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Multisource approaches in taxonomy gather different lines of evidence in order to draw strongly supported taxonomic conclusions and constitute the basis of integrative taxonomy. In the case of overlooked taxa with disjunct distributions for which sampling is more challenging, integrative approaches help to propose stable hypotheses at the species and subspecies levels. Here, based on genetic and semio-chemical traits, we performed an integrative taxonomic analysis to evaluate species delimitation hypotheses within a monophyletic group of bumblebees (Hymenoptera, Apidae, Bombus) including the formerly recognised subgenera Eversmannibombus, Laesobombus and Mucidobombus which are now included in the subgenus Thoracobombus. Our results demonstrate the conspecificity of several polytypic taxa, and we formally recognise the subspecies Bombus laesus aliceae comb. nov. Cockerell, 1931, endemic to North Africa, based on its allopatry, unique mitochondrial haplotype and divergent cephalic labial gland secretions. This highlights the need to maintain studying polytypic complexes of bumblebee taxa for which phylogenetic relationships could be still entangled and eventually implement conservation strategies for taxonomically differentiated lineages.

The latest progress of the taxonomy is the use of integrative approach for species delimitation based on a multisource dataset. However, the taxonomic decision that should be made when convergence between the different lines of evidence is not observed remains debated. Here, we investigate the consequences of the application of an ‘integration by cumulation’ approach on the taxonomic statuses within the Bombus lapidarius complex when using an integrative taxonomic framework (i.e. nuclear and mitochondrial markers along with reproductive traits) compared with a strict ‘integration by congruence’ method. Our results show similar taxonomic conclusions whatever the decision-making approach used except for one taxon. According to the differentiation observed in our integrative taxonomic framework, recent divergence time and other field observations for this taxon, we assume that a too strict decision-making method could fail to detect recently diverged species. This is exemplified by the new species Bombus bisiculus sp. n. occurring in South Italy and Sicily.

Social parasitic Hymenopterans have evolved morphological, chemical, and behavioral adaptations to overcome the sophisticated recognition and defense systems of their social host to invade host nests and exploit their worker force. In bumblebees, social parasitism appeared in at least 3 subgenera independently: in the subgenus Psithyrus consisting entirely of parasitic species, in the subgenus Alpinobombus with Bombus hyperboreus, and in the subgenus Thoracobombus with B. inexspectatus. Cuckoo bumblebee males utilize species-specific cephalic labial gland secretions for mating purposes that can impact their inquiline strategy. We performed cephalic labial gland secretions in B. hyperboreus, B. inexspectatus and their hosts. Males of both parasitic species exhibited high species specific levels of cephalic gland secretions, including different main compounds. Our results showed no chemical mimicry in the cephalic gland secretions between inquilines and their host and we did not identify the repellent compounds already known in other cuckoo bumblebees.

Cold-adapted species are expected to have reached their largest distribution range during a part of the Ice Ages whereas postglacial warming has led to their range contracting toward high-latitude and high-altitude areas. This has resulted in an extant allopatric distribution of populations and possibly to trait differentiations (selected or not) or even speciation. Assessing inter-refugium differentiation or speciation remains challenging for such organisms because of sampling difficulties (several allopatric populations) and disagreements on species concept. In the present study, we assessed postglacial inter-refugia differentiation and potential speciation among populations of one of the most common arcto-alpine bumblebee species in European mountains, Bombus monticola Smith, 1849. Based on mitochondrial DNA/nuclear DNA markers and eco-chemical traits, we performed integrative taxonomic analysis to evaluate alternative species delimitation hypotheses and to assess geographical differentiation between interglacial refugia and speciation in arcto-alpine species. Our results show that trait differentiations occurred between most Southern European mountains (i.e. Alps, Balkan, Pyrenees, and Apennines) and Arctic regions. We suggest that the monticola complex actually includes three species: B. konradini stat.n. status distributed in Italy (Central Apennine mountains), B. monticola with five subspecies, including B. monticola mathildis ssp.n. distributed in the North Apennine mountains; and B. lapponicus. Our results support the hypothesis that post-Ice Age periods can lead to speciation in cold-adapted species through distribution range contraction. We underline the importance of an integrative taxonomic approach for rigorous species delimitation, and for evolutionary study and conservation of taxonomically challenging taxa.

Species taxonomy of bumblebees (Bombus Latreille, 1802) is well known to be problematic due to a potentially high intra-specific variability of morphological traits while different species can converge locally to the same color pattern (cryptic species). Assessing species delimitation remains challenging because it requires to arbitrarily select variable traits whose accuracy continues to be debated. Integrative taxonomic approach seems to be very useful for this group as different independent traits are assessed to propose a rational taxonomic hypothesis. Among operational criteria to assess specific status, the reproductive traits involved in the pre-mating recognition (i.e., the male cephalic labial gland secretions, CLGS) have been premium information. Since these secretions are supposed to be species-specific, these chemical traits can bring essential information where species delimitation is debated. Here, we describe and compare the CLGS of 161 male specimens of nine Alpinobombus taxa: alpinus, balteatus, helleri, hyperboreus, kirbiellus, natvigi, neoboreus, polaris, and pyrrhopygus. We aim also to test the congruence between this new information (reproductive traits) and published genetic dataset. Our results emphasized six distinct groups with diagnostic major compounds: (a) alpinus + helleri with hexadec-9-en-1-ol; (b) polaris + pyrrhopygus with two major compounds hexadec-9-en-1-ol and hexadec-9-enal; (c) balteatus with tetradecyl acetate; (d) kirbiellus with geranyl geranyl acetate; (e) hyperboreus + natvigi with octadec-11-en-1-ol; (f) neoboreus with octadec-9-en-1-ol. Based on this new information, we can confirm the species status of B. alpinus, B. balteatus, B. hyperboreus, B. kirbiellus, B. neoboreus, and B. polaris. We also confirm the synonymy of helleri (Alps) with alpinus (Sweden). However, the specific status of natvigi (Alaska) and pyrrhopygus (Sweden) is questionable and these taxa do not have specific CLGS composition.

Climate change is threatening species and habitats. Altitudinal shifts uphill and negative population trends are commonly observed in altitude-related taxa. The bumblebee Bombus alpinus (Linnaeus, 1758) has a disjoint distribution restricted to Fennoscandia and the Alps, and is considered threatened. We studied the ecology and distribution of B. alpinus in the Alps, where the endemic subspecies Bombus alpinus helleri Dalla Torre 1882 is found, as a case-model because of its rarity, habitat, and mutual dependence with the ecosystem for pollination and resources. We developed species distribution models including both climatic and habitat variables to obtain the surface suitable for this subspecies and quantified its protected portion. Our analyses indicate that this bumblebee is restricted to the upper altitudes and has a narrow niche mainly related to the presence of glaciers, the cool temperature, a low temperature variation, and a specific range of precipitation. A strong altitudinal shift is also taking place probably due to climate change. After years of no changes in altitudinal distribution, its lowest altitudinal limit has moved up 479 m since the year 1984, while its upper altitudinal limit has remained unchanged. Over half of the suitable area in the Alps is included within protected areas, but conservation has not been planned yet. However, rare species with narrow niche, such as B. alpinus, are highly threatened by climate change. Potential short-term mitigation actions are discussed, including exchange of males between locations and integral protection of prairies in the vicinity of glaciers.

Aim Conventional species distribution models (SDMs) usually focus on the species level but disregard intraspecific variability. Phylogeographic structure and evolutionary significant units (ESU) have been proposed as pragmatic proxies to incorporate intraspecific differentiation in SDMs. Nevertheless, the efficiency of using these proxies in SDMs has been poorly investigated. We analysed how the projections of current and future climatically suitable areas can be affected when using ESU‐based or lineage‐based models compared to a species‐level model. Location West‐Palaearctic region. Methods As examples, we used three bumblebee species (133,787 observations). We assessed potential climatic niche differentiation between species level, lineages and ESUs, by determining the niche position and niche breadth for each classification level by outlying mean index analyses. Subsequently, we developed SDMs for each species and classification level separately using boosted regression trees prior to a comparison of their performances. Finally, we used the alternative models to project the extent of climatically suitable areas in 2070. Results We found that in spite of highly similar overall model accuracy, integrating intraspecific variability significantly increases model sensitivity (i.e., better predicting presences) while decreased model specificity (i.e., over‐predicting the range). Consequently, both predictions of current and projections of future suitable conditions differed among the three approaches. Main conclusions We showed that although integrating lineage or ESU information did not improve the accuracy of conventional species‐level SDMs, it led to considerably different conclusions. As SDM‐based climatic risk assessments are increasingly used to help and improve conservation plans, divergences and limitations of each modelling approach should be taken into account for developing efficient biodiversity management strategies. Lineage and ESU‐based SDMs offer the ad

Pollination of wild and crop plants by animal pollinators is a key ecosystem service that is important to human welfare. Across Europe, climatic conditions are the most important drivers of occurrence and richness of pollinators followed by land cover and soil conditions. However, the example of recent range shifts of important pollinators such as the bumblebees shows that northern range expansions can be limited while southern range contractions can be considerable, leading to severe consequences under future scenarios. The way we utilize our landscape is a likely reason for such strong effects since the response to changing temperature conditions strongly depends on the amount of semi-natural area available in a landscape. In particular, the number of bee species is less sensitive to increasing temperatures when the amount of semi-natural habitat is high, while species richness drastically declines in intensively used agricultural landscapes and even more so with increasing temperatures. Such interactive effects of major drivers of global change bear a big chance for enhancing resilience in pollinator communities and thus in food production systems, e.g. by increasing the amount of semi-natural habitat as is the goal of the EU strategy for Green Infrastructure and some of the regulations in the EU Common Agricultural Policy (CAP).

Body size latitudinal clines have been widley explained by the Bergmann’s rule in homeothermic vertebrates. However, there is no general consensus in poikilotherms organisms in particular in insects that represent the large majority of wildlife. Among them, bees are a highly diverse pollinators group with high economic and ecological value. Nevertheless, no comprehensive studies of species assemblages at a phylogenetically larger scale have been carried out even if they could identify the traits and the ecological conditions that generate different patterns of latitudinal size variation. We aimed to test Bergmann’s rule for wild bees by assessing relationships between body size and latitude at continental and community levels. We tested our hypotheses for bees showing different life history traits (i.e. sociality and nesting behaviour). We used 142 008 distribution records of 615 bee species at 50 x 50 km (CGRS) grids across the West Palearctic. We then applied generalized least squares fitted linear model (GLS) to assess the relationship between latitude and mean body size of bees, taking into account spatial autocorrelation. For all bee species grouped, mean body size increased with higher latitudes, and so followed Bergmann’s rule. However, considering bee genera separately, four genera were consistent with Bergmann’s rule, while three showed a converse trend, and three showed no significant cline. All life history traits used here (i.e. solitary, social and parasitic behaviour; ground and stem nesting behaviour) displayed a Bergmann’s cline. In general there is a main trend for larger bees in colder habitats, which is likely to be related to their thermoregulatory abilities and partial endothermy, even if a ‘season length effect’ (i.e. shorter foraging season) is a potential driver of the converse Bergmann’s cline particularly in bumblebees.