Performing Department
(N/A)
Non Technical Summary
Managed bumble bees (Bombus impatiens) and various species of wild bumble bees are vital pollinators in U.S. agriculture. However, disease threatens the sustainability of their pollination services. Moreover, efforts to optimize the health and pollination performance of commercially produced B. impatiens colonies are still in their infancy. Recent research shows that bacterial probiotics are a highly promising tool for bolstering disease resistance and performance of honey bees. However, as honey bee bacteria generally fail to establish in bumble bees, there is a need to identify bumble bee-specific bacteria that could be used to support their health and pollination.The overall goal of this project is to develop bacterial probiotics specific to B. impatiens that improve performance and sustain pollination services in the face of disease and other stressors. The supporting objectives are: 1) identify gut bacteria from bumble bees that promote resistance to Crithidia bombi, a common parasite in managed colonies that can spread to wild bumble bees; 2) identify gut bacteria that improve pollination-relevant aspects of bumble bee performance (cognition, lifespan, and reproduction); 3) build a culture collection targeted to promising bacterial species. A "rewilding" approach will be used to discover beneficial probiotics. From cryopreserved gut material derived from wild B. impatiens populations, bacterial strains will be isolated, identified, and experimentally inoculated into bumble bees under controlled laboratory conditions. Strains that promote one or more aspects of bee health will be prioritized as probiotic candidates for further development. Overall, this work will accomplish the first key steps toward naturally derived probiotics for managed B. impatiens that support bumble bee health and production of bumble bee-pollinated crops.
Animal Health Component
0%
Research Effort Categories
Basic
85%
Applied
(N/A)
Developmental
15%
Goals / Objectives
The overall goal of the project is to develop probiotics that will ultimately improve disease resistance and performance of managed bumble bees (Bombus impatiens) in the United States. Managed bumble bees are agriculturally important for crop pollination, but often suffer from disease or other factors that reduce their productivity. Further, they have been linked to pathogen spillover into wild and declining bumble bee species. One potential strategy for addressing this problem is based in the gut microbiome, which is known to improve bees' pathogen resistance and nutrition. The project will take the first steps toward microbiome-targeted bee management by identifying and culturing probiotic bacterial strains that support bumble bee health.The supporting objectives are:1. Identify gut bacterial strains and species that promote bumble bee resistance to parasites.2. Identify gut bacterial strains and species that improve pollination-relevant aspects of bee performance.3. Build a culture collection, targeted to the most promising bacterial species, for evaluation as probiotics for managed Bombus impatiens.
Project Methods
1. The first experiments will evaluate which bacteria improve the parasite resistance of bumble bees (Bombus impatiens).Different strains and species of bacteria, isolated from wild Bombus impatiens, will be cultured and inoculated individually into the diet of germ-free (sterile) bumble bees, following established techniques. Subsequently, bees will be exposed to a defined dose of parasite (Crithidia bombi) cells. After two weeks, Crithidia infection levels will be measured. Experiments will be replicated across bee colonies and across microcolonies (small cages with three worker bees each). Generalized linear models will be used to identify strains showingstatistically significant reductions in C. bombi load relative to controls, accounting for microcolony and colony identity as random effects. 16S rRNA gene sequencing will be used to determine colonization success of the focal bacterial strains. Strains that both colonize the bees, and reduce parasite infection, will be prioritized for the culture collection as candidate probiotics. Success will be evaluated as production of robust data on Crithidia loads across bacterial strain treatments.2. The second experiments will adopt the same design as above, but with different focal phenotypes. Specifically, lifespan, reproductive output, and cognitive ability will be used as metrics of overall performance. Lifespan will be measured by checking survival every 2 days. Reproduction will be measured as the number and size of brood produced over the lifespan of each microcolony. Cognition will be assessed through a collaboration with Dr. Felicity Muth. Dr. Muth's free-moving proboscis extension response assay will be applied to age-controlled bees to measure associative learning and memory retention. Similar statistical analyses will be used as above to assess relationships between bacterial treatment and performance metrics, but modified to account for differences in data structure. 16S rRNA gene sequencing will again be used to determine colonization success of the focal bacterial strains. Strains that both colonize the bees, and improve one or more of the performance metrics, will be prioritized for the culture collection as candidate probiotics. Success will be evaluated as production of robust data on bee performance traits across bacterial strain treatments.3. Strains identified from the above experiments as having one or more positive effects on bumble bees will be used to establish a culture collection. The strains, which will be first identified by 16S rRNA gene sequencing, will also be submitted for whole-genome sequencing. After locating an appropriate repository that can provide it upon request (such as the USDA ARS Culture Collection), and after creating backup glycerol stocks of all strains, the culture collection will be deposited for use by the research community. Success of this objective will be evaluated as production of a collection of bacterial strains, with known positive effects on bumble bees, and deposition of this collection in an accessible repository.