Incidental captures of Bombus species in traps: A national survey

Federal and state agencies conduct annual field surveys for non-native lepidopteran pests in agricultural fields throughout the U.S. It is well known that Bombus are commonly captured within these traps; however, no study has assessed regional variation in bycatch composition. Therefore, our objectives were to characterize the scope of Bombus bycatch throughout the U.S. to better understand regional effects of traps on pollinator assemblages and to determine the effect of landscape composition and configuration on pollinator diversity. Bycatch was collected from pest traps within agricultural fields throughout Florida, Indiana, Kansas, Kentucky, Maryland, South Carolina, Utah, Virginia, and West Virginia from 2018 to 2020. Bombus fervidus, B. bimaculatus, B. impatiens, B. pensylvanicus, and B. huntii were the five most abundant species, comprising 84% of total captures. Collection rates varied by state and year, ranging from one Bombus per week in Florida (2019) to over thirty in Utah (2018 and 2020) and West Virginia (2019). Species richness was consistent with published data suggesting that Bombus bycatch is representative of the resident community. However, some of the species collected (B. fervidus, B. fraternus, B. pensylvanicus, and B. auricomus) are historically uncommon throughout parts of their ranges. Therefore, their captures may indicate they are increasing in prevalence within these areas. Further, land use diversity, evenness, patch richness, spatial connectedness, and elevation positively influenced Bombus diversity and abundance in most regions. Our results suggest that future management practices should focus on increasing landscape diversity and connectivity at a local level to promote diverse pollinator populations.