Captive Rearing Success and Critical Thermal Maxima of Bombus griseocollis (Hymenoptera: Apidae): A Candidate for Commercialization?

Commercialized bumble bees (Bombus) are primary pollinators of several crops within open field and

greenhouse settings. However, B. impatiens is the only species widely available for purchase in North

America. As an eastern species, concerns have been expressed over their transportation outside of their

native range. Therefore, there is a need to identify regionally appropriate candidates for commercial crop

pollination services, especially in the western U.S.A. In this study, we evaluated the commercialization

potential of B. griseocollis, a broadly distributed species throughout the U.S.A., by assessing nest initiation

and establishment rates of colonies produced from wild-caught gynes, creating a timeline of colony

development, and identifying lab-reared workers’ critical thermal maxima (CTMax) and lethal temperature

(ecological death). From 2019 to 2021, 70.6% of the wild-caught B. griseocollis gynes produced brood in a

laboratory setting. Of these successfully initiated nests, 74.8% successfully established a nest (produced a

worker), providing guidance for future rearing efforts. Additionally, lab-reared workers produced from wildcaught

B. griseocollis gynes had an average CTMax of 43.5°C and an average lethal temperature of 46.4°C,

suggesting B. griseocollis can withstand temperatures well above those commonly found in open field

and greenhouse settings. Overall, B. griseocollis should continue to be evaluated for commercial purposes

throughout the U.S.A.