Brain size predicts bees' tolerance to urban environments.

The rapid conversion of natural habitats to anthropogenic landscapes is threatening insect pollinators worldwide, raising concern regarding the negative consequences on their fundamental role as plant pollinators. However, not all pollinators are negatively affected by habitat conversion, as certain species find appropriate resources in anthropogenic landscapes to persist and proliferate. The reason why some species tolerate anthropogenic environments while most find them inhospitable remains poorly understood. The cognitive buffer hypothesis, widely supported in vertebrates but untested in insects, offers a potential explanation. This theory suggests that species with larger brains have enhanced behavioural plasticity, enabling them to confront and adapt to novel challenges. To investigate this hypothesis in insects, we measured brain size for 89 bee species, and evaluated their association with the degree of habitat occupancy. Our analyses revealed that bee species mainly found in urban habitats had larger brains relative to their body size than those that tend to occur in forested or agricultural habitats. Additionally, urban bees exhibited larger body sizes and, consequently, larger absolute brain sizes. Our results provide the first empirical support for the cognitive buffer hypothesis in invertebrates, suggesting that a large brain in bees could confer behavioural advantages to tolerate urban environments.

Determining Minnesota bee species' distributions and phenologies with the help of participatory science.

The Minnesota Bee Atlas project contributed new information about bee distributions, phenologies, and community structure by mobilizing participatory science volunteers to document bees statewide. Volunteers submitted iNaturalist (©2016 California Academy of Sciences) photograph observations, monitored nest-traps for tunnel-nesting bees, and conducted roadside observational bumble bee surveys. By pairing research scientists and participatory science volunteers, we overcame geographic and temporal challenges to document the presence, phenologies, and abundances of species. Minnesota Bee Atlas project observations included new state records for Megachile inimica, Megachile frugalis, Megachile sculpturalis, Osmia georgica, Stelis permaculata, and Bombus nevadensis, nesting phenology for 17 species, a new documentation of bivoltinism for Megachile relativa in Minnesota, and over 500 observations of the endangered species Bombus affinis. We also expanded known ranges for 16 bee species compared with specimens available from the University of Minnesota (UMN) Insect Collection. Surveys with standardized effort across the state found ecological province associations for six tunnel-nesting species and lower bumble bee abundance in the Prairie Parkland ecological province than the Laurentian Mixed Forest or Eastern Broadleaf Forest ecological provinces, indicating potential benefit of a focus on bumble bee habitat management in the Prairie Parkland. Landcover analysis found associations for four tunnel-nesting species, as well as a possible association of B. affinis with developed areas. These data can inform management decisions affecting pollinator conservation and recovery of endangered species. By engaging over 2,500 project volunteers and other iNaturalist users, we also promoted conservation action for pollinators through our educational programs and interactions.

Forest habitats and plant communities strongly predicts Megachilidae bee biodiversity.

Megachilidae is one of the United States' most diverse bee families, with 667 described species in 19 genera. Unlike other bee families, which are primarily ground nesters, most megachilid bees require biotic cavities for nesting (i.e., wood, pithy stems, etc.). For this group, the availability of woody-plant species may be as important as nectar/pollen resources in maintaining populations. We studied Megachilidae biodiversity in the continental United States. We confirmed that the highest species richness of Megachilidae was in the southwestern United States. We examined the relationship between species richness and climate, land cover, tree species richness, and flowering plant diversity. When examining environmental predictors across the conterminous United States, we found that forested habitats, but not tree diversity, strongly predicted Megachilidae richness. Additionally, Megachilidae richness was highest in areas with high temperature and low precipitation, however this was not linearly correlated and strongly positively correlated with flowering plant diversity. Our research suggests that the availability of nesting substrate (forested habitats), and not only flowering plants, is particularly important for these cavity-nesting species. Since trees and forested areas are particularly susceptible to climate change, including effects of drought, fire, and infestations, nesting substrates could become a potential limiting resource for Megachilidae populations.

Effects of season of fire on bee-flower interaction diversity in a fire-maintained pine savanna.

Whereas the Coastal Plain of the southeastern United States historically experienced fire primarily during the mid-summer lightning season, managers today typically apply prescribed fire during the late winter or early spring months. The ecological implications of this discrepancy remain poorly understood, especially with regard to pollinators and their interactions with flowers. In a replicated field experiment, we compared the abundance and richness of bees and bee-flower interactions among pine savanna plots in Florida that were burned either during the winter, spring, summer, or fall. We netted 92 bee species from 77 species of flowers, representing 435 unique bee-flower interactions in total. When analyzing the results from each month separately, we detected significant short-term reductions in the number of bees and bee-flower interactions following fires regardless of season. Although bee abundance and richness did not differ over the entire season, bee-flower interaction richness was significantly higher overall in spring and summer plots than in fall plots and the composition of both bees and bee-flower interactions differed significantly among treatments. Several bee-flower interactions were significantly associated with one or more of the treatments. Some of these associations could be attributed to differences in flowering phenology among treatments. Taken together, our findings suggest that season of fire has modest but potentially important implications for interactions between bees and flowers in southeastern pine ecosystems. Because most flowering plants within our study region are pollinated by a variety of bees and other insects, and most bees endemic to the region are polylectic, season of fire may not be very important to either group overall. However, the timing of fire may be more important to particular species including certain flower specialists and fire-sensitive taxa such as butterflies. Future research targeting such species would be of interest.

Stingless bee classification and biology (Hymenoptera, Apidae): a review, with an updated key to genera and subgenera.

Stingless bees (Meliponini) are a ubiquitous and diverse element of the pantropical melittofauna, and have significant cultural and economic importance. This review outlines their diversity, and provides identification keys based on external morphology, brief accounts for each of the recognized genera, and an updated checklist of all living and fossil species. In total there are currently 605 described extant species in 45 extant genera, and a further 18 extinct species in nine genera, seven of which are extinct. A new fossil genus, Adactylurina Engel, gen. nov., is also described for a species in Miocene amber from Ethiopia. In addition to the systematic review, the biology of stingless bees is summarized with an emphasis on aspects related to their nesting biology and architecture.

The evolutionary history of bees in time and space.

Bees are the most significant pollinators of flowering plants. This partnership began ca. 120 million years ago, but the uncertainty of how and when bees spread across the planet has greatly obscured investigations of this key mutualism. We present a novel analysis of bee biogeography using extensive new genomic and fossil data to demonstrate that bees originated in Western Gondwana (Africa and South America). Bees likely originated in the Early Cretaceous, shortly before the breakup of Western Gondwana, and the early evolution of any major bee lineage is associated with either the South American or African land masses. Subsequently, bees colonized northern continents via a complex history of vicariance and dispersal. The notable early absences from large landmasses, particularly in Australia and India, have important implications for understanding the assembly of local floras and diverse modes of pollination. How bees spread around the world from their hypothesized Southern Hemisphere origin parallels the histories of numerous flowering plant clades, providing an essential step to studying the evolution of angiosperm pollination syndromes in space and time.

Primer registro de la abeja colectora de óleo Centris (Odontoxys) melanochlaena Smith, 1874 (Hymenoptera, Apidae) en Nicaragua

Se presenta el primer reporte de la abeja colectora de óleo Centris (Odontoxys) melanochlaena Smith, 1874 en Nicaragua. Esta especie se distribuye en varios países de Centroamérica y México, siendo este el primer reporte en el occidente de Nicaragua. Este registro contribuye al conocimiento del rango de distribución de esta especie, así como también incrementa la lista de especies de abejas nativas de Nicaragua.

The first report of the oil-collecting bee Centris (Odontoxys) melanochlaena Smith, 1874 in Nicaragua is presented. This species occurs in several Central American countries and Mexico, being this the first record from western Nicaragua. This record contributes to the knowledge of the distribution range of this species, as well as increases the list of native bees occurring in Nicaragua.

Invertebrate biodiversity continues to decline in cropland.

Modern agriculture has drastically changed global landscapes and introduced pressures on wildlife populations. Policy and management of agricultural systems has changed over the last 30 years, a period characterized not only by intensive agricultural practices but also by an increasing push towards sustainability. It is crucial that we understand the long-term consequences of agriculture on beneficial invertebrates and assess if policy and management approaches recently introduced are supporting their recovery. In this study, we use large citizen science datasets to derive trends in invertebrate occupancy in Great Britain between 1990 and 2019. We compare these trends between regions of no- (0%), low- (greater than 0-50%) and high-cropland (greater than 50%) cover, which includes arable and horticultural crops. Although we detect general declines, invertebrate groups are declining most strongly in high-cropland cover regions. This suggests that even in the light of improved policy and management over the last 30 years, the way we are managing cropland is failing to conserve and restore invertebrate communities. New policy-based drivers and incentives are required to support the resilience and sustainability of agricultural ecosystems. Post-Brexit changes in UK agricultural policy and reforms under the Environment Act offer opportunities to improve agricultural landscapes for the benefit of biodiversity and society.

Long-term recovery of Mediterranean ant and bee communities after fire in southern Spain.

Wildfires play a determinant role in the composition and structure of animal communities, especially for groups closely associated with the vegetation and soil, such as bees or ants. The effects of fire on animal communities depend on the functional traits of each group. Here, we assessed the impacts of fire and time since fire on the taxonomic and functional responses of ant and bee communities. We sampled 35 pine forests in Andalusia (southern Spain) that had experienced fire in the past (0 to 41 years ago). Specifically, we explored whether a) fire increased taxonomic and functional diversity and changed community composition in communities in the short term and b) fire influence (increase or decrease) on ant communities would be dependent on time since fire. We found that ant and bee taxonomic richness increased regardless of time since fire. Different approaches gave the same result, such as taxonomic diversity indexes (ant abundance, ant richness and ant Shannon diversity index), the changes in species richness in ant and bee communities, as well as the higher number of ant and bee species prone to the burned habitat than to the unburned habitat, using the Ihabitat Index. Besides environmental variables (such as the effects of different Pinus species or elevation), time since fire changed the taxonomic composition of ant communities and the functional composition of bee communities. Moreover, six of the 13 ant functional traits explored differed between burned and unburned areas, with the degree of difference declining as time since fire increased. For example, burned areas contained ant communities with more ground-nesting species and strictly diurnal species, functional traits that are characteristic of open areas. In contrast, other traits persisted in burned areas over the long term, notably a higher degree of worker polymorphism and species monogyny. Our study shows how much short- and long-term effects of fire on ant and bee communities differ; while richness increases in the long-term, some functional traits are also filtered in the short-term. We suggest that fire in Mediterranean coniferous ecosystems could have a positive effect on these groups and should not be overlooked.

The bee genus Anthidiellum in Vietnam: descriptions of five new species and the first male of Anthidiellumcoronum (Hymenoptera, Megachilidae).

The Vietnamese fauna of bees in the Anthidiellum Cockerell (Megachilinae, Anthidiini) is reviewed. Seven species are recognized, representing two subgenera. Five new species are described and figured as: Anthidiellum (Clypanthidium) nahang Tran, Engel & Nguyen, sp. nov., A. (Pycnanthidium) ayun Tran, Engel & Nguyen, sp. nov., A. (P.) chumomray Tran, Engel & Nguyen, sp. nov., A. (P.) flavaxilla Tran, Engel & Nguyen, sp. nov., and A. (P.) cornu Tran, Engel & Nguyen, sp. nov. from the northern and central highlands of Vietnam. Two previously described species are newly recorded for the fauna: A. (P.) carinatum (Wu) and A. (P.) coronum (Wu), with the male of the latter species described and illustrated for the first time. An identification key is provided for all species of Anthidiellum occurring in Vietnam.

Evolution of piggyBac Transposons in Apoidea.

In this study, we investigated the presence of piggyBac (PB) transposons in 44 bee genomes from the Apoidea order, which is a superfamily within the Hymenoptera, which includes a large number of bee species crucial for pollination. We annotated the PB transposons in these 44 bee genomes and examined their evolution profiles, including structural characteristics, distribution, diversity, activity, and abundance. The mined PB transposons were divided into three clades, with uneven distribution in each genus of PB transposons in Apoidea. The complete PB transposons we discovered are around 2.23-3.52 kb in length and encode transposases of approximately 580 aa, with terminal inverted repeats (TIRs) of about 14 bp and 4 bp (TTAA) target-site duplications. Long TIRs (200 bp, 201 bp, and 493 bp) were also detected in some species of bees. The DDD domains of the three transposon types were more conserved, while the other protein domains were less conserved. Generally, most PB transposons showed low abundance in the genomes of Apoidea. Divergent evolution dynamics of PB were observed in the genomes of Apoidea. PB transposons in some identified species were relatively young, whiles others were older and with some either active or inactive. In addition, multiple invasions of PB were also detected in some genomes of Apoidea. Our findings highlight the contribution of PB transposons to genomic variation in these species and suggest their potential as candidates for future gene transfer tools.

Outcomes of wasp and bee stings in Taiwan.

BACKGROUND: The families of Hymenoptera causing commonly poisonous animal stings in Taiwan include Apoidea (bee) and Vespidae (wasp). This study aimed to investigate the epidemiologic, clinical characteristics, and outcomes of the severity of envenomation following wasp or bee stings in Taiwan. METHODS: We conducted a retrospective study by identifying all wasp and bee sting-related envenomation reported to the Taiwan National Poison Control Center between January 2001 and November 2021. Data were reviewed and abstracted by two independent reviewers. We then used ordinal logistic regression analysis to find potential predictors of severe wasp and bee sting-related envenomation. RESULTS: In Taiwan, bee or wasp stings mainly occur in late summer and autumn. A total of 611 patients were reported to the Taiwan National Poison Control Center with 7.5% resulting in severe or fatal envenomation. Four-hundred and forty-one patients were eligible for the final analysis of the predictors of severity. Logistic regression analysis showed that a greater number of stings, being stung by wasps, older age, and stings over the body were significant predictors for greater severity. The systemic effects following wasp and bee sting included anaphylactic reaction, prolongation of activated partial thromboplastin time, rhabdomyolysis, acute kidney injury, and elevated liver enzymes. CONCLUSIONS: Wasps generally inflicted more severe envenomation than bees. Only 7.5% of patients had severe or fatal outcomes. Patients with older age, multiple stings, and/or multiple sites of stings were more likely to have severe outcomes.

Impacts of Semiochemical Traps Designed for Bruchus rufimanus Boheman 1833 (Coleoptera: Chrysomelidae) on Nontarget Beneficial Entomofauna in Field Bean Crops.

Broad bean weevils (BBWs-Coleoptera: Chrysomelidae) are serious pests of field bean seeds that hamper the promotion of this crop in the diversification of European cropping systems. Recent research has identified different semiochemical lures and trap devices for the development of semiochemical-based control strategies of BBWs. In this study, two field trials were carried out in order to provide necessary information supporting the implementation of sustainable field use of semiochemical traps against BBWs. More particularly, three principal objectives were followed including (i) the identification of the most efficient traps for BBWs capture and the influence of trapping modality on BBWs sex-ratio, (ii) the assessment of eventual collateral effects on crop benefits including aphidophagous and pollinator insects such as Apidae, Syrphidae and Coccinellidae, (iii) the assessment of the crop developmental stage influence on the capture by semiochemical traps. Three different semiochemical lures were tested in combination with two trapping devices across two field trials in early and late flowering field bean crops. The crop phenology and climate parameters were integrated into the analyses to interpret the spatiotemporal evolution of the captured insect populations. A total of 1380 BBWs and 1424 beneficials were captured. White pan traps combined with floral kairomones were the most efficient traps for the capture of BBWs. We demonstrated that the crop phenology (c.f., the flowering stage) exerted strong competition on the attractiveness of semiochemical traps. Community analysis revealed that only one species of BBWs was captured in field bean crops (i.e., Bruchus rufimanus), and no trend was highlighted concerning the sex ratios according to the trapping devices. The beneficial insect community included 67 different species belonging to bees, hoverflies and ladybeetles. Semiochemical traps manifested a strong impact on beneficial insect communities that included some species under extinction threats and need to be further adapted to minimize such collateral effects. Based on these results, recommendations are provided for the implementation of the most sustainable BBWs control method that minimizes the impact on the recruitment of beneficial insects, which is an important ecosystem service for faba bean crops.

Apoidea of the collections of Lyon, Aix-en-Provence, Marseille and Toulon Museums of Natural History (France).

Background: Many insect species have shown dramatic declines over the last decades, as a result of man-related environmental changes. Many species which were formerly widespread are now rare. To document this trend with evidence, old records of collected specimens are vital. New information: We provide here the data on 9752 bee (Hymenoptera: Apoidea) specimens hosted in several museums of south-east France: Musée des Confluences in Lyon, Muséum d'Histoire Naturelle de Marseille, Muséum d'Aix-en-Provence and the Muséum Départemental du Var in Toulon. Most of the specimens (9256) come from France and include data on 552 named species. For most of these specimens, the geographical location, including geographical coordinates, is based on the locality (town or village) where they were collected. The specimens were captured from the beginning of the nineteenth century to 2018. The identifications of 1377 specimens, mainly belonging to the genus Bombus, are considered reliable, as these were performed or been checked since 2009. All the other reported identifications are the original ones given by the original collectors.

New records of megachilid bees (Hymenoptera: Megachilidae) for Colombia

The bee family Megachilidae consists of solitary species, some of which are important pollinators of cultivated plants. Although literature records indicate the existence of about 50 species of 10 genera of megachilid bees in Colombia, taxonomic studies are lacking and thus limited information is available on their identity as well as their distribution in the country. Herein, we provide new geographical records for the following ten species: Anthidium sanguinicaudum Schwarz, Chelostomoides otomita (Cresson), Hoplostelis bilineolata (Spinola), Megachile amparo Gonzalez, M. kalina Gonzalez et al., M. lorenziensis Mitchell, M. moderata Smith, M. simillima Smith, Pseudomegachile lanata (Fabricius), and Stelis costaricensis Friese. We report M. kalina for the first time for the country.

Las abejas de la familia Megachilidae son especies solitarias, algunas de ellas importantes polinizadores de cultivos. Aunque en la literatura se registran cerca de 50 especies de 10 géneros de abejas megachilidas en Colombia, faltan estudios taxonómicos y, por lo tanto, se dispone de información limitada sobre la identidad y la distribución de este grupo en el país. En este trabajo proporcionamos nuevos registros geográficos para 10 especies poco conocidas [Anthidium sanguinicaudum Schwarz, Chelostomoides otomita (Cresson), Hoplostelis bilineolata (Spinola), Megachile amparo Gonzalez, M. kalina Gonzalez et al., M. lorenziensis Mitchell, M. moderata Smith, M. simillima Smith, Pseudomegachile lanata (Fabricius), y Stelis costaricensis Friese]. Megachile kalina se registra por primera vez para Colombia.

A new genus of minute stingless bees from Southeast Asia (Hymenoptera, Apidae).

A new genus of minute stingless bees (Meliponini: Hypotrigonina) is described from Southeast Asia. Ebaiotrigona Engel & Nguyen, gen. nov., is based on the type species Lisotrigonacarpenteri Engel, recorded from Vietnam, Thailand, Laos, Cambodia, and southern China. The species was previously considered an enigmatic member of Lisotrigona Moure, but is removed to a new genus based on its unique male terminalia that differs considerably from that of Lisotrigona and instead shares resemblances with Austroplebeia Moure, and the presence of yellow maculation (also similar to that of Austroplebeia). It is possible that Ebaiotrigona is the extant sister group of Austroplebeia, but this requires confirmation by future phylogenetic analyses. Based on available biological observations, Ebaiotrigonacarpenteri could not be confirmed as lachryphagous as is well documented from the tear-drinking species of Lisotrigona and Pariotrigona Moure.

Nestmate recognition in the Amazonian stingless bee Melipona paraensis.

Meliponine bees use chemical-based nestmate discrimination to protect their colonies from unrelated intruders. However, species from the Amazon basin are relatively poorly known from this perspective. Here, we investigated Melipona paraensis nestmate discrimination in different contexts (nests vs. neutral arenas), testing aggression in bees facing other bees varying in age and origin (same/different colony or a different kleptoparasitic meliponine species) or experimentally treated with odors from unrelated colonies. As expected, M. paraensis did not discriminate against callow non-nestmate workers with weak/undifferentiated chemical signatures. Workers specialized in nest defense aggressed intruders more often than non-specialized workers, but were less aggressive in neutral arenas than in the nest. Our study provides novel behavioral information relevant for social insect research and meliponiculture.

Phylogenetic, functional and taxonomic responses of wild bee communities along urbanisation gradients.

Increasing urbanisation is one of the primary drivers of land-use change that threaten biodiversity. Wild bee communities have been reported with contrasting responses to urbanisation, with varying effects on abundance and taxonomical diversity. The suite of functional traits exhibited by wild bee species might determine their persistence in urban areas. Urbanisation thus can impose an environmental filter with potential consequences on the functional and phylogenetical diversity of wild bee communities. Here, we sampled 2944 wild bee specimens from 156 species in 29 sites located along an urbanisation gradient using a replicated design in three mid-sized cities in the Loire valley (France). We show that urban landscape cover has a negative effect on overall species richness and taxonomical diversity indices, while total abundance remains constant. Species loss was taxon dependent, mainly driven by Andrenidae and Halictidae. Only a few species, especially of the genus Lasioglossum, were positively affected by the urban landscape cover. Urban and peri-urban areas differed in their composition of bee assemblages. Species turnover was the main component of beta diversity, driving community dissimilarities through the urban gradient. Urbanisation favours bees with small body sizes, social structure and extended flight periods but did not affect the phylogenetic or the functional diversity of communities. Our findings have implications for understanding the factors involved in the environmental filter exerted through the urban gradient on bee communities helping to implement conservation measures and managing urban spaces for bees.

Non-Native Non-Apis Bees Are More Abundant on Non-Native Versus Native Flowering Woody Landscape Plants.

Urban ecosystems can support diverse communities of wild native bees. Because bloom times are conserved by geographic origin, incorporating some non-invasive non-native plants in urban landscapes can extend the flowering season and help support bees and other pollinators during periods when floral resources from native plants are limiting. A caveat, though, is the possibility that non-native plants might disproportionately host non-native, potentially invasive bee species. We tested that hypothesis by identifying all non-native bees among 11,275 total bees previously collected from 45 species of flowering woody landscape plants across 213 urban sites. Honey bees, Apis mellifera L., accounted for 22% of the total bees and 88.6% of the non-native bees in the collections. Six other non-native bee species, accounting for 2.86% of the total, were found on 16 non-native and 11 native woody plant species. Non-Apis non-native bees in total, and Osmia taurus Smith and Megachile sculpturalis (Smith), the two most abundant species, were significantly more abundant on non-native versus native plants. Planting of favored non-native hosts could potentially facilitate establishment and spread of non-Apis non-native bees in urban areas. Our host records may be useful for tracking those bees' distribution in their introduced geographical ranges.

Testing the systematic status of Homalictus and Rostrohalictus with weakened cross-vein groups within Halictini (Hymenoptera: Halictidae) using low-coverage whole-genome sequencing.

The halictid genus Lasioglossum, as one of the most species-rich bee groups with persistently contentious subgeneric boundaries, is one of the most challenging bee groups from a systematic standpoint. An enduring question is the relationship of Lasioglossum and Homalictus, whether all halictine bees with weakened distal wing venation comprise one or multiple genera. Here, we analyzed the phylogenetic relationships among the subgroups within Lasioglossum s.l. based on thousands of single-copy orthologs and ultraconserved elements, which were extracted from 23 newly sequenced low-coverage whole genomes alongside a published genome (22 ingroups plus 2 outgroups). Both marker sets provided consistent results across maximum likelihood and coalescent-based species tree approaches. The phylogenetic and topology test results show that the Lasioglossum and Hemihalictus series are reciprocally monophyletic and Homalictus and Rostrohalictus are valid subgenera of Lasioglossum. Consequently, we lower Homalictus to subgenus status within Lasioglossum again, and we also raise Rostrohalictus to subgenus status from its prior synonymy with subgenus Hemihalictus. Lasioglossum przewalskyi is also transferred to the subgenus Hemihalictus. Ultimately, we redefine Lasioglossum to include all halictine bees with weakened distal wing venation.