away from greenhouses - the disease centers for wild pollinators - both the frequency and severity of infections declined.

Otterstatter and Thomson developed a mathematical model that predicts grim results over time for the wild bee population. The model forecasts a large-scale epidemic among wild bees over time due to the pathogen spillover from commercial bees that introduces disease to wild pollinator populations near greenhouses.

"Given the available evidence, it is likely that pathogen spillover from commercial bees is contributing to the ongoing decline of wild Bombus [bee genus] in North America. Improved management of domestic bees, for example by reducing their parasite loads and their overlap with wild congeners, could diminish or even eliminate pathogen spillover," conclude the authors.

Does Pathogen Spillover from Commercially Reared Bumble Bees Threaten Wild Pollinators?
Otterstatter MC, Thomson JD
PLoS ONE (2008). 3(7): e2771.
doi:10.1371/journal.pone.0002771
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About PLoS ONE

PLoS ONE is the first journal of primary research from all areas of science to employ both pre- and post-publication peer review to maximize the impact of every report it publishes. PLoS ONE is published by the Public Library of Science (PLoS), the open-access publisher whose goal is to make the world's scientific and medical literature a public resource.

About the Public Library of Science

The Public Library of Science (PLoS) is a non-profit organization of scientists and physicians committed to making the world's scientific and medical literature a freely available public resource. For more information, visit http://www.plos.org

Written by: Peter M Crosta
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