A combination of Tropilaelaps mercedesae and imidacloprid negatively affects survival, pollen consumption and midgut bacterial composition of honey bee

Interactive effects of chlorothalonil and Varroa destructor on Apis mellifera during adult stage

The interaction between environmental factors affecting honey bees is of growing concern due to their potential synergistic effects on bee health. Our study investigated the interactive impact of Varroa destructor and chlorothalonil on workers' survival, fat body morphology, and the expression of gene associated with detoxification, immunity, and nutrition metabolism during their adult stage. We found that both chlorothalonil and V. destructor significantly decreased workers' survival rates, with a synergistic effect observed when bees were exposed to both stressors simultaneously. Morphological analysis of fat body revealed significant alterations in trophocytes, particularly a reduction in vacuoles and granules after Day 12, coinciding with the transition of the bees from nursing to other in-hive work tasks. Gene expression analysis showed significant changes in detoxification, immunity, and nutrition metabolism over time. Detoxification genes, such as CYP9Q2, CYP9Q3, and GST-D1, were downregulated in response to stressor exposure, indicating a potential impairment in detoxification processes. Immune-related genes, including defensin-1, Dorsal-1, and Kayak, exhibited an initially upregulation followed by varied expression patterns, suggesting a complex immune response to stressors. Nutrition metabolism genes, such as hex 70a, AmIlp2, VGMC, AmFABP, and AmPTL, displayed dynamic expression changes, reflecting alterations in nutrient utilization and energy metabolism in response to stressors. Overall, these findings highlight the interactive and dynamic effects of environmental stressor on honey bees, providing insights into the mechanisms underlying honey bee decline. These results emphasize the need to consider the interactions between multiple stressors in honey bee research and to develop management strategies to mitigate their adverse effects on bee populations.

Interactive effects of dinotefuran and Nosema ceranae on the survival status and gut microbial community of honey bees

Growing evidences have shown that the decline in honey bee populations is mainly caused by the combination of multiple stressors. However, the impacts of parasitic Nosema ceranae to host fitness during long-term pesticide exposure-induced stress is largely unknown. In this study, the effects of chronic exposure to a sublethal dose of dinotefuran, in the presence or absence of N. ceranae, was examined in terms of survival, food consumption, detoxification enzyme activities and gut microbial community. The interaction between dinotefuran and Nosema ceranae on the survival of honey bee was synergistic. Co-exposure to dinotefuran and N. ceranae led to less food consumption and greater changes of enzyme activities involved in defenses against oxidative stress. Particularly, N. ceranae and dinotefuran-N. ceranae co-exposure significantly impacted the gut microbiota structure and richness in adult honey bees, while dinotefuran alone did not show significant alternation of core gut microbiota compared to the control group. We herein demonstrated that chronical exposure to dinotefuran decreases honey bee's survival but is not steadily associated with the gut microbiota dysbiosis; by contrast, N. ceranae parasitism plays a dominant role in the combination in influencing the gut microbial community of the host honey bee. Our findings provide a comprehensive understanding of combinatorial effects between biotic and abiotic stressors on one of the most important pollinators, honey bees.

Synergistic activation of persulfate by FeS@SBA-15 for imidacloprid degradation: Efficiencies, activation mechanism and degradation pathways

In this work, FeS supported SBA-15 mesoporous silica catalyst (FeS@SBA-15) was synthesized successfully, characterized and first applied to persulfate (PS) activation for the degradation of imidacloprid in wastewater. The as-prepared 3.5-FeS@SBA-15 presented an impressive imidacloprid removal efficiency of 93.1% and reaction stoichiometric efficiency (RSE) of 1.82% after 5 min, ascribed to the synergetic effects of improved FeS dispersion and abundant surface sites by SBA-15. Electron paramagnetic resonance spectra and quenching experiments proved that both SO4·- and ·OH were produced in FeS@SBA-15/PS system, and SO4·- played a dominant role in the degradation process. The S2- can accelerate the cycling of Fe(III)/Fe(II) during activation and increase the steady-state concentration of Fe(II). More importantly, the constructed heterogeneous system exhibited an efficient and stable catalytic activity over a wide range of pH (3.0-9.0), temperature (283K-313K), inorganic ion (NO3-) and humic acid (1-20 mg/L). Moreover, the density functional theory calculations were conducted to predict the potential reaction sites of imidacloprid. Based on eighteen identified intermediates, four main degradation pathways were proposed: hydroxylation, dechlorination, hydrolysis, and the ring cleavage of the imidazolidine. ECOSAR analysis indicated hydroxylation and dechlorination played a key role in the detoxification of the formed compounds. These findings would provide new insights into the application of FeS@SBA-15 catalyst in wastewater treatment and the removal mechanism of imidacloprid from wastewater.

Tropilaelaps mercedesae Infestation Is Correlated with Injury Numbers on the Brood and the Population Size of Honey Bee Apis mellifera

Tropilaelaps mercedesae, one of the most devastating parasitic mites of honey bee Apis mellifera hosts, is a major threat to honey products by causing severe damage to honey bee colonies. Here, we recorded injury numbers caused by T. mercedesae to different body parts of the larval, pupal, and crippled adult stages of honey bee A. mellifera. We evaluated the relationship between infestation rate and injury numbers per bee for both larvae and pupae. We also noted the total bee numbers per beehive and examined the relationship between the infestation rate and population size. T. mercedesae infested all developmental stages of honey bees, with the highest injury numbers in the abdomens of bee pupae and the antennas of crippled adult bees. Although larvae received more injury numbers than pupae, both infestation rate and injury numbers decreased as the larval stage progressed to the pupal stage. The infestation rate increased as the population size per beehive decreased. This study provided new perspectives to the understanding of changes in the effects of T. mercedesae infestations on different developmental stages of honey bees. It also showed useful baseline information for screening honey bee stock that might have high defensive behaviors against mite infestation.

Consumption Structure Optimization Strategy for Scenic Spots Using the Deep Learning Model under Digital Economy

The purpose is to find out the problems existing in the consumption economy structure of the scenic spots and to promote the rationalization of the consumption economy of the scenic spots. Based on the analysis of the applicability of the backpropagation neural network (BPNN) model, it uses BPNN to analyze the economic development level of Overseas Chinese Town East (OCT East). Firstly, the weight of each index is determined by the Analytic Hierarchy Process (AHP), and the expected value of the comprehensive evaluation is obtained. Secondly, to ensure the validity of the evaluation model for the development level of the tourism complex, the BPNN model is trained and tested to enable it to be applied to the evaluation of the economic development level of OCT East. The development level of OCT East from 2012 to 2021 is divided into three stages: high, higher, and lower. The development characteristics and existing problems of the OCT East are analyzed, and the optimization strategy of the consumption economy of the scenic spots is put forward in a targeted manner. The research results manifest, that from 2012 to 2021, the development level index of OCT East increased from 0.2457 to 0.5304, and it was in a state of steady growth. In 2019, the development level index reached 0.6497, and it was upgraded to "high-level," but the average development level index of OCT East was only 0.5662, and there was a lot of room for improvement. According to the divided evaluation indicators, the development level of OCT East is evaluated. In 2012, the development level was low. From 2013 to 2018, it was at a high level, and from 2019 to 2021, it was a high level of development. By studying the Tourism Consumption Structure (TCS) of scenic spots in the OCT East, the research method of the consumption economic structure has been expanded. Therefore, it not only provides a reference for optimizing the consumption of scenic spots, but also contributes to the progress of the social tourism economy.

Toxicity of Formulated Systemic Insecticides Used in Apple Orchard Pest Management Programs to the Honey Bee (Apis mellifera (L.))

Honey bees (Apis mellifera) are one of the most important pollinating species of flowering plants. Recently, populations of honey bees have been declining due to a combination of factors, including the widespread use of agricultural pesticides. Laboratory studies were conducted to determine the acute oral toxicity of different formulated pesticides to honey bee adults. In particular, we assessed the acute oral toxicity of two neonicotinoids (acetamiprid, Assail 30SG and thiamethoxam, Actara 25WDG) and two other systemic insecticide products (sulfoxaflor, Closer 2SC and flupyradifurone, Sivanto 200SL), all of which are generally used in pest management programs in commercial apple orchards in the Eastern United States. Honey bees were fed a range of doses of each pesticide in order to create a response curve, and LC50, LC90, and LD50 values were determined. The pesticide formulation containing flupyradifurone as the active ingredient was found to be the least toxic to honey bees followed by the formulations containing sulfoxaflor and acetamiprid. The toxicity values obtained in this study differ from other studies testing only technical active ingredient compounds, suggesting the need to evaluate formulated products while conducting ecotoxicological risk assessment.

Chlorothalonil alters the gut microbiota and reduces the survival of immature honey bees reared in vitro

BACKGROUND

Chlorothalonil is a nonsystemic fungicide, and it is one of the most widely detected pesticides in bee hives. The effect of chlorothalonil on the survival, weight, and gut microbiota of immature Apis mellifera L. reared in vitro was studied.

RESULTS

Larvae were fed 1, 2, 4, 8, and 16 μg/mL chlorothalonil and compared with larvae fed the negative control (diet without any additives), positive control (45 mg/L dimethoate), and solvent control (2% acetone). Compared with the control groups, the survival of the 2, 4, 8, and 16 μg/mL chlorothalonil treatments was significantly reduced. The no-observed-adverse-effect concentration of chlorothalonil was 1 μg/mL. Chlorothalonil had no significant effect on larval weight. The gut bacterial community composition of newly emerged bees was determined by PacBio 16S rDNA gene sequencing. linear discriminant analysis effect size (LEFSe) analysis showed that Pseudomonadales and Burkholderiales were affected by exposure to chlorothalonil.

CONCLUSION

Chlorothalonil reduced the survival of honey bee larvae and altered the gut microbiota of newly emerged bees. The risk of pesticides to honey bees is related to their toxicity and exposure dose.

Impact of imidacloprid exposure on the biochemical responses, transcriptome, gut microbiota and growth performance of the Pacific white shrimp Litopenaeus vannamei

The widespread use of neonicotinoid insecticides, such as imidacloprid, in agriculture is one of the key factors for the drop in the survival of invertebrates, including decapod crustaceans. However, there is currently a lack of comprehensive studies on the chronic toxicity mechanisms in decapod crustaceans. Here, the concentration-dependent effects of imidacloprid on the physiology and biochemistry, gut microbiota and transcriptome of L. vannamei , and the interaction between imidacloprid, gut microbiota and genes were studied. Imidacloprid caused oxidative stress, leading to reduced growth and to immunity and tissue damage in L. vannamei . Imidacloprid increased the gut pathogenic microbiota abundance and broke the steady state of the gut microbiota interaction network, resulting in microbiota function disorders. Chronic imidacloprid exposure induced overall transcriptome changes in L. vannamei . Specifically, imidacloprid caused a large number of differentially expressed genes (DEGs) to be significantly downregulated. The inhibition of autophagy-related pathways revealed the toxic process of imidacloprid to L. vannamei . The changes in phase I and II detoxification gene expression clarified the formation of a detoxification mechanism in L. vannamei . The disturbance of circadian rhythm (CLOCK) caused by imidacloprid is one of the reasons for the increase in gut pathogenic microbiota abundance.

Tropilaelaps mercedesae parasitism changes behavior and gene expression in honey bee workers

Tropilaelaps mercedesae is one of the most problematic honey bee parasites and has become more threatening to the beekeeping industry. Tropilaelaps can easily parasitize immature honey bees (larvae and pupae) and have both lethal and sublethal effects on the individual worker bees. Our study for the first time experimentally assessed the effects of T. mercedesae on olfactory learning, flight ability, homing ability as well as transcriptional changes in parasitized adult honey bees. T. mercedesae infestation had negative impacts on olfactory associated function, flight ability, and homing rate. The volume of the mushroom body significantly increased in infested honey bees, which may be correlated to the lower sucrose responsiveness as well as lower learning ability in the infested bees. The gene expression involved in immune systems and carbohydrate transport and metabolism were significantly different between infested bees and non-infested bees. Moreover, genes function in cell adhesion play an essential role in olfactory sensory in honey bees. Our findings provide a comprehensive understanding of European honey bees in response to T. mercedesae infestation, and could be used to further investigate the complex molecular mechanisms in honey bees under parasitic stress.

In recent decades, there has been serious concern about the decline of honey bees in the world. One of the most serious factors contributing to bee population declines is mite parasitism. Although Varroa destructor is the most widespread globally, Tropilaelaps mercedesae displays greater threat to bee colonies due to its smaller size, shorter phoretic phase, more rapid locomotion, as well as faster reproductive rate. Tropilaelaps mites, originally parasite of the giant Asian honey bees, now becoming an emerging threat of European honey bees (Apis mellifera) in Asian area. This work aimed to investigate the influence of T. mercedesae infestation on behavior and gene expression in A. mellifera. Our results highlight the T. mercedesae infestation induced negative effects of olfactory learning, flight ability, homing ability of honey bee workers. Moreover, we found that T. mercedesae infestation caused the up-regulation of genes involved in immune systems and carbohydrate mechanism which were correlated to the different olfactory learning performance in infested honeybee. In addition, genes function in cell adhesion play an essential role in olfactory sensory in honey bees. Our results increase the knowledge of proximate mechanisms in honey bee responding to parasitic stress.