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Many diapausing insects undergo a nutrient storage period prior to their entry into diapause. Bumble bee queens diapause as adults in the winter preceding their spring nest initiation period. Before diapause, they sequester glycogen and lipids, which they metabolize during the overwintering period. We used RNA sequencing to examine how age and nectar diet (specifically, the concentration of sucrose in nectar) impact gene expression in the pre‐overwintering bumble bee queen fat body, the "liver‐like" organ in insects with broad functions related to nutrient storage and metabolism. We found that diet on its own, and in combination with age, impacts the expression of genes involved in detoxification. Age was also a strong driver of gene expression, especially at earlier ages (up to 3 days). In addition to these molecular correlates of diet and age, we also found a putative molecular signature of diapause entry or preparation in adult queens in the oldest age group (12 days) fed the most sucrose‐rich diet, based on comparisons between our data set and another transcriptome data set from bumble bee queens. This transcriptomic pattern suggests that preparation for (or entry into) diapause might be in part mediated by nutritional state in bumble bee queens. Collectively, these findings show that there are molecular processes in the fat body that are responsive to sucrose levels in the diet and/or associated with age‐related maturational changes. A better understanding of these processes may shed light on important aspects of bumble bee biology, such as queen responses to nutritional and other forms of stress, and the factors that regulate their entrance into diapause. [ABSTRACT FROM AUTHOR]

Mexico and Central America are among the most biodiverse regions on Earth, harboring many species with high levels of interpopulation morphological and genetic diversity. The mountainous topography of this region contains isolated sky island habitats that have the potential to promote speciation. This has been studied in vertebrates, yet few studies have examined the phylogeographic and genetic structure of insect species encompassing this region. Here we investigate geographic patterns of genetic and morphological divergence and speciation among widespread populations of the highly polymorphic bumble bee Bombus ephippiatus and its closest relative B. wilmattae. We used DNA sequences from a fragment of cytochrome oxidase I (COI), genotypes for twelve microsatellite markers, and morphometric data from wings to construct a well-supported inference of the divergences among these taxa. We have found complex patterns of genetic isolation and morphological divergence within B. ephippiatus across its geographic range and present evidence that B. ephippiatus comprises multiple independent evolutionary lineages. The pattern of their diversification corresponds to geographic and environmental isolating mechanisms, including the Mexican highlands, the lowlands of the Isthmus of Tehuantepec in southern Mexico, the Nicaraguan Depression, the patchily distributed volcanic ranges in Nuclear Central America and Pleistocene glacial cycles. These results have important implications for the development and distribution of B. ephippiatus as a commercial pollinator in Mexico and Central America. [ABSTRACT FROM AUTHOR]

Bumble bees are generalist pollinators that typically collect floral rewards from a wide array of flowering plant species. Topics discussed include loss of floral resource abundance and diversity in the landscapes they inhabit, pollen diet impacts early nesting success later-stage brood werefound in nests provided with the Cistus pollen Linnaeus (Cistaceae), relative to the predominantly Asteraceae pollen.

Emergent fungal diseases are critical factors in global biodiversity declines. The fungal pathogen Nosema bombi was recently found to be widespread in declining species of North American bumble bees (Bombus), with circumstantial evidence suggesting an exotic introduction from Europe. This interpretation has been hampered by a lack of knowledge of global genetic variation, geographic origin, and changing prevalence patterns of N. bombi in declining North American populations. Thus, the temporal and spatial emergence of N. bombi and its potential role in bumble bee decline remain speculative. We analyze Nosema prevalence and genetic variation in the United States and Europe from 1980, before an alleged introduction in the early 1990s, to 2011, extracting Nosema DNA from Bombus natural history collection specimens from across this time period. Nosema bombi prevalence increased significantly from low detectable frequency in the 1980s to significantly higher frequency in the mid- to late-1990s, corresponding to a period of reported massive infectious outbreak of N. bombi in commercial bumble bee rearing stocks in North America. Despite the increased frequency, we find no conclusive evidence of an exotic N. bombi origin based on genetic analysis of global Nosema populations; the widespread Nosema strain found currently in declining United States bumble bees was present in the United States before commercial colony trade. Notably, the US N. bombi is not detectably different from that found predominantly throughout Western Europe, with both regions characterized by low genetic diversity compared with high levels of diversity found in Asia, where commercial bee breeding activities are low or nonexistent. [ABSTRACT FROM AUTHOR]

The article reports on the colony characteristics of and the presence of the fungal parasite Nosema bombi in a Bombus auricomus colony obtained from the crawl space beneath a home near Urbana, Illinois on August 2, 2014. Topics discussed include the insect's geographucal distribution, morphology and taxonomy. The effect of the Nosema parasite on host lifespan and colony growth is explored.

Few insects exhibit the striking colour pattern radiation found in bumble bees ( Bombus), which have diversified globally into a wide range of colours and patterns. Their potent sting is often advertised by conspicuous bands of contrasting colour commonly mimicked by scores of harmless ( Batesian mimics) and noxious species ( Müllerian co-mimics). Despite extensive documentation of colour pattern diversification, next to nothing is known about the genetic regulation of pattern formation in bumble bees, hindering progress toward a more general model of the evolution of colour pattern mimicry. A critical first step in understanding the colour pattern genotype is an unambiguous understanding of the phenotype under selection, which has not been objectively defined in bumble bees. Here, we quantitatively define the principal colour pattern elements that comprise the phenotype array across all species. Matrix analysis of meticulously scored colour patterns of ∼95% of described species indicates there are 12 discrete primary 'ground plan' elements in common among all species, many of which correspond to segmentation patterning. Additional secondary elements characterize individual species and geographical variants. The boundaries of these elements appear to correspond to expression patterns of Hox genes in Drosophila and Apis but also suggest novel post- Hox specialization of abdominal patterning. Our findings provide the first foundation for exploring candidate genes regulating adaptive pattern variation in bumble bees and broaden the framework for understanding common genetic mechanisms of pattern evolution in insects. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113, 384-404. [ABSTRACT FROM AUTHOR]

Abstract: Bumble bees (Bombus Latreille) are an important group of social insects, well recognized throughout northern temperate regions as important pollinators of wild and agricultural plants. Little is known about the biology of this group in southern portions of the Americas, especially in Mesoamerica, a region of geological and ecological complexity from Mexico through Central America. One ubiquitous Mesoamerican species, Bombus ephippiatus, is enigmatic. Like many other Bombus, this species is homogeneous in body structure yet exhibits striking intraspecific color pattern polymorphism across its range, leading to uncertainty about its genealogical boundaries. It has been grouped taxonomically with B. wilmattae, a species narrowly restricted to southern Mexico and northern Guatamala. Furthermore, the relationships between these two taxa and a third species, B. impatiens, found only in America north of Mexico, have been controversial. Our phylogenetic analysis of DNA sequences from mitochondrial COI and nuclear PEPCK and CAD resolves the phylogeny of these three taxa as (B. impatiens, (B. ephippiatus, B. wilmattae)). Additional data from eight nuclear microsatellite markers reveal complex patterns of genetic divergence and isolation among populations of B. ephippiatus across its extensive geographic range, providing evidence for multiple independent evolutionary lineages. These lineages correspond not only to geographic and habitat variation across their range, but also to distinct color pattern groups present in the species. Knowledge of the phylogeny and genetic divergence of the B. ephippiatus group will provide a framework for understanding evolutionary and ecological origins of color pattern polymorphism in bumble bees, as well as providing insight into geographical factors enhancing speciation in Mesoamerica. [Copyright &y& Elsevier]

1. Social insect castes and sexes differ in many ways, including morphology, behavior, and sometimes ploidy level. Recent studies have found that consuming sunflower pollen reduces the gut pathogen Crithidia bombi in workers of the common eastern bumble bee (Bombus impatiens). Here, this work is extended to the reproductive individuals that represent colony fitness – males and queens – to assess if the medicinal effects of sunflower pollen vary with bee caste and sex. 2. This study examined the effect of sunflower pollen compared to a diverse wildflower pollen mix on infection in worker, male, and daughter queen commercial B. impatiens. Bees were infected, fed either sunflower pollen or wildflower pollen for 7 days, and then infection levels were assessed. 3. Compared to wildflower pollen, sunflower pollen dramatically reduced Crithidia infection in workers and daughter queens, but not males. Infection levels were very low for both diets in males; this could be due to low pollen consumption or other mechanisms. 4. Reducing Crithidia infection in young queens before they undergo hibernation is important for population dynamics since infected queens are less likely to survive hibernation, and those that do are less likely to successfully establish a nest the following spring. Because sunflowers bloom in late summer when new queens are emerging, sunflowers could provide an important dietary component for queens during this critical life stage. Deepening our understanding of how diet impacts pathogens in reproductive bees, as well as workers, is crucial to maintain healthy pollinator populations. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented that responds to the report "Climate Change Impacts on Bumblebees Converge Across Continents" by J. T. Kerr et al. in the July 10, 2015 issue.