Search Results (220)

Honey bee colonies play a vital role in ecosystem stability and global food security. Together with bumble bees and other wild bee species, they form a diverse pollinator community that is particularly vulnerable to environmental pollution. Among stressors, environmental xenobiotics including heavy metals, metalloids, pesticides, polycyclic aromatic hydrocarbons, per- and polyfluoroalkyl substances, and emerging contaminants such as microplastics pose a growing concern due to their persistence, bioaccumulation potential and capacity to trigger oxidative stress and interact with pathogens, nutritional stress and climate-related extremes. The antioxidant defense system, encompassing enzymatic components (superoxide dismutase, catalase, glutathione-dependent enzymes and glutathione-S-transferase) and non-enzymatic antioxidants, represents a key protective mechanism, and its disruption leads to redox imbalance, immunosuppression, and behavioral alterations that can reduce honey bee colony vitality. This review synthesizes current knowledge on the sources, exposure pathways and toxicological effects of major environmental xenobiotics on the antioxidant defense systems of honey bees, with particular emphasis on oxidative-stress biomarkers for early detection of sublethal impairment in field and experimental settings. Where available, evidence from bumble bees and other wild bees is considered to place findings in a broader pollinator-health context and to highlight taxa-specific sensitivities. Work should now concentrate on a validated core panel of redox biomarkers, on chronic multi-stressor exposures that include PFAS and plastic particles, and on biomarker baselines for bumble bees and solitary bees tied to colony- or population-level endpoints. Full article

Pollinators, particularly bees, are essential for the reproduction of flowering plants, including ornamentals, and for maintaining ecosystem balance, benefitting gardens by supporting plant health and promoting robust flowering. However, pollinator populations are declining, with pesticide exposure recognized as one of several contributing stressors. Thiamethoxam, a commonly used systemic insecticide in ornamental horticulture (and its toxic metabolite clothianidin), has been found in nectar resources at levels harmful to bees. This study evaluated the impact of different thiamethoxam application rates on pollen contamination in blanket flower (Gaillardia pulchella L.), a popular source of pollen for bee pollinators. Container plants were drench-treated with low (0.30 g/L) and high (0.64 g/L) rates of thiamethoxam during the mature floral bud stage. The results show that thiamethoxam and clothianidin were present in pollen at both application rates. However, only clothianidin levels significantly increased with the application rate (p = 0.0009). When the pesticide concentrations measured in pollen were used to calculate the estimated exposure doses based on pollen consumption, the values exceeded published median lethal doses (LD50) for the common eastern bumble bee (Bombus impatiens Cresson) and buff-tailed bumble bee (Bombus terrestris L.), indicating substantial ecological risk. These findings underscore the potential threat posed to some pollinator species by thiamethoxam-treated ornamentals. Full article

Honey bee (Apis mellifera) colonies are exposed to multiple environmental stressors, including pesticide contamination and landscape changes, which may affect colony dynamics and colony condition. This study evaluated pesticide residue occurrence, landscape quality through the Agroecosystem Apibotanical Interest Index (AABI), and colony demographic structure across five contrasting agricultural systems in Uruguay using a comparative case-study approach. Pesticide residues were analyzed in multiple hive matrices, and residue occurrence was assessed using cumulative hazard quotients (HQ). Colony dynamics were characterized using population variables and the adult-to-brood ratio, associations were evaluated with generalized linear models. Pesticide diversity and cumulative HQ values were higher in intensively managed landscapes, particularly in horticultural and soybean systems, whereas forestry systems showed consistently low values. Residues were detected in all matrices, with greater diversity in wax and bee bread. Colony dynamics varied among landscapes, with more stable patterns in native forest systems. Demographic states based on the adult-to-brood ratio were consistently associated with colony demographic structure. We identified a significant negative statistical association between AABI and the demographic state defined by the adult-to-brood ratio, whereas cumulative HQ showed only marginal effects. Given the observational nature of the study and the multifactorial determinants of colony dynamics, this relationship should be interpreted as an observed pattern within the studied dataset rather than evidence of a direct biological effect of landscape quality on colony adult-to-brood ratio. Overall, the results suggest associations between environmental conditions and colony adult-to-brood ratio. Full article

Pollinators play a critical role in agricultural productivity and the maintenance of flowering plant diversity, yet their health is increasingly threatened by multiple environmental stressors. While research has traditionally focused on pathogens, pesticides, habitat loss, and nutritional limitation, fungal secondary metabolites, mycotoxins, remain an underappreciated risk factor. This review synthesizes current knowledge on the presence, exposure pathways, and biological impacts of key mycotoxins, including aflatoxin B1, ochratoxin A, deoxynivalenol, zearalenone, and T-2 toxin, in bee-collected pollen and bee bread. We discuss how contaminated food matrices act as reservoirs of chronic exposure, linking forager activity, nurse bee physiology, brood development, and colony-level outcomes. Evidence from laboratory studies highlights sublethal effects on survival, hypopharyngeal gland development, immunity, and gut microbiota, with potential interactions with pathogens, nutritional stress, pesticides, and climate change. Furthermore, we extend these insights to wild pollinators, emphasizing differences in colony size, diet breadth, and detoxification capacity. Analytical methods for detecting mycotoxins, including HPLC, LC-MS/MS, and ELISA, are evaluated in terms of sensitivity, specificity, and relevance to field exposure. By integrating environmental concentrations with laboratory toxicity thresholds, this review identifies critical knowledge gaps and proposes a mechanistic framework linking mycotoxin exposure to colony-level risk. The findings underscore the need for targeted monitoring, improved risk assessment, and multi-stressor evaluation to safeguard both managed and wild pollinator populations. Full article

Botanical insecticides have re-emerged as promising tools within Integrated Pest Management (IPM) due to their biodegradability, chemical diversity, and potential compatibility with resistance management strategies. Although frequently considered safer alternatives to synthetic pesticides, growing evidence indicates that these compounds may also affect non-target organisms, particularly bees. This review discusses the selectivity of botanical insecticides toward pollinators by integrating historical perspectives, mechanisms of action, ecotoxicological effects, and current limitations in risk assessment approaches. Botanical insecticides may induce both lethal and sublethal effects, including alterations in behavior, locomotion, feeding, development, reproduction, and physiology across different bee groups. We also demonstrate that most available studies remain concentrated on Apis mellifera, adult workers, and acute laboratory assays, while important pollinator groups and chronic exposure scenarios remain poorly explored. Furthermore, current regulatory protocols are still largely based on models developed for synthetic pesticides. Expanding ecotoxicological approaches is therefore essential to improve pollinator safety assessments and support more sustainable pest management strategies. Full article

As the only reproductive female in the colony, the honey bee queen (Apis mellifera) is essential to colony survival, productivity, and the sustainability of pollination services that underpin food security and global agriculture. The biological, physiological, molecular, and commercial elements that affect queen fertility throughout the commercial lifecycle, from mating and development to sperm storage, banking, transportation, and colony establishment, are examined in this review. According to available data, successful queen reproduction depends on effective mating, long-term sperm viability in the spermatheca, stable hormonal regulation, and adequate nutritional and environmental support. However, a number of interrelated stressors, including temperature changes during storage and transportation, confinement, inadequate nutrition, pesticides, pathogens, parasites, and climate-related pressures, can reduce sperm viability, impair ovarian function, and increase colony losses. Precision apiculture, cryopreservation, instrumental insemination, and omics-based biomarkers are examples of emerging technologies that offer promising techniques to enhance queen resilience and commercial management. However, there are still significant information gaps, especially in the areas of integrated multi-omics techniques across the commercial lifespan and standardized queen-quality evaluation. Future advancements are needed to preserve queen fertility and protect pollination services. This will require integrating reproductive physiology, biotechnology, and commercial management to build climate-resilient, biosecure, and sustainable systems. Full article

Honey bees are constantly exposed to various environmental threats, among which pesticide pollution, including fungicides, is one of the most serious. The bees were 3 days old when they received the experimental solution. This study aimed to evaluate the behavior and mortality of honey bee workers exposed to a commercial formulation of the fungicide tebuconazole (Tebu^® EW, a.i. 25.8%; HELM, Hamburg, Germany). The experiment was conducted under laboratory conditions and lasted 7 days for all experimental groups. The fungicide solution was prepared by adding 6.25 mL of Tebu^® EW per 1 L of water, corresponding to 156.25 mg of tebuconazole (active ingredient) in the prepared solution of sugar syrup. The solution was served in 5 mL dispensers (=group feeding) placed in the cages. This concentration was used for the acute-exposure group (24 h). After 24 h bees were supplied with untreated sugar syrup for the remainder of the experiment. For the chronic-exposure group (168 h), the solution was a 1000-fold dilution of the acute solution, containing 0.15625 mg tebuconazole, dissolved in sugar syrup, provided continuously for 7 days with daily replacement. After 7 days, bee behavior was recorded using a camera and analyzed with Noldus Observer XT software (12.5: Windows 7 64-bit (SP1) version) Five basic honey bee behaviors were examined: walking, flight, self-grooming, contact between individuals and stillness. The results showed statistically significant differences between the experimental groups and the control group (α = 0.05) in the duration of walking, contact between individuals and self-grooming, and the frequency of walking and flight. This was particularly evident for self-grooming; the longer the group was exposed to tebuconazole, the less time the bees spent on this behavior (the acute group spent 47% less time self-grooming and the chronic group spent 88.8% less time self-grooming compared to the control group). Meanwhile, the frequency of walking and flying increased significantly with increasing exposure. No significant differences were observed in the survival between the groups. Based on these findings, it can be concluded that the fungicide containing tebuconazole significantly affects the behavior of honey bee workers. Full article

Hops (Humulus lupulus L.) is a plant species with a multitude of uses in medicine, food science and agriculture. Xanthohumol, the major prenylflavonoid in hop cone extract, possesses anti-cancer activity. Xanthohumol also exhibits strong antimicrobial activity against Gram-positive bacteria (e.g., S. aureus), but not against Gram-negative bacteria. Xanthohumol can reduce blood glucose levels and body fat in obese male rats (not females), and mature hop bitter acids (MHBAs) have been found to decrease visceral and abdominal human fat. Xanthohumol can increase bone mineral density, decrease osteoclast numbers, and protect osteoblasts from oxidative stress in osteoporotic mice. Further clinical research, xanthohumol and bitter acids could be sourced from hop cone extracts to formulate novel drugs that can successfully treat a variety of diseases and potentially replace current therapies that have negative effects. In the food industry, hop cone extracts are mainly used in the brewing industry, with 98% of the world’s hop cones being used in brewing beer. Hop cone extracts are also used as food/drink preservatives due to their antimicrobial abilities, as previously mentioned, although there is less of a need for hops in extending food/drink shelf-life. Finally, hop cone extracts have several uses in agriculture, mainly as pesticides. For example, hop extracts can kill varroa mites, a parasite that impairs honeybee health. This benefits honeybee farmers as increased bee survival means more honey production, increasing profits. Overall, this review paper brings together recent studies that highlight hop extracts as valuable bioactive compound mixtures with many useful applications. Full article

Honey bees rely on a specialized gut microbiota for nutrition, detoxification, and immune function, yet the effects of emerging insecticides on this symbiotic system remain poorly understood. We compared the acute toxicity and short-term gut microbiota responses of Apis mellifera ligustica workers exposed to two insecticides with contrasting toxicity classes: the highly toxic emamectin benzoate-lufenuron (EB-LFR) and the low-toxicity ecdysone agonist RH-5849. EB-LFR was associated with observed reductions in core gut symbionts (Gilliamella, Snodgrassella, Lactobacillus), a transient increase in Bifidobacterium, and the detection of opportunistic taxa such as Serratia marcescens and Enterobacter hormaechei. In contrast, RH-5849 was associated with broad reductions in beneficial bacteria without detectable pathogen emergence, suggesting a more moderate alteration of microbiota composition. Because microbiota analyses were based on single pooled samples per treatment, these results represent exploratory, qualitative insights into early microbial responses. Together with acute toxicity data, the findings suggest that insecticides with contrasting toxicity classes may differentially affect gut microbiota composition in honey bees and highlight the value of incorporating gut microbiota endpoints into pesticide risk-assessment frameworks to better anticipate sublethal effects on pollinator health. Full article

Brazil hosts the world’s greatest stingless bee diversity but remains a leading pesticide consumer. This study evaluated the effects of thiamethoxam on Melipona scutellaris (Apidae) and Scaptotrigona postica (Apidae) larvae using standardized in vitro protocols and patented biomimetic technologies. Larvae were exposed to a field-realistic dose (RD) of 0.02292 ng a.i./larva—calculated using the BeeRex model for citrus crops—and two lower doses: RD/10 and RD/100. Thiamethoxam exposure resulted in significant mortality and developmental alterations, even at 100-fold dilutions. In M. scutellaris, mortality was dose-dependent; RD and RD/10 induced body malformation and reduced food consumption, resulting in >98% mortality. At RD/100, surviving individuals showed significant reductions in body size. In S. postica, all tested doses induced larval darkening and accelerated fungal growth, leading to 100% mortality during the feeding period, including at RD/100. This pattern contrasts with the greater tolerance reported for the adult stage of this species. Overall, the results suggest that larval stages may be more sensitive to thiamethoxam exposure than adults, highlighting the importance of considering different life stages in pesticide risk assessment. These findings also emphasize the need for validated experimental approaches to support environmental risk evaluation for Neotropical pollinators. Full article

Despite the undisputable ecosystem importance of honeybees, human activities have a substantial impact on their health. Since foraging is directly linked to a wide range of crops and bee-attracting flowers, plant protection products are at the forefront of chemical scrutiny, along with contamination of pollen, nectar, beehive components and water by other xenobiotics. In this study, a non-targeted Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS) screening was applied to 25 honeybee samples collected after reported death incidents in Greece. This approach led to the tentative annotation of over 50 compounds across various chemical classes, including pesticides, PFAS candidates not included in the EFSA “PFAS-4”, pharmaceuticals, antibiotics, industrial chemicals, and natural product constituents. In parallel, targeted pesticide residue analysis using liquid and gas chromatography coupled to tandem mass spectrometry (LC-MS/MS and GC-MS/MS) was performed, covering more than 250 active substances and providing direct quantitative results, revealing 11 active substances in concentrations ranging from <limit of quantification (LOQ) to 0.95 mg/kg, overlapping substantially with the HRMS detection. Overall, this study does not allow concrete causal attribution of mortality to specific chemicals; however, it documents complex co-occurrence patterns (pesticides together with other xenobiotics and plant bioactives), not excluding sublethal and mixture-toxicity effects. Quantified pesticide concentrations were below acute LD50-based thresholds, yet selected samples combined neonicotinoid/pyrethroid/fungicide signatures and other contaminants, supporting the need for mixture-toxicity frameworks and effect-based follow-ups. Full article

As the predominant native pollinator across Asia, Apis cerana is essential for the maintenance of biodiversity and agricultural productivity. The gut microbiota of honeybees plays a central role in host nutrition, detoxification, and immune function. p-Coumaric acid, a widespread phenolic acid enriched in pollen and nectar, has been reported to promote honeybee health by prolonging lifespan and increasing the expression of detoxification-related genes, hence improving tolerance to pesticides. Its influence on gut microbial communities, however, remains insufficiently characterized in A. cerana. This study evaluated the effects of dietary p-coumaric acid on survival, sucrose solution consumption, and gut microbiome composition in A. cerana workers using absolute quantification sequencing. Bees were provided sucrose solutions containing p-coumaric acid at concentrations of 41.0, 82.0, and 164.0 mg/L for durations of 5 and 10 days. The results indicated no effect on survival but revealed time-dependent changes in sucrose solution consumption. p-Coumaric acid exposure altered the abundance of non-core bacterial taxa, including Bombella and Apilactobacillus, whereas the core gut microbiota (Lactobacillus, Gilliamella, Snodgrassella, Apibacter, and Bifidobacterium) remained stable. These results suggest that p-coumaric acid modulates sucrose solution consumption and selectively influences non-core gut bacteria without disrupting survival or core microbiota stability, underscoring its role in regulating host–microbe interactions in honeybees. Full article

Neonicotinoids are widely used pesticides that have caused a catastrophic decrease in bee and bumblebee populations worldwide. In addition to insects, neonicotinoids induce toxic effects in other species, including lizards, birds, and mammals. Previous studies have shown that gestational exposure to thiacloprid promotes transgenerational effects in the testes and thyroid. In this project, we described the epigenetic effects of thiacloprid on prostate tissue in directly exposed F1 and non-directly exposed F3 outbred Swiss male mice. We used paraffin sections for morphological analysis and frozen tissue for immunofluorescence analysis, RT–qPCR, and protein analysis. We purified histones and analyzed them through Western blot. We used ChIP–qPCR for histone H3K4me3 occupancy analysis. A tendency to increase in epithelial hyperplasia in F1 but not in F3 prostate was detected. Elevated levels of phosphorylated histone H3 at serine 10, a marker of mitosis, in both the F1 and F3 prostates were noted. A significant increase in the level of the Ki-67 marker of proliferation was detected in the F1 but not in the F3 anterior prostate. Hox gene expression was upregulated in the F1 and downregulated in the F3 prostate. The changes in gene expression were positively associated with histone H3K4me3 alterations at the promoters of the Hoxa and Hoxb13 genes. We determined that regions of Hox genes that play important roles in prostate development had altered DNA methylation in the sperm of F1 and F3. These alterations in DNA methylation were negatively related to gene expression. This is an observational study, as it was part of our previous research on the effects of thiacloprid on the testis and thyroid. Our analysis revealed that gestational exposure to thiacloprid induced an increase in cell proliferation in the prostates of directly exposed F1. Some persistent epigenetic alterations in the prostate of F3 males were not associated with phenotypic changes. Full article

Honey bees are exposed to a wide range of environmental and ecological stressors that threaten individual health and colony sustainability. Growing evidence suggests that many of these stressors converge on a common target: the gut microbiome and its metabolic functions. The honey bee microbiome–metabolome axis represents a central regulatory system linking microbial symbionts with host nutrition, detoxification, immune competence, neural signaling, and social behavior. This review synthesizes current knowledge on how major stressors—including pesticides, antibiotics, pathogens, nutritional imbalance, thermal stress, habitat change, and environmental contaminants—reprogram honey bee chemistry by disrupting microbial community structure and, importantly, microbial and host metabolic pathways. We highlight recurring patterns consistent with functional dysbiosis, characterized by impaired energy metabolism, reduced production of short-chain fatty acids, altered amino acid and lipid metabolism, compromised antioxidant and detoxification capacity, and weakened immune regulation. However, much of the current evidence is correlative and derived from short-term or laboratory-focused studies; longitudinal and multi-site field validation of causal links remains limited. Importantly, emerging multi-omics studies suggest that profound metabolic disturbances can occur even when taxonomic changes in the microbiome are modest, emphasizing the need to move beyond descriptive community profiling toward functional and mechanistic assessments. We further discuss how stress-induced metabolic reprogramming at the individual level scales up to influence behavior, division of labor, and colony-level resilience. Finally, we propose a conceptual model illustrating how diverse stressors converge to disrupt the microbiome–metabolome axis, potentially leading to functional dysbiosis and host impairment. Full article

The extensive utilization of TMX, a substance characterized by its high toxicity towards honeybees, has exerted a deleterious influence on the employment of neonicotinoid insecticides and the proliferation of bee colonies. However, there is a lack of effective solutions to mitigate the toxicological impact of neonicotinoid insecticides on bees. The present study proposes a method of using MB to alleviate TMX poisoning in honeybee (Apis mellifera ligustica) larvae. The results demonstrated that when bee larvae ingested MB at a concentration of 0.32 mg·L⁻¹, the mortality rate of larvae could be reduced from 47.2% to 25.0%. Transcriptome analysis identified the honeybee dihydrolipoyl dehydrogenase (AmDld) gene as one of the main genes involved in the function of MB. AmDld was highly expressed in larval hemolymph. Its expression levels and enzymatic content were suppressed by either TMX or MB alone but restored by the TMX+MB combination. RNAi-mediated knockdown of AmDld decreased AmDld content and increased larval mortality under the TMX+MB co-treatment from 25.0% to 40.6%. This indicated that the TMX+MB combination rescued AmDld levels, thereby alleviating TMX toxicity to bee larvae. The present study has demonstrated that the ingestion of MB by honeybee larvae has the capacity to reduce the toxicity of TMX, a toxic substance, through the action of the AmDld gene. This provides a novel approach to mitigating pesticide poisoning in bees. Full article