Apidologie最新文献

Nectar composition is an important driver of insect attractiveness. Although bumblebees prefer sucrose-rich nectar, they were found to be the main pollinators of Gentiana lutea, whose nectar is low on sucrose. Therefore, we tested the hypothesis that bumblebees are attracted to the amino acids proline and β-alanine, which are both naturally occurring at high concentrations in the nectar of G. lutea. We analysed the solution consumption and survival of Bombus terrestris L. (Hymenoptera: Apidae) workers fed with artificial nectars enriched with proline, β-alanine or both, at natural and twice the natural concentrations. We found that consumption of nectar enriched with proline at twice the natural concentration was strongly positively correlated with bumblebee weight. However, when adjusting for individual weight, we found that this solution was the least consumed, suggesting the presence of a regulatory mechanism of proline intake to reduce negative effects on survival. We did not find any direct effect of β-alanine on consumption, although our findings suggest a potential interplay between proline and β-alanine in the regulation of proline intake. Bumblebee survival was not affected by any nectar composition. These results suggest that the high visitation rate to flowers of G. lutea by bumblebees observed in natural populations can be partially related to its nectar amino acidic composition, and that protein and non-protein amino acids can affect pollinator preference and foraging behaviour.

In the coming decades, the human population will grow and demand more food. Therefore, agricultural practices are expected to be intensified. Among these practices is pesticide application. However, pesticides threaten bees and, thus, crop pollination, ultimately jeopardizing our own food security. This dilemma makes precisely quantifying the magnitude of these threats urgent, so we can improve our agricultural management practices. By conducting a systematic review followed by a meta-analysis, we estimated the effect sizes of pesticide application on bees and their crop pollination service. Our results show that pesticides reduce bee survival almost five times. Even when bees survive, sublethal effects can impair crop pollination. The consequences for bee communities and their crop pollination service might not be immediately evident but can be magnified in the long-term. Finally, we conclude that conserving the vegetation surrounding crops and minimizing pesticide use are key to protecting bees and ensuring crop pollination. Moreover, the adoption of integrated pest management (IPM) protocols can ultimately contribute to solving this problem and achieving UN’s sustainable Development Goal 2 (Zero Hunger).

Plebeia is a taxonomically complex genus of stingless bees characterized by remarkable interspecific morphological similarity. On the other hand, cytogenetic data have been useful to resolve taxonomic uncertainties and to infer the diversification processes. Therefore, the goal of this study was to provide a karyotypic analyses in five nominal taxa of Plebeia from northeastern Brazil: P. droryana Friese (Természetrajzi Füzetek kiadja a Magyar nemzeti Muzeum 23:381–394, 1900), P. cf. mosquito Smith 1863, Plebeia aff. droryana 1, Plebeia aff. droryana 2, and Plebeia aff. fravocincta based on traditional and molecular cytogenetic methods to test their applicability in cytotaxonomy and to understand the karyoevolutionary processes in these bees. All species shared a chromosomal number of 2n = 34, except for some individuals of Plebeia aff. flavocincta that presented up to two small and heterochromatic B chromosomes. Species-specific karyotype formulae were observed while the heterochromatin segments were mainly distributed on short arms and pericentromeric regions of most chromosomes, including subtle C-banding differences in each species. The 18S rDNA sites were terminally located on pair 3 of P. droryana, P. cf. mosquito, Plebeia aff. droryana 2, and Plebeia aff. droryana 1, and on the first metacentric pair in Plebeia aff. flavocincta. These data reinforced the efficiency of cytogenetics as an informative tool to discriminate Plebeia species. The present data suggest that structural rearrangements such as inversions and duplications/deletions of heterochromatin and ribosomal clusters are the main drivers of karyotypic evolution in Plebeia.

In the darkness of their nests, most social insect species communicate relying on chemical, tactile, electrical and mechanical signals. In honeybees, vibrational signals play a role not only in worker communication but also in communication among virgin queens in the process of swarming. Whereas the sensitivity to vibrations has been well studied in worker bees, vibrational sensitivity of queens and drones has never been investigated. We therefore studied the sensitivity to vibrations comparatively in workers, virgin and laying queens and in drones, focusing on the frequency range mainly used by virgin queens (350–500 Hz). Bees were tested behaviorally for responses to pulses of substrate borne vibrations in arenas placed on vibrational exciters. Vibrational amplitudes were measured using (LDV-calibrated) accelerometers. Real stimuli and sham stimuli were presented in a pseudorandom order. The threshold was defined as the lowest tested amplitude at which significantly more behavioral reactions were shown to real stimuli than to sham stimuli. Workers and virgin queens respond to amplitudes down to 0.25 m/s². The thresholds of laying queens are substantially higher and they respond to minimum amplitudes of 0.55 m/s². Drones show responses to amplitudes down to 0.6 m/s². We conclude that sex and caste have effects on vibrational sensitivity in honeybees: virgin queens are significantly more sensitive than laying queens, indicating that a high sensitivity is crucial for survival during the process of swarming; workers are likewise highly sensitive to execute efficient everyday work; drones are significantly the least sensitive.

Our insights into the responses of immature stages of vernal solitary bees to the thermal challenges of spring weather mostly come from studies of cavity-nesting megachilid bees in constant temperature incubators. Most of these studies reported either the average timing of adult emergence or the general pace of immature development. In this study, we tracked the longevity and developmental fates of eggs laid by nearly 200 female Osmia lignaria (Hymenoptera: Megachilidae) occupying observation nests set outdoors in a nature preserve. In the spring of 2022, the nesting population was challenged by a prolonged period of unseasonably chilly wet weather. As a consequence, fewer nest cells were provisioned, and hatching among the 2416 eggs was delayed for as much as a month. Surprisingly, these delays incurred no ill-effects on either egg survival or subsequent larval development, both of which were comparable to the much warmer spring of 2021 (3630 eggs). The population’s 33% reproductive shortfall in 2022 was instead attributable to limited hours warm enough for flight and foraging, in part evidenced by the paucity of multi-cell days. Eggs and larvae of this bee, and probably other vernal solitary bees, readily tolerate prolonged episodes of cold springtime weather.

Bees are often exposed to pesticide residues during their foraging trips in agricultural landscapes. The analysis of in-hive stored pollen reflects the spectrum of visited plants and can be almost used to link the exposure to pesticides.In the current study, bee bread samples were collected in May and July from 17 sites located in southern Slovakia. Samples were analysed using a multi-residue pesticide analysis method for a broad spectrum of active substances and microscopic for pollen identification.Our results revealed a bee bread contamination with 19 different active substances, with fungicides being predominant. Sixteen of them are authorized in the EU, but chlorpyrifos, chlorpyrifos-methyl, and chloridazon are not. The highest concentrations for pendimethalin (1400 µg/kg), fluazifop-butyl (640 µg/kg), fenpropidin (520 µg/kg), fluopyram (130 µg/kg), and difenoconazole (95 µg/kg) were detected. The total residue load in bee bread sampled in the early season (May) was significantly higher than in the late season (July). The mean residue load of insecticides analysed in July comprised 46% of May’s load, which is alarming due to the importance of bee bread in the diet for winter-rearing bees. Moreover, results from both sampling periods showed that fungicides were positively associated with plant families Apiaceae and Papaveraceae and herbicides with Aceraceae, Salicaceae, and Brassica-type/Brassicaceae.Hence, bee bread can be considered a suitable matrix and a good bio-indicator reflecting honey bee exposure to pesticides over the season.

How beekeepers can propagate the Varroa-resistant traits they have in their colonies depends on how varroa resistance, i.e. the key hygienic behavioural traits, is passed onto the next generation. This study investigates if the key hygienic traits are passed between workers via learning as is known to happen in bumble bees, or are the resistant traits encoded into the queens and thus her offspring. To test this, we re-queened known mite-resistant colonies with mite-naïve (susceptible) queens in both Hawaii and the UK. We also placed resistant queens in susceptible colonies in the UK. After 5 months in Hawaii and 12 months in the UK, mite levels in adults and brood were measured. In Hawaii, mite removal and cell recapping levels were also assessed. In both locations, the mite levels in colonies headed by suspectable (mite-naïve) queens or their daughters significantly exceeded that found in colonies headed by resistant queens or their daughters. The initial presence of resistant or suspectable workers did not affect the result. Therefore, to propagate mite-resistant traits, beekeepers only need to re-queen a colony with a locally mated queen from an established resistant population, as some UK and Hawaiian beekeepers are already doing.

Nectar, an important reward in plant-pollinator interactions, mainly provides sugars, but also other nutrients. Nectar sugar content is known to affect pollinator preferences, while the effect of other nectar nutrients on flower visitor choices is less well understood. To explore whether nectar nutrients affect the foraging preferences of the stingless bee Trigona fulviventris, we conducted feeding choice experiments with sucrose solution enriched with either an amino acid mixture (in high and low concentrations), sodium chloride (table salt), a fatty acid mixture, or quinine (a bitter tasting substance used as negative control) against pure sucrose solution in a lowland rainforest in Costa Rica. Bees were first trained to feeders presenting either a yellow (only sucrose solution) or a blue (sucrose solution plus tested substance) visual cue that the bees could use to associate with the solution content. They were subsequently offered a choice between the blue and yellow feeders in an unrewarded test. The bees preferred pure sucrose solutions over sucrose solutions with quinine, amino acids, or fatty acids, but not over solutions with salt. Our findings indicate that T. fulviventris is able to differentiate various nutrients in nectar and prefers pure sucrose solution or sucrose solutions with salt. Sugar and salt may therefore represent important nutrients in nectar and are likely key cues to assess nectar quality in tropical stingless bees. In contrast, other nutrients appear to compromise the bees’ taste for nectar and are likely obtained from other sources.

Honey bee (Apis mellifera) breeding has intensified as populations experience increasing stress and pollination demand increases. Breeding programmes risk genetic diversity losses as mating is focused on a small group of individuals. Loss of diversity at the complementary sex determiner (csd) locus results in decreased viability and reduced honey production. Bees that are homozygous at csd become inviable males rather than workers. We examined csd diversity in four Australian breeding populations: a queen bee breeder from New South Wales, another from Queensland, a Western Australian breeding programme involving 11 bee breeders, and a research population at the NSW Department of Primary Industries. We found 82 unique csd alleles across the four populations, 16 of which have not been previously reported. This study provides a snapshot of csd diversity in Australia which will be useful for the national honey bee genetic improvement programme (Plan Bee).

Climate change and/or land use change were repeatedly reported as important for both range expansion of alien bee species and range shrinking for native bee species. However, environmental changes may also positively affect native species that may expand across contiguous areas to their native ones. Here, we focused on Halictus scabiosae (Rossi, 1790) (Hymenoptera: Halictidae), a ground-nesting, primitively eusocial wild bee that has its primary distribution in Western-Southern Europe but that was recently recorded in Eastern-Central Europe. In particular, we studied the range expansion patterns of H. scabiosae, and we hypothesized that previously unsuitable areas may be currently colonized because of environmental changes. In the last 5 years, H. scabiosae moved its densest record areas to North-Eastern Europe, but its ecological niche remained almost unchanged from 1970 to date, suggesting that this bee species is following its preferred conditions (high temperature, high temperature seasonality, and low precipitation seasonality). Potential distribution models revealed high suitability in still unoccupied North-Eastern areas, with urbanization increasingly important as potential stepping stones towards the expansion. The relevant role of urbanization is confirmed by the increase in the number of urban records through time and by the fact that cities with greater population density and greater fragmentation are more likely associated with this species’ occurrence. Halictus scabiosae is thus expanding its range because climate change is producing—and urban environment is offering—suitable conditions in areas previously inadequate for its establishment.