Search for: All records

Abstract Accurate species delimitation is critical to identifying the conservation status of species. Molecular species delimitation methods have revealed previously unrecognized cryptic species across the taxonomic spectrum. However, studies vary in the molecular markers selected, analytical approaches used, and taxon sampling, which sometimes results in conflicting conclusions. One example of such a conflict is seen in the species delimitation analyses of the western bumble bee,Bombus occidentalis. This species was once an abundant insect pollinator in western North America but has declined severely since the mid 1990s and is predicted to continue to diminish under even optimistic future climate scenarios. Complicating this conservation crisis, the species status ofB. occidentalishas varied over time, with most recent studies recognizing one or two species. Previous studies that used molecular methods to address this question focused on a Bayesian phylogeny of the mitochondrialcytochrome oxidase I(COI) gene. Phylogenetic studies that focus on a single gene are criticized for misrepresenting the evolutionary history of species because nuclear and mitochondrial genomes, and even some genes within them, may have different evolutionary patterns. We tested a two species hypothesis of theB. occidentaliscomplex using nuclear (ultraconserved elements) and mitochondrial (COI) markers to infer maximum likelihood and Bayesian phylogenies for the taxa. We present our results and conclusions from eight species delimitation methods. Based on the genomic, morphological and geographic differences between the taxa we find support for the two species hypothesis, withB. occidentalisandB. mckayias separate species. We discuss the strengths and limitations of each genetic dataset and delimitation method, make recommendations for best practices, and highlight opportunities for equitable knowledge and technology development for phylogenomics in conservation biology. 

Abstract Bombus vosnesenskii Radowszkowski, 1862 is one of three bumble bee species commercially available for pollination services in North America; however, little is documented about B. vosnesenskii colony life cycle or the establishment of ex situ rearing, mating, and overwintering practices. In this study, we documented nest success, colony size, and gyne production; recorded the duration of mating events; assessed overwintering survival of mated gynes; and evaluated second-generation nest success for colonies established from low- and high-elevation wild-caught B. vosnesenskii gynes. Of the 125 gynes installed, 62.4% produced brood cells (nest initiation) and 43.2% had at least 1 worker eclose (nest establishment). High-elevation B. vosnesenskii gynes had significantly higher nest initiation and establishment success than low-elevation gynes. However, low-elevation colonies were significantly larger with queens producing more gynes on average. Mating was recorded for 200 low-elevation and 37 high-elevation gynes, resulting in a mean duration of 62 and 51 min, respectively. Mated gynes were then placed into cold storage for 54 days to simulate overwintering, which resulted in 59.1% of low-elevation gynes surviving and 91.9% of high-elevation gynes surviving. For second-generation low-elevation gynes, 26.4% initiated nesting and 14.3% established nesting. Second-generation high-elevation gynes did not initiate nesting despite CO2 narcosis treatments. Overall, these results increase our understanding of B. vosnesenskii nesting, mating, and overwintering biology from 2 elevations. Furthermore, this study provides information on successful husbandry practices that can be used by researchers and conservationists to address knowledge gaps and enhance the captive rearing of bumble bees. 

The commercial production and subsequent movement of bumble bees for pollination of agricultural field and greenhouse crops is a growing industry in North America and globally. Concerns have been raised about the impacts of pathogen spillover from managed bees to wild pollinators, including from commercial bumble bees. We recommend development of a program to mitigate disease risk in commercial bumble bee production, which will in turn reduce disease stressors on wild pollinators and other insects. We provide recommendations for the components of a clean stock program with specific best management practices for rearing commercial bumble bees including related products such as wax, pollen, and nesting material. 

Bumble bees (Bombus spp.) are important pollinators for both wild and agriculturally managed plants. We give an overview of what is known about the diverse community of internal potentially deleterious bumble bee symbionts, including viruses, bacteria, protozoans, fungi, and nematodes, as well as methods for their detection, quantification, and control. We also provide information on assessment of risk for select bumble bee symbionts and highlight key knowledge gaps. This information is crucial for ongoing efforts to establish parasite-free programs for future commerce in bumble bees for crop pollination, and to mitigate the problems with pathogen spillover to wild populations. 

Bumble bees are important pollinators for a great diversity of wild and cultivated plants, and in many parts of the world certain species have been found to be in decline, gone locally extinct, or even globally extinct. A large number of symbionts live on, in, or with these social bees. We give an overview of what is known about bumble bee ecto-symbionts and parasitoids. We provide information on assessment of risks posed by select bumble bee symbionts and methods for their detection, quantification, and control. In addition, we assess honey bee hive products such as pollen and wax that are used in commercial bumble bee production, and highlight key risks and knowledge gaps. Knowledge of these potential threats to native pollinators is important and they need to be managed in the context of national and international commercial trade in bumble bees to prevent pest introduction and pathogen spillover that can threaten native bees. 

Abstract Biogeographic clines in morphology along environmental gradients can illuminate forces influencing trait evolution within and between species. Latitude has long been studied as a driver of morphological clines, with a focus on body size and temperature. However, counteracting environmental pressures may impose constraints on body size. In montane landscapes, declines in air density with elevation can negatively impact flight performance in volant species, which may contribute to selection for reduced body mass despite declining temperatures. We examine morphology in two bumble bee (Hymenoptera: Apidae: Bombus Latreille) species, Bombus vancouverensis Cresson and Bombus vosnesenskii Radoszkowski, across mountainous regions of California, Oregon, and Washington, United States. We incorporate population genomic data to investigate the relationship between genomic ancestry and morphological divergence. We find that B. vancouverensis, which tends to be more specialized for high elevations, exhibits stronger spatial-environmental variation, being smaller in the southern and higher elevation parts of its range and having reduced wing loading (mass relative to wing area) at high elevations. Bombus vosnesenskii, which is more of an elevational generalist, has substantial trait variation, but spatial-environmental correlations are weak. Population structure is stronger in the smaller B. vancouverensis, and we find a significant association between elevation and wing loading after accounting for genetic structure, suggesting the possibility of local adaptation for this flight performance trait. Our findings suggest that some conflicting results for body size trends may stem from distinct environmental pressures that impact different aspects of bumble bee ecology, and that different species show different morphological clines in the same region.