Bee declines driven by combined stress from parasites, pesticides, and lack of flowers

Assessing the impact of co-exposure to succinate dehydrogenase inhibitor (SDHI) fungicides and the intestinal parasite Nosema ceranae in the honey bee Apis mellifera

Over the past few decades, significant mortality rates have been reported in honey bee populations. The decline of these pollinators is thought to be linked to a combination of stressors, including both pathogens and pesticides. Here, we investigated the impact of chronic exposure of honey bees to a class of fungicides that inhibit succinate dehydrogenase (SDHI), in combination with the parasite Nosema ceranae. Bees were exposed under controlled laboratory conditions to N. ceranae and/or fed with two environmental concentrations of four different SDHIs (boscalid, bixafen, fluopyram, and fluxapyroxad). The bees were monitored for 21 days, during which several health parameters were evaluated, including survival, food consumption, parasitic load and lipid reserves. Additionally, a global RNA-Seq approach was used to analyze midgut transcriptional changes in non-infected and N. ceranae-infected bees treated with fluopyram. The results indicate complex and deleterious interactions of SDHI active substances, characterized by dose-response effects and non-monotonic reactions in uninfected bees. However, co-exposure to N. ceranae significantly modified these responses, with an antagonistic effect on survival and lipid reserves, which could be linked to mitochondrial disruption and activation of detoxification mechanisms. These results highlight the importance of considering bee co-exposure to multiple stressors over their lifespan.

Genomic prediction and association analyses for breeding parthenocarpic blueberries

Parthenocarpy is a desirable trait that enables fruit set in the absence of fertilization. While blueberries typically depend on pollination for optimal yield, certain genotypes can produce seedless fruits through facultative parthenocarpy, eliminating the need for pollination. However, the development of parthenocarpic cultivars has remained limited by the challenge of evaluating large breeding populations. Thus, establishing molecular breeding tools can greatly accelerate genetic gain for this trait. In the present study, we evaluated two blueberry breeding populations for parthenocarpic fruit set and performed genome-wide association studies (GWAS) to identify markers and candidate genes associated with parthenocarpy. We also compared the predictive ability (PA) of three molecular breeding approaches, including (i) genomic selection (GS); (ii) GS de novo GWAS (GSdnGWAS), which incorporates significant GWAS markers into the GS model as prior information; and (iii) in silico marker-assisted selection (MAS), where markers from GWAS were fitted as fixed effects with no additional marker information. GWAS analyses identified 55 marker-trait associations, revealing candidate genes related to phytohormones, cell cycle regulation, and seed development. Predictive analysis showed that GSdnGWAS consistently outperformed GS and MAS, with PAs ranging from 0.21 to 0.36 depending on the population of study and the specific markers utilized. MAS showed PAs comparable to GS in some cases, suggesting it could be a cost-effective alternative to genome-wide sequencing. Together, these findings demonstrate that molecular breeding techniques can be used to improve facultative parthenocarpy, offering new avenues to develop high-yielding blueberry varieties that are less reliant on pollination.

A stitch in time: integrating energy infrastructure into the fabric of conservation habitats

Insect communities are declining globally as a result of multiple, interacting drivers, including habitat loss due to agricultural intensification and urbanization. Biodiversity losses necessitate immediate conservation efforts, including the creation of new habitats, but it can be challenging to find suitable spaces in which to implement such mitigation actions. However, energy infrastructure, including solar farms and rights-of-way, presents opportunities to enhance insect conservation efforts by adding to the existing patchwork of habitats across working landscapes. While research has already demonstrated the potential for new habitats in homogenous, resource-poor landscapes, pairing these habitats with energy infrastructure has not been fully explored or utilized, although the evidence base is growing. Here, we examine the challenges of finding opportunities to establish insect habitats in working landscapes, discuss the potential for energy infrastructure as spaces for habitats, and propose solutions to move this potential new means of insect conservation forward.

A gut bacterial supplement for Asian honey bee (Apis cerana) enhances host tolerance to nitenpyram: Insight from microbiota-gut-brain axis

The widespread use of neonicotinoid pesticides has severely impacted honey bees, driving population declines. Gut microbiota are increasingly recognized for their role in mitigating pesticide toxicity. This study evaluated the ability of Gilliamella sp. G0441, a core microbiome member of the Asian honey bee (Apis cerana), to confer resistance to the toxicity of a neonicotinoid nitenpyram. Newly emerged Asian honey bees were first colonized with gut microbiota in the source colony, then divided into four treatments: SS (fed sucrose solution throughout), SN (fed sucrose solution, then exposed to nitenpyram), GS (fed Gilliamella, then sucrose solution), and GN (fed Gilliamella, then exposed to nitenpyram), and their responses-mortality, food consumption, body weight, and sucrose sensitivity-were assessed. The protective effects of Gilliamella administration on the host were further validated using a microbiota-free bee model. Gilliamella supplementation significantly mitigated nitenpyram-induced appetite suppression, weight loss, impaired learning, and gut microbiota disruption. Mechanistic analyses revealed that nitenpyram disrupted brain metabolism via the intestinal MAPK pathway, reducing ascorbate and aldarate metabolism. Prophylactic Gilliamella treatment reversed these effects, restored metabolic balance, and modulated esterase E4 expression, enhancing pesticide resistance. This study underscores Gilliamella's vital role in honey bee resilience to neonicotinoids, offering insights into the microbiota-gut-brain axis (MGBA) as a pathway for enhancing pesticide tolerance and ecological health.

Insecticide and pathogens co-exposure induces histomorphology changes in midgut and energy metabolism disorders on Apis mellifera

Honey bees in agroecosystems face increasingly exposure to multiple stressors, such as pesticides and pathogens, making it crucial to assess their combined impacts rather than focusing on individual factors alone. This study examined the adverse effects of single exposure acetamiprid, Varroa destructor, and Nosema ceranae, both individually and in combination, on honey bee survival, midgut integrity and transcriptomic changes to understand the molecular mechanisms involved. The findings revealed that combination of acetamiprid and N. ceranae induced significant energetic stress, as evidenced by disruptions in energy metabolism. The synergistic effects of V. destructor and N. ceranae led to severe alterations in midgut histomorphology, particularly damaging the midgut epithelium. Concurrent exposure to acetamiprid and V. destructor inhibited the immune response and energy metabolism of honey bees, thereby exacerbating the vulnerability to pathogens and destabilizing their physiological equilibrium. The combination of all three stressors caused the most dramatic damage, disrupting midgut structure as well as aromatic amino acids and lipid metabolism. Our study underscored the complexity and unpredictability of stressor interactions, emphasizing the need to consider environmental context when assessing the risks of honey bee health.

Honey Bee Viromes From Varroa destructor-Resistant and Susceptible Colonies

Honey bees (Apis mellifera) play a crucial role in global food production through pollination services. However, their populations are threatened by various stressors, like the ectoparasitic mite Varroa destructor and associated viral pathogens. In this study, we aimed to characterise and compare the viral communities (viromes) in V. destructor-resistant and susceptible colonies using high-throughput sequencing. Our findings revealed differences in virome composition associated with the season and not with the resistance or susceptibility to V. destructor. Furthermore, we detected Apis mellifera filamentous virus (AmFV) and Lake Sinai virus (LSV) for the first time in Uruguay, and obtained the complete or partial genomes of both viruses, along with those of other previously described viruses, such as Acute bee paralysis virus (ABPV), Black queen cell virus (BQCV), Deformed wing virus (DWV), and Sacbrood virus (SBV). This study contributes to a deeper understanding of the virome dynamics in honey bees. It highlights the importance of this type of study for the early detection of new viral pathogens, which could help to understand the tripartite network involving V. destructor, honey bees, and viruses.

Can Ahiflower® (Buglossoides arvensis) seed-oil supplementation help overcome the adverse effects of imidacloprid in honey bees?

In this study, we investigated the effects of nutritional supplementation as a strategy to mitigate the impacts of imidacloprid (neonicotinoid) on honey bees by using Ahiflower® (Buglossoides arvensis) seed-oil. This oil is rich in stearidonic-acid (SDA, 18:4n3), which is a precursor to eicosapentaenoic-acid (EPA) and docosahexaenoic-acid (DHA) that are known for their beneficial and protective effects. Specifically, we chronically fed newly emerged worker bees with sucrose syrup and pollen patties (control) that we supplemented with (i) imidacloprid (0.375 ng·μl-1), (ii) Ahiflower® oil (5 %) + imidacloprid (0.375 ng·μl-1), and (iii) Ahiflower® oil (5 %). Survival was recorded, and after 21 days, worker bees were sampled to measure mitochondrial respiration, ATP5A1 content, adenylate energy charge, lipid peroxidation in thorax as well as fatty acid composition and peroxidation index in whole bees. Our results indicate that (i) imidacloprid mostly hampers mitochondria, increases saturated fatty acids and decreases survival, (ii) oxidation of alternative substrates allows full recovery of mitochondrial respiration in the imidacloprid-treated group demonstrating mitochondrial flexibility, (iii) Ahiflower® oil in combination with imidacloprid partially restores mitochondrial respiration at the level of complexes I and II, restores fatty acid composition but fails to restore survival. These findings confirm the deleterious effects of imidacloprid on mitochondria while highlighting, for the first time, the potential benefits of Ahiflower® oil in mitochondrial function, though not on honey bee survival. In addition, this study highlights the importance of mitochondrial flexibility when organisms are exposed to toxicants at environmentally relevant levels.

Probiotic effects on ectoparasitic mite infestations in honey bees (Apis mellifera) are modulated by environmental conditions and route of administration

Beneficial bacteria can improve the health of managed honey bees (Apis mellifera) via immune system support as well as direct inhibition of pathogens. However, our understanding of how environmental factors and delivery methods impact treatment outcomes is limited. Here, we evaluated how supplementation of a three-strain lactobacilli consortium (Lactiplantibacillus plantarum Lp39, Apilactobacillus kunkeei BR-1, and Lacticaseibacillus rhamnosus; LX3) affects ectoparasitic mite (Varroa destructor) and bacterial (Paenibacillus larvae) load. We measured this effect following delivery of LX3 in either edible (protein patty) or topical (spray) forms and did so across three distinct habitats (forage-rich, agricultural, and urban). Results demonstrate significant control of mite infestation levels following patty delivery, relative to untreated patty controls. Spray methods, by contrast, were ineffective. Specifically, a control group that received only an uninoculated patty carried more mites than any other group, suggesting excess protein within hives is a catalyst for mite proliferation. This effect, whereby the excess-protein group had the highest parasite load, was pronounced in the most natural (forage-rich) environment type, indicating a significant site-by-treatment interaction. No influence of LX3 on P. larvae loads was observed in the asymptomatic colonies studied, which is likely attributable to the already low levels of pathogenic spores present and challenges associated with detection limits. In summary, this multi-site field study suggests that an LX3-infusion of standard protein patties is an effective method to control Varroa destructor infestations in commercial honey bee colonies.IMPORTANCECommercial beekeeping operations typically have a narrow profit range that depends on maintaining healthy hives throughout the season. Unfortunately, parasitic Varroa mites and bacterial pathogens can contribute to colony losses. The plight of honey bees can in turn affect the price and availability of produce on the agri-food market. There is therefore a need for innovation in the beekeeping industry to help secure bee livestock from season to season. One relatively new approach to sustainable beekeeping is the use of beneficial bacterial supplements that beekeepers can feed to or otherwise apply to hives in aid of the bee's natural health and abilities as mediated through their gut-brain axis. Our multi-site field study applies this approach. We find that a pollen protein patty is an effective vehicle for delivering probiotic bacteria to commercial honey bee colonies and for helping to keep Varroa destructor infestation levels in check.

The thiamethoxam-based insecticide Cruiser 350 Fs induced histopathological and oxidative stress in the stingless bee Partamona helleri (Hymenoptera: Apidae: Meliponini)

The stingless bee Partamona helleri plays a crucial role in pollinating both native and cultivated plants. However, the intensive use of pesticides in agriculture are contributing to the decline of its population. Thiamethoxam, a systemic neonicotinoid insecticide, acts on the nervous system, however, it can also affect other non-target insect organs. This study evaluated the sublethal effects of chronic oral exposure to a thiamethoxam formulation on the fat body and Malpighian tubules in P. helleri workers. Bees were exposed orally for seven days to sublethal concentration of thiamethoxam (0.09 ng g-1). The results revealed histopathological alterations in the fat body and Malpighian tubules, including changes in protein and carbohydrate reserves, nuclear pyknosis, cytoplasmic vacuolization, and affect lipid peroxidation in P. helleri. These findings indicate that chronic exposure of P. helleri workers to the residual concentration of thiamethoxam found in the field elicits a detoxification response in the fat body and Malpighian tubules; however, the previously reported high mortality rate suggests that these physiological responses are insufficient to mitigate the toxic effects of thiamethoxam on this pollinator.

Impacts of almond pollination service and inter-row cover cropping on honey bee colony strength and performance

Intensive agriculture has become necessary to meet the growing global demand for food and in some crops, successful fruit and seed production involves the activity of insect pollinators. Among insects, honey bees are one of the most efficient pollinators and in the agriculture industry, worth over 200 billion dollars annually, economic yield of some commodity crops, such as almonds, are heavily reliant upon pollination by honey bees. Almonds are a quintessential example of the commercial application of plant-pollinator dependency. Acreages of almonds mostly comprise of self-incompatible varieties that need bees for transferring pollen from the flowers of 'pollenizer' varieties to those of nut-yielding varieties, facilitating cross-pollination. Early season flowering phenology of almonds, when there are very few other plants in bloom, facilitates honey bee colony growth after the overwintering quiescence. Here, (i) we assessed colony strength and performance before and after almond pollination service and (ii) the impacts of availability of flowering interrow mustard-mix cover crops. Results show that there were consistently more frames of bees, pollen stores, brood, and adult bees in colonies returning from almond pollination service. The availability of mustard-mix cover crops supports increased colony strength through the season, facilitating long lasting positive impacts on honey bee health. Our findings suggest that agroecosystem management practices such as interrow cover cropping, strengthen the immediate and long-term positive impacts from pollination services by improving honey bee colony performance while simultaneously promoting ecosystem function.

Do bumble bees make optimal nutritional choices?

Nutrition is crucial for bees, impacting their health, survival, and pollination performance in ecosystems and agriculture. Bees get essential nutrients such as carbohydrates, proteins, lipids, vitamins, and minerals, primarily from nectar and pollen. Many bee species are experiencing declines linked partially to nutritional stress, often exacerbated by climate change, pesticides, and pathogens, highlighting the need to understand and support optimal bee nutrition to mitigate these stressors. Bumble bees, such as Bombus impatient and Bombus terrestris, essential pollinators in agriculture, are known to regulate their nutrient intake. However, whether their dietary choices improve fitness is poorly understood. We tested diets with varying protein, lipid, and carbohydrate compositions, analyzing impacts on consumption, body mass, egg laying, and ovarian activation. Results showed that bees overconsumed pollen on protein-enriched diets and under consumed it on lipid-enriched and glucose-based diets. Nectar overconsumption was observed on low-concentration sucrose diets. These patterns, however, did not correspond to improved fitness, as egg laying and body mass were negatively correlated with consumption in diets enriched with protein and sugar. Ovarian activation was largely unaffected across most diets, indicating it may not be a reliable indicator of diet quality. These findings raise doubts about whether bees make optimal nutritional choices and suggest that diet consumption alone may not be a reliable indicator of their optimal diet. Alternatively, bees made the best possible decisions under circumstances that presented a lose-lose tradeoff across all the diets provided. These data can inform future studies on nutritional stress, enhance interpretations of bee diet preferences in bioassays, and guide bumble bee management practices.

Dissection of genetic basis underlying heat stress response of Apis cerana

The honeybee Apis cerana as an important pollinator contributes significantly to ecological diversity. In recent years, it has been used as a common pollinator in greenhouses, but it is highly susceptible to heat stress, which affects its behavior, physiology, survival, and gene expression. Here, we conducted transcriptomic analysis to identify differentially expressed genes (DEGs) and reveal the associated biological processes in the queen head and ovary of honeybee A. cerana under different temperatures. Differential expression analysis revealed 116 DEGs (72 upregulated, 44 downregulated) in the head and 106 DEGs (78 upregulated, 28 downregulated) in the ovary after 24 h of heat stress. At 96 h, 29 DEGs (17 upregulated, 12 downregulated) were identified in the head, and 44 DEGs (34 upregulated, 10 downregulated) in the ovary. After 168 h, the number of DEGs increased significantly: 846 DEGs (567 upregulated, 279 downregulated) in the head, 479 DEGs (296 upregulated, 183 downregulated) in the ovary, and 582 DEGs (338 upregulated, 244 downregulated) in the thorax. DEGs associated with metabolic processes, signaling, and transport pathways were significantly altered under heat stress, potentially contributing to the reduced reproductive and growth capacity of bees. Additionally, genes related to antioxidant activity, nutrient metabolism, heat shock proteins, zinc finger proteins, and serine/threonine-protein kinases were differentially expressed across treatments. Overall, the head and ovaries of honeybee queens show a significant response to heat shock, and these responses are related to antioxidant genes, heat shock proteins, and metabolic regulation, our findings provide genetic information for the breeding of heat-resistant bee strains.

Toxicity and biochemical effects of four pesticides on honey bee, Apis mellifera under laboratory conditions

The widespread use of insecticides can cause negative side effects on pollinators, resulting undesirable effects in crop productivity. So, this study was conducted to evaluate the toxicity and biochemical changes in honey bees, Apis mellifera (Hymenoptera: Apidae) enzymes, treated with four insecticides i.e. lambda-cyhalothrin, hexythiazox, fenpyroximate and thiamethoxam under laboratory conditions. The obtained results revealed that thiamethoxam was extremely toxic to A. mellifera adults (LC50=0.006 ppm) followed by lambda-cyhalothrin (LC50=0.053 ppm) and fenpyroximate (LC50=2.29 ppm) after 24 h of treatment, however, hexythiazox was relatively less toxic to bees (110.09 ppm). The sub-lethal concentration LC25 and LC50 of tested pesticides, reduced the activity of AChE, GST, MFO and esterase's activities in honey bee adults, where, lambda-cyhalothrin and thiamethoxam induced the highest effects compared with other two pesticides and control. In contrast, the tested insecticides activated PPO enzyme at LC25 concentration, while PPO activity was reduced after treating adult bees with LC50. Lambda-cyhalothrin, thiamethoxam, fenpyroximate and hexythiazox disrupted the physiology of honey bees, thereby reducing the efficiency of this beneficial pollinator. Overall, the obtained results are valuable not only in evaluating the toxicity of common insecticides onto honey bees, but also in highlighting the validity of enzyme activities as appropriate indicators for exposure to agrochemicals.

Early life imidacloprid and copper exposure affects the gut microbiome, metabolism, and learning ability of honey bees (Apis mellifera)

The pesticide imidacloprid and the heavy metal copper provide some degree of protection to plants, while at the same time causing varying degrees of damage to bees. However, few studies have investigated the negative effects of imidacloprid and copper exposure on newly emerged bees (young bees), especially when both are present in a mix. In this study, young bees were exposed to sterile sucrose solutions containing imidacloprid (10 μg/L, 100 μg/L), copper (10 mg/L, 50 mg/L), or a mix of both (10 μg/L + 10 mg/L) for 5 days to assess their gut system and behavior, with survival and dietary consumption recorded over 21 days. We found that imidacloprid and copper reduced honeybee survival, dietary intake, and learning ability, decreased gut microbiota diversity, and caused metabolic disruptions. Notably, the mix of imidacloprid and copper had a synergistic negative effect. Correlation analyses revealed that the honeybee gut microbiota influences bee immunity and behavior by regulating metabolic pathways related to ascorbate, tryptophan, and carbohydrates. Our results demonstrate that imidacloprid and copper, either alone or in a mix, alter young bee health through a complex mechanism of toxicity. These findings highlight imidacloprid and copper's negative effects on young honeybees, offering insights for future pesticide and heavy metal impact research.

Time dynamics models for oxidative stress markers in honey bees (Apis mellifera) following paraquat-induced stress

Many agrochemicals disrupt redox homeostasis, yet the dynamics of oxidative stress responses in honey bees (Apis mellifera) remain insufficiently understood. This study established a controlled model to monitor ROS-related markers over time following paraquat injection, using Bayesian modeling to characterize time-dependent changes. We observed a transient rise in hydroperoxides and early fluctuation in adipokinetic hormone (AKH) levels, which declined and stabilized within 8hours. No significant differences were detected in secondary lipid peroxidation products (TBARS) among treatments. While injection does not represent natural exposure pathways, it enables precise dosing and timing, avoiding variability from oral intake. This experimental design provides a tractable system to investigate oxidative stress mechanisms under defined conditions. Our findings underscore the importance of time-resolved analysis in redox physiology and offer a mechanistic framework to complement field-relevant toxicological studies in bees and other beneficial insects.

Concrete consequences: construction on prime honey bee habitat doubles foraging distances

Human-induced land-use change is a well-documented driver of species decline, including bees, but its true cost may be underestimated. The effects of habitat conversion on honey bee foraging metabolic costs are not well documented. Here, we quantify the impact of land use change on the foraging of freely flying honey bees (Apis mellifera) before (2018-2019, n=382) and after (2022, n=502) their historical foraging habitat is developed. We decoded and analyzed honey bee waggle dances, through which returning foragers communicate the vector of forage. We found that bees increased (from 2.4% to 8.4%) their use of undisturbed microhabitat within the development. The small-scale developments, covering just 1% of the foraging range, nearly doubled flight distance and energy expenditure. Average distance increased from 0.69 to 1.28 kilometers (from 7 to 13 Joules). Our study updates our understanding of land development costs on local bees, revealing concrete consequences to changing land upon which pollinators depend.

Land-use impacts on crop yield: direct and indirect roles of arthropods and associated ecosystem services in European farmland

Context

Land-use intensification to increase yields is often detrimental to biodiversity undermining the provision of ecosystem services. However, it is questionable if ecosystem service providers contribute to ecological intensification by achieving the same or higher yields than conventional high-intensity agriculture.

Objectives

In this study, we aimed to disentangle the effects of local and landscape-scale land-use intensification on arthropod communities and their contribution to ecosystem services and crop yield. A set of meta-analytic structural equation models allowed us to assess direct and indirect relationships in the cascade from land use to yield.

Methods

We selected 37 datasets containing information on land use, community composition, levels of pollination and natural pest control services, and crop yield. We quantified functional diversity of communities by collecting trait information for three exemplary groups of service-providers: bees, ground beetles, and spiders.

Results

Local land-use intensification reduced the abundance of all arthropod groups. Spiders were the only group whose species richness was negatively related to a higher percentage of arable land in the landscape. High abundance of bees related positively to oilseed rape pollination and crop yields. In the models for the two predator groups, crop yield was strongly determined by land use, independent of the pest control services provided by natural enemies.

Conclusions

Our results suggest a potential for ecological intensification mediated by land-use change in crops where pollination benefits yield, but suggest more nuanced effects for pest control. Our study also calls for experiments on multiple taxonomic groups and ecosystem services that apply comparable methods at similar scales.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10980-025-02117-w.

Honeybee toxicity of pesticides used in United States maize and soybean production, 1998-2020

Pesticides are widely used around the world and have demonstrated benefits to crop production. However, pesticides have also been associated with negative impacts to nontarget organisms, including pollinators. Here, we combined pesticide usage and toxicity data to create a toxicity index, which shows that pesticide hazard to honeybees (Apis mellifera) has changed substantially in U.S. maize (Zea mays) and soybean (Glycine max) production between 1998 and 2020. To reduce potential risks to honeybees and increase the eco-efficiency of crop production, efforts should be made to refine management strategies for pests that contribute most to the honeybee toxicity index. In maize, Coleoptera and Lepidoptera pests drive pesticide usage most responsible for hazard to honeybees, although the relative hazard from targeting those pests has decreased over time. In soybean, hemipteran pests were the largest relative contributor to insecticide honeybee hazard. Specific pests that contributed to honeybee toxicity hazard included corn rootworm species (Diabrotica spp.), silk-eating insects, and cutworms in maize, and stink bugs (family Pentatomidae) and aphid species (Family Aphididae) in soybean. We combined crop yield data with the toxicity index to quantify the eco-efficiency, a measure of crop yield per unit of toxicity hazard. While crop yield for both maize and soybean increased steadily throughout the study period, eco-efficiency decreased in both crops between 2012 and 2020, suggesting increases in crop yield have failed to keep pace with increases in insecticide hazard to honeybees.

Polyfloral nutritional resources promote bumble bee colony development after exposure to a pesticide mixture

Bumble bees are important pollinators of crops in the field and greenhouses. They are naturally exposed to a combination of interacting stressors, e.g., loss of flowering resources and exposure to plant protection products. Mass-flowering crops are important resources for bees, but they may result in unbalanced nutrition due to different nutritional values. In this study, a semi-field experiment was conducted to evaluate the response of Bombus terrestris colonies after the application of a tank mixture containing the insecticide chlorantraniliprole and the fungicide prochloraz, either in monofloral-managed lupin (Lupinus albus) as high pollen protein resource or in presence of an additional polyfloral flower mixture. Our results demonstrate an evident effect on worker mortality after application of the tank mixture. Higher worker mortality in polyfloral treatments compared to the untreated control was observed. The number of young brood and pupae in colonies in polyfloral control were significantly higher than in monofloral treatment. However, no long-term effects on the number or weight of new queens were found. Furthermore, flowering resources, but not pesticide exposure, affected colony weight. Exposure to the tank mixture resulted in declining nectar yeasts abundance and an increasing proportion of phylloplane yeasts in forager guts. In conclusion, diverse flowering resources are important for a bumble bee colony's development. Even in a high pollen protein crop, low flower diversity may act as an additional stressor. Thus, we suggest further maintaining and promoting flowering strips or flowering fields in agricultural landscapes, even near high pollen protein crops, to enhance bee health.

Impact of a lambda-cyhalothrin formulation residues on larval Apis mellifera: examining midgut and fat body morphological response to insecticide chronic exposure

Pollination by honey bees (Apis mellifera) is crucial for maintaining biodiversity and crop yields. However, the widespread use of pesticides may threaten bees' survival by contaminating their resources. Lambda-cyhalothrin, a neurotoxic insecticide commonly used in agricultural pest control, poses particular risks. In insects, the midgut and fat body serve as primary barriers against xenobiotics, and exposure to these chemicals during larval development can impact adult bees. This study aimed to assess whether the residual concentration of lambda-cyhalothrin in pollen grains affects the midgut and fat body of larval A. mellifera workers after chronic exposure. The midgut epithelium of larvae exposed to a lambda-cyhalothrin-based insecticide (λ-CBI) exhibited autophagic vacuoles, apical cell protrusions, apocrine secretion, nuclear pyknosis, and high levels of polysaccharides and glycoconjugates in the cytoplasm, with smaller amounts in the brush border. Histochemical analysis revealed areas of vacuolation and damage to cell integrity in the midgut. In fat body cells, the insecticide increased polysaccharide storage and decreased lipid droplet diameter. Despite the histopathological damage, no effects were found in the larval development and adult emergence. These findings suggest the occurrence of apoptosis and autophagy in midgut cells and alterations in nutrient storage in the fat body of A. mellifera larvae exposed to the λ-CBI, potentially impacting the physiology and development of this pollinator with possible effects on adult workers.

Protective effects of resveratrol on honeybee health: Mitigating pesticide-induced oxidative stress and enhancing detoxification

The widespread use of pesticides poses a significant threat to honeybee health by impacting their survival, behavior, immune function, and detoxification capacity. While phytochemicals such as resveratrol (RSV) have shown potential in mitigating oxidative stress and enhancing antioxidant defenses, their role in improving honeybee tolerance to pesticide exposure remains underexplored. In this study, we investigated the effects of RSV supplementation on honeybees exposed to three pesticides: dinotefuran (DIN), tebuconazole (TEB), and deltamethrin (DEL). The results showed that RSV supplementation significantly improved survival, feed intake, mobility, and gustatory sensitivity, indicating its protective effects against pesticide toxicity. Furthermore, RSV helped normalize impaired detoxification enzyme activities, including SOD, POD, catalase, and glutathione reductase, and reduced ROS levels and lipid peroxidation. Gene expression analysis revealed that RSV modulates Toll pathway-related genes like defensin and apidaecin, alleviating immune suppression caused by pesticides. Additionally, RSV influenced the insulin/insulin-like growth factor signaling (IIS) pathway by reducing ilp1 and inr1 expression, potentially mitigating metabolic stress. These findings demonstrate that protective effects of RSV may be linked to its ability to counter oxidative stress, restore mitochondrial function, and enhance energy metabolism. Furthermore, RSV is widely available, cost-effective, and easily incorporated into bee feed, making it feasible for large-scale application. This study highlights the protective role of RSV in pesticide detoxification in honeybees, offering new perspectives for honeybee health management and environmental toxicology research. By reducing the adverse effects of pesticides on honeybees, the application of RSV not only contributes to maintaining ecological balance but also supports sustainable agricultural practices. Future research should focus on optimizing its dosage, evaluating long-term effects, and investigating its impact on colony dynamics to facilitate its practical implementation in apiculture.

Romance in peril: A common pesticide impairs mating behaviours and male fertility of solitary bees (Osmiabicornis)

Mating behaviour and fertility are strong selective forces, driving the reproductive trends of animals. Mating disorders may therefore contribute to the recent decline in insect and pollinators health worldwide. While the impact of pesticides on pollinators is widely considered as a driving factor for reducing pollinators health, their effect on mating behaviour and male fertility remains widely overlooked. Here, we assessed the effects of field-realistic exposure to a common pesticide used as a neonicotinoid substitute worldwide, sulfoxaflor, on the behaviour and male physiology of the solitary bee, Osmia bicornis. We measured a variety of parameters focusing on behaviours occurring before, and during mating, as well as sperm quantity. For the first time, we demonstrate that short-term chronic, field-realistic exposure to a common pesticide reduced pre-copulatory display (-36 %) and sounds (-27 %), increased the number of copulations (+110 %) and the mating duration (+166 %), while finally reducing sperm quantity (-25 %) and mating success (-43 %). Our research raises considerable concern on the impact of field-realistic, low sublethal pesticide levels on the fertility and reproductive success of pollinators. Assessing the impact of pesticides on fitness parameters and implementing more sustainable agricultural solutions would allow mitigating the ongoing threat of pesticide pollution on wild insect populations and the broader environment.

A guide to sunflowers: floral resource nutrition for bee health and key pollination syndromes

Sunflower, Helianthus annuus L., is a prominent global oilseed crop with rising cultivation and appeal as a bee-friendly plant by providing abundant floral resources for pollinators. Mass-flowering crops can increase the availability of resources, and sunflower is a good opportunity to relieve pollen scarcity during the late summer in agricultural landscapes. Yet this should be taken with caution as they also provide a homogeneous source of nutrition. This study aimed to review and summarize the nutritional profile of sunflower pollen, nectar, bee bread, and honey, while assessing their effects on bee survival, development, and health. Furthermore, we present here the general state of knowledge on additional pollinator syndromes that extend beyond floral resources, including those influencing pollinator visual and olfactory attraction. We found that while sunflower pollen's nutritional quality is questioned due to lower protein and amino acid deficiencies, its nutrient content, like nectar sugars, had large variability. Sunflower pollen consumption showed mixed effects on Apis mellifera and Bombus species, sometimes negatively impacting development and survival. However, studies have conveyed a positive impact on bee health as sunflower pollen consistently reduced the infection intensity of the gut parasite, Crithidia bombi, in Bombus species. This probes the question on defining the quality of floral resources, emphasizing the need for caution when categorizing sunflower as a low quality nutritional resource. This review also outlines the importance of sunflower nectar characteristics (sugar content and volume) and floral morphology (flower pigmentation and corolla length) on pollinator foraging preferences. A prominent knowledge gap persists regarding nectar chemistry and sunflowers' extensive volatile profile to better understand the pollination syndromes that drive its pollinator interactions.

Urban wild bee well-being revealed by gut metagenome data: A mason bee model

Wild bees are ecologically vital but increasingly threatened by anthropogenic activities, leading to uncertain survival and health outcomes in urban environments. The gut microbiome contains features indicating host health and reflecting long-term evolutionary adaptation and acute reactions to real-time stressors. Moving beyond bacteria, we propose a comprehensive analysis integrating diet, bacteriome, virome, resistome, and their association to understand the survival status of urban lives better. We conducted a study on mason bees (Osmia excavata) across 10 urban agricultural sites in Suzhou, China, using shotgun gut metagenome sequencing for data derived from total gut DNA. Our findings revealed that most ingested pollen originated from Brassica crops and the unexpected garden tree Plantanus, indicating that floral resources at the 10 sites supported Osmia but with limited plant diversity. Varied city landscapes revealed site-specific flowers that all contributed to Osmia sustenance. The gut bacterial community, dominated by Gammaproteobacteria, showed remarkable structural stability across 8 sites but suggested perturbations at 2 sites. Antibiotic resistance gene profiles highly varied across 10 sites with prevalent unclassified drug classes, highlighting environmental threats to both bees and humans. The virome analysis identified honeybee pathogens, suggesting potential virus spillover. Many unknown bacteriophages were detected, some of which targeted the core gut bacteria, underscoring their role in maintaining gut homeostasis. These multifaceted metagenomic insights hold the potential to predict bee health and identify environmental threats, thereby guiding probiotic development and city management for effective bee conservation.

Evaluating the combined toxicity of broflanilide and myclobutanil on honeybees (Apis mellifera L.): Molecular mechanisms and protective effects of curcumin

Pesticide toxicity to honeybees has become a pressing ecological issue, yet the effects of pesticide co-exposure are still not fully understood. This research investigates the toxicological implications of concurrent exposure to broflanilide (BFL), a novel diamide insecticide, and myclobutanil (MYC), a commonly used triazole fungicide, on honeybees (Apis mellifera L.), while exploring potential preventive strategies. Acute toxicity tests revealed a significantly lower 96-hour lethal concentration 50 (LC50) for BFL (0.34 mg a.i. L-1) compared to MYC (82.3 mg a.i. L-1), and their co-exposure resulted in pronounced synergistic toxicity. Worker bees were exposed to environmentally relevant doses of BFL and MYC for 7 days, and midgut toxicity was assessed. The co-exposure caused severe midgut damage, including G-layer deterioration, loss of columnar epithelium integrity, and downregulation of the tight junction protein ZO-2. Additionally, oxidative stress-related genes (Sod1, Catalase, SelK, GstD1) were upregulated, accompanied by higher MDA levels and increased CAT and SOD activities. Furthermore, a greater number of TUNEL-positive cells were detected, along with elevated expression of apoptosis-related genes (Caspase-3-like, Caspase-8-like, Caspase-9-like) and higher caspase enzyme activities. Curcumin (Cur) was tested for its protective effects, and it significantly alleviated midgut damage, oxidative stress, and apoptosis. This study reveals the synergistic ecotoxicological effects of pesticide combinations and suggests Cur as a potential prevention strategy for mitigating their harmful impact on honeybees.

First Report on Antifungal Activity of Metschnikowia pulcherrima Against Ascosphaera apis, the Causative Agent of Chalkbrood Disease in Honeybee (Apis mellifera L.) Colonies

Chalkbrood is the manifestation of the fungal disease caused by Ascosphaera apis, which affects broods of developing honeybees, particularly in Apis mellifera colonies. Recently, Metschnikowia pulcherrima has been proposed as a biocontrol agent in winemaking and for the management of major postharvest and soil-borne plant pathogenic fungi. In this study, the antagonistic activity of three M. pulcherrima strains against fifteen A. apis strains, isolated from contaminated hives of A. mellifera, was evaluated, with a specific focus on the potential antifungal activity of volatile organic compounds (VOCs). The study revealed that M. pulcherrima was effective against A. apis and that the antifungal activity was related to various mechanisms including competition for nutrients, secretion of pulcherriminic acid, and biosynthesis of specific antifungal VOCs. We also found that each M. pulcherrima strain produced a unique combination of VOCs, and the antifungal activity was strain-dependent and varied depending on the specific yeast-mold combination. In addition, preliminary analyses showed that a temperature of 30 °C and a higher amount of glucose (40 g/L) in the growing medium promote the growth of A. apis. These results could be useful for designing new strategies for the biocontrol of chalkbrood disease in honeybee colonies.

Flupyradifurone Exhibits Greater Toxicity to the Asian Bumblebee Bombus lantschouensis Compared to the European Bumblebee Bombus terrestris

Pesticides are considered a major factor in the decline of bee populations. Flupyradifurone, a novel insecticide, is believed to be relatively 'bee-safe'. This study aims to evaluate the acute and chronic toxicity of flupyradifurone and assess its risks to both commercial bumblebee Bombus terrestris and the Asian native species B. lantschouensis. Oral toxicity tests demonstrated species-specific sensitivity, with B. lantschouensis exhibiting 5.4-fold higher acute toxicity (72-h LD50: 5.1 μg/bee vs. 28 μg/bee) and 3-fold lower chronic toxicity (No Observed Adverse Effect Concentration, NOAEC: 20 μg/mL vs. 60 μg/mL) compared to B. terrestris. Risk assessments indicated low Hazard Quotients (HQ) of 4 for B. terrestris and 20 for B. lantschouensis. However, the Exposure Toxicity Ratio (ETR) values from both screening and first-tier assessments exceeded the trigger levels, necessitating further testing. This study provides crucial data on the acute and chronic toxic effects of flupyradifurone and highlights the need for more comprehensive insecticide risk assessments, particularly for non-Apis pollinators, to better protect these vital species.

Polyamine dynamics and transcriptomic changes in honey bees (Apis mellifera, L.) during aging

Honey bees (Apis mellifera, L.) play an important role in ecosystems due to their pollination, which directly impacts biodiversity and agricultural production. Understanding the biological mechanisms that determine bee aging is important for conserving bee populations and the ecosystems they serve. This study explored the dynamics of polyamine level changes and transcriptomic alterations during the aging of summer and winter worker bees. The present study's results indicate that the polyamine content in summer bees decreased overall with age, while winter bees exhibited a biphasic pattern, with an initial decrease followed by an increase in older individuals. These differences likely reflect distinct physiological needs during summer (work-intensive) and winter (survival-focused) periods. Transcriptomic analyses identified age-related changes, with key driver gene analysis highlighting critical genes associated with cuticle formation, venom activity, and polyamine metabolism, indicating structural and metabolic adaptations with age. KEGG pathway analysis identified enrichments in pathways related to peroxisome function, lipid metabolism, glycan degradation, lysosomal activity, and others underscoring shifts in cellular maintenance and energy regulation. This study underscores the complexity of polyamine dynamics and molecular adaptations in honey bee aging and provides a foundation for conserving bee populations and better understanding longevity across species.

Toward Better Biodiversity Impact Assessment of Agricultural Land Management through Life Cycle Assessment: A Systematic Review

Agricultural intensification has driven global biodiversity loss through land management change. However, there is no consensus on assessing the biodiversity impacts of changes in land management practices and intensity levels using life cycle assessment (LCA). This study reviews 7 expert scoring-based (ESB) and 19 biodiversity indicator-based (BIB) LCA methods used to assess biodiversity impacts, aiming to evaluate their quality and identify research needs for incorporating land management change in LCA. Overall, BIB methods outperformed ESB methods across general criteria, especially in robustness (95% higher). BIB methods assess biodiversity impacts based on land management intensity levels, whereas ESB methods emphasize specific land management practices. Neither approach fully captures biodiversity impacts across supply chains. For future studies, it is advisable to (1) model the direct (on-farm) impacts of land management change at the midpoint level; (2) establish cause-effect relationships between key land management practices and biodiversity indicators, while distinguishing between direct (on-site) and indirect (off-site) biodiversity impacts resulting from land management change; (3) characterize land-use intensity levels with specific land management practices and include the positive impacts from agroecological practices. This Review examines LCA methods for biodiversity concerning land management practices and discusses improvements to better account for the biodiversity impacts of agricultural land management.

Food as Medicine: A Review of Plant Secondary Metabolites from Pollen, Nectar, and Resin with Health Benefits for Bees

Bees rely on pollen and nectar for nutrition, but floral products provide more than just macronutrients; many also contain an array of plant secondary metabolites (PSMs). These compounds are generally thought to serve primarily defensive purposes but also appear to promote longevity and immune function, protect against disease agents, and detoxify toxicants. This review presents a comprehensive overview of PSMs, as well as some fatty acids, with documented health benefits for eusocial bees at ecologically relevant exposure levels and the plant species whose floral products and/or resin are known to contain them. We find medicinal metabolites to be widespread but unevenly distributed across the plant phylogeny, with a few families containing a majority of the species known to produce PSMs with documented health benefits. We discuss the current state of knowledge and identify gaps in our understanding. The existing literature on the health benefits of metabolites, and particularly PSMs, to bees is spread across multiple fields; our hope is that this review will bring these fields closer together and encourage further investigation of the role of metabolites in promoting bee health in ecological contexts.

Pesticide residues in honey: Agricultural landscapes and commercial wax foundation sheets as potential routes of chronic exposure for honey bees

Pesticides pose significant threats to pollinators, and honey bees are frequently exposed through foraging and beekeeping practices. We assessed honey bee pesticide exposure by analyzing 92 pesticide residues in honey from 30 hobbyist apiaries across Massachusetts, along with store-bought honey and commercial wax foundation. For all samples, we calculated the risk of multiresidue toxicity to honey bees and assessed the role of landscape composition in predicting pesticides in local honey. Both honey and wax contained multiple pesticides, particularly neonicotinoids and piperonyl butoxide. Store-bought honey accumulated at least two times more residues than local, but did not differ significantly in toxicity. Overall, honey toxicity levels remained below thresholds of concern for bees and human consumption. Although our study had low agricultural land (∼6 %), croplands were positively correlated with pesticides in honey, while wetlands (∼ 15 %) were negatively correlated. Additionally, our study suggests that commercial wax exacerbates pesticide exposure.

On-farm wildflower plantings generate opposing reproductive outcomes for solitary and bumble bee species

Pollinator habitat can be planted on farms to enhance floral and nesting resources, and subsequently, pollinator populations. There is ample evidence linking such plantings to greater pollinator abundance on farms, but less is known about their effects on pollinator reproduction. We placed Bombus impatiens Cresson (Hymenoptera: Apidae) and Megachile rotundata (F.) (Hymenoptera: Megachilidae) nests out on 19 Mid-Atlantic farms in 2018, where half (n = 10) the farms had established wildflower plantings and half (n = 9) did not. Bombus impatiens nests were placed at each farm in spring and mid-summer and repeatedly weighed to capture colony growth. We quantified the relative production of reproductive castes and assessed parasitism rates by screening for conopid fly parasitism and Nosema spores within female workers. We also released M. rotundata cocoons at each farm in spring and collected new nests and emergent adult offspring over the next year, recording female weight as an indicator of reproductive potential and quantifying Nosema parasitism and parasitoid infection rates. Bombus impatiens nests gained less weight and contained female workers with Nosema spore loads over 150 times greater on farms with wildflower plantings. In contrast, M. rotundata female offspring weighed more on farms with wildflower plantings and marginally less on farms with honey bee hives. We conclude that wildflower plantings likely enhance reproduction in some species, but that they could also enhance microsporidian parasitism rates in susceptible bee species. It will be important to determine how wildflower planting benefits can be harnessed while minimizing parasitism in wild and managed bee species.

Complex dynamics in plant-pollinator-parasite interactions: facultative versus obligate behaviors and novel bifurcations

Understanding the dynamics of plant-pollinator interactions is crucial for maintaining ecosystem stability and biodiversity. In this paper, we formulate a novel tripartite plant-pollinator-parasite model that incorporates the influence of parasites on mutualistic relationships. Our model consists of the plant-pollinator subsystem, which exhibits equilibrium dynamics with up to four bistable states; the pollinator-parasite subsystem, where stability is significantly affected by pollinator density and growth rate; and the complete system combining all three species. We perform comprehensive mathematical and bifurcation analyses on both the subsystems and the full system. We have many interesting findings, including that (1) plant-pollinator-parasite interactions are dependent on the properties of plants and pollinators (i.e., facultative or obligate interactions). For example, systems with facultative pollinators are more likely to exhibit multistability and periodic oscillations, thereby enhancing resilience, whereas scenarios with obligate pollinators are more likely to lead to system collapse. (2) Critical parameters such as parasite mortality and conversion rates can drive complex behaviors, including supercritical and subcritical Hopf bifurcations, saddle-node bifurcations, chaos, and heteroclinic orbits. Notably, we introduce three new concepts-the left bow, right bow, and wave bow phenomena-to characterize variations in oscillation amplitude resulting from parameter bifurcations. These important results provide theoretical guidance for ecological management strategies aimed at enhancing ecosystem resilience and stability by considering the complex interactions among plants, pollinators, and parasites.

Island-wide removal of honeybees reveals exploitative trophic competition with strongly declining wild bee populations

High densities of managed honeybees (Apis mellifera) can threaten wild bees through exploitative competition, thus leading to population declines of the latter. Although reviews have outlined key steps to demonstrate these impacts-measuring resource overlap, changes in wild bee behavior, and population trends-studies that comprehensively address these aspects are virtually absent. We were granted access to the entire protected island of Giannutri (2.6 km2) and to the apiary (18 hives) located there during the early phase of coexistence between honeybees and wild bees. Using the island as an open-air laboratory, we experimentally manipulated honeybee pressure by closing the hives on selected days during the peak of the wild bee foraging period. In the plants most visited by pollinators, even short-term honeybee removals (11 h per day) increased nectar volume (∼60%) and pollen availability (∼30%). In the absence of honeybees, target wild bees (Anthophora dispar and Bombus terrestris) became dominant in the insect-plant visitation network, and the potential apparent competition significantly decreased. Accordingly, both species intensified their foraging activity and increased nectar suction time, a recognized proxy for the quantity of probed nectar, and Bombus terrestris also shortened the time of pollen searching. Transect monitoring revealed an alarming ∼80% decline in both species over 4 years, consistent with honeybee monopolization of floral resources, thus reducing availability for wild pollinators and altering their foraging budget. These findings underscore the risks of introducing high densities of honeybees into protected areas and emphasize the need for rigorous preventive ecological assessments.

Insect immunity in the Anthropocene

Anthropogenic activities result in global change, including climate change, landscape degradation and pollution, that can alter insect physiology and immune defences. These changes may have contributed to global insect decline and the dynamics of insect-transmitted diseases. The ability of insects to mount immune responses upon infection is crucial for defence against pathogens and parasites. Suppressed immune defences reduce fitness by causing disease-driven mortality and elevated immune responses reduce energy available to invest in other fitness traits such as reproduction. Understanding the impact of anthropogenic factors on insect-pathogen interactions is therefore key to determining the contribution of anthropogenic global change to pathogen-driven global insect decline and the emergence and transmission of insect-borne diseases. Here, we synthesise evidence of the impact of anthropogenic factors on insect immunity. We found evidence that anthropogenic factors, such as insecticides and heavy metals, directly impacting insect immune responses by inhibiting immune activation pathways. Alternatively, factors such as global warming, heatwaves, elevated CO2 and landscape degradation can indirectly reduce insect immune responses via reducing the energy available for immune function. We further review how anthropogenic factors impact pathogen clearance and contribute to an increase in vector-borne diseases. We discuss the fitness cost of anthropogenic factors via pathogen-driven mortality and reduced reproductive output and how this can contribute to species extinction. We found that most research has determined the impact of a single anthropogenic factor on insect immune responses or pathogen resistance. We recommend studying the combined impact of multiple stressors on immune response and pathogen resistance to understand better how anthropogenic factors affect insect immunity. We conclude by highlighting the importance of initiatives to mitigate the impact of anthropogenic factors on insect immunity, to reduce the spread of vector-borne diseases, and to protect vulnerable ecosystems from emerging diseases.

Fungicide consumption exacerbates the negative effects of a common gut parasite in bumble bee microcolonies

Bumble bees face numerous environmental stressors, including gut-parasite infection and exposure to agricultural fungicides, which can negatively impact colony health. This study evaluates the interactive effects of these stressors on bumble bee (Bombus impatiens) microcolonies, focusing on colony development, worker survival and parasite infection dynamics. Our aim in evaluating these interactions was to determine if bees would experience synergistic negative health outcomes compared to single- stressor exposures. We reared 40 queenless bumble bee microcolonies, and treated them with either fungicide-contaminated pollen, inoculation with a gut parasite, both, or neither. Contrary to original expectations, we did not observe significant synergistic interactions between the two stressors; however, we found that consumption of fungicide was associated with higher likelihood of gut-parasite infection, and delayed recovery from infection. Fungicide consumption was also connected to smaller workers, and smaller male offspring. We also found that gut-parasite infection was correlated with decreased pollen consumption overall, decreased worker survival and fewer developed pupae. This study provides insights into the impacts of co-occurring stressors affecting bumble bees and emphasizes the importance of sublethal effects on pollinator health.

Fire Is Associated With Positive Shifts in Bumble Bee (Bombus vosnesenskii) Body Size and Bee Abundance in the Southern Sierra Nevada Mountains

Climate change is increasing the frequency and severity of wildfires worldwide. Although wildfires are typically viewed as destructive, emerging research suggests they may have benefits for some species, including some pollinators. One reason for this is that wildfires can increase floral resource availability in the years immediately following the burn, potentially creating more favorable conditions for pollinator foraging and reproduction. In this study, we focused on how the 2021 KNP Complex Fire impacted the bumble bee Bombus vosnesenskii in the Southern Sierra Mountains, where the effects of fire on this pollinator species have not been previously explored. Consistent with bumble bee studies in other areas, we found an increase in the size of B. vosnesenskii workers in recently burned areas. This effect was detectable despite a limited number of sampling events and locations in our study, and irrespective of the habitat type (meadow vs. forest) in which sampling occurred. We failed to detect increased floral resource availability (abundance or diversity) in burned areas but did observe unique floral communities in burned areas. Our findings contribute to our growing understanding of fire's impact on pollinators and support the broad idea that fire might have benefits for some organisms.

Effect of farm size on vulnerability in beekeeping: Insights from mediterranean Spain

There is broad consensus on the socioeconomic importance of beekeeping and the essential services it provides through pollination. However, beekeeping is being impacted by global environmental changes, and more specific insights are needed. Beekeeping is not a homogeneous activity; it is practiced in various ways and contexts. This study examines how these changes affect beekeeping operations of different sizes in Mediterranean Spain and whether size influences adaptation. Structured interviews were conducted to assess the sector's vulnerability, with climate change identified as a key contributing factor. The findings reveal that the vulnerability of beekeeping is shaped not only by multiple transformations but also by the diverse adaptive capacities of beekeepers. Additionally, the size of beekeeping operations significantly influences this capacity, a factor that should be integrated into policymaking given the sector's highly polarized nature.

Diversity of plant pollen sources, microbial communities, and phenolic compounds present in bee pollen and bee bread

The pollination of several crops, as well as wild plants, depends on honeybees. To get the nutrients required for growth and survival, honeybee colonies are dependent on pollen supply. Bee pollen (BP) is partially packed in honeycomb cells and processed into beebread (BB) by microbial metabolism. The composition of pollen is highly variable and is mainly dependent on ecological habitat, geographical origin, honey plants, climatic conditions, and seasonal variations. Although there are important differences between the BP and the BB, little comparative chemical and microbiological data on this topic exists in the literature, particularly for samples with the same origin. In this study, BP and BB pollen samples were collected from two apiaries located in the Campania and Molise regions of Southern Italy. Phenolic profiles were detected via HPLC, while antioxidant activity was determined by ABTS·+ and DPPH· assay. The next-generation sequencing (NGS) based on RNA analysis of 16S (rRNA) and internal transcribed spacer (ITS2) regions were used to investigate the microbial community (bacteria and fungi) and botanical origin of the BP and BB. Chemical analysis showed a higher content of flavonols in BP (rutin, myricetin, quercetin, and kaempferol), while in BB there was a higher content of phenolic acids. The NGS analysis revealed that the microbial communities and pollen sources are dependent on the geographical location of apiaries. In addition, diversity was highlighted between the microbial communities present in the BP and BB samples collected from each apiary.

Environmental pollution effect on honey bees and their derived products: a comprehensive analysis

Several factors, including environmental degradation, air pollution, intense urbanization, excessive agriculture, and climate change, endanger the well-being of animals and plants. One of the major issues with an increasingly negative impact is agricultural contamination with pesticides and antibiotics. Seed coatings with neonicotinoid insecticides used as a protective layer against pests are shown to exceed the permissible limits in most cases. Neonicotinoid compounds bind to nicotinic acetylcholine receptors, therefore affecting the honey bees' brain. Heavy metals in higher concentrations are lethal for honey bees, and the residue in bee products might pose a threat to human health. Highly effective acaricides used to treat Varroa destructor infestations in honey bee colonies have negative effects on honey bee reproduction, olfaction, and honey production. Furthermore, amitraz and fluvalinate are mostly found in the highest amounts and lead to decreased honey production and reduced colony reproduction, along with decreased learning ability and memory. However, scientific studies have shown that honey bees act as a reliable bio-indicator of environmental pollution. In response to the growing demand for bee products, the effects of adulteration and improper storage conditions have gotten worse and represent a new risk factor. In light of the shifting global economy, it is important to analyze consumer expectations and adjust manufacturing accordingly. By ensuring the manufacture of high-quality, traceable products devoid of drug residues, consumers will be better protected from subsequent health problems. This review's objectives are based on the necessity of identifying the risks associated with honey bees and bee products.

Mitigating pesticide risk on bee pollinators and angiosperm biodiversity in the Ndop wetlands: A conservation approach

This study aimed to assess the risk of pesticides on bee pollinators and propose strategies to conserve entomophilous angiosperm species in the Ndop wetlands. Results showed that the applied pesticide doses were often excessive, increasing the exposure toxicity ratios (ETR). Among the pesticides, insecticides posed the highest risk to bee pollinators, with Emamectin benzoate (ETR=591.4) presenting the highest risk, followed by imidacloprid (ETR=517.5), fipronil (ETR=496.4), chlorpyrifos (ETR=240.7), and cypermethrin (ETR=131). Lambda-cyhalothrin (ETR=50.53) posed a possible risk. The study found that imidacloprid, fipronil, and chlorpyrifos posed definite risks through dietary exposure, while Emamectin benzoate, fipronil, and cypermethrin posed risks through direct contact. Approximately 46.03 % of angiosperms are anemophilous while 53 % are entomophilous with bee pollinators facilitating the pollination of nearly 90 % of the entomophilous species. To mitigate pesticide risks and for conservation purposes, farmers should refrain from applying pesticides during blooming and peak pollinator activity times, particularly midday.

Evaluating LiDAR-Derived Structural Metrics for Predicting Bee Assemblages in Managed Forests

Globally, many insects depend on forest habitat for critical nesting and floral resources. Forest structural complexity can affect the distribution of these resources and likewise alter insect assemblages within forests. Despite the importance of temperate deciduous forests for bees and their outsized contribution to pollination services within forests and beyond, the relationship between forest structure and bees has received scant attention. This is especially true in managed temperate deciduous forests, where management strategies alter forest structural complexity and may therefore affect bee communities. We investigated whether structural metrics derived from light detection and ranging (LiDAR) data could predict bee diversity and abundance, as well as bee functional trait composition within managed and unmanaged forests in the central hardwood region in southern Illinois, United States of America. We addressed three specific questions: (1) How does forest management affect structural complexity; (2) Can structural metrics predict bee diversity and abundance in spring and summer; and (3) How are structural metrics related to bee functional trait composition? We found that LiDAR-derived structural metrics could not differentiate between management types and were weak predictors of bee diversity and abundance and bee functional trait composition. Metrics related to understory and midstory vegetation structure showed the strongest association with forest bee community patterns. Specifically, vegetation density in the understory (0-2 m) had a positive effect on bee diversity and abundance in spring, while in summer, vegetation density in the mid-canopy (2-5 m) negatively affected bee communities. Our findings suggest mid- and understory vegetation structure, specifically vegetation density, may influence forest bee communities. Future studies should focus on the structural elements of these forest strata to improve understanding of how structural complexity influences bee communities within managed forests and evaluate the potential for using LiDAR-derived structural metrics to monitor and predict biodiversity patterns.

Honey bee immune response to trace concentrations of clothianidin goes beyond the macronutrients found in artificial diets

Honey bees (Apis mellifera) often encounter a variety of stressors in their environment, including poor nutrition and pesticides. These stressors interact and can be exacerbated in large-scale agroecosystems. We investigated how diets varying in macronutrient ratios can affect nurse bee susceptibility to pesticide stressors. Nurse bees were fed trace concentrations of clothianidin (CLO), a neonicotinoid insecticide known to have sublethal and lethal effects on honey bees, after newly emerged bees were given diets varying in proteins and lipids, a natural pollen diet, or sucrose solution diet. Bees given pollen had improved longevity, physiology, enzyme activity, and gene expression related to pesticide detoxification. The artificial diets helped improve bee health and physiology but did little to promote bee detoxification enzymes and genes. There was no effect of the trace CLO treatments on its own, but there was an interactive effect between our higher CLO treatment and poor nutrition on bee longevity and vitellogenin expression. Our results suggest that (1) exposure to even trace concentrations of CLO can interact with poor nutrition to undermine adult bee health and (2) macronutrients in artificial diets can help promote bee physiology, but other nutrients in pollen, such as potentially phytochemicals, are more directly linked honey bee tolerance to pesticide stress.

Neonicotinoid and EBI fungicide in combination hazard the population of red mason bees under field conditions

Mixing several agrochemicals, e.g., insecticides, fungicides, and herbicides, is a common practice by farmers, enhancing the economic and efficacy of a single application. Their effects on non-target organisms are not routinely evaluated during the authorisation of single products. A field study was conducted in Germany to assess the performance and exposure level of red mason bees after application of a combination of products containing the insecticide thiacloprid and the fungicide prochloraz to winter oilseed rape. The number of offspring of exposed bees was significantly reduced by 49.8 % compared to unexposed bees. Lower residues of applied active substances were found in mud walls than in pollen provision. The maximum detected concentrations in pollen provisions were 129.95 µg/kg for thiacloprid and 149.96 µg/kg for prochloraz, whereas 4.70 µg/kg for thiacloprid and 65.83 µg/kg for prochloraz in mud walls. An application restriction during flowering will minimize exposure and mitigate the high risk.

Sublethal pesticide exposure decreases mating and disrupts chemical signaling in a beneficial pollinator

Pesticides provide vital protection against insect pests and the diseases they vector but are simultaneously implicated in the drastic worldwide decline of beneficial insect populations. Convincing evidence suggests that even sublethal pesticide exposure has detrimental effects on both individual- and colony-level traits, but the mechanisms mediating these effects remained poorly understood. Here, we use bumble bees to examine how sublethal exposure to pesticides affects mating, a key life history event shared by nearly all insects, and whether these impacts are mediated via impaired sexual communication. In insects, mate location and copulation are primarily regulated through chemical signals and rely on both the production and perception of semiochemicals. We show through behavioral bioassays that mating success is reduced in bumble bee gynes after exposure to field-relevant sublethal doses of imidacloprid, and that this effect is likely mediated through a disruption of both the production and perception of semiochemicals. Semiochemical production was altered in gyne and male cuticular hydrocarbons (CHCs), but not in exocrine glands where sex pheromones are presumably produced (i.e., gyne mandibular glands and male labial glands). Male responsiveness to gyne mandibular gland secretion was reduced, but not the queen responsiveness to the male labial secretion. In addition, pesticide exposure reduced queen fat body lipid stores and male sperm quality. Overall, the exposure to imidacloprid affected the fitness and CHCs of both sexes and the antennal responses of males to gynes. Together, our findings identify disruption of chemical signaling as the mechanism through which sublethal pesticide exposure reduces mating success.

An RPA-CRISPR/Cas12a based platform for rapid, sensitive, and visual detection of Apis mellifera filamentous virus

Apis mellifera filamentous virus (AmFV) is an emerging DNA virus significantly affecting honey bee health. AmFV infections weaken bee resistance to other pathogens, and can cause tissue lysis and death. Early, accurate detection of AmFV is crucial for timely intervention and preventing large-scale outbreaks. Current AmFV detection relies largely on polymerase chain reaction (PCR)-based methods. To enable rapid field detection of AmFV, we developed a rapid and ultrasensitive detection platform using recombinase polymerase amplification (RPA) combined with clustered regularly interspaced short palindromic repeats (CRISPR) / CRISPR-associated nuclease 12a (Cas12a) technology. A CRISPR RNA (crRNA1) specifically targeting the AmFV Bro gene was designed, ensuring no cross-reactivity with other insect DNA viruses or uninfected honey bees. After optimization of the reaction time, the platform generated results within 35 min: 20 min for the RPA reaction and 15 min for CRISPR-mediated cleavage. Two visualization approaches, fluorescence-based and lateral flow dipstick, were used to display the detection results. The detection sensitivity of both approaches was as few as 10 copies of the AmFV genome. Validation with field-collected honey bee samples demonstrated consistency with conventional PCR, revealing widespread latent AmFV infections in the field. Taken together, we successfully developed an RPA-CRISPR/Cas12 platform for rapid, specific, and sensitive detection of AmFV in Apis mellifera and Apis cerana. This platform holds promise as a simple, accurate, and cost-effective tool for point-of-care AmFV diagnosis in the field.

Reduced Honeybee Pollen Foraging under Neonicotinoid Exposure: Exploring Reproducible Individual and Colony Level Effects in the Field Using AI and Simulation

Honeybees (Apis mellifera) are important pollinators. Their foraging behaviors are essential to colony sustainability. Sublethal exposure to pesticides such as neonicotinoids can significantly disrupt these behaviors, in particular pollen foraging. We investigated the effects of sublethal doses of the neonicotinoid imidacloprid on honeybee foraging, at both individual and colony levels, by integrating field experiments with artificial intelligence (AI)-based monitoring technology and mechanistic simulations using the BEEHAVE model. Our results replicated previous findings, which showed that imidacloprid selectively reduces pollen foraging at the colony level, with minimal impact on nectar foraging. Individually marked exposed honeybees exhibited prolonged pollen foraging trips, reduced pollen foraging frequency, and instances of drifting pollen foraging trips, likely due to impaired cognitive functions and altered metabolism. These behavioral changes at the individual level corroborated the previous model predictions derived from BEEHAVE, which highlights the value of combining experimental and simulation approaches to disentangle underlying mechanisms through which sublethal effects on individual foragers scale up to impact colony dynamics. Our findings have implications for future pesticide risk assessment, as we provide a robust feeding study design for evaluating pesticide effects on honeybee colonies and foraging in real landscapes, which could improve the realism of higher-tier ecological risk assessment.

Evaluation of herbicide formulations and spreading agents on survival of the bumblebee Bombus impatiens following spray and contact exposure

Surfactants are often included as co-formulants in the application of herbicides to aid in spreading and adherence to plant surfaces, but toxicity to native bees has not been extensively tested. In a set of progressive experiments, we evaluated effects of products containing glyphosate and spreading agents, as well as spreading agents alone, on bumblebees (Bombus impatiens Cresson) using parametric survival analysis. We test spreaders from multiple chemical classes including Silwet L-77© (trisiloxane), Alligare 90© (polyoxyethylene), and Southern Ag SA-50© (C10-16 alcohols). We report low lethality of high-glyphosate herbicide formulations (Rodeo©), but bee mortality increased ~20% with addition of a silicone-based spreading agent (Silwet L-77©). Spreaders alone strongly affected bee survival: effects were concentration-specific and did not differ depending on exposure method (spray application vs. application to surfaces contacted by bees). The widely used trisiloxane-based spreader Silwet L-77© was especially hazardous, and exposure to high concentrations of Silwet L-77© caused rapid and near-total mortality in B. impatiens. Analysis of whole-bee cuticle extracts after exposure revealed clear differences in the cuticular hydrocarbon profiles associated with exposure to spreading agents: the alkane n-hexacosane was present in all extracts but was detected in greater relative abundance from bees exposed to Silwet L-77© and Alligare 90©. To support wild bee conservation efforts, we recommend substituting alcohol-based spreaders for siloxane-based spreaders when possible. In addition, certain cuticular hydrocarbons may be useful as biomarkers of previous exposure to certain surfactants, which can aid investigations evaluating causes of bumblebee decline across landscapes.

Lactic Acid Bacteria: A Probiotic to Mitigate Pesticide Stress in Honey Bee

Using probiotics, especially those containing lactic acid bacteria (LAB), to support honey bee health and alleviate the negative effects of pesticides represents a promising approach for sustainable beekeeping. Probiotics have shown their ability to boost honey bee immune systems, counteract pesticide impacts, and lower disease rates. Bacteria like Lactobacillus and Bifidobacterium have demonstrated their ability to degrade organophosphorus pesticides using phosphatase enzymes. Additionally, these bacteria are resistant to the harmful effects of pesticides and aid in detoxification. Furthermore, supplementing with LAB positively affects colony growth, resulting in increased honey production, improved pollen storage, and higher brood counts. Various methods of delivering probiotics, such as powdered supplements, sucrose syrup, and pollen patties, have been explored, each with its own set of challenges and considerations. Despite making significant progress, further study is still required to fully comprehend the precise interactions between probiotics and the physiology of honey bees, to improve delivery strategies, and to evaluate the wider ecological effects on hive microbiomes. By implementing probiotic strategies in beekeeping practices, we can create stronger and more resilient honey bee colonies that can thrive amidst environmental challenges, thus promoting the sustainability of pollination services.

Forecasting the Impact of Climate Change on Apis dorsata (Fabricius, 1793) Habitat and Distribution in Pakistan

Climate change has led to global biodiversity loss, severely impacting all species, including essential pollinators like bees, which are highly sensitive to environmental changes. Like other bee species, A. dorsata is also not immune to climate change. This study evaluated the habitat suitability of A. dorsata under climate change in Pakistan by utilizing two years of occurrence and distribution data to develop a Maximum Entropy (MaxEnt) model for forecasting current and future habitat distribution. Future habitat projections for 2050 and 2070 were based on two shared socioeconomic pathways (SSP245 and SSP585) using the CNRM-CM6-1 and EPI-ESM1-2-HR-1 global circulation models. Eight bioclimatic variables (Bio1, Bio4, Bio5, Bio8, Bio10, Bio12, Bio18, and Bio19) were selected for modeling, and among the selected variables, the mean temperature of the wettest quarter (Bio8) and precipitation of the warmest quarter (Bio18) showed major contributions to the model building and strongest influence on habitat of A. dorsata. The model estimated 23% of our study area as a suitable habitat for A. dorsata under current climatic conditions, comprising 150,975 km2 of moderately suitable and 49,792 km2 of highly suitable regions. For future climatic scenarios, our model projected significant habitat loss for A. dorsata with a shrinkage and shift towards northern, higher-altitude regions, particularly in Khyber Pakhtunkhwa and the Himalayan foothills. Habitat projections under the extreme climatic scenario (SSP585) are particularly alarming, indicating a substantial loss of the suitable habitat for the A. dorsata of 40% under CNRM-CM6-1 and 79% for EPI-ESM1-2-HR-1 for the 2070 time period. This study emphasizes the critical need for conservation efforts to protect A. dorsata and highlights the species' role in pollination and supporting the apiculture industry in Pakistan.