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

Abstract

Commercialized bumble bees (Bombus) are primary pollinators of several crops within open field and greenhouse settings. However, the common eastern bumble bee (Bombus impatiens Cresson, 1863) 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 brown-belted bumble bees (Bombus griseocollis De Geer, 1773), 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 wild-caught 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.

Variation in North American bumble bee nest success and colony sizes under captive rearing conditions

“…Meanwhile, B. griseocollis had the highest rate of nest success (quantified by nest initiation and establishment rates) across the 11-yr period, followed by B. occidentalis , B. vosnesenskii , and B. huntii. Bombus griseocollis initiated and established nesting at a rate of 76.1% and 54.6%, respectively, which was similar to findings from a study by Christman et al (2022) (initiation: 70.6%; establishment: 52.8%). In addition to having the highest rate of nest success, B. griseocollis also had the fastest nest initiation rate among species, with an average of 8.4 ± 6.7 days to first brood.…”

“…This then increases oviposition and establishment success rates ( Sladen 1912 , Plowright and Jay 1966 , Bernasconi and Keller 1996 , Ptáček et al 2000 , Strange 2010 ). After placement into rearing chambers, each gyne or pair of gynes was provisioned with 2 g of a multifloral honey bee collected pollen diet mixture and a feeder filled with 50% sugar solution with additives (artificial nectar) ( Christman et al 2022 , Rowe et al 2023 ). Preparation of multifloral pollen provisions and artificial nectar followed methodology described in Rowe et al (2023) .…”

“…However, capturing this information in wild colonies is difficult given that the nests are cryptic and often below ground. Obtaining data from colonies reared from wild-caught queens in controlled laboratory environments can increase knowledge on Bombus species nesting biology, although rearing bumble bees for research purposes has resulted in varying degrees of success ( Plowright and Jay 1966 , Kearns and Thomson 2001 , Evans et al 2007 , Salvarrey et al 2013 , Ptáček et al 2015 , Strange 2015 , Carnell et al 2020 , Christman et al 2022 ).…”

“…Recent efforts toward rearing bumble bees in captivity have improved techniques available to conservationists and researchers, which can be used to assess the commercial viability of nondomesticated Bombus species and to establish conservation techniques for imperiled species ( Macfarlane et al 1994 , Strange et al 2011 , Christman et al 2022 , Rowe et al 2023 ). For example, conservation propagation methods (i.e., assisted reintroductions) have been proposed as a recovery action to augment wild populations ( Smith et al 2020 ).…”

Bumble Bee Responses to Climate and Landscapes: Investigating Habitat Associations and Species Assemblages Across Geographic Regions in the United States of America

“…This was likely due to the climatic extremes at these sites, with temperatures ranging from 32.29–34.17°C and precipitation ranging from 26.36–28.51 cm. While this temperature range is well below critical thermal maximas for many species (Oyen et al, 2016; Christman et al, 2022b), this is still a high temperature for cold-adapted bumble bees to sustain if held constant over long periods of time. Further, the high levels of precipitation at these sites likely prevents foraging in these fields and may even result in the flooding of nearby colonies, resulting in a lack of bumble bees at these sites (Peat and Goulson, 2005; Sanderson et al, 2015; Goulson et al 2018).…”