Seed Keepers

["Lawrence F. London, Jr." <venaurafarm@bellsouth.net>]

-------- Original Message --------
Subject: [SANET-MG] bumblr bees crash
Date: Thu, 6 Jan 2011 08:27:51 -0500
From: joe cummins <jcummins@UWO.CA>
To: SANET-MG@LISTS.IFAS.UFL.EDU

Proc Natl Acad Sci U S A. 2011 Jan 3. [Epub ahead of print]
Patterns of widespread decline in North American bumble bees.
Cameron SA, Lozier JD, Strange JP, Koch JB, Cordes N, Solter LF,
Griswold TL.
Department of Entomology and Institute for Genomic Biology, University
of Illinois, Urbana, IL 61801.
Abstract
Bumble bees (Bombus) are vitally important pollinators of wild plants
and agricultural crops worldwide. Fragmentary observations, however,
have suggested population declines in several North American species.
Despite rising concern over these observations in the United States,
highlighted in a recent National Academy of Sciences report, a national
assessment of the geographic scope and possible causal factors of bumble
bee decline is lacking. Here, we report results of a 3-y
interdisciplinary study of changing distributions, population genetic
structure, and levels of pathogen infection in bumble bee populations
across the United States. We compare current and historical
distributions of eight species, compiling a database of >73,000 museum
records for comparison with data from intensive nationwide surveys of
> 16,000 specimens. We show that the relative abundances of four species
have declined by up to 96% and that their surveyed geographic ranges
have contracted by 23-87%, some within the last 20 y. We also show that
declining populations have significantly higher infection levels of the
microsporidian pathogen Nosema bombi and lower genetic diversity
compared with co-occurring populations of the stable (nondeclining)
species. Higher pathogen prevalence and reduced genetic diversity are,
thus, realistic predictors of these alarming patterns of decline in
North America, although cause and effect remain uncertain.