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Insects perform essential roles within ecosystems and can be vulnerable to climate change because of their small body size and limited capacity to regulate body temperature. Several groups of insects, such as bees and flies, are important pollinators of wild and cultivated plants. However, aspects of their thermal biology remain poorly studied, which limits predictions of their responses to climate change. We assessed the critical thermal maximum (CTMax) of bees and flies visiting flowers in urban and periurban areas in tropical and subtropical regions of the Americas. We also assessed the effect of the foraging time of the day on CTMax. Overall, we found that bees displayed higher CTMax than flies. Flies foraging in the morning and afternoon displayed similar CTMax while bees in the morning displayed a higher CTMax than in the afternoon. The results of this study suggest differences in the vulnerability to climate change between these two major groups of pollinators, with flies being more at risk. 

Abstract Coloration is an important phenotypic trait for taxonomic studies and has been widely used for identifying insect species and populations. However, coloration can be a poor diagnostic character for insect species that exhibit high polymorphism in this trait, which can lead to over-splitting of taxonomic units. In orchid bees, color variation has been interpreted by different taxonomists as either polymorphism associated with Müllerian mimicry complexes or diagnostic traits for species identification. Despite this uncertainty, integrative approaches that incorporate multiple independent datasets to test the validity of hair coloration as a character that identifies independent evolutionary units have not been used. Here, we use phylogenomic data from Ultraconserved Elements (UCEs) to explore whether color phenotypes in the widespread orchid bee species complexes Eulaema meriana and Eulaema bombiformis (Hymenoptera: Apidae: Euglossini) correspond to independent lineages or polymorphic trait variation within species. We find that lineages within both species are structured according to geography and that color morphs are generally unassociated with evolutionarily independent groups except for populations located in the Atlantic Forest of Brazil. We conclude that there is compelling evidence that E. atleticana and E. niveofasciata are subspecies of E. meriana and E. bombiformis, respectively, and not different species as previously suggested. Therefore, we recognize Eulaema meriana atleticanacomb. n. and Eulaema bombiformis niveofasciatacomb. n. and discuss their morphological characteristics. We make recommendations on the use of color traits for orchid bee taxonomy and discuss the significance of subspecies as evolutionary units relevant for conservation efforts. 

Species delimitation is a rich scientific field that often uses different sources of data to identify independently evolving lineages that might be recognized as species. Here, we use an integrative approach based on morphometrics, COI-barcoding, and phylogenomics using ultraconserved elements (UCEs) to investigate whether the orchid bee species Eulaema cingulata (Fabricius, 1804) and E. pseudocingulata Oliveira, 2006 represent a single variable taxon or two different species. We analyzed 126 specimens across the geographical range of these nominal species to test species hypotheses using the general lineage concept. We found substantial overlap in wing and head morphometrics, and both taxa form one phylogenetic lineage based on COI mitochondrial and UCE data. Our results support the recognition of both forms as members of the same evolutionary unit and E. pseudocingulata is herein recognized as a junior synonym of E. cingulata . 

Bumble bees are characterized by their thick setal pile that imparts aposematic color patterns often used for species-level identification. Like all bees, the single-celled setae of bumble bees are branched, an innovation thought important for pollen collection. To date no studies have quantified the types of setal morphologies and their distribution on these bees, information that can facilitate understanding of their adaptive ecological function. This study defines several major setal morphotypes in the common eastern bumble bee Bombus impatiens Cresson, revealing these setal types differ by location across the body. The positions of these types of setae are similar across individuals, castes, and sexes within species. We analyzed the distribution of the two most common setal types (plumose and spinulate) across the body dorsum of half of the described bumble bee species. This revealed consistently high density of plumose (long-branched) setae across bumble bees on the head and mesosoma, but considerable variation in the amount of metasomal plumosity. Variation on the metasoma shows strong phylogenetic signal at subgeneric and smaller group levels, making it a useful trait for species delimitation research, and plumosity has increased from early Bombus ancestors. The distribution of these setal types suggests these setae may serve several functions, including pollen-collecting and thermoregulatory roles, and probable mechanosensory functions. This study further examines how and when setae of the pile develop, evidence for mechanosensory function, and the timing of pigmentation as a foundation for future genetic and developmental research in these bees. 

Context Bees are the most important pollinators of crops worldwide. For most bees, patches of semi-natural habitat within or adjacent to crops can provide important nesting and food resources. Despite this, land cover change is rapidly reducing the abundance of semi-natural habitat within agroecological landscapes, with potentially negative consequences for bee communities and the services they provide. Objectives Identify how the availability of semi-natural habitat impacts bee communities across biogeographic regions, which may reveal commonalities and key governing principles that transcend a single region or taxa. Methods We analyze and compare the drivers of bee community composition in cotton fields within Brazil and the U.S. to reveal how land cover and land cover change impact bee community composition across these two regions. Results We show that the most critical factors impacting bee communities in cotton agroecosystems are the same in Brazil and the U.S.: bee abundance increases with cotton bloom density and the abundance of semi-natural habitat. Further, the loss of semi-natural habitat over a 5-year period negatively impacts bee abundance in both agroecosystems. Conclusions Given the importance of bee abundance for the provision of pollination service in cotton plants, our findings highlight the significance of small semi-natural habitat fragments in supporting key ecosystem service providers for both tropical and temperate cotton agroecological systems. We underscore the important role that local land managers play in biodiversity conservation, and the potential contribution they can make to pollination provision by supporting agricultural landscapes that conserve fragments of semi-natural habitat.