Museum Artifacts that Tell More than History Lessons

A critically endangered bumble bee in the western United States may help researchers develop conservation strategies to protect the species as well as other pollinators that are vital to U.S. agriculture production.  

Located in the hills of southwest Oregon and northern California, the Franklin’s bumble bee (Bombus franklini) is a generalist pollinator that collects nectar and pollen in its native region, primarily from alpine flowering plants. After experiencing severe population declines since the 1990s, the bee was last observed in the wild in 2006 and is currently listed as endangered under the U.S. Endangered Species Act. 

It was initially unknown what caused the population decline, but common theories include diseases, erratic weather conditions, and humans as possible contributors. To figure out what really happened, ARS researchers and university collaborators examined museum specimens because wild Franklin’s bumble bees aren’t available. They collected whole-genome sequence data spanning four decades, to develop a genetic and demographic history of the bee species. 

“Specimens from natural history collections, also known as museomics, and reference genomes can be effective tools for assessing bee species’ statuses,” said Rena Schweizer, Research Entomologist and Computational Biologist at the ARS Pollinating Insect Research Unit in Logan, UT. “We used advanced genomic techniques on historical museum specimens and reconstructed the Franklin’s bumble bees’ evolutionary history. We pieced together a more detailed picture of the genetic and demographic changes that occurred leading up to the bee’s population decline.”

According to Schweizer, the data shows that the Franklin’s bumble bee may have been on a trajectory of decline starting thousands of years ago, prior to human impacts.  

“Its history revealed the combination of critically low genetic diversity and effectively low population size could have led to the bee’s population decline, or made it more susceptible to environmental stressors,” said Schweizer. “We found little to no genomic evidence implicating diseases or pathogens in the species’ decline.”

The study’s results will help researchers with conservation efforts in protecting the endangered species and other pollinators. Other bee species experiencing similar declines could be prioritized for conservation. Demonstrating that other species do not have historical decline could help researchers pinpoint and mitigate more recent stressors, focusing the effort and resources where they are most needed. 

“The results of our study will be essential for developing effective conservation strategies to prevent the complete loss of this species, as well as providing a framework to detect declines in real-time in other imperiled bee species, including those species that are important agricultural pollinators” said Schweizer. 

The recent study was published in PNAS and is part of the Beenome100 project, a first-of-its-kind effort to create a library of high-quality, highly detailed genome maps of 100 or more diverse bee species found in the United States. 

“This was a real collaborative effort between government and academic researchers and would not have been possible without the expertise and resources that ARS laboratories have developed to harvest genomic data from small insect specimens,” said the study’s senior author Michael Branstetter, a Research Entomologist in Logan, UT.  “It also highlights the significant value of natural history collections, which store priceless information about our national biodiversity.” 

The research was conducted in collaboration with the U.S. Pacific Basin Agricultural Research Center, Tropical Pest Genetics and Molecular Biology Research Unit, the University of Montana’s Division of Biological Sciences and Flathead Lake Biological Station; the University of California, Davis’s Department of Entomology and Nematology; and the University of Hawai‘i’s College of Natural Sciences. – by Jessica Ryan, ARS Office of Communications

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