January 11, 2011 | vol. 108 | no. 2 | Sydney A. Cameron, Jeffrey D. Lozier, James P. Strange, Jonathan B. Koch, Nils Cordes, Leellen F. Solter, and Terry L. Griswold
The study by Cameron et al. (2010) examines the widespread decline of North American bumble bee species, highlighting the importance of these pollinators in both wild plant communities and agricultural crops. The authors conducted a 3-year interdisciplinary study to assess the changing distributions, population genetic structure, and levels of pathogen infection in bumble bee populations across the United States. They compared current and historical distributions of eight species, using a database of over 73,000 museum records and intensive nationwide surveys of over 16,000 specimens. The results show that the relative abundances of four species have declined by up to 96%, and their geographic ranges have contracted by 23-87% within the last 20 years. The declining populations exhibit significantly higher infection levels of the microsporidian pathogen Nosema bombi and lower genetic diversity compared to stable species. The study suggests that higher pathogen prevalence and reduced genetic diversity are realistic predictors of the alarming patterns of decline in North America, although the cause and effect remain uncertain. The findings highlight the need for further research to understand the complex interactions of habitat fragmentation, loss of floral and nesting resources, disease, and climate change, and to develop conservation strategies to mitigate further losses.The study by Cameron et al. (2010) examines the widespread decline of North American bumble bee species, highlighting the importance of these pollinators in both wild plant communities and agricultural crops. The authors conducted a 3-year interdisciplinary study to assess the changing distributions, population genetic structure, and levels of pathogen infection in bumble bee populations across the United States. They compared current and historical distributions of eight species, using a database of over 73,000 museum records and intensive nationwide surveys of over 16,000 specimens. The results show that the relative abundances of four species have declined by up to 96%, and their geographic ranges have contracted by 23-87% within the last 20 years. The declining populations exhibit significantly higher infection levels of the microsporidian pathogen Nosema bombi and lower genetic diversity compared to stable species. The study suggests that higher pathogen prevalence and reduced genetic diversity are realistic predictors of the alarming patterns of decline in North America, although the cause and effect remain uncertain. The findings highlight the need for further research to understand the complex interactions of habitat fragmentation, loss of floral and nesting resources, disease, and climate change, and to develop conservation strategies to mitigate further losses.