Under the Wisconsin summer sun, biologist Jade Kochanski searches a prairie's wildflowers for a rare prize: the endangered rusty patched bumblebee. As a University of Wisconsin-Madison PhD student, she carefully collects non-lethal genetic samples from captured bees for analysis in Utah labs.
Once common across eastern North America, Bombus affinis populations have plummeted over 90% in recent decades due to habitat loss, pesticides, disease, and climate change. Now restricted to fragmented areas in the Upper Midwest and Northeast, it became the first U.S. bumblebee listed as endangered in 2017.
This listing prompted immediate action. Coordinated by U.S. Fish and Wildlife biologist Tamara Smith, researchers including Kochanski launched a multi-state effort in 2020 to gather genetic material across the bee's range. "Genetics emerged as the foundational question," Smith explains, essential for effective conservation.
Their landmark study in the Journal of Insect Science provides the first comprehensive genetic analysis, yielding vital conservation insights alongside recovery concerns. "Genetically, they're more precarious than hoped," Smith states.
Crucially, bumblebee populations are measured by colonies (originating from a single queen), not individuals. Observing multiple workers doesn't indicate numerous colonies. The research reveals alarmingly few colonies, increasing vulnerability to local extinction from events like prairie fires. Consequently, Kochanski is developing refined burn guidelines, balancing essential land management with bee protection.
Colony scarcity also means removing even one queen for captive breeding could devastate a local population. While such programs can boost numbers and genetic diversity, Smith cautions they require extremely careful protocols. "We must rigorously weigh risks against species-wide benefits," she notes, acknowledging managed care might sometimes offer better survival odds.
Genetic analysis detected significant inbreeding, evidenced by 15% of males being diploid (two chromosome sets) instead of the typical haploid state. These diploid males arise when fertilized eggs fail to develop into females due to low genetic diversity, signaling reduced resilience. Researchers Jonathan Koch (USDA) and John Mola stress that while 15% seems concerning, its abnormality is unclear. Comparisons with pre-1990s museum specimens are underway.
Furthermore, the study identified three genetically distinct populations: Minnesota, the central Midwest (Wisconsin, Illinois, and Iowa), and the Appalachians. This unexpected differentiation profoundly impacts management. "We cannot rear bees in one region and transplant them elsewhere," emphasizes conservationist Jay Watson.
While the rusty patched bumblebee is an icon for pollinator conservation, Smith underscores populations remain "stable or declining—definitely not increasing." Despite challenges, she draws hope from recoveries of other endangered species, affirming further genetic monitoring and refined management offer paths forward.