Characterizing the venom composition of Bombus (Psithyrus) insularis, a social bumble bee parasite, along an elevation gradient

Bombus insularis is an inquiline social parasite, which relies on usurping other bumble bee nests to reproduce. B. insularis uses its venom both as defense and as a weapon to invade host colonies. Predator and prey dynamics can affect venom composition in many species, including bumble bees. Environmental variables, such as elevation, impact the community dynamics and composition in mountainous habitats, including parts of B. insularis’ range in Utah. This variation creates a diverse host population which supports a large B. insularis population. However, the venomics of B. insularis has never been studied. The goal of this study is to characterize the venom proteome of Bombus insularis queens and compare their toxin abundances across different elevations. Field trips will take place from June to August 2023 between three transects in Logan, Utah. Each transect will have one high-elevation and one low-elevation site. B. insularis queens will be captured using nets and their venom will be extracted. Qualitative and quantitative proteomic analyses will be done on each venom sample using liquid chromatography-mass spectrometry. The results of this study will provide a general understanding of the venom proteome and morphological characteristics of the sting apparatus of B. insularis, a potential pest to commercial pollinators. We will also identify new venom toxins and elucidate whether there are Psithyrus-specific peptides with sequential similarities to bumble bee-specific venom peptides, bombolitins. This study will be a first step into future studies focusing on the functional and structural properties of potential bioactive compounds in Psithyrus venom.