Apidologie最新文献

Understanding which ant species interacting with honeybees can transmit or acquire viruses is crucial for managing honeybee health. Our objective was to develop a new methodology using two indices, based on a per-hive approach, to identify ant-virus combinations with high transmission potential (Matching Index) and to assess the relative risk posed to honeybees (Risk-to-Bee Index). Our survey in apiaries in Buenos Aires Province, Argentina, revealed that honeybee hives more infested by ants had smaller colonies. The Argentine ant, Linepithema humile, was among the top three ant species infesting hives. Ant brood and queens showed higher virus detection rates compared to workers, increasing virus prevalence in ants. Four viruses were detected in L. humile, but only deformed wing virus (DWV) was more prevalent in honeybees in hives with L. humile. Argentine ants tested negative for chronic bee paralysis virus, which was common in Camponotus species. In our study, per-hive indices suggest that Argentine ants would transmit DWV and black queen cell virus to honeybees, while honeybees would transmit DWV and acute bee paralysis virus to Argentine ants and Camponotus mus. Importantly, although our indices are simpler than previous tools to evaluate interspecific virus transmission, they do not provide definitive conclusions. However, the suggestions they offered align with all existing empirical data, highlighting their robustness. Thus, this approach provides a novel tool for prioritizing research on high-risk virus transmission between honeybees and ants, emphasizing its potential impact on honeybee management.

Previous work from our group identified distinct microbiome profiles in thriving versus non-thriving honeybee colonies in southwest Ireland, and highlighted seasonality, rather than location, as a significant factor in microbiome dynamics. Ireland harbours a relatively pure population of Apis mellifera mellifera, a subspecies in decline across mainland Europe, that is threatened by introgression from imported honeybee types such as the Buckfast hybrid and C-lineage honeybees. In this pilot study, we identified mitotypes of 30 honeybee colonies across southern Ireland and sequenced the nuclear genome of 9 colonies to assess hybridization levels. We profiled the microbiome of these colonies to investigate if mitotype interacted with the microbiome. Of the 30 colonies tested, 18 were M-mitotypes, but 9 C- and 3 A-mitotypes were also detected. Nuclear genome SNP analysis revealed that M-mitotype colonies were relatively pure, displaying little to no introgression, whereas A-mitotypes displayed a hybridised genome predominantly composed of M-lineage SNPs. C-mitotype colonies also displayed varying levels of M-lineage SNPs. Microbiome composition did not differ significantly across mitotypes, with individual colony being the most significant determinant of microbiome diversity. These findings provide further evidence that the Irish honeybee population is predominantly composed of native M-lineage honeybees, though its genetic integrity is threatened by the presence of imported lineages. While this native population does not possess a unique microbiome compared to that of other lineages, these results further our understanding of factors which determine the microbiome composition of honeybee colonies in Ireland.

The choice of honey bee genetic stock represents an important management decision for beekeepers to improve resilience against biotic and abiotic stressors impacting their operations. Three different genetic stocks of honey bees (Pol-line, Russian and Italian) were monitored in southern Arizona field experiments for two successive 9-month periods (June to February). Continuous monitoring techniques and detailed hive assessments were used to measure differences in colony performance and behavior. On average, Italian colonies produced significantly more brood compared to both Pol-line and Russian bees and had significantly more foragers and adult bees on average than Pol-line colonies. However, both Pol-line and Russian colonies exhibited a faster rate of weight gain during the primary nectar and pollen flow season (June–September) and slower weight loss during the dearth season (October–February) compared to Italian colonies, which corresponded to results from published cage studies. Pol-line colonies started flight activity 10 min later on average than Italian colonies and ended daily flight activity about 30 min later on average than Russian colonies. There were no internal hive temperature differences among bee stocks, but Pol-line colonies maintained the highest carbon dioxide (CO₂) concentrations. Finally, Varroa mite levels in Pol-line and Russian colonies were significantly lower than Italian colonies and were correlated with brood area. Our findings highlight the potential advantages of Russian and Pol-line bees for use in commercial beekeeping operations. These observed stock differences could translate to improved crop pollination efficiency and reduced reliance on chemical mite controls.

From 1984 to 2015, the Bee Disease Diagnostic Lab at the USDA-ARS Beltsville Bee Research Laboratory (MD, USA) analyzed 66,056 samples submitted for disease diagnosis, comprising 35,883 adult bees and 30,173 brood samples collected from symptomatic colonies nationwide. This dataset provided valuable insights into honey bee disease dynamics over three decades. Adult bee samples were screened for Nosema spp. and tracheal mite (Acarapis woodi). Brood samples were microscopically analyzed for the presence of both Paenibacillus larvae and Melissococcus plutonius, the causative agents of American foulbrood (AFB) and European foulbrood (EFB) diseases, respectively. Antibiotic resistance was tested in AFB-positive samples (n = 6,785) for tetracycline and tylosin. Longitudinal analysis revealed significant (p < 0.001) inter-state and seasonal differences in disease prevalence. AFB was significantly more prevalent nationwide (44.71%) compared to EFB (10.01%), with a negative correlation between the two diseases (R = -0.4, p < 0.01). P. larvae resistance to tetracycline and tylosin declined significantly (p < 0.001) in later years, with national resistance averages of 42.52% and 27.78%, respectively. Additionally, positive correlations were recorded between AFB prevalence and P. larvae resistance to both antibiotics. Nosema spp. prevalence ranged from 0% to 77.9% across states, with a national average of 24.09% and significant seasonal variations (p < 0.001). From 2008 to 2015, Nosema infection rates increased significantly, contrasting with a marked decline in tracheal mite prevalence since 2007 (national average of 12.48%), which was negatively correlated with Nosema infection (R = -0.3, p < 0.05). This study provides unprecedented longitudinal insights into honey bee disease dynamics in the United States, highlighting the significant emergence of EFB and Nosema as threats from 2008 to 2015 and a drastic reduction in tracheal mite prevalence. These findings underscore the need for continued monitoring and adaptive management strategies to protect honey bee health and ensure sustainable pollination services.

Female (diploid) honeybee (Apis mellifera) larvae are developmentally plastic and may become either queens or workers, depending on the nutritional stimuli received during the larval stages. Caste-specific diets activate distinct regulatory networks, leading to differential expression of coding and non-protein-coding genes, splicing variants, differences in the chromatin structures, and DNA methylation patterns, as well as variations in proteomic landscapes and the activity of key signaling pathways. Previous studies have reported the involvement of RNA epigenetics in honeybee caste fate. To further explore this and gain new insights on RNA modifications in caste diphenism, we predicted m⁶A and m⁵C RNA methylation sites in differentially expressed transcriptomes of the fourth instar larvae (L4) of queens and workers. We showed enriched functions among upregulated transcripts in L4 workers with predicted m⁶A and m⁵C sites, such as the metabolism of macromolecules and juvenile hormone synthesis. In L4 queens, these sites were predicted in upregulated transcripts that participate in mitochondrial energy metabolism, cytoskeletal organization, transport, and localization of molecules. Our findings add relevant information and novel perspectives on the potential role of the epitranscriptomic layer in the complex molecular interactions that guide the process of caste differentiation.

Urban beekeeping is common and has become a permanent part of the landscape of many cities. However, there is scarce information about the health of honey bees (Apis mellifera) from apiaries in cities. Here, we present that the living environment of bees from urban apiaries is not indifferent to their total antioxidant capacity, immune system (defensin-2), and proteostasis (Hsp70). Still, the city does not always have only negative effects. Using an experimental system of genetically related bee colonies located in urban and rural environments, we found that genetic factors, environmental factors, or both impact the levels of the analyzed stress biomarkers. The response to environmental stress in the urban and rural areas was tissue-dependent and changed during the season. Our results will be valuable in discussing bee welfare in cities.

The use of fungus-based biopesticides has grown worldwide as an effective and ecologically sustainable strategy for the control of crop pests, which in turn increases the need to investigate potential harmful effects on non-target organisms in tropical agroecosystems. However, such effects of commercial formulations based on the entomopathogenic fungus Beauveria bassiana on stingless bees, the main pollinators of a wide range of flowering crops, remains largely unexplored. Here, we tested if Boveril^®WP, a commercial bioinsecticide, affects survival, cuticular hydrocarbon profile and social recognition in the stingless bee Scaptotrigona depilis. Combining exposure assay, cuticular hydrocarbon profiling, and lure presentation, we found that this mycopesticide causes the following: (1) lethal effects when topically applied on the thorax (LT₅₀ = 30 min) or abdomen (LT₅₀ = 24 h) of foragers; (2) quantitative changes in cuticular hydrocarbon profile of foragers within 12 h, containing significantly higher proportions of three linear alkanes and one methylated alkane; (3) subtle effect on social recognition by entrance guards, with lower aggression rates toward exposed foragers (nestmates or not), which may facilitate the transmission of lethal pathogens into and among colonies. This study demonstrates the potential incompatibility of a common biopesticide with a native pollinator, thus highlighting the much-needed Integrated Pest and Pollinator Management (IPPM) approaches for the best use of ecological services provided by non-target organisms.

Heteroplasmy is characterized by different mitochondrial haplotypes within the same organism. After evidence of heteroplasmy was found in mitochondrial sequences in Tetragonisca angustula—a bee species of great economic and ecological importance—the aim of this study was to confirm the presence of heteroplasmy in the species, analyse the frequency of synonymous and non-synonymous mutations, and classify them according to their impact on the protein’s tertiary structure. For this purpose, mitochondrial DNA was isolated from nuclear DNA in two T. angustula individuals, a portion of COI was amplified by PCR from pure mitochondrial DNA, and the different mitochondrial haplotypes were recovered through vector cloning in competent bacteria. Our results confirmed the presence of 11 and 17 different mitochondrial haplotypes in the first and second samples analysed, respectively. These different mitochondrial haplotypes are characterized by the predominance of synonymous mutations or mild and moderate non-synonymous mutations, meaning they have little impact on the protein’s tertiary structure. These results strongly support the presence of heteroplasmy in T. angustula and provide some insights into its characterization and inheritance.

There are several honey bee (Apis mellifera) stocks with desirable traits that have been developed through selective breeding, but there are likely to be resultant trade-offs due to biological constraints or neutral evolution. The Russian honey bee (RHB) stock has higher resistance to Varroa mites (Varroa destructor) and tends to have more frequent brood rearing breaks relative to the common Italian honey bee (IHB) stock, which requires high levels of food consumption to sustain long brood rearing cycles. Here, we investigate how queens from the two stocks perform following prolonged nutritional stress in the form of chronic pollen deprivation and a 3-week recovery period. Overall, we find that IHB queens are heavier regardless of their nutritional treatment and that those that did not experience pollen dearth lay more eggs with a higher protein to egg weight ratio. While we cannot rule out the influence of external factors present in the colony setting such as pathogens, our findings suggest that IHB queen egg laying performance may be relatively higher when pollen resources are abundant, but at the same time, they have a higher level of sensitivity to nutritional stress. In addition, our results suggest that the more frequent brood rearing breaks exhibited by RHBs may not be due to reductions in queen egg laying in response to nutritional stress. We find that the best performing honey bee queen (RHB or IHB) is context dependent due to specific trade-offs in performance, which beekeepers may want to consider in the future for honey bee breeding and management.

The intensification of pesticide use is believed to be one of the main causes of the global decline in pollinators. The ability to forage resources effectively and return to the colony is crucial for individual eusocial bees and their colonies, and some pesticides are known to disturb this ability. Our study investigated the effects of the most widely used type of pesticide, glyphosate-based herbicides (GBHs), on the foraging and homing ability of the buff-tailed bumblebee, Bombus terrestris (L.) (Hymenoptera: Apidae). We conducted two experiments in which we exposed bees to field-realistic doses of GBH at colony and/or individual levels and observed their foraging activity and the homing ability of displaced bees. We found that 24-h colony-level GBH exposure increased the number of bumblebees’ foraging bouts, but it did not affect the duration of bouts or the homing ability. Regarding the homing rate, there was a marginally significant interaction between acute individual-level treatment and release distance from the colony. Even though the negligible impacts of short-term GBH exposure on homing ability are encouraging, the greater number of (possibly unnecessary) foraging bouts after colony-level GBH exposure might be costly for bumblebees.