Apidologie最新文献

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.

With the expansion of industrial activities, the escalation of pollution by trace metals poses an increasing threat to bees. While the effects of metals on adult bees have been extensively studied in ecotoxicological research, a critical gap persists concerning their impact on bee larvae. Here, we conducted the first study exposing bumble bee larvae to field-realistic concentrations of copper via an in vitro assay, over a span of 25 days. We monitored the duration of their developmental stages, including moments of defecation, pupation, and emergence, alongside their survival rates. Additionally, we recorded their area growth as well as their adult body mass post-emergence. Despite copper exposure exhibiting no discernible influence on the overall duration of development, survival, growth, or adult mass, a significant positive effect was observed on the pupation rate. This outcome is likely attributable to heightened copper-dependent metabolic activities and disturbances in the redox balance. Furthermore, our investigation underscored the pivotal role of initial body size in developmental success, with larger larvae showing elevated emergence and survival rates. Given the efficacy of this assay, we urge regulatory institutions responsible for approving pesticides and other xenobiotics for market use to embrace this experimental approach in future risk assessments.

Certain populations of feral or wild European Honey Bees (EHB), Apis mellifera, have developed a tolerance of or persistence against the parasitic mite Varroa destructor in the USA. Although the grooming or mite-biting behavior is a trait bees use to defend against parasitic Varroa mites, little information is available concerning the grooming or mite-biting behavior of feral EHBs. Accordingly, we observed damaged mites of feral bees in Ohio (Apis mellifera ligustica) and commercial bees in four field seasons, 2020 to 2023, as well as feral bees in Kentucky (A. mellifera mellifera) in 2023, for a total of 7494 mites. When the mite-biting behavior was compared among these three populations, feral bees of Ohio (A. m. ligustica) and Kentucky (A. m. mellifera) displayed a significantly higher percentage (22% and 27% more) than the commercial bees. To investigate the mechanism of the mite-biting behavior, we examined bee mandibles. Mandibles are the primary mouthparts and tools used to remove or amputate the Varroa mites. Gentle Africanized honey bees (gAHB, A. mellifera scutellata-hybrid) in Puerto Rican exhibit mite resistance through microevolution on the island. Asian honey bees (A. cerana) are the original natural host of V. destructor. However, little has been reported on the morphometric analysis of mandibles between the two species A. cerana and A. mellifera and between the subspecies A. m. scutellata-hybrid and A. m. ligustica. Utilizing X-ray micro-computed tomography (microCT), we then examined the three-dimensional morphology of mandibles in (1) A. cerana, (2) gAHB A. m. scutellata-hybrid, (3) Ohio feral A. m. ligustica, and (4) package or commercial colonies A. m. ligustica. Our findings revealed distinctive three-dimensional shapes of mandibles, indicating substantial variations among these populations. These variations suggest that mandible morphology has an integral role in the bee’s defensive mechanisms against parasitic mites. We also developed the first smartphone application to quantify the mite damage by applying artificial intelligence to image analysis. This research contributes valuable insights into the prospective selection and breeding of honey bees with enhanced mite resistance, thus promoting the sustainability of apiculture.

Queen health and quality play a significant role in the survival, expansion, and productivity of honey bee colonies. Nevertheless, modern beekeeping practices, intensified agriculture, and climate change can leave queens vulnerable to diverse stressors. These stressors can exert a negative impact on queens, resulting in a range of morphological and physiological abnormalities. The repercussions of queen stress may not only cause direct impacts on her survival and performance, but it may also extend to the offspring of surviving queens through transgenerational mechanisms. Here, we review the current knowledge regarding the effects of major abiotic stressors (namely, nutrition, pesticides, and extreme temperatures) on queen health and their potential impacts on the queen’s progeny. Gaining insight into the effects of these factors across individual and colony levels is vital for prioritizing further research on queen and colony health.

Increased temperature variability and extreme weather events associated with climate change can be detrimental to bees and lead to their population declines. While there is some research on the effects of heatwaves on insect biology and reproduction, impacts on male insect reproduction are not well described. Solitary bees may be more exposed to temperature variation than social bees, since there is no mitigation by group thermoregulation. Here, we evaluated the effects of sublethal heat exposure (at 30 °C and 38 °C) on reproductive fitness of adult males of a solitary bee species, Osmia cornifrons. After 4 h of heat exposure, bees were maintained at 24 °C for 48 h in laboratory cages to reach sexual maturity and later analyzed for sperm abundance (quantity) and proportion of viable sperm (quality). Bees that were reared and maintained at 24 °C served as controls. Despite rehabilitation after heat exposure, both sperm quantity and quality of male O. cornifrons bees were significantly reduced in heat-treated groups compared to controls. These results demonstrate that the exposure to elevated non-lethal temperatures, even for short periods and allowing time for recovery, may negatively affect the reproductive capacity of male solitary bees. Our findings reveal a possible mechanistic explanation for wild bee population declines. Given the importance of solitary bee species (such as O. cornifrons) in natural and agricultural landscapes, our study provides valuable insights into the potential consequences of climate change on these insect populations and the ecosystems they inhabit.

Insects rely on chemical information from the environment to survive. The reception of this information mainly occurs through the antennae, when the stimuli contact the sensory receptors located within specialized structures named sensilla. Some bee species present a different number of olfactory sensilla on both antennae and dissimilar responses, denoting olfactory lateralization evidenced by asymmetrical learning abilities. Here, we studied the antennae sensilla pattern and antennal odor detection in the bumblebee Bombus pauloensis, to evaluate olfactory lateralization. By scanning electron microscopy, we quantified and identified antennae sensilla types, and, by electroantennography, we recorded the responses to odors with different hedonic values. We found nine types of sensilla, being the trichodea the most prevalent type. Neither the number of sensilla nor the olfactory responses were different between the left and right antennae. Our findings suggest the absence of olfactory lateralization in B. pauloensis, providing new insights into the complexity of the bee olfactory system and shedding light on the biology of this commercially important bumblebee species, widely employed for crop pollination services.

Since the rapid spread and establishment of Africanized honey bee populations in South America, Africanized bees have persisted as the dominant strain. Remarkably, Chile has remained free of Africanized bee populations, making the country a valuable exporter of mated queens. Given Chile’s pivotal role in the apiculture industry, monitoring the genetic makeup of its honey bee colonies is crucial, yet documentation has been limited to a few studies. Here, we evaluate the ancestral composition of honey bees across eleven different regions in Chile. We find that Chilean honey bees have low levels of admixture, which is markedly lower relative to commercial colonies located internationally. The genetic ancestry of Chilean honey bees is primarily of Eastern European origin, with low levels of Western European ancestry. Finally, we detect a significant relationship between geography and genetic ancestry, suggesting regional adaptations that warrant further investigation.