Project Number: 5428-21000-013-08
Project Type: Reimbursable

Start Date: Oct 01, 2007
End Date: Aug 14, 2010

Objective:
It is clear that the problem of decline in distribution and abundance of the Nation¿s wild bumble bee (Bombus) has become a matter of grave concern to agriculture and to the reproductive success of native wild and cultivated flowering plants. Although there is suggestive evidence of decline for several species, documentation of population changes and potential causes is gravely incomplete. This proposal seeks to accomplish the following goals: 1. quantify the status targeted American bumble bee species, 2. develop protocols for assessing status and potential causes of decline, and 3. investigate two hypothesized causes of putative decline: 1) low levels of genetic variation in fragmented populations and 2) disease from an introduced European strain of the microsporidium Nosema bombi. The synthetic goal of this research is understand the dynamics underlying sudden decreases in bumble bee populations.

Approach:
We are targeting six species for study, three western US species and three Midwestern species. ARS will focus effort on the western species and collaborate with researchers at University of Illinois and the Illinois Natural History Survey to study the Midwestern species. Historical range maps and population data will be synthesized for the six species to determine the health and distribution of the species. Much of this will focus on site visits to entomological museums. Current data will be gathered by collection of wild bumble bees at sites of known historic abundance to determine modern presence or absence and if presence, relative abundance. This work is concurrent with studies of all bumble bee taxa in the western US. Samples of bees from extant populations will be analyzed for pathogen levels, genetic diversity and parasite loads. We will also begin to attempt laboratory rearing of bumble bees in this project to test susceptibility to pathogens of interest. The molecular methods used to test the genetic diversity of species include using multilocus microsatellite genotypes to test populations for diversity, and historic population bottlenecks.