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Both the identity and prevalence of parasitoid dipterans associated with bumble bees (Bombus spp.) in southern South America are little known. Between 2009 and 2017, a total of 2978 bumble bees were individually collected in 63 localities from 11 provinces of the country. After dissections, the presence of parasitoids was observed in the native bumble bees Bombus pauloensis, B. bellicosus, B. opifex, and B. brasiliensis, plus in the exotic invasive species B. terrestris. A combination of both morphological and molecular analysis based on the COI gene allowed the isolation of two species of Physocephala (Conopidae) and one of Helicobia (Sarcophagidae), expanding their host range and geographic distribution. The second instar larva of Helicobia aurescens is described. [ABSTRACT FROM AUTHOR]

A problem for understanding bumblebee biogeography is that if bumblebees dispersed from Asia through North America to South America, if they are poor at long-distance dispersal with establishment over sea, and if the land bridge between North and South America was not established until c. 3 Ma BP, then there is an apparent conflict with the divergence among currently endemic South American lineages having been dated as early as 15–17 Ma. Using the first complete phylogenetic trees for all known and accepted extant species of the groups involved, we show how this conflict could be resolved. We suggest that characterizing bumblebees as being associated generally with temperate flower-rich meadows conflates divergent habitat specializations between two early lineages, associated with northern lowland grasslands and with southern montane grasslands respectively, which may have driven divergences in behaviour and in biogeographic processes. First, for most of the lowland grassland group of bumblebees, estimated dates of divergence are consistent with dispersal to South America via the land-bridge corridor that opened at c. 3 Ma, followed by extant endemic lineages diverging in situ within South America. In contrast, for the second group that occupies montane grassland habitats (and for a few montane lineages of the 'lowland' group), we suggest that dispersal to South America at c. 3 Ma could be consistent with older divergence for currently endemic species if: (1) many of the extant South American lineages had already diverged outside the region before 3 Ma in neighbouring Mesoamerica; and (2) they had been constrained within the high mountains there, dispersing southwards into South America only once the isthmus corridor had become established; and (3) some of those ancestral montane lineages had become extirpated from Mesoamerica during subsequent warm climatic fluctuations. This interpretation re-emphasizes that biogeographic studies need to consider habitat-specific dispersal models that change through time. [ABSTRACT FROM AUTHOR]

A detailed phylogeny of bumblebees is urgently needed to understand speciation and biogeographic diversification in the Neotropical region. We sequenced autosomal and mtDNA loci from nine Brazilian bumblebee species and compiled it with the data already available to obtain highly resolved phylogenetic trees with fossil-calibrated dates. The ancestral Bombus lineage was estimated to diversify between 47.08 and 34.27 million years ago (Ma) in the Holarctic region, but largely restricted to the eastern Old World. The Neotropical region was initially colonized in the Late Miocene, where bumblebee diversification was shown to be consistent with geologic and climatic events of the Late Cenozoic. Neotropical bumblebees likely originated from Nearctic lineages, which dispersed towards South America after 29 Ma. [ABSTRACT FROM AUTHOR]

While feeding, foragers can alter their environment. Such alteration constitutes ecological niche construction (ENC) if it enables future benefits for the constructor and conspecific individuals. The environmental modification may also affect non‐constructing, bystander species, especially if they share resources with constructor species. If so, ENC could confer the constructor species a competitive advantage by both enhancing its foraging returns and reducing those of bystander species.Expectations – (E1) ENC frequency should vary positively with the recent and current density of the constructor species, and (E2) constructors should use modifications disproportionately. In contrast, bystanders should (E3) experience intensified competition for the affected resource, and (E4) exhibit diverse, possibly mitigating, responses to ENC, depending on opportunity and relative benefits.We investigated these expectations in Argentina for competition for Fuchsia magellanica nectar between an invasive bumble bee Bombus terrestris (terr: putative constructor), which often bites holes at the bases of floral tubes to rob nectar, and native B. dahlbomii (dahl: bystander), which normally accesses Fuchsia nectar through the flower mouth (front visits). Robbing holes constitute ENC, as they persist until the 7‐day flowers wilt. The dynamics of the incidence of robbed flowers, abundance of both bees and the number and types of their flower visits (front or robbing) were characterised by alternate‐day surveys of plants during 2.5 months.After initially accessing Fuchsia nectar via front visits, terr switched to robbing and its abundance on Fuchsia increased 20‐fold within 10 days (E2). Correspondingly, the incidence of robbed flowers varied positively with recent and past terr abundance (E1). In contrast, dahl abundance remained low and varied negatively with the incidence of robbed flowers (E3). When terr ceased visiting Fuchsia, dahl abundance increased sixfold within 10 days (E3), possibly because many dahl previously had avoided competition with terr by feeding on other plant species (E4). While terr was present, dahl on Fuchsia used front visits (tolerance) or used existing robbing holes (adoption: E4). The diverse dahl responses suggest partial compensation for competition with terr.ENC alters competitive asymmetry, favouring constructor species. However, bystander responses can partially offset this advantage, perhaps facilitating coexistence. [ABSTRACT FROM AUTHOR]

Invasive species are one of the main biodiversity loss drivers. Some species can establish and thrive in novel habitats, impacting local communities, as is the case of managed pollinators. In this regard, an invasive species' expansion process over time is critical for its control and management. A good example is the European bumblebee Bombus terrestris, which has rapidly invaded the southern part of South America after being repeatedly introduced in Chile for crop pollination since 1997. We assessed the temporal dynamics of B. terrestris invasion in Argentina and Chile by compiling 562 occurrence points from 2000 to 2019. We used two estimators (minimum convex polygon and 95% fixed kernel) to estimate the increase of the invaded area over time. We found that the area invaded by B. terrestris in the southern part of South America presents a linear increase over time, which was consistent for both estimators. In this scenario, species traits, environmental characteristics, and introduction dynamics facilitate a rapid invasion process that will continue to expand, reaching other South American countries in the near future. As this bumblebee is a super-generalist, it probably will expand across South America, as climate niche modelling predicts, if no actions were taken. [ABSTRACT FROM AUTHOR]

Bumble bees (Bombus spp.) are important pollinators insects involved in the maintenance of natural ecosystems and food production. Bombus pauloensis is a widely distributed species in South America, that recently began to be managed and commercialized in this region. The movement of colonies within or between countries may favor the dissemination of parasites and pathogens, putting into risk while populations of B. pauloensis and other native species. In this study, wild B. pauloensis queens and workers, and laboratory reared workers were screened for the presence of phoretic mites, internal parasites (microsporidia, protists, nematodes and parasitoids) and RNA viruses (Black queen cell virus (BQCV), Deformed wing virus (DWV), Acute paralysis virus (ABCV) and Sacbrood virus (SBV)). Bumble bee queens showed the highest number of mite species, and it was the only group where Conopidae and S. bombi were detected. In the case of microsporidia, a higher prevalence of N. ceranae was detected in field workers. Finally, the bumble bees presented the four RNA viruses studied for A. mellifera, in proportions similar to those previously reported in this species. Those results highlight the risks of spillover among the different species of pollinators. [ABSTRACT FROM AUTHOR]

Bumblebees (Hymenoptera: Apidae: genus Bombus Latreille, 1802) constitute an important group of pollinators for many wild plants and crops in north temperate regions and South America. Although knowledge of these insects has been increasing over the last decades, some geographic areas remain poorly studied and additions to the knowledge of their faunas are infrequent. Afghanistan is one example of a country that is currently underrepresented in the scientific literature despite its high species diversity. For this study, more than 420 new occurrence records were gathered for 17 bumblebee species belonging to all eight subgenera recorded in the country, including the first record of a species closely related to the B. longipennis group. Additionally, the first standardized database for Afghan bees is launched, which we hope will be enriched in the future to allow further assessments of population trends for the bumblebees of Afghanistan. Finally, the previously published species records for the country are discussed considering the most recent taxonomic revisions of the genus and key perspectives are highlighted for further work in this understudied country and neighboring regions. [ABSTRACT FROM AUTHOR]

Chronic bee paralysis virus (CBPV) is a positive single-stranded RNA virus that exhibits a worldwide distribution. Although the effects of this virus on honeybees' health are well known, its presence in other bee species has not been fully studied. In this work, CBPV was detected in several native bees from Argentina, including Bombus pauloensis, Halictillus amplilobus, Peponapis fervens, and members of the genus Xylocopa. Here, we report for the first time the presence of CBPV in native bees from South America. [ABSTRACT FROM AUTHOR]

Climate change has been commonly associated with a decline of bumblebee populations around the world. However, most information regarding the impacts of climate change on bumblebees is derived from North America and Europe, and little is known about South American species.Here we applied ecological niche modelling techniques to estimate the past, present and future distributions of six Bombus species found in South America. These data were used to estimate climatically stable areas (CSAs) for each species and, combined with information on land cover and protected area network, identify species and areas for the conservation of these important pollinators.The models predicted a reduction in climatically suitable habitats from Last Glacial Maximum (LGM) to the present for most species. Similarly, all species were predicted to lose climatically suitable areas in future climate scenarios, ranging from 9% to 78%, depending on the species and climate change scenario.The percentage of legally protected CSAs varied between 4.0% and 48.2% among species, mainly due to differences in the protected area network among the biomes in which they occur. A significant portion of the distribution range of most species includes agricultural areas, which likely increases bumblebee exposure to pesticides.Based on the estimated habitat loss due to climate change, as well as from land cover and protected area, our results indicate that Bombus bellicosus, Bombus brevivillus and Bombus brasiliensis are the most endangered species of those evaluated.Synthesis and applications. Our findings provide a framework for conservation strategies of six species of South American bumblebees, by prioritizing species and areas for conservation considering their distribution range and the climatically stable areas under different climate change scenarios. [ABSTRACT FROM AUTHOR]

• Biological invasions are a major driver of biodiversity loss. • Citizen science can provide valuable information to understand invasion processes. • We used citizen science information on two exotic and one native bumblebee species. • Exotic bumblebees mainly visited exotic plants preferring certain colours. • Ornamental exotic plant species may act as steppingstones facilitating invasion. Invasive species are one of the most important drivers of biodiversity loss worldwide. As exotic species invade new ecosystems, they establish ecological interactions with the existing species, which may facilitate their spread. Flower colour is an important trait that influences pollination and pollinator preferences. To determine the role of these variables on the bumblebee preferences, we compared the floral associations of two exotic bumblebee species: Bombus terrestris and B. ruderatus (introduced two decades ago for crop pollination) and the native B. dahlbomii with native and exotic plants in Chile. We analysed 3,019 citizen science records in order to understand bumblebee associations with native and exotic plant species regarding flower colour. We found that the exotic bumblebees were mainly recorded visiting flowers of exotic plants (86% for B. terrestris and 93% for B. ruderatus), while the native B. dahlbomii visited exotic and native plant species in a similar proportion. Also, the exotic bumblebees visited purple and pink flowers more often, while the native bumblebee species frequently visited white, pink, and purple flowers. Although the three species share trichromatic vision, they seem to have different flower colour preferences. The association of B. terrestris and B. ruderatus with exotic non-crop species (i.e., exotic ornamental plants) may be acting as steppingstones from croplands to other habitats, facilitating the bee invasion process. Despite its inherent limitations, citizen science data provide large amounts of valuable information that is difficult to be obtained otherwise, which can be used to improve our understanding of invasion processes, as is the case of exotic Bombus species in southern South America. [ABSTRACT FROM AUTHOR]

Here we describe for the first time the nesting behavior and the colony of Bombus ( Thoracobombus) brevivillus, a Neotropical species native only to South America. We discovered and observed seven B. brevivillus colonies between August and September 2012 in the state of Ceará, NE Brazil. Observations showed that B. brevivillus seems to be opportunistic in relation to nesting sites and brood protection, even though there is meager investment in nest building and offspring protection. Observations suggest that may be young B. brevivillus colonies invest strongly in brood production and colony development, before reproducing. More studies are necessary to evaluate the feasibility of captivity breeding of this species. [ABSTRACT FROM AUTHOR]

Bumble bees are some of the most important insect pollinators. However, knowledge on parasites associated to bumble bees in South America is very limited. This study reports the first isolation of a sphaerularid nematode parasitizing queens of the native bumble bee Bombus atratus in Argentina. Measurements and morphological characters of eggs, juveniles, and adults strongly suggest that the species is Sphaerularia bombi, a parasite that affects the reproduction and foraging behavior of the host. The nematode was detected in bumble bees of San Carlos de Bariloche, northwestern Patagonia region, and the surroundings of La Plata, northeastern Pampas region. Prevalence varied between 8% and 20%. [ABSTRACT FROM AUTHOR]

The Neotropical bumblebee Bombus (Fervidobombus) atratus Franklin is widely distributed in South America ranging from tropical and subtropical lowlands to high altitudes in the Andes. Thermal investigations of the Neotropical bumblebee Bombus atratus at rest were performed by means of thermometry. Most social insects are diurnal foragers. When they are inside their nests during the night, they carry out some tasks such as cleaning the nest, brood care or nest thermoregulation. However, forager bees generally pause at night in a sleep-like state. A bumblebee nest was transferred to a brood chamber which was maintained at approximately constant temperature (28 ± 1 °C) to prevent the workers from building the protecting involucrum so that one could mark them at birth. To provide a temperature gradient, two chambers were installed adjacent to the brood chamber, so that the workers had the chance to choose between 3 temperatures: the first one kept at 22 ± 1 °C, the second at 19 ± 1 °C and 28 ± 1 °C. The temperatures of the chambers were recorded continuously by a four channel data logger. Three categories of tasks performed by workers were registered in this investigation: warming brood (task 1), feeding brood (task 2) and foragers (task 3). During the experiment 357 workers were born and 252 (71%) of them showed sleep-like behaviour. The total sleep time in hours according to the work done by the workers was task 1 (240.6 h) > task 3 (236.0 h) > task 2 (227.3 h). The workers who performed tasks 1 and 2 preferred to sleep at the highest temperature (28 ± 1 °C) and the forager workers at 22 ± 1 °C. [ABSTRACT FROM AUTHOR]

It has been argued that trichromatic bees with photoreceptor spectral sensitivity peaks in the ultraviolet (UV), blue and green areas of the spectrum are blind to long wavelengths (red to humans). South American temperate forests (SATF) contain a large number of human red-looking flowers that are reported to be visited by the bumblebee Bombus dahibomli. In the present study, B. dahlbomii's spectral sensitivity was measured through electroretinogram (ERG) recordings. No extended sensitivity to long wavelengths was found in B. dahlbomii. The spectral reflectance curves from eight plant species with red flowers were measured. The color loci occupied by these flowers in the bee color space was evaluated using the receptor noise-limited model. Four of the plant species have pure red flowers with low levels of chromatic contrast but high levels of negative L-receptor contrast. Finally, training experiments were performed in order to assess the role of achromatic cues in the detection and discrimination of red targets by B. dahlbomii. The results of the training experiments suggest that the bumblebee relies on achromatic contrast provided by the L-receptor to detect and discriminate red targets. These findings are discussed in the context of the evolutionary background under which the relationship between SATF species and their flower visitors may have evolved. [ABSTRACT FROM AUTHOR]