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Over two million commercial bumblebee colonies are used on an annual basis to pollinate around 20 crop types worldwide. Despite their use, especially with crops grown in greenhouses, there is mounting evidence that many individuals also forage outside of them. Hence, the use of commercial bumblebees poses a risk to wild pollinators, especially to those who share floral resources and pathogens. To date, however, there is little evidence about the impact of commercial bumblebees on pollinator communities in Europe. We surveyed the abundance of commercial Bombus terrestris and the prevalence of four of its parasites in natural areas at increasing distances from vegetable crops in Cabo de Gata-Níjar (Almería, SE Spain), the most extensive greenhouse cultivation area in the world. We also estimated resource niche overlap (i.e., shared plants used) between commercial bumblebees and the native pollinator community. Finally, we explored whether the abundance and diversity of pollinators in natural habitats were influenced by agricultural expansion (i.e., distance to greenhouses) and bumblebee abundance. We found a sharp reduction in commercial bumblebee densities at increasing distances from greenhouses, with most bumblebees (95%) foraging within a radius of less than 200 m from them. However, these commercial bumblebees had high parasite prevalence (41% of individuals infected) of trypanosomatids, microsporidians and neogregarines. Moreover, their diet particularly overlapped with honeybees and large wild bees. Yet, pollinator density and diversity were not related to the distance from greenhouses or to bumblebee abundance. Although our results suggest that commercial bumblebees do not significantly harm wild pollinators, actions like preventing their escape from greenhouses, monitoring their health and optimising their use should be considered so as to minimise future risks.

First data about Halictidae (Hymenoptera: Apoidea) in the region of Batna (Eastern Algeria) Investigations carried out on Halictidae bees in different localities in the region of Batna during the s...

(1) Intensive agriculture has a high impact on pollinating insects, and conservation strategies targeting agricultural landscapes may greatly contribute to their maintenance. The aim of this work was to quantify the effect that the vegetation of crop margins, with either herbaceous or shrubby plants, had on the abundance and diversity of bees in comparison to non-restored margins. (2) The work was carried out in an area of intensive agriculture in southern Spain. Bees were monitored visually and using pan traps, and floral resources were quantified in crop margins for two years. (3) An increase in the abundance and diversity of wild bees in restored margins was registered, compared to non-restored margins. Significant differences in the structure of bee communities were found between shrubby and herbaceous margins. Apis mellifera and mining bees were found to be more polylectic than wild Apidae and Megachilidae. The abundance of A. mellifera and mining bees was correlated to the total floral resources, in particular, to those offered by the Boraginaceae and Brassicaceae, wild Apidae and Megachilidae were associated with the Lamiaceae. (4) This work emphasises the importance of floral diversity and shrubby plants for the maintenance of rich bee communities in Mediterranean agricultural landscapes.

In recent decades, there has been a remarkable expansion of pollinator-dependent crops. An increase in the use of commercial pollinator colonies associated with these crops may promote the spillover of managed pollinators into nearby natural habitats. There, these managed pollinators can exploit floral resources similar to those of wild pollinators, and thus increase competition for local resources. Nonetheless, managed pollinator spillover has been poorly studied and research has focused on only one species, the western honeybee (Apis mellifera). In south-western Spain, we investigated the presence, density and exploitation of floral resources by managed (Bombus terrestris) and native bumblebees (B. t. lusitanicus) in 19 Mediterranean pinewood understories across a landscape gradient of strawberry polytunnel greenhouse cover. Sampling was performed over two consecutive years in two seasons: winter, when strawberries begin flowering and farmers frequently use colonies, and spring, when there is greater availability of floral resources and wild pollinators thrive. In winter, the density of managed bumblebees in pinewoods was higher than that of native bumblebees. The presence of managed and native bumblebees in pinewoods showed contrasting patterns in relation to greenhouse cover in the landscape. The presence of managed bumblebees was positively associated with greenhouse cover, whereas that of native bumblebees was negatively associated with greenhouse cover. Overall, the presence and density of bumblebees did not differ between seasons. The two bumblebee subspecies showed similar wild flowering plant preferences, particularly in winter, when flowering plant species are scarce. We conclude that, although managed bumblebees are placed in greenhouse crops, their pollination role extends beyond these crops. Further studies are needed to assess the pollination function of managed pollinators in crops in order to reduce their spillover into natural habitats and thus, the risks posed to native pollinators., Funding was provided by the Spanish Ministry of Economy and Competitiveness project FLORMAS (‘Influence of mass flowering crops on pollinator biodiversity, project no CGL2012-33801’) and by the Biodiversa-FACCE project ECODEAL (‘Enhancing biodiversity-based ecosystem services to crops through optimised densities of green infrastructure in agricultural landscapes, project no PCIN-2014-048’). AT was supported by a Severo-Ochoa Predoctoral Fellowship (SVP-2013-067592). JPGV was funded by an Individual Fellowship from the Marie Sklodowska-Curie Actions (H2020-MSCA-IF-2014-656572).

Extreme specialization is a common phenomenon in antagonistic biotic interactions but it is quite rare in mutualistic ones. Indeed, bee specialization on a single flower species (monolecty) is a questioned fact. Here, we provide multiple lines of evidence on true monolecty in a solitary bee (Flavipanurgus venustus, Andrenidae), which is consistent across space (18 sites in SW Iberian Peninsula) and time (three years) despite the presence of closely related congeneric plant species whose flowers are morphologically similar. The host flower (Cistus crispus, Cistaceae) is in turn a supergeneralist, visited by at least 85 insect species. We uncover ultraviolet light reflectance as a distinctive visual cue of the host flower, which can be a key mechanism because bee specialization has an innate basis to recognize specific signals. Moreover, we hypothesized that a total dependence on an ephemeral resource (i.e. one flower species) must lead to spatiotemporal matching with it. Accordingly, we prove that the bee's flight phenology is synchronized with the blooming period of the host flower, and that the densities of bee populations mirror the local densities of the host flower. This case supports the `predictable plethora' hypothesis, that is, that host-specialization in bees is fostered by plant species providing predictably abundant floral resources. Our findings, along with available phylogenetic information on the genus Cistus, suggest the importance of historical processes and cognitive constraints as drivers of specialization in bee-plant interactions.

Pollinator spill-over among habitats can arise in order to fulfill the pollination function and whenever differences in floral offering change over time or space. Flowering crops offer pulsed and abundant floral resources (i.e., mass flowering crops) that might promote pollinator spill-over between cultivated and adjacent natural areas. We explored pollinator patterns in the mass flowering legume crop Hedysarum coronarium and its influence on the bee pollinator communities of adjacent shrublands in a heterogeneous and patchy agricultural landscape. We studied the temporal (i.e., during vs. after mass flowering in adjacent shrublands) and spatial (i.e., inside crops, adjacent and distant shrublands during mass flowering) functional pollinator spill-over. The honeybee was highly attracted to Hedysarum crops, yet its abundance and that of other bee species visiting native plants in adjacent shrublands did not differ during and after Hedysarum mass flowering. However, at the landscape scale, the honeybee and the other bee species were less abundant in shrublands adjacent to Hedysarum crops compared to distant ones; their visitation rates showing a similar trend. These results show that some mass flowering crops can influence pollinator patterns in the surrounding landscape by competing for generalist pollinators with native plants. The characteristics of the crop species and the landscape can modulate and determine the role of mass flowering crops as competitors or supporters of wild pollinators for adjacent natural areas.

Entomophilous and obligate out-crossing non-native plants need to become well integrated in the resident plant–pollinator network to set seeds and become established. However, it is largely unknown how pollination patterns differ between native ranges and those where plants have been introduced. We compared the identity, abundance and visitation rates of pollinators, insect pollen loads, pollen deposition on stigmas, and fruit and seed sets of Hedysarum coronarium, an entomophilous short lived N-fixing perennial, in populations from native and introduced ranges in Spain (South of mainland Spain and Menorca Island, respectively). In both areas, Hedysarum was visited by a similar number of species, mainly hymenopterans; seven species were common between native and introduced areas. However, pollinator richness, abundance, and visits per flower were greater in the native than in the introduced range, as were fruit and seed sets. Hedysarum pollen loads on stigmas and on Apis mellifera, the most common pollinator, did not differ between areas. Lower abundance of pollinators might be causing lower visitation rates, and to some extent reducing Hedysarum fruit and seed sets in the introduced area. Our biogeographical approach shows that integration of a non-native plant in a resident pollinator network does not prevent pollen limitation in the introduced area. Therefore, despite being necessary, pollination mutualistic relationships might not be the key for non-native plant establishment success in the introduced area.

IntroductionAposematism is a defense system against predators consisting of the toxicity warning using conspicuous coloration. If the toxin production and aposematic coloration is costly, only individuals in good physical condition could simultaneously produce abundant poison and striking coloration. In such cases, the aposematic coloration not only indicates that the animal is toxic, but also the toxicity level of individuals. The costs associated with the production of aposematic coloration would ensure that individuals honestly indicate their toxicity levels. In the present study, we examine the hypothesis that a positive correlation exists between the brightness of warning coloration and toxicity level using as a model the paper wasp (Polistes dominula).ResultsWe collected wasps from 30 different nests and photographed them to measure the brightness of warning coloration in the abdomen. We also measured the volume of the poison gland, as well as the length, and the width of the abdomen. The results show a positive relationship between brightness and poison-gland size, which remained positive even after controlling for the body size and abdomen width.ConclusionThe results suggest that the coloration pattern of these wasps is a true sign of toxicity level: wasps with brighter colors are more poisonous (they have larger poison glands).

Arthropods frequently use empty snail shells as shelter or nesting sites. This study analyses the use of shells from the arid-dwelling land snail Sphincterochila candidissima (Draparnaud 1801) by arthropods in the Sierra Elvira (south-eastern Spain). Arthropods of 11 different orders occupied 15.6% of shells. Salticidae (54.6%) and Apoidea (21.3%) comprised the majority of arthropods. Shells were used primarily when environmental temperatures were lowest, suggesting that, in the Sierra Elvira, arthropods use shells to escape from the cold. Weather explained 73% of the variation in shell occupation. However, Apoidea used shells independently of weather, occupying shells as nesting chambers. These results suggest that snail shells may be important refugia and nesting sites for arthropod fauna. Resume. Conditions meteorologiques et utilisation des coquilles vides de gasteropodes par les arthropodes. Les arthropodes utilisent frequement les coquilles vides d'escargots comme abris ou comme sites de nidifi cation. Cette etude analyse l'utilisation par les arthropodes des coquilles d'un escargot aridicole, Sphincterochila candidissima (Draparnaud 1801), dans la Sierra Elvira (sud-est de l'Espagne). Les arthropodes de 11 ordres differents ont ete trouves dans 15,6% des coquilles. Les Salticidae (54,6%) et les Apoidea (21,3%) constituaient la majorite des arthropodes. Les coquilles ont ete utilisees principalement lorsque la temperature de l'environnement etait basse. Cela suggere que, dans la Sierra Elvira, les arthropodes utilisent les coquilles pour echapper au froid. Les conditions meteorologiques expliquent 73% des variations d'occupation des coquilles observees. Toutefois, les Apoidea ont utilise les coquilles independamment du temps, en les occupant comme des chambres de nidifi cation. Ces resultats suggerent que les coquilles d'escargots peuvent etre importants comme refuges et comme sites de nidifi cation pour la faune d'arthropodes.

Study of recently collected bees from south-eastern Spain revealed a new species of subgenus Panurgus (Pachycephalopanurgus) Patiny, 1999, closely related to P. canescens Latreille, 1811, and P. calceatus Pérez, 1895. Within this group of three species, P. meridionalis sp.nov. is characterized by the presence of a pair of latero-ventral teeth on the third tergum of the male (unique among Panurginae). This new species is only the second species of Pachycephalopanurgus recorded from Europe, the other five being North African. Distributional patterns in subgenus Pachycephalopanurgus are mapped and summarized.