Factors related to bumblebee parasitism in urban and wild Wyoming

Globally, pollinator populations are declining due to a combination of anthropogenic, environmental, and biological changes to their habitats and communities. Contributing factors include pesticide use, land development, the introduction of non-native species, novel pathogens, and climate change. Untangling the causes of these declines requires extensive data, but publicly available data are often inadequate for forming broad hypotheses. Few species have long-term range and abundance data, making it difficult to measure the outcomes of broad pollinator conservation goals. In Wyoming, data on bee communities and their health is particularly sparse. Currently, five bumblebee species are petitioned for listing under the Endangered Species Act, demonstrating the need to gather foundational data on bumblebees in the Intermountain West. Over two seasons, we collected data on bee communities and habitats across Wyoming to establish a baseline for future research. Additionally, we investigated parasitism in Bombus species to assess patterns and trends related to a probable cause of bee decline. We collected 14 Bombus species across the state using vane traps and hand netting. Of the initial 897 bumblebees processed during the first season of collection, 48.44% had external parasites such as mites or beetles present. A higher percentage of male bumblebees (62.5%) had external parasites than female bumblebees (39.27%).