Apidologie最新文献

Eusociality in honeybees (Apis mellifera) is characterised by a reproductive division of labour, where the queen monopolises reproduction while worker reproduction is constrained. This constraint is mediated by queen mandibular pheromone (QMP), which inhibits worker ovary development through Notch signalling and possibly oocyte apoptosis. Dopamine has been implicated in regulating reproduction in worker honeybees, with prior studies suggesting that dietary dopamine enhances ovary activity in queen-less workers. This study aimed to test whether dopamine supplementation could overcome QMP-mediated reproductive constraint in worker honeybees. Using caged honeybee experiments, we administered dopamine and its precursor L-dopa at a range of concentrations, both in the presence and absence of QMP. Results showed that neither dopamine nor L-dopa supplementation affected ovary development, survival rates, or food intake, which contrasts with a previous study. These findings suggest that dopamine may not be a major factor in QMP-mediated reproductive inhibition. Instead, we suggest that the multifaceted nature of QMP’s components together with the complexity of neuroendocrine signalling makes it likely that multiple redundant mechanisms regulate worker reproduction. Future research should investigate the interplay between nutrition, dopamine and QMP components to fully understand the regulation of ovary activation in honeybee workers.

Honey bee (Apis mellifera) colonies usually survive less than 16 months if populations of parasitic mite (Varroa destructor) are not controlled. The timing of when to control Varroa populations is aided by using methods that estimate the number of Varroa in hives. The relative efficacy of eight methods used to calculate the number of Varroa in samples of 300 adult bees was established: icing sugar shake (78%), low-suds detergent wash (86%), ethanol wash (72%), 10-min exposure to Apistan^® (42%), ether roll (42%), a 30-s exposure to grapefruit leaf smoke (5%), a 30-s exposure to fluvalinate smoke (0%), and a 30-s exposure to tobacco leaf smoke (0%). A range of approaches were investigated to improve the efficacy and reliability of some of the methods. The following approaches improved the efficacy of four methods so that more than 95% of the Varroa were recovered: two 15-s shakes with at least 10 g of icing sugar; three 15-s washes with low-suds detergent; three 30-s washes with ethanol; and a 35-min exposure to an Apistan^® strip.

Global commercial honey bee keeping for crop pollination and honey production is increasingly identified as a threat to wild bee populations. Intensive honey bee keeping is particularly alarming in Mediterranean regions that are considered global diversity hotspots for bees. Yet, the effects on the bee communities and their variation as a function of the distance to apiaries (i.e. collection of bee hives) remain poorly explored. To fill this gap, we investigated 56 sites adjacent and far (> 1 km) from apiaries in three large nature reserves in Northern Israel. We explored the effects of proximity to apiaries on wild bee taxonomic and phylogenetic diversity and compared bee community composition between sites far and near to apiaries. Our records of 295 bee species include regionally restricted and undescribed species and contribute to the knowledge of Israel’s bee fauna. We found that proximity to apiaries reduced both the taxonomic and phylogenetic diversity of wild bees, and that this impact depended on individual abundance. We show that across nature reserves, 41.7 to 56.5% of the bee species diversity is concentrated in sites far from apiaries, with fewer species shared between near and far sites. Our results suggest that honey bee keeping is correlated with lower species richness in wild Mediterranean bee communities, potentially disrupting pollination processes and ultimately compromising ecosystem stability. We caution against intensive bee keeping in or near nature reserves for the conservation and safeguarding of diverse Mediterranean wild bee communities.

Apis mellifera often encounters the fungicide boscalid in agricultural landscape. In this study, we assessed the impacts of ingesting boscalid and Pictor Pro® (a commercial formulation of boscalid) at environmentally relevant doses during the larval development phase. Following chronic exposure, we measured survival, development time, and gene expression in both larvae and in 10-day-old workers. The genes analyzed were involved in immunity, detoxification, development, and mitochondrial activity pathways. We found no significant impact of boscalid in larval survival and emergence. However, genes related to cytochrome b, succinate dehydrogenase, and catalase were downregulated in larvae and adult workers exposed to boscalid, though the differences were not significant when compared to the solvent control. Late variation was observed in 10 days adult bees’ overexpression of the vitellogenin gene, which is linked to development. The effects observed with boscalid molecule were not seen with the commercially formulated product, Pictor Pro®.

Bumblebees are ubiquitous, cold-adapted, primitively eusocial bees and important pollinators for crops and vegetation. However, many species are declining worldwide due to multiple factors, including human-induced habitat loss, agricultural chemicals, global warming, and climate change. In particular, future climate scenarios predict a shift in the spatial distribution of bumblebees under global warming, with some species declining and others potentially expanding. Here, we report a de novo genome assembly and annotation for Bombus lapidarius and Bombus niveatus to decipher species-specific potential genomic capacity against such environmental stressors. With harboring more than 23,000 protein-coding genes, the assembled genomes of B. lapidarius and B. niveatus are 244.44 Mb (scaffold N50 of 9.45 Mb) and 259.84 Mb (scaffold N50 of 10.94 Mb), respectively, which exhibit similar trends in terms of genome size and composition with other bumblebees. Gene family analysis reveals differences in species-specific expanded gene families. B. lapidarius exhibits expanded genes related to pre/postsynaptic organization, while B. niveatus shows a distinct expansion in gene families regulating cellular growth, aging, and responses to abiotic and biotic stressors, such as those containing SCAN domains, WD-repeats, and Ras-related proteins. Our genome-wide screens revealed positive selection on environmental stress-responsive genes such as dip2, yme1l, and spg7 in B. lapidarius, whereas positive selection signatures were found in genes such as myd88, mybbp1A, and rhau, which are involved in environmental stress resistance for B. niveatus. These high-quality genome assemblies and comparative genome analysis unveil potential drivers that underlie genome evolution in bumblebees, offering valuable insights into environmental adaptation and conservation efforts.

Honey bees (Apis mellifera) confront a multitude of challenges to their health throughout their lifespan and have naturally evolved protective mechanisms to defend against biological stressors. Transgenerational immune priming (TGIP) is one such defense mechanism that confers protection against bacterial infections from parents to offspring. However, it is unclear whether TGIP in honey bees also protects against viral infections, which may offer a promising pathway to decrease the honey bees’ susceptibility to viral infections. We studied our hypothesis that honey bees can prime their offspring against Israeli acute paralysis virus (IAPV). We tested the prediction that the offspring of queens exposed to thermally inactivated IAPV would exhibit higher survival of an acute IAPV infection than the offspring of sham-treated queens. Based on pilot studies that compared the effects of different inoculation methods, we topically inoculated experimental queens with heat-inactivated IAPV and compared survival of an infection with active IAPV between their offspring and offspring of sham-treated control queens. IAPV infection significantly decreased offspring survival but maternal exposure to the inactive virus did not affect this outcome. Our results fail to support the notion that maternal exposure confers the same level of protection against virus infections as observed against bacterial infections, at least in this specific instant, underscoring the intricate nature of the honey bees’ transgenerational immune response. Further development of effective strategies against viral threats to improve honey bee health is needed.

The present study evaluated the potential use of methanolic extracts from two seaweeds from the Argentine Patagonian coasts, Macrocystis pyrifera and Undaria pinnatifida, as natural alternatives against Paenibacillus larvae. We carried out a detailed characterization of both seaweeds, comparing vegetative and reproductive thallus portions. We also assessed their phenolic content and antioxidant activity and evaluated the in vitro antibacterial action. Based on the minimal inhibitory concentration results, extracts from sporophyll of Undaria (US) and basal thallus portion of Macrocystis (MB) are strong inhibitors. US showed the best activity against P. larvae strain CMM(B)35 (12.2 μg/mL), and MB showed the same activity for strains CMM(B)35 and MAR1 (18.6 μg/mL). Antioxidant activity was higher in US, followed by MB, and a positive correlation was found with phenolic content. Taken together, our results indicate the role of specific chemical compounds present in algal extracts on antioxidant properties and antibacterial activity against P. larvae. We conclude that these seaweeds are promising alternatives against P. larvae.

This study aims to classify honey bee genotypes by integrating explainable artificial intelligence techniques, particularly decision trees, with both morphometric and molecular data. A total of 4949 samples were collected from 500 colonies across five regions in Türkiye, representing diverse subspecies and ecotypes. Morphometric data included 16 key wing characteristics, while molecular data contained 26 highly informative SSR loci. First, we used 16 morphometric wing parameters to classify bees into five regions where they originate. The decision tree algorithm resulted in a tree with wing length and O26 and L13 angles, but the classification accuracy was low (51%). Later, we included 26 molecular variables and obtained a decision tree with four SSR loci—Ap218, Ap274, Ap001, and Ap289—and achieved a high classification accuracy of 96.38%. The findings also revealed the first-ever identification of a SSR locus (Ap218) strongly associated with wing length in honey bees. Finally, we explained wing length with molecular data by modeling a regression decision tree. This tree identified Ap218, Ap223, and Ap001 as the most significant SSR loci for the wing length model. This study provides a powerful approach for differentiating honey bee genotypes while offering valuable insights into the genetic factors influencing wing morphology. The results have significant implications for the conservation and sustainable management of honey bee genetic resources, particularly in regions like Türkiye where genetic diversity is at risk.

Commercially reared bees provide economically important pollination services for a diversity of crops. Improving their health is important both to maximise their pollination services and to avoid possible pathogen spillover or spillback with wild pollinators. Diet quality may directly or indirectly affect diverse aspects of bumblebee health, including colony development, individual size and immune health, but the impact of this remains unclear. Here we investigate experimentally the effect of diet quality during bumblebee colony development using three diets: (1) a standard pollen diet used in commercial rearing of colonies for sale, (2) an enhanced diet comprised of a wildflower pollen mix that was expected to be nutritionally superior (including by having an elevated protein content) and (3) a diet of pollen substitute mixed with the standard diet that was expected to be nutritionally poorer. The effect of diet quality on colony health was quantified using colony-level measures (colony weight, size [number of live workers] and number of dead individuals), and individual-level measures (body size, fat body size [proportion of body weight], total haemocyte count and phenoloxidase immune enzyme activity). Diet quality significantly affected colony growth, with colonies fed the enhanced diet growing larger and producing more reproductives than those fed either a standard or poor diet. The enhanced diet also resulted in bees that were significantly larger and had better immune health. The results show that diet can have important effects on the health of commercially reared bumblebees and suggest that the enhancement of standard-rearing diets may improve colony health.