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

<em>Commercialized bumble bees (Bombus) are primary pollinators of several crops within open field and</em> <em>greenhouse settings. However, B. impatiens is the only species widely available for purchase in North</em> <em>America. As an eastern species, concerns have been expressed over their transportation outside of their</em> <em>native range. Therefore, there is a need to identify regionally appropriate candidates for commercial crop</em> <em>pollination services, especially in the western U.S.A. In this study, we evaluated the commercialization</em> <em>potential of B. griseocollis, a broadly distributed species throughout the U.S.A., by assessing nest initiation</em> <em>and establishment rates of colonies produced from wild-caught gynes, creating a timeline of colony</em> <em>development, and identifying lab-reared workers’ critical thermal maxima (CT</em><em>Max</em><em>) and lethal temperature</em> <em>(ecological death). From 2019 to 2021, 70.6% of the wild-caught B. griseocollis gynes produced brood in a</em> <em>laboratory setting. Of these successfully initiated nests, 74.8% successfully established a nest (produced a</em> <em>worker), providing guidance for future rearing efforts. Additionally, lab-reared workers produced from wildcaught</em> <em>B. griseocollis gynes had an average CT</em><em>Max </em><em>of 43.5°C and an average lethal temperature of 46.4°C,</em> <em>suggesting B. griseocollis can withstand temperatures well above those commonly found in open field</em> <em>and greenhouse settings. Overall, B. griseocollis should continue to be evaluated for commercial purposes</em> <em>throughout the U.S.A.</em>