[Pollinator] FW: Can you help with evidence that the commercial bumble bee is spreading disease?

Fri Jan 15 05:34:38 PST 2010

Hi all,
It is hard to provide direct proof that the declines of Bombus sensu strictu (B.affinis, B. terricola, B.occidentalis and B. franklini) are attributed to disease because it is very difficult to do the rigorous experiments required when individuals of these species, let alone spring queens to rear colonies from, are scarce. I know this because I tried to collect B.terricola queens to do susceptibility experiments last spring but could not find any. I believe some experiments with B.occidentalis are ongoing but until those are published here is some the evidence we have so far:
1) Diseases such as N.bombi have been observed being transmitted from greenhouse bees to wild bees
Plight of the bumble bee: Pathogen spillover from commercial to wild populationsSheila R. Colla, Michael C. Otterstatter, Robert J. Gegear and James D. ThomsonDepartment of Zoology, University of Toronto, 25 Harbord Street, Toronto, Ont., Canada M5S 3G5
Received 1 September 2005;  revised 7 November 2005;  accepted 20 November 2005.  Available online 3 January 2006. 
AbstractPathogen spread or ‘spillover’ can occur when heavily infected, domestic hosts interact with closely-related wildlife populations. Commercially-produced bumble bees used in greenhouse pollination often have higher levels of various pathogens than wild bumble bees. These pathogens may spread to wild bees when commercial bees escape from greenhouses and interact with their wild counterparts at nearby flowers. We examined the prevalence of four pathogens in wild bumble bee populations at locations near and distant to commercial greenhouses in southern Ontario, Canada. Bumble bees collected near commercial greenhouses were more frequently infected by those pathogens capable of being transmitted at flowers (Crithidia bombi and Nosema bombi) than bees collected at sites away from greenhouses. We argue that the spillover of pathogens from commercial to wild bees is the most likely cause of this pattern and we discuss the implications of such spillover for bumble bee conservation.
Does Pathogen Spillover from Commercially Reared Bumble Bees Threaten Wild Pollinators?Author(s): Otterstatter MC (Otterstatter, Michael C.), Thomson JD (Thomson, James D.)Source: PLOS ONE    Volume: 3    Issue: 7  Article Number: e2771    Published: JUL 23 2008 Abstract: The conservation of insect pollinators is drawing attention because of reported declines in bee species and the 'ecosystem services' they provide. This issue has been brought to a head by recent devastating losses of honey bees throughout North America (so called, 'Colony Collapse Disorder'); yet, we still have little understanding of the cause(s) of bee declines. Wild bumble bees (Bombus spp.) have also suffered serious declines and circumstantial evidence suggests that pathogen 'spillover' from commercially reared bumble bees, which are used extensively to pollinate greenhouse crops, is a possible cause. We constructed a spatially explicit model of pathogen spillover in bumble bees and, using laboratory experiments and the literature, estimated parameter values for the spillover of Crithidia bombi, a destructive pathogen commonly found in commercial Bombus. We also monitored wild bumble bee populations near greenhouses for evidence of pathogen spillover, and compared the fit of our model to patterns of C. bombi infection observed in the field. Our model predicts that, during the first three months of spillover, transmission from commercial hives would infect up to 20% of wild bumble bees within 2 km of the greenhouse. However, a travelling wave of disease is predicted to form suddenly, infecting up to 35-100% of wild Bombus, and spread away from the greenhouse at a rate of 2 km/wk. In the field, although we did not observe a large epizootic wave of infection, the prevalences of C. bombi near greenhouses were consistent with our model. Indeed, we found that spillover has allowed C. bombi to invade several wild bumble bee species near greenhouses. Given the available evidence, it is likely that pathogen spillover from commercial bees is contributing to the ongoing decline of wild Bombus 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.

2) B.terrestris (also a member of Bombus sensu strictu)fitness' is negatively impacted by pathogens such as N. bombi 
(One example of many papers)
Nosema bombi: A pollinator parasite with detrimental fitness effectsOliver Otti,  and Paul Schmid-HempelaExperimental Ecology, Institute of Integrative Biology Zurich (IBZ), ETH Zurich, 8092 Zurich, SwitzerlandbWissenschaftskolleg zu Berlin, Wallotstrasse 19, D-14193 Berlin, Germany
Received 30 October 2006;  accepted 27 March 2007.  Available online 31 March 2007. 
AbstractNosema bombi is an obligate intracellular parasite that infects different bumblebee species at a substantial, though variable, rate. To date its pathology and impact on host fitness are not well understood. We performed a laboratory experiment investigating the pathology and fitness effects of this parasite on the bumblebeeBombus terrestris. We experimentally infected one group of colonies with N. bombi spores at the start of the worker production, while a second uninfected group of colonies served as controls. During colony development we collected live workers for dissections to measure infection intensities. In parallel, we measured several life history traits, to investigate costs to the host. We succeeded in infecting 11 of 16 experimental colonies. When infection occurred at an early stage of colony development, virtually all individuals were infected, with spores being found in a number of tissues, and the functional fitness of males and young queens was reduced to zero. Further, the survival of workers from infected colonies and infected males were reduced. With such severe effects, N. bombi appears to decrease its opportunities for transmission to the next host generation.

3) Members of the subgenus were quite common until the early 1990s coinciding with the emergence of the greenhouse industry in N.A.
-This requires a trip to an insect collection, by looking at the literature for when B.affinis and B.occidentalis were no longer used as model systems, talking to Robbin about his data on B.franklini or by looking at recent Bombus decline papers. 

I agree that much work is needed and the evidence isn't as strong as it could be, but in this case quick action is warranted. That is why Paul and Mike recommended those passages sent around by Sarina. It is likely that native bumble bees are facing many stressors, as many animals do in today's world, but the threat of disease introduction from managed congeners is very serious. A quick literature search on pathogen spillover in the salmon and livestock industry can show you how detrimental uncontrolled management practices can be to wild animals over short periods of time. At this time, I don't think we know enough about the diseases as they do in honey bees or elsewhere to just ask for parasite-free bees.
Take care,
Sheila Colla

From: ladadams at aol.com
Date: Thu, 14 Jan 2010 14:55:59 -0500
To: pollinator at nappc.org
Subject: [Pollinator] Can you help with evidence that the commercial bumble	bee is spreading disease?

We have been asked several questions about the recent articles that have 
appeared on the LISTSERV, particularly the following quote from the NY Times 
article,

"The groups said Tuesday that four species of bumblebees once common in the 
United States have seen drastic declines -- and the evidence points to 
diseases spreading out of greenhouses that use domesticated bumblebees. 
'

It is clear that there have been (at least) four species of bumble 
bees in decline, but does anyone know of a published study that 
provides evidence to support that this is the result of diseases spreading out 
of greenhouses using domesticated bumble bees?

Thanks.

Laurie Davies Adams
Executive 
Director
Pollinator Partnership 
423 Washington Street, 5th 
floor
San Francisco, CA 
94111
415-362-1137
LDA at pollinator.org

www.pollinator.org
www.nappc.org

National Pollinator Week is June 21-27, 2010. 
Beecome 
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