The nuclear and mitochondrial genomes of the bellicose bumblebee (Bombus bellicosus, Hymenoptera: Apidae), a threatened pollinator in a changing South American landscape.

Abstract

We present the first genome of a Brazilian bumblebee species, the bellicose bumblebee (Bombus bellicosus). This is an endemic species in southern South America facing local extinction due to habitat loss and climate change. During the COVID-19 social distancing in Brazil, we launched a citizen science initiative via social media to locate remaining bellicose bumblebee populations, leading to the collection of a specimen for genome sequencing. Analysis of the novel genome revealed lower genetic diversity in the bellicose bumblebee compared to a widespread related species (B. pascuorum). However, the absence of extensive runs of homozygosity indicated a lack of recent inbreeding, offering a promising perspective for the conservation of this species. Furthermore, demographic history analysis indicates population expansion during past glacial periods, in contrast to Palearctic bumblebees which suffered a stark decline during glaciations. Our findings provide invaluable information for the conservation of this species and for further studies about its biology and evolution, particularly under a scenario of rapid environmental change.