Search Results (450)

Honeybees (Apis mellifera) are pollinators for most crops in nature and a core species for the production of bee products. Body size and body weight are crucial breeding traits, as colonies possessing individuals with large body weight tend to be healthier and exhibit high productivity. In this study, small interfering RNA (siRNA) targeting 15-Hydroxyprostaglandin dehydrogenase (15-PGDH) was incorporated into the feed for feeding worker bee larvae, thereby achieving the silencing of this gene’s expression. The research further analyzed the impact of the RNA expression level of the 15-PGDH gene on the juvenile hormone (JH) titer and its subsequent effects on the body weight and size of worker bees. The results show that inhibiting the expression of 15-PGDH in larvae could significantly increase JH titer, which in turn led to an increase in the body weight of worker bees (1.13-fold higher than that of the control group reared under normal conditions (CK group); p < 0.01; SE: 7.85) and a significant extension in femur (1.08-fold longer than that of the CK group; p < 0.01; SE: 0.18). This study confirms that 15-PGDH can serve as a molecular marker related to body weight and size in honey bees, providing an important basis for molecular marker-assisted selection in honey bee breeding. Full article

The morphological diversity of Moroccan honey bees (Apis mellifera) was investigated using geometric morphometrics to assess wing venation patterns among three populations representing three climatic zones: desert, semiarid, and Mediterranean. A total of 193 honey bee samples were analyzed and compared to historical reference samples from the Morphometric Bee Data Bank in Oberursel, representing the three subspecies: A. m. intermissa, A. m. sahariensis, and A. m. major. Principal component analysis and linear discriminant analysis revealed significant, yet overlapping morphological differences among the climatic groups. Spatial modeling showed a significant southwest–northeast clinal gradient in wing morphology. Almost all samples were assigned to the African evolutionary lineage, except one, suggesting a dominant African genetic background. Interestingly, all three populations showed greater morphological affinity to A. m. intermissa than to A. m. sahariensis, which could indicate introgression or limitations in the current reference dataset. These discrepancies highlight the necessity of revising subspecies boundaries using updated morphometric and genomic approaches. These findings improve our understanding of honey bee biodiversity in Morocco and provide valuable information for conservation and breeding programs. Full article

Crop fidelity is a desirable trait for managed pollinators and is influenced by factors like competing forage sources and colony knowledge of the surrounding environment. In European honey bees (Apis mellifera L.), colonies deployed when the crop is flowering display the highest fidelity. We tested for a similar outcome using a stingless bee species that is being increasingly used as a managed pollinator in Australian macadamia orchards. We observed Tetragonula carbonaria (Smith) colonies deployed in macadamia orchards at three time points: (1) before crop flowering (“permanent”), (2) early flowering (“early”), and (3) later in the flowering period (“later”). We captured returning pollen foragers weekly and estimated crop fidelity from the proportion of macadamia pollen they collected, using light microscopy. Pollen foraging activity was also assessed via weekly hive entrance filming. The early and later introduced colonies initially exhibited high fidelity, collecting more macadamia pollen than the permanent colonies. In most cases, the permanent colonies were already collecting diverse pollen species from the local environment and took longer to shift over to macadamia. Pollen diversity increased over time in all colonies, which was associated with an increase in the proportion of pollen foragers. Our results indicate that stingless bees can initially prioritize a mass-flowering crop, even when flowering levels are low, but that they subsequently reduce fidelity over time. Our findings will inform pollinator management strategies to help growers maximize returns from pollinator-dependent crops like macadamia. Full article

The European honey bee (Apis mellifera) significantly contributes to Australian agriculture, especially in honey production and the pollination of key crops. However, managed bee populations are declining due to pathogens, agrochemicals, poor forage, climate change, and habitat loss. Major threats include bacteria, fungi, mites, and pests. With the increasing demand for pollination and the movement of bee colonies, monitoring these threats is essential. It has been demonstrated that honey constitutes an easily accessible source of environmental DNA. Environmental DNA in honey comes from all organisms that either directly or indirectly aid in its production and those within the hive environments. In this study, we extracted eDNA from 135 honey samples and tested for the presence of DNA for seven key honey bee pathogens and pests—Paenibacillus larvae, Melissococcus plutonius (bacterial pathogens), Nosema apis, Nosema ceranae (microsporidian fungi), Ascosphaera apis (fungal pathogen), Aethina tumida, and Galleria mellonella (arthropod pests) by using end-point singleplex and multiplex PCR assays. N. ceranae emerged as the most prevalent pathogen, present in 57% of the samples. This was followed by the pests A. tumida (40%) and G. mellonella (37%), and the pathogens P. larvae (21%), N. apis (19%), and M. plutonius (18%). A. apis was detected in a smaller proportion of the samples, with a prevalence of 5%. Additionally, 19% of the samples tested negative for all pathogens and pests analysed. The data outlines essential information about the prevalence of significant arthropod, fungal, and bacterial pathogens and pests affecting honey bees in Australia, which is crucial for protecting the nation’s beekeeping industry. Full article

Honey bees (Apis mellifera ligustica) are essential pollinators in both ecosystems and agricultural production. However, their populations are declining due to various factors, including pesticide exposure. Despite their importance, the reproductive castes, particularly drones, remain understudied in terms of pesticide effects. To investigate the effects of azoxystrobin and picoxystrobin on honey bee drones, the drones were exposed to different concentrations of azoxystrobin and picoxystrobin for 14 days; the drone survival, body weight, nutrient content, reproductive organs, and sperm concentration were assessed. Results showed that exposure to both fungicides caused a significant reduction in drone survival rates, with survival rates decreasing progressively as the duration of exposure increased. Compared to the control group, the body weights of drones in all treatment groups were significantly lower on days 7 and 14. Nutrient analysis revealed that low concentrations of azoxystrobin and picoxystrobin increased protein levels, while free fatty acid content decreased significantly in all treatment groups. No significant changes were observed in the total carbohydrate content. Morphological examination of reproductive organs showed that the lengths of the mucus glands and seminal vesicles in drones were significantly shorter in the treatment groups compared to the control group. Furthermore, exposure to azoxystrobin and picoxystrobin resulted in a significant decline in sperm concentration in the drones. These findings indicate that azoxystrobin and picoxystrobin have adverse effects on the health and reproductive capacity of honey bee drones. The present study highlights the need to reassess the risks posed by these fungicides to pollinators, particularly given the critical role of drones in maintaining the genetic diversity and resilience of honey bee colonies. Further research is warranted to elucidate the underlying mechanisms of these effects and explore potential mitigation strategies. Full article

Effective control of the parasitic mite Varroa destructor in honey bee (Apis mellifera) colonies relies on integrated pest management (IPM) strategies to prevent mite populations from reaching economic injury levels. Formulations of oxalic acid combined with glycerin may provide a viable summer treatment option in continental Northern climates. This study evaluated the efficacy of oxalic acid and glycerin strips compared to oxalic acid dribble and 65% formic acid when applied in mid-August. Mite levels and colony health parameters were assessed, and honey samples from oxalic acid-treated colonies were analyzed for residue levels. Results showed that the oxalic acid and glycerin strips had a moderate acaricidal efficacy (55.8 ± 3.2%), which was significantly higher than those of 65% formic acid (42.6 ± 3.2%) and oxalic acid dribble (39.5 ± 4.3%), which did not differ between them, suggesting potential for summer mite control. No significant adverse effects on cluster size, worker mortality, queen status, or colony survival were observed. Oxalic acid and glycerin increased the proportion of spotty brood patterns at early timepoints after treatment, but recovery was noted after 45 days of starting the treatment. Similar effects on brood were observed with 65% formic acid 14 days after starting the treatment, with recovery by 28 and 45 days after starting the treatment. No significant differences in oxalic acid residues in honey from the control and treatment colonies were found. Oxalic acid and glycerin strips might help control varroa mite populations, delaying their exponential growth and helping reduce economic losses for beekeepers, but this treatment should be considered as part of an IPM strategy and not a stand-alone method for V. destructor control. Full article

Honey bees (Apis mellifera) are major pollinators, playing a critical role in global food production, biodiversity, and ecosystem stability. However, their populations are increasingly threatened by multiple interacting stressors, including pesticide exposure. Among these, agricultural insecticides and anti-Varroa acaricides such as dinotefuran and amitraz can persist in hive matrices, resulting in chronic and combined exposure. This study investigates the low lethal (LC₁₀ and LC₃₀) effects of these compounds, individually and in combination, on honey bee survival, immune function, oxidative stress responses, detoxification pathways, and hypopharyngeal gland morphology. Both pesticides negatively affected honey bee health at low lethal concentrations, with dinotefuran showing higher toxicity. Exposure led to the reduced survival, suppression of vitellogenin expression, and dysregulation of genes related to antioxidant defense, immunity, and detoxification. Additionally, high concentrations of dinotefuran and its combination with amitraz impaired hypopharyngeal gland morphology. Notably, co-exposure resulted in synergistic toxic effects, exacerbating physiological damage beyond individual treatments. These findings emphasize the potential risks of combined exposure to agricultural and beekeeping pesticides. A more comprehensive risk assessment and stricter regulations are urgently needed. Full article

We explored the stationarity, trend, and seasonality of the hive weight and in-hive temperature of ten managed honey bee (Apis mellifera) colonies at a research apiary of the Carl Hayden Bee Research Center in Tucson, Arizona, USA. The hives were monitored with electronic scales and in-hive temperature sensors from June to October 2022. The weight and temperature were recorded every five minutes around the clock. The collected data were curated into 2160 timestamped weight and 2160 timestamped temperature observations. We performed a systematic autoregressive integrated moving average (ARIMA) time series analysis to answer three fundamental questions: (a) Does seasonality matter in the ARIMA forecasting of hive weight and in-hive temperature? (b) To what extent do the best forecasters of one hive generalize to other hives? and (c) Which time series type (i.e., hive weight or in-hive temperature) is better predictable? Our principal findings were as follows: (1) The hive weight and in-hive temperature series were not white noise, were not normally distributed, and, for most hives, were not difference- or trend-stationary; (2) Seasonality matters, in that seasonal ARIMA (SARIMA) forecasters outperformed their ARIMA counterparts on the curated dataset; (3) The best hive weight and in-hive temperature forecasters of the ten monitored colonies appeared to be colony-specific; (4) The accuracy of the hive weight forecasts was consistently higher than that of the in-hive temperature forecasts; (5) The weight and temperature forecasts exhibited common qualitative patterns. Full article

Bee pollen’s aroma combined with other floral components serve various purposes, including attracting pollinators and signaling the availability of food sources. The present study aimed to comparatively analyze the volatile profiles of unifloral pollen taxa. Bee pollen loads were collected using pollen traps and sorted based on their botanical origin, determined by color and pollen grain morphology. The separated pollen samples were analyzed using a Purge & Trap/GC-MS system, identifying the volatile profiles of pollen from 16 plant species. The analysis revealed distinguished differences in the total volatile organic compounds (VOCs) among the various pollen species. Notably, the pollen from Erica manipuliflora, Papaver rhoeas, and Sisymbrium irio contained the highest number of VOCs, with 54, 51, and 42 substances detected, respectively. Certain volatile compounds appeared to correlate with increased bee visitation. For instance, 4-methyl-5-nonanone was uniquely found in E. manipuliflora pollen, while isothiocyanate compounds were exclusively present in species of the Brassicaceae family. Therefore, given the significant impact of VOCs on honey bees’ preferences, it is essential to consider not only the nutritional value of bee pollen when evaluating its beekeeping value, but also its aroma profile. Full article

One of the common causes of mass death in bee colonies is the infectious disease nosemosis, which is caused by two types of microsporidia, Nosema apis and Nosema ceranae. Of the many factors contributing to the spread of nosemosis, in this paper we consider the hybridization of subspecies of Apis mellifera L. In most of Russia, the native subspecies is the dark forest bee Apis mellifera mellifera, which is representative of the evolutionary lineage M. The export of bee packages and queens from the southern regions of Russia and other countries has led to the fragmentation of the range of these subspecies. First, we determined the maternal and paternal ancestry of 349 honey bee colonies across 12 beekeeping regions of Russia using the mitochondrial tRNAleu-COII locus and nine nuclear SSR markers (Ap243, 4a110, A024, A008, A43, A113, A088, Ap049, and A028). Among them, 140 colonies belonged to subspecies A. m. mellifera, 58 colonies were of hybrid origin, and 151 colonies belonged to evolutionary lineage C. Then, using microscopy and PCR analysis, we performed diagnostics of nosemosis in the studied colonies: N. apis was detected in 87 colonies, N. ceranae in 102 colonies, and coinfection was observed in 36 colonies. The results of our study indicate that the main reservoir of Nosema microsporidia was bees of evolutionary lineage C. Full article

Honey is a sugar-rich product produced by Apis mellifera bees, with significant variability in properties due to the influence of geographic and climatic conditions and the predominant flora in the production region. Economically, beekeeping is an activity that generates profit and fulfills environmental and social functions, reinforcing the pillars of sustainability. This study aimed to characterize samples of honey sold in southern Brazil, including physicochemical analyses, the detection of microbiological contaminants with potential impact on human health, and the detailed identification of bacterial composition through the Next-Generation Sequencing (NGS). The present study was divided into five main stages: (1) sample collection; (2) sample fractionation; (3) physicochemical analysis; (4) microbiological analysis; (5) 16S metataxonomy analysis. The physicochemical analyses agreed with the regulated values, indicating the good quality of the honey and the absence of adulteration. The microbiological analyses indicated the absence of Salmonella spp., in addition to a low count of total coliforms. The limits for molds and yeasts were exceeded in three samples, indicating non-compliance with current MERCOSUR legislation. Metabarcoding analysis identified a total of 15,736 OTUs divided into three different genera: Bacillus (41.54%), Lysinnibacillus, and Rossellomorea, all belonging to the Bacillaceae family. Some pathogenic species were identified, namely the Bacillus cereus group and Bacillus pumilus. Our results point to an increased need for surveillance, as honey contamination can lead to public health problems, requiring improvements in legislation and control parameters. Full article

The enzymes in honey can originate not only from bees and the plants from which the bees collect pollen and nectar but also from feed provided by beekeepers. Enzymes that hydrolyze sucrose—present in honey (α-glucosidase) or honey adulterated with invert syrup (β-fructofuranosidase)—can be distinguished using zymography, where enzymatic bands are detected with nitroblue tetrazolium (NBT) after sugar removal via ultrafiltration. This method enables the identification of honey produced in hives that have been improperly fed with invert syrup, leading to the mixture of natural honey and syrup, and offers a practical tool to detect indirect adulteration. The NBT assay, in combination with ultrafiltration, was used to determine the isoelectric point of honey bee α-glucosidases. The pI value of 6.63 for isoforms found in the head, midgut, and natural honey extracts during winter can be attributed to α-glucosidase III. Two additional isoforms with isoelectric points of 5.20 and 5.77 were observed in the midgut extract and may correspond to α-glucosidase I and II. The difference between α-glucosidase and β-fructofuranosidase was confirmed using a substrate specificity test, followed by thin-layer chromatography, where it was confirmed that α-glucosidase from natural honey, bee head, and bee midgut does not hydrolyze raffinose, in contrast to yeast β-fructofuranosidase. Full article

This study evaluated immune gene expression and locomotor behavior across five Apis mellifera subspecies (Carniolan, Caucasian, Syrian, Muğla ecotype, and Yığılca ecotype) following controlled Vairimorpha ceranae infection. Six days post-infection, Caucasian, Carniolan, and Yığılca bees exhibited a significant upregulation of antimicrobial peptide (AMP) transcripts—hymenoptaecin, abaecin, defensin, and apidaecin—indicating a robust humoral response. Conversely, Syrian and Muğla bees showed weaker AMP expression and higher V. ceranae mRNA levels, indicating lower immunity and higher susceptibility. Positive correlations among AMP transcripts, especially in Caucasian, Carniolan, and Yığılca bees, suggested a coordinated response. Eater gene expression, critical for cellular immunity, decreased in infected Caucasian and Yığılca bees, coinciding with AMP upregulation. Vitellogenin expression, linked to immunity and longevity, increased in Carniolan and Syrian bees, correlating with higher early locomotor activity. Locomotor analysis revealed subspecies-specific behavioral responses. Syrian bees maintained the highest activity despite elevated V. ceranae mRNA and minimal AMP expression, suggesting unique resilience possibly mediated by vitellogenin. Muğla bees, despite high pathogen loads, exhibited decreased activity. Caucasian bees showed strong immune responses but reduced activity post-infection, reflecting potential physiological trade-offs. Overall, these findings underscore the role of genetic variability in shaping honey bee immune and behavioral responses to Vairimorpha and support subspecies-targeted breeding and disease management strategies to enhance resilience. Full article

Alfalfa (Medicago sativa) is an important fodder crop with 16–25% protein and 20–30% fibre content. It requires pollinators for seed development through a process known as “tripping”. Honey bees are preferred for their easy management and mass rearing to enhance pollination. In a field experiment, we tested three treatments: two honey bee colonies (moderately supplemented), three honey bee colonies (highly supplemented), and a control with no honey bee colonies. The colonies European honey bee, A. mellifera, were used, starting at the flowering stage. We assessed the abundance, foraging, and tripping behaviour of pollinators, as well as the number of seeds per pod, pod weight, and seed weight. Honey bees were the most abundant in supplemented plots, followed by solitary bees, with increased honey bee visitation in the second year. Megachile cephalotes, M. hera, and A. mellifera were the most efficient pollinators regarding seeds per pod and seed weight. The plot with two honey bee colonies had a higher seed yield than the one with three colonies. Conservation of these pollinators and the introduction of managed A. mellifera colonies can lead to sustainable alfalfa seed production. Our findings suggest that honey bee supplementation, along with conservation efforts for solitary bees, can enhance pollination and seed yield in alfalfa. Full article

Honey bees are one of the most significant pollinators and contribute to the pollination of various crops. The honey bee, Apis mellifera (Linnaeus, 1758), has unique characteristics that could be successfully used to improve biomonitoring approaches in assessing environmental interactions. Three apiaries with different rates of honey bee colony losses were included in the study—Dimovtsi, Plovdiv, and Krasnovo, Bulgaria. Male individuals (immature and mature) were collected from five colonies for each of the three apiaries and studied for histopathological changes in the gonads. The results concerning the rate of honey bee colony losses in the studied apiaries from 2022 and 2023 showed honey bee losses in the tested colonies due to queen problems, which were reported for Plovdiv, as well as the death of honey bees or a reduction in their number to a few hundred bees in the colony. The chemical analysis showed the presence of different organic substances, such as Coumaphos, DEET (N, N-diethyl-M-toluamide), Fluvalinate, and Piperonyl-butoxide, in the alive and dead honey bee samples and those of food stocks (wax, pollen, and honey) within the hives. Among the sample types, those of the dead honey bees contained the greatest variety of pesticide residues, particularly in Plovdiv and Dimovtsi, reinforcing the link between pesticide exposure and honey bee mortality. The histopathological alterations were mainly associated with the thinning of the covering epithelium of the seminiferous tubules and the detachment of the basement membrane of the seminiferous tubules. The more severe histopathological lesion, necrosis, was observed in a higher degree of expression in the drones from Plovdiv, indicating a higher pollution level in this region. Full article