Nitenpyram disturbs gut microbiota and influences metabolic homeostasis and immunity in honey bee (Apis mellifera L.)

Knockdown of the β-N-acetylhexosaminidase genes by RNA interference inhibited the molting and increased the mortality of the white-backed planthopper, Sogatella furcifera

β-N-Acetylglucosaminidases and/or β-N-acetylhexosaminidases (NAGs / Hexes) are crucial exonucleases, playing a crucial role in the insect molting process. SfHex3 and SfHex4 contain conserved catalytic domains of GH20 and GH20b, clustered into NAG2 and NAG1 group, respectively. SfHex3 and SfHex4 were mainly highly expressed in the 4th-5th instar nymphs, as well as in the integument and ovary. The expression level of SfHex3 gradually decreased in male and female adults, and SfHex4 on the first day of female was significantly higher than that on the first day of male. In addition, RNA interference (RNAi) results demonstrated that the downregulation of SfHex3 and SfHex4 expression in 5th-instar nymphs resulted in failed molting, and a high mortality. Furthermore, after RNAi with SfHex3 and SfHex4, the transcript levels on key genes of the chitin metabolism pathway (SfCHS1, SfCHS1a, SfCHS1b, SfTRE1, SfTRE2, SfCht5, and SfCht7) were significantly decreased compared to the control group. Meanwhile the expression levels of SfHex3 and SfHex4 were up-regulated after 6 h and 12 h of 20E treatment. And the transcription levels of SfHex3 and SfHex4 were significantly inhibited at nitenpyram LC20, LC50, and LC90 after 96 h of treatment, in 3rd nymphs of Sogatella furcifera. In conclusion, SfHex3 and SfHex4 play important roles in the nymphal development of S. furcifera, contributing to the molting process from nymph to adult. This study not only enhances our understanding of the nitenpyram in pest control, but also provides a foundation for the development of new control strategies using RNAi to targeting SfHex3 and SfHex4.

Novel neonicotinoid insecticide cycloxaprid exhibits sublethal toxicity to honeybee (Apis mellifera L.) workers by disturbing olfactory sensitivity and energy metabolism

The risk of neonicotinoid insecticides to honeybees is a global issue. Cycloxaprid (CYC) is a novel neonicotinoid insecticide with outstanding activities, good safety profiles, and no cross-resistance with other neonicotinoids. Information on the environmental risks of CYC is limited, especially its effects on honeybees. Herein, the acute and chronic toxicities of CYC on honeybees were evaluated, and the underlying mechanisms were explored via transcriptomics and molecular docking. The results indicate that CYC had high toxicity to honeybees, with a 48-h oral median lethal dose of 32.8 ng/bee. Over a 10-days of chronic exposure to CYC at sublethal concentration 30 μg/L, the honeybees showed significantly decreased survival rates and food consumption. Additionally, the sensitivity of honeybees to sucrose and odors and CO2 production was significantly reduced. Furthermore, molecular docking revealed that CYC has higher binding affinity than odors to odorant-binding proteins, and the olfactory and metabolism pathways gene expression was negatively affected at transcriptome level. These findings indicate that CYC at sublethal concentration can pose risks to honeybees by affecting their olfactory function and energy metabolic balance. Further study and consideration are needed to fully exploit the benefits of this pesticide.

Examination of intestinal microbiota abundance of honey bees supplemented and unsupplemented with probiotic bacteria by QPCR

The aim of this study is to compare the bacterial load in the guts of honey bees supported and unsupplemented with probiotic supplements. To investigate the effects of a commercial bee probiotic containing different Lactobacillus species and different spice extracts on the composition of the gut microbiota of honey bees, QPCR counts of Lactobacillus spp. and Firmicutes phylum gene copies in gut mixtures from 12 different bee groups with and without probiotic supplementation were performed. There was a significant difference between the levels of Lactobacillus spp. in the guts of both groups. When Lactobacillus spp. levels in the guts of honey bees not given probiotics were compared to the Lactobacillus spp. levels in the guts of honey bees given probiotics, it was determined that there was an approximately 5.5-fold difference. However, it was observed that there was no significant difference in the Firmicutes load in the bee guts of both groups. These findings show that the applied probiotic formulation significantly affects the intestinal microbiome of healthy individuals and provides a proportional change in microbial abundance, especially in terms of Lactobacillus spp.

Simple preparation of nitenpyram-intercalated clay nanosheets with reduced leaching risk and improved safety to insect pollinators

Neonicotinoids, highly toxic to insects, are among the world's most used insecticides. However, their harmful effects on pollinators like honeybees and potential to contaminate water bodies have drawn significant criticism. Herein, a nanopesticide, NTP@LDH, was developed by intercalating the model neonicotinoid insecticide nitenpyram (NTP) within layered double hydroxide (LDH) materials using a simple one-pot method. The NTP@LDH showed a nano-sized sheet structure, with an average particle size of 206.2 nm and a loading capacity of 14.6 %. The release rate of NTP@LDH under acidic conditions was higher than that under alkaline or neutral conditions. The photodegradation capacity and insecticidal activity of NTP were unaffected by intercalation in LDH. Importantly, NTP@LDH could significantly enhance the foliar adhesive properties of NTP, retard its leaching through the soil, and improve its safety for honeybees. Moreover, LDH was safe for crops and can improve their growth. This work provides a promising strategy with a simple procedure that could reduce leaching risks of neonicotinoids while concurrently enhancing their safety to pollinating creatures.

The effect of lambda-cyhalothrin nanocapsules on the gut microbial communities and immune response of the bee elucidates the potential environmental impact of emerging nanopesticides

Emerging nanopesticides are gradually gaining widespread application in agriculture due to their excellent properties, but their potential risks to pollinating insects are not fully understood. In this study, lambda-cyhalothrin nanocapsules (LC-NCs) were constructed by electrostatic self-assembly method with iron mineralization optimization, and their effects on bee gut microbial communities and host immune-related factors were investigated. Microbiome sequencing revealed that LC-NCs increase the diversity of gut microbial communities and reduce the complexity of network features, disrupting the overall structure of the microbial communities. In addition, LC-NCs also had systemic effects on the immune response of bees, including increased activity of SOD and CAT enzymes and expression of their genes, as well as downregulation of Defensin1. Furthermore, we noticed that the immune system of the host was activated simultaneously with a rise in the abundance of beneficial bacteria in the gut. Our research emphasizes the importance of both the host and gut microbiota of holobiont in revealing the potential risks of LC-NCs to environmental indicators of honey bees, and provides references for exploring the interactions between host-microbiota systems under exogenous stress. At the same time, we hope that more research can focus on the potential impacts of nanopesticides on the ecological environment.

Enhanced capacity of a leaf beetle to combat dual stress from entomopathogens and herbicides mediated by associated microbiota

Herbicides have demonstrated their impact on insect fitness by affecting their associated microbiota or altering the virulence of entomopathogenic fungi toward insects. However, limited research has explored the implications of herbicide stress on the intricate tripartite interaction among insects, associated bacterial communities, and entomopathogens. In this study, we initially demonstrated that associated bacteria confer a leaf beetle, Plagiodera versicolora, with the capability to resist the entomopathogenic fungus Aspergillus nomius infection, a capability sustained even under herbicide glyphosate stress. Further analysis of the associated microbiota revealed a significant alteration in abundance and composition due to glyphosate treatment. The dominant bacterium, post A. nomius infection or following a combination of glyphosate treatments, exhibited strong suppressive effects on fungal growth. Additionally, glyphosate markedly inhibited the pathogenic associated bacterium Pseudomonas though it inhibited P. versicolora's immunity, ultimately enhancing the beetle's tolerance to A. nomius. In summary, our findings suggest that the leaf beetle's associated microbiota bestow an augmented resilience against the dual stressors of both the entomopathogen and glyphosate. These results provide insight into the effects of herbicide residues on interactions among insects, associated bacteria, and entomopathogenic fungi, holding significant implications for pest control and ecosystem assessment.

Honeybee gut bacterial strain improved survival and gut microbiota homeostasis in Apis mellifera exposed in vivo to clothianidin

Pesticides are causing honeybee mortality worldwide. Research carried out on honeybees indicates that application of pesticides has a significant impact on the core gut community, which ultimately leads to an increase in the growth of harmful pathogens. Disturbances caused by pesticides also affect the way bacterial members interact, which results in gut microbial dysbiosis. Administration of beneficial microbes has been previously demonstrated to be effective in treating or preventing disease in honeybees. The objective of this study was to measure under in vivo conditions the ability of two bacterial strains (the Enterobacter sp. and Pantoea sp.) isolated from honeybee gut to improve survival and mitigate gut microbiota dysbiosis in honeybees exposed to a sublethal clothianidin dose (0.1 ppb). Both gut bacterial strains were selected for their ability to degrade clothianidin in vitro regardless of their host-microbe interaction characteristics (e.g., beneficial, neutral, or harmful). To this end, we conducted cage trials on 4- to 6-day-old newly emerging honeybees. During microbial administration, we jointly monitored the taxonomic distribution and activity level of bacterial symbionts quantifying 16S rRNA transcripts. First, curative administration of the Pantoea sp. strain significantly improved the survival of clothianidin-exposed honeybees compared to sugar control bees (i.e., supplemented with sugar [1:1]). Second, curative administration of the Enterobacter sp. strain significantly mitigated the clothianidin-induced dysbiosis observed in the midgut structural network, but without improving survival.

IMPORTANCE

The present work suggests that administration of bacterial strains isolated from honeybee gut may promote recovery of gut microbiota homeostasis after prolonged clothianidin exposure, while improving survival. This study highlights that gut bacterial strains hold promise for developing efficient microbial formulations to mitigate environmental pesticide exposure in honeybee colonies.

Transcriptional response of laboratory-reared Mexican fruit flies (Anastrepha ludens Loew) to desiccation

Confronting environments with low relative humidity is one of the main challenges faced by insects with expanding distribution ranges. Anastrepha ludens (the Mexican fruit fly) has evolved to cope with the variable conditions encountered during its lifetime, which allows it to colonise a wide range of environments. However, our understanding of the mechanisms underpinning the ability of this species to confront environments with low relative humidity is incomplete. In this sense, omic approaches such as transcriptomics can be helpful for advancing our knowledge on how this species copes with desiccation stress. Considering this, in this study, we performed transcriptomic analyses to compare the molecular responses of laboratory-reared A. ludens exposed and unexposed to desiccation. Data from the transcriptome analyses indicated that the responses to desiccation are shared by both sexes. We identified the up-regulation of transcripts encoding proteins involved in lipid metabolism and membrane remodelling, as well as proteases and cuticular proteins. Our results provide a framework for understanding the response to desiccation stress in one of the most invasive fruit fly species in the world.

Early-Life Sublethal Exposure to Thiacloprid Alters Adult Honeybee Gut Microbiota

Thiacloprid, a neonicotinoid pesticide, is known to affect the gut microbiome of honeybees, yet studies often focus on immediate alternations during exposure, overlooking long-term microbiological impacts post-exposure. This study investigates the influences of sublethal thiacloprid administered during the larval developmental stage of honeybees on physiological changes and gut microbiota of adult honeybees. We found that thiacloprid exposure increased mortality and sugar intake in emerged honeybees. Using 16S rDNA sequencing, we analyzed intestinal microbial diversity of honeybees at one and six days post-emergence. Our findings reveal a significant but transient disruption in gut microbiota on day 1, with recovery from dysbiosis by day 6. This study emphasizes the importance of evaluating chronic sublethal exposure risks of thiacloprid to protect honeybee health.

Uncovering hidden dangers: The combined toxicity of abamectin and lambda-cyhalothrin on honey bees

Studying the toxic effects of pesticides on bees has consistently been a prominent area of interest for researchers. Nonetheless, existing research has predominantly concentrated on individual toxicity assessments, leaving a gap in our understanding of mixed toxicity. This study delves into the individual and combined toxic effects of abamectin (ABA) and lambda-cyhalothrin (LCY) on honey bees (Apis mellifera) in laboratory settings. We discovered that ABA (96 h-LC50 value of 0.079 mg/L) exhibited greater acute toxicity to honey bees compared to LCY (96 h-LC50 value of 9.177 mg/L). Moreover, the mixture of ABA and LCY presented an acute antagonistic effect on honey bees. Additionally, our results indicated that exposure to LCY, at medium concentration, led to a reduction in the abundance of gut core bacterium Snodgrassella. However, an increase in the abundance of Bifidobacterium was noted when exposed to a medium concentration of LCY and its mixture with ABA. Transcriptomic analysis revealed significant regulation of certain genes in the medium concentration of all three treatments compared to the control group, primarily enriching in metabolism and immune-related pathways. Following chronic exposure to field-relevant concentrations of ABA, LCY, and their mixture, there were significant alterations in the activities of immunity-related enzyme polyphenol oxidase (PPO) and detoxification enzymes glutathione S-transferase (GST) and carboxylesterase (CarE). Additionally, the expression of four genes (abaecin, cyp9e2, cyp302a1, and GstD1) associated with immune and detoxification metabolism was significantly altered. These findings suggest a potential health risk posed by the insecticides ABA and LCY to honey bees. Despite exhibiting acute antagonistic effect, mixed exposure still induced damage to bees at all levels. This study advances our knowledge of the potential adverse effects of individual or combined exposure to these two pesticides on non-target pollinators and offers crucial guidance for the use of insecticides in agricultural production.

Toxic effects of acaricide fenazaquin on development, hemolymph metabolome, and gut microbiome of honeybee (Apis mellifera) larvae

Fenazaquin, a potent insecticide widely used to control phytophagous mites, has recently emerged as a potential solution for managing Varroa destructor mites in honeybees. However, the comprehensive impact of fenazaquin on honeybee health remains insufficiently understood. Our current study investigated the acute and chronic toxicity of fenazaquin to honeybee larvae, along with its influence on larval hemolymph metabolism and gut microbiota. Results showed that the acute median lethal dose (LD50) of fenazaquin for honeybee larvae was 1.786 μg/larva, and the chronic LD50 was 1.213 μg/larva. Although chronic exposure to low doses of fenazaquin exhibited no significant effect on larval development, increasing doses of fenazaquin resulted in significant increases in larval mortality, developmental time, and deformity rates. At the metabolic level, high doses of fenazaquin inhibited nucleotide, purine, and lipid metabolism pathways in the larval hemolymph, leading to energy metabolism disorders and physiological dysfunction. Furthermore, high doses of fenazaquin reduced gut microbial diversity and abundance, characterized by decreased relative abundance of functional gut bacterium Lactobacillus kunkeei and increased pathogenic bacterium Melissococcus plutonius. The disrupted gut microbiota, combined with the observed gut tissue damage, could potentially impair food digestion and nutrient absorption in the larvae. Our results provide valuable insights into the complex and diverse effects of fenazaquin on honeybee larvae, establishing an important theoretical basis for applying fenazaquin in beekeeping.

Exposure to nanoplastics and nanomaterials either single and combined affects the gill-associated microbiome of the Antarctic soft-shelled clam Laternula elliptica

Nanoplastics and engineering nanomaterials (ENMs) are contaminants of emerging concern (CECs), increasingly being detected in the marine environment and recognized as a potential threat for marine biota at the global level including in polar areas. Few studies have assessed the impact of these anthropogenic nanoparticles in the microbiome of marine invertebrates, however combined exposure resembling natural scenarios has been overlooked. The present study aimed to evaluate the single and combined effects of polystyrene nanoparticles (PS NP) as proxy for nanoplastics and nanoscale titanium dioxide (nano-TiO2) on the prokaryotic communities associated with the gill tissue of the Antarctic soft-shell clam Laternula elliptica, a keystone species of marine benthos Wild-caught specimens were exposed to two environmentally relevant concentrations of carboxylated PS NP (PS-COOH NP, ∼62 nm size) and nano-TiO2 (Aeroxide P25, ∼25 nm) as 5 and 50 μg/L either single and combined for 96h in a semi-static condition.Our findings show a shift in microbiome composition in gills of soft-shell clams exposed to PS NP and nano-TiO2 either alone and in combination with a decrease in the relative abundance of OTU1 (Spirochaetaceae). In addition, an increase of gammaproteobacterial OTUs affiliated to MBAE14 and Methylophagaceae (involved in ammonia denitrification and associated with low-quality water), and the OTU Colwellia rossensis (previously recorded in polluted waters) was observed. Our results suggest that nanoplastics and nano-TiO2 alone and in combination induce alterations in microbiome composition by promoting the increase of negative taxa over beneficial ones in the gills of the Antarctic soft-shell clam. An increase of two low abundance OTUs in PS-COOH NPs exposed clams was also observed. A predicted gene function analysis revealed that sugar, lipid, protein and DNA metabolism were the main functions affected by either PS-COOH NP and nano-TiO2 exposure. The molecular functions involved in the altered affiliated OTUs are novel for nano-CEC exposures.

Sublethal acetamiprid affects reproduction, development and disrupts gene expression in Binodoxys communis

At present, understanding of neonicotinoid toxicity in arthropods remains limited. We here evaluated the lethal and sublethal effects of acetamiprid in F0 and F1 generations of Binodoxys communis using a range of sublethal concentrations. The 10% lethal concentration (LC10) and half lethal concentration (LC25) of ACE had negative effects on the B. communis survival rate, adult longevity, parasitism rate, and emergence rate, and significantly prolonged the duration of the developmental cycle. ACE also had intergenerational effects, with some biological indices affected in the F1 generation after pesticide exposure. Transcriptomic analysis demonstrated that differentially expressed genes were enriched in specific pathways including the amino acid metabolism, carbohydrate metabolism, energy metabolism, exogenous metabolism, signal transduction, and glutathione metabolism pathways. These results indicated strong contact toxicity of ACE to B. communis, which may inhibit their biological control capacity. These results improve our understanding of the toxicological mechanisms of parasitic natural enemies in response to insecticide exposure.

Prospects of probiotics in beekeeping: a review for sustainable approach to boost honeybee health

Honeybees are vital for global crop pollination, making indispensable contributions to agricultural productivity. However, these vital insects are currently facing escalating colony losses on a global scale, primarily attributed to parasitic and pathogenic attacks. The prevalent response to combat these infections may involve the use of antibiotics. Nevertheless, the application of antibiotics raises concerns regarding potential adverse effects such as antibiotic resistance and imbalances in the gut microbiota of bees. In response to these challenges, this study reviews the utilization of a probiotic-supplemented pollen substitute diet to promote honeybee gut health, enhance immunity, and overall well-being. We systematically explore various probiotic strains and their impacts on critical parameters, including survival rate, colony strength, honey and royal jelly production, and the immune response of bees. By doing so, we emphasize the significance of maintaining a balanced gut microbial community in honeybees. The review also scrutinizes the factors influencing the gut microbial communities of bees, elucidates the consequences of dysbiosis, and evaluates the potential of probiotics to mitigate these challenges. Additionally, it delineates different delivery mechanisms for probiotic supplementation and elucidates their positive effects on diverse health parameters of honeybees. Given the alarming decline in honeybee populations and the consequential threat to global food security, this study provides valuable insights into sustainable practices aimed at supporting honeybee populations and enhancing agricultural productivity.

A systemic study of cyenopyrafen in strawberry cultivation system: Efficacy, residue behavior, and impact on honeybees (Apis mellifera L.)

The pesticide application method is one of the important factors affecting its effectiveness and residues, and the risk of pesticides to non-target organisms. To elucidate the effect of application methods on the efficacy and residue of cyenopyrafen, and the toxic effects on pollinators honeybees in strawberry cultivation, the efficacy and residual behavior of cyenopyrafen were investigated using foliar spray and backward leaf spray in field trials. The results showed that the initial deposition of cyenopyrafen using backward leaf spray on target leaves reached 5.06-9.81 mg/kg at the dose of 67.5-101.25 g a.i./ha, which was higher than that using foliar spray (2.62-3.71 mg/kg). The half-lives of cyenopyrafen in leaves for foliar and backward leaf spray was 2.3-3.3 and 5.3-5.9 d, respectively. The residues (10 d) of cyenopyrafen in leaves after backward leaf spray was 1.41-3.02 mg/kg, which was higher than that after foliar spraying (0.25-0.37 mg/kg). It is the main reason for the better efficacy after backward leaf spray. However, the residues (10 d) in strawberry after backward leaf spray and foliar spray was 0.04-0.10 and < 0.01 mg/kg, which were well below the established maximum residue levels of cyenopyrafen in Japan and South Korea for food safety. To further investigate the effects of cyenopyrafen residues after backward leaf spray application on pollinator honeybees, sublethal effects of cyenopyrafen on honeybees were studied. The results indicated a significant inhibition in the detoxification metabolic enzymes of honeybees under continuous exposure of cyenopyrafen (0.54 and 5.4 mg/L) over 8 d. The cyenopyrafen exposure also alters the composition of honeybee gut microbiota, such as increasing the relative abundance of Rhizobiales and decreasing the relative abundance of Acetobacterales. The comprehensive data on cyenopyrafen provide basic theoretical for environmental and ecological risk assessment, while backward leaf spray proved to be effective and safe for strawberry cultivation.

Exposure to a fungicide for a field-realistic duration does not alter bumble bee fecal microbiota structure

Social bees are frequently exposed to pesticides when foraging on nectar and pollen. Recent research has shown that pesticide exposure not only impacts social bee host health but can also alter the community structure of social bee gut microbiotas. However, most research on pesticide-bee gut microbiota interactions has been conducted in honey bees; bumble bees, native North American pollinators, have received less attention and, due to differences in their ecology, may be exposed to certain pesticides for shorter durations than honey bees. Here, we examine how exposure to the fungicide chlorothalonil for a short, field-realistic duration alters bumble bee fecal microbiotas (used as a proxy for gut microbiotas) and host performance. We expose small groups of Bombus impatiens workers (microcolonies) to field-realistic chlorothalonil concentrations for 5 days, track changes in fecal microbiotas during the exposure period and a recovery period, and compare microcolony offspring production between treatments at the end of the experiment. We also assess the use of fecal microbiotas as a gut microbiota proxy by comparing community structures of fecal and gut microbiotas. We find that chlorothalonil exposure for a short duration does not alter bumble bee fecal microbiota structure or affect microcolony production at any concentration but that fecal and gut microbiotas differ significantly in community structure. Our results show that, at least when exposure durations are brief and unaccompanied by other stressors, bumble bee microbiotas are resilient to fungicide exposure. Additionally, our work highlights the importance of sampling gut microbiotas directly, when possible.IMPORTANCEWith global pesticide use expected to increase in the coming decades, studies on how pesticides affect the health and performance of animals, including and perhaps especially pollinators, will be crucial to minimize negative environmental impacts of pesticides in agriculture. Here, we find no effect of exposure to chlorothalonil for a short, field-realistic period on bumble bee fecal microbiota community structure or microcolony production regardless of pesticide concentration. Our results can help inform pesticide use practices to minimize negative environmental impacts on the health and fitness of bumble bees, which are key native, commercial pollinators in North America. We also find that concurrently sampled bumble bee fecal and gut microbiotas contain similar microbes but differ from one another in community structure and consequently suggest that using fecal microbiotas as a proxy for gut microbiotas be done cautiously; this result contributes to our understanding of proxy use in gut microbiota research.

Fitness effect and transcription profile reveal sublethal effect of nitenpyram on the predator Chrysopa pallens (Neuroptera: Chrysopidae)

Although neonicotinoids are widely used and important insecticide, there are growing concerns about their effect on nontarget insects and other organisms. Moreover, the effects of nitenpyram (NIT), a second generation of neonicotinoid insecticides, on Chrysopa pallens are still unclear. Therefore, this study purposed to investigate the acute toxicity of NIT to C. pallens using the spotting method. To examine the potential effects of a sublethal dose of NIT (LD30 , 1.85 ng of active ingredient per insect) on C. pallens, we constructed the life tables and analyzed the transcriptome data. The life table results showed that the period of second instar larvae, adult pre-oviposition period and total pre-oviposition period were significantly prolonged after exposure to sublethal dose of NIT, but had no significant effects on the other instars, longevity, oviposition days, and fecundity. The population parameters, including the preadult survival rate, gross reproduction rate, net reproductive rate, the intrinsic rate of increase, and finite rate of increase, were not significantly affected, and only the mean generation time was significantly prolonged by NIT. Transcriptome analysis showed that there were 68 differentially expressed genes (DEGs), including 50 upregulated genes and 18 downregulated genes. Moreover, 13 DEGs related to heat shock protein, nose resistant to fluoxetine protein 6, and prophenoloxidas were upregulated. This study showed the potential effects of sublethal doses of NIT on C. pallens and provided a theoretical reference for the comprehensive application of chemical and biological control in integrated pest management.

The brown planthopper NlDHRS11 is involved in the detoxification of rice secondary compounds

BACKGROUND

The brown planthopper (Nilaparvata lugens, BPH) is the most destructive serious pest in rice production. Resistant varieties are effective means to defend against BPH, but the impact of the ingestion of resistant rice on BPH transcriptional regulation is still unclear. Here, we explore the molecular basis of the regulation by BPH feeding on resistant rice.

RESULTS

BPH nymphs preferentially selected susceptible rice TN1 at 24 h after release in a choice test. Feeding on resistant rice IR56 under nonselective conditions increased mortality, decreased growth rate, and prolonged the molting time of BPH. Transcriptomic sequencing revealed 38 dysregulated genes, including 31 down-regulated and seven up-regulated genes in BPH feeding on resistant rice for 7 days compared with feeding on susceptible rice TN1. These genes were mainly involved in the pathways of growth and development, metabolism, energy synthesis, and transport. Finally, we showed that the toxicities of rice defensive compounds to BPH were dose-dependent, and silencing of the BPH gene dehydrogenase/reductase SDR family member 11 (NlDHRS11) increased sensibility to the rice secondary compounds ferulic acid and resorcinol.

CONCLUSION

The adaption of BPH feeding on resistant rice is orchestrated by dynamically regulating gene expressions, and NlDHRS11 is a gene involved in the detoxification of plant defensive chemicals. The current work provides new insights into the interaction between insects and plants, and will help to develop novel BPH control strategies. © 2023 Society of Chemical Industry.

Assessment of the risk of imidaclothiz to the dominant aphid parasitoid Binodoxys communis (Hymenoptera: Braconidae)

The neonicotinoid of imidaclothiz insecticide with low resistance and high efficiency, has great potential for application in pest control in specifically cotton field. In this systematically evaluate the effects of sublethal doses of imidaclothiz (LC10: 11.48 mg/L; LC30: 28.03 mg/L) on the biology, transcriptome, and microbiome of Binodoxys communis, the predominant primary parasitic natural enemy of aphids. The findings indicated that imidaclothiz has significant deleterious effects on the survival rate, parasitic rate, and survival time of B. communis. Additionally, there was a marked reduction in the survival rate and survival time of the F1 generation, that is, the negative effect of imidaclothiz on B. communis was continuous and trans-generational. Transcriptome analysis revealed that imidaclothiz treatment elicited alterations in the expression of genes associated with energy and detoxification metabolism. In addition, 16S rRNA analysis revealed a significant increase in the relative abundance of Rhodococcus and Pantoea, which are associated with detoxification metabolism, due to imidaclothiz exposure. These findings provide evidence that B. communis may regulate gene expression in conjunction with symbiotic bacteria to enhance adaptation to imidaclothiz. Finally, this study precise evaluation of imidaclothiz's potential risk to B. communis and provides crucial theoretical support for increasing the assessment of imidaclothiz in integrated pest management.

Pantoea bathycoeliae sp. nov and Sodalis sp. are core gut microbiome symbionts of the two-spotted stink bug

Stink bug species (Pentatomoidea superfamily) have developed an interdependence with obligate bacterial gut symbionts in specialized midgut crypts (M4 sub-region). Species of the Enterobacteriaceae family (predominantly Pantoea) are vertically transferred to their offspring and provide nutrients that cannot be obtained from plant sap food sources. However, the bacteria in the other gut compartments of stink bugs have rarely been investigated. The two-spotted stink bug, Bathycoelia distincta, is a serious pest of macadamias in South Africa. Nothing is currently known regarding its gut microbiome or how symbionts are transferred between insect generations. In this study, the consistency of B. distincta gut bacteria across geographic locations and life stages was determined with 16S rRNA metabarcoding, considering both the M4 and other gut compartments. A novel Pantoea species was found to be the primary M4 gut symbiont and is vertically transferred to the offspring. The other gut compartments had a low bacterial diversity and genera varied between stink bug populations but a Sodalis species was prominent in all populations. Sequence data of the M4 compartment were used to produce high-quality metagenome-assembled genomes (MAGs) for the Pantoea and Sodalis species. Functional analyses suggested a similar role in nutrient provision for the host, yet also unique metabolites produced by each species. The Sodalis sp. also had additional traits, such as secretion systems, that likely allowed it to establish itself in the host. The Pantoea species was described as Pantoea bathycoeliae sp. nov based on the rules of the SeqCode.

Gut microbiota in parasite-transmitting gastropods

BACKGROUND

Gastropoda, the largest class within the phylum Mollusca, houses diverse gut microbiota, and some gastropods serve as intermediate hosts for parasites. Studies have revealed that gut bacteria in gastropods are associated with various biological aspects, such as growth, immunity and host-parasite interactions. Here, we summarize our current knowledge of gastropod gut microbiomes and highlight future research priorities and perspectives.

METHODS

A literature search was undertaken using PubMed, Web of Science and CNKI for the articles on the gut microbiota of gastropods until December 31, 2022. We retrieved a total of 166 articles and identified 73 eligible articles for inclusion in this review based on the inclusion and exclusion criteria.

RESULTS

Our analysis encompassed freshwater, seawater and land snails, with a specific focus on parasite-transmitting gastropods. We found that most studies on gastropod gut microbiota have primarily utilized 16S rRNA gene sequencing to analyze microbial composition, rather than employing metagenomic, metatranscriptomic, or metabolomic approaches. This comprehensive review provided an overview of the parasites carried by snail species in the context of gut microbiota studies. We presented the gut microbial trends, a comprehensive summary of the diversity and composition, influencing factors, and potential functions of gastropod gut microbiota. Additionally, we discussed the potential applications, research gaps and future perspectives of gut microbiomes in parasite-transmitting gastropods. Furthermore, several strategies for enhancing our comprehension of gut microbiomes in snails were also discussed.

CONCLUSIONS

This review comprehensively summarizes the current knowledge on the composition, potential function, influencing factors, potential applications, limitations, and challenges of gut microbiomes in gastropods, with a specific emphasis on parasite-transmitting gastropods. These findings provide important insights for future studies aiming to understand the potential role of gastropod gut microbiota in controlling snail populations and snail-borne diseases.

Composition and diversity of bacterial communities associated with honey bee foragers from two contrasting environments

The honey bee is associated with a diverse community of microbes (viruses, bacteria, fungi, and protists), commonly known as the microbiome. Here, we present data on honey bee microbiota from two localities having different surrounding landscapes - mountain (the Rhodope Mountains) and lowland (the Danube plain). The bacterial communities of abdomen of adult bees were studied using amplicon sequencing of the 16S rRNA gene. The composition and dominance structure and their variability within and between localities, alpha and beta diversity, and core and differential taxa were compared at different hierarchical levels (operational taxonomic units to phylum). Seven genera (Lactobacillus, Gilliamella, Bifidobacterium, Commensalibacter, Bartonella, Snodgrassella, and Frischella), known to include core gut-associated phylotypes or species clusters, dominated (92-100%) the bacterial assemblages. Significant variations were found in taxa distribution across both geographical regions and within each apiary. Lactobacillus (Firmicutes) prevailed significantly in the mountain locality followed by Gilliamella and Bartonella (Proteobacteria). Bacteria of four genera, core (Bartonella and Lactobacillus) and non-core (Pseudomonas and Morganella), dominated the bee-associated assemblages of the Danube plain locality. Several ubiquitous bacterial genera (e.g., Klebsiella, Serratia, and Providencia), some species known also as potential and opportunistic bee pathogens, had been found in the lowland locality. Beta diversity analyses confirmed the observed differences in the bacterial communities from both localities. The occurrence of non-core taxa contributes substantially to higher microbial richness and diversity in bees from the Danube plain locality. We assume that the observed differences in the microbiota of honey bees from both apiaries are due to a combination of factors specific for each region. The surrounding landscape features of both localities and related vegetation, anthropogenic impact and land use intensity, the beekeeping management practices, and bee health status might all contribute to observed differences in bee microbiota traits.

The impact of Parkinson's disease-associated gut microbiota on the transcriptome in Drosophila

Parkinson's disease (PD) is a common neurodegenerative disease in middle-aged and elderly people, and many studies have confirmed that the disorder of gut microbiota is involved in the pathophysiological process of PD. However, the molecular mechanism of gut microbiota in regulating the pathogenesis of PD is still lacking. In this study, to investigate the impact of PD-associated gut microbiota on host transcriptome, we established various PD models with fecal microbiota transplantation (FMT) in the model organism Drosophila followed by integrative data analysis of microbiome and transcriptome. We first constructed rotenone-induced PD models in Drosophila followed by FMT in different groups. Microbial analysis by 16S rDNA sequencing showed that gut microbiota from PD Drosophila could affect bacterial structure of normal Drosophila, and gut microbiota from normal Drosophila could affect bacterial structure of PD Drosophila. Transcriptome analysis revealed that PD-associated gut microbiota influenced expression patterns of genes enriched in neuroactive ligand-receptor interaction, lysosome, and diverse metabolic pathways. Importantly, to verify our findings, we transplanted Drosophila with fecal samples from clinical PD patients. Compared to the control, Drosophila transplanted with fecal samples from PD patients had reduced microbiota Acetobacter and Lactobacillus, and differentially expressed genes enriched in diverse metabolic pathways. In summary, our results reveal the influence of PD-associated gut microbiota on host gene expression, and this study can help better understand the link between gut microbiota and PD pathogenesis through gut-brain axis. IMPORTANCE Gut microbiota plays important roles in regulating host gene expression and physiology through complex mechanisms. Recently, it has been suggested that disorder of gut microbiota is involved in the pathophysiological process of Parkinson's disease (PD). However, the molecular mechanism of gut microbiota in regulating the pathogenesis of PD is still lacking. In this study, to investigate the impact of PD-associated gut microbiota on host transcriptome, we established various PD models with fecal microbiota transplantation in the model organism Drosophila followed by integrative data analysis of microbiome and transcriptome. We also verified our findings by transplanting Drosophila with fecal samples from clinical PD patients. Our results demonstrated that PD-associated gut microbiota can induce differentially expressed genes enriched in diverse metabolic pathways. This study can help better understand the link between gut microbiota and PD pathogenesis through gut-brain axis.

Immunometabolic regulation during the presence of microorganisms and parasitoids in insects

Multicellular organisms live in environments containing diverse nutrients and a wide variety of microbial communities. On the one hand, the immune response of organisms can protect from the intrusion of exogenous microorganisms. On the other hand, the dynamic coordination of anabolism and catabolism of organisms is a necessary factor for growth and reproduction. Since the production of an immune response is an energy-intensive process, the activation of immune cells is accompanied by metabolic transformations that enable the rapid production of ATP and new biomolecules. In insects, the coordination of immunity and metabolism is the basis for insects to cope with environmental challenges and ensure normal growth, development and reproduction. During the activation of insect immune tissues by pathogenic microorganisms, not only the utilization of organic resources can be enhanced, but also the activated immune cells can usurp the nutrients of non-immune tissues by generating signals. At the same time, insects also have symbiotic bacteria in their body, which can affect insect physiology through immune-metabolic regulation. This paper reviews the research progress of insect immune-metabolism regulation from the perspective of insect tissues, such as fat body, gut and hemocytes. The effects of microorganisms (pathogenic bacteria/non-pathogenic bacteria) and parasitoids on immune-metabolism were elaborated here, which provide guidance to uncover immunometabolism mechanisms in insects and mammals. This work also provides insights to utilize immune-metabolism for the formulation of pest control strategies.

Prolonged darkness attenuates imidacloprid toxicity through the brain-gut-microbiome axis in zebrafish, Danio rerio

The present study investigated the toxic effects of IMI on brain and gut of zebrafish (Danio rerio) by a combination of transcriptome and microbiome analysis. In addition, the involvement of light/dark period was also evaluated. An acute toxic test was conducted on adult zebrafish weighing 0.45 ± 0.02 g with 4 experimental groups (n = 15): 1) IMI group (Light: Dark = 12: 12 h), 2) prolonged light group (Light: Dark = 20: 4 h), 3) prolonged darkness group (Light: Dark = 4: 20 h) which received 20 mg/L of IMI, and 4) control group, which was not treated with IMI (Light: Dark = 12: 12 h). The results showed that prolonged darkness improved the survival rate of zebrafish upon IMI exposure for 96 h. In the sub-chronic test, zebrafish were divided into the same 4 groups and exposed to IMI at 1 mg/L for 14 d (n = 30). The results showed that IMI induced oxidative stress in both IMI and prolonged light groups by inhibition of antioxidant activities and accumulation of oxidative products. Transcriptome analysis revealed a compromise of antioxidation and tryptophan metabolism pathways under IMI exposure. Several genes encoding rate-limiting enzymes in serotonin and melatonin synthesis were all inhibited in both IMI and LL groups. Meanwhile, significant decrease (P < 0.5) of serotonin and melatonin levels was observed. However, there's remarkable improvement of biochemical and transcriptional status in prolonged darkness group. In addition, microbiome analysis showed great alteration of gut bacterial community structure and inhibition of tryptophan metabolism pathway. Similarly, the gut microbiota dysbiosis induced by IMI was alleviated in prolonged darkness. In summary, sub-chronic IMI exposure induced neurotoxicity and gut toxicity in zebrafish by oxidative stress and impaired the brain-gut-axis through tryptophan metabolism perturbation. Prolonged darkness could effectively attenuate the IMI toxicity probably through maintaining a normal tryptophan metabolism.

Dinotefuran exposure induces autophagy and apoptosis through oxidative stress in Bombyx mori

As a third-generation neonicotinoid insecticide, dinotefuran is extensively used in agriculture, and its residue in the environment has potential effects on nontarget organisms. However, the toxic effects of dinotefuran exposure on nontarget organism remain largely unknown. This study explored the toxic effects of sublethal dose of dinotefuran on Bombyx mori. Dinotefuran upregulated reactive oxygen species (ROS) and malondialdehyde (MDA) levels in the midgut and fat body of B. mori. Transcriptional analysis revealed that the expression levels of many autophagy and apoptosis-associated genes were significantly altered after dinotefuran exposure, consistent with ultrastructural changes. Moreover, the expression levels of autophagy-related proteins (ATG8-PE and ATG6) and apoptosis-related proteins (BmDredd and BmICE) were increased, whereas the expression level of an autophagic key protein (sequestosome 1) was decreased in the dinotefuran-exposed group. These results indicate that dinotefuran exposure leads to oxidative stress, autophagy, and apoptosis in B. mori. In addition, its effect on the fat body was apparently greater than that on the midgut. In contrast, pretreatment with an autophagy inhibitor effectively downregulated the expression levels of ATG6 and BmDredd, but induced the expression of sequestosome 1, suggesting that dinotefuran-induced autophagy may promote apoptosis. This study reveals that ROS generation regulates the impact of dinotefuran on the crosstalk between autophagy and apoptosis, laying the foundation for studying cell death processes such as autophagy and apoptosis induced by pesticides. Furthermore, this study provides a comprehensive insight into the toxicity of dinotefuran on silkworm and contributes to the ecological risk assessment of dinotefuran in nontarget organisms.

Pesticide exposure and the microbiota-gut-brain axis

The gut microbiota exist within a dynamic ecosystem shaped by various factors that includes exposure to xenobiotics such as pesticides. It is widely regarded that the gut microbiota plays an essential role in maintaining host health, including a major influence on the brain and behaviour. Given the widespread use of pesticides in modern agriculture practices, it is important to assess the long-term collateral effects these xenobiotic exposures have on gut microbiota composition and function. Indeed, exposure studies using animal models have shown that pesticides can induce negative impacts on the host gut microbiota, physiology and health. In tandem, there is a growing body of literature showing that the effects of pesticide exposure can be extended to the manifestation of behavioural impairments in the host. With the increasing appreciation of the microbiota-gut-brain axis, in this review we assess whether pesticide-induced changes in gut microbiota composition profiles and functions could be driving these behavioural alterations. Currently, the diversity of pesticide type, exposure dose and variation in experimental designs hinders direct comparisons of studies presented. Although many insights presented, the mechanistic connection between the gut microbiota and behavioural changes remains insufficiently explored. Future experiments should therefore focus on causal mechanisms to examine the gut microbiota as the mediator of the behavioural impairments observed in the host following pesticide exposure.

Atrazine exposure can dysregulate the immune system and increase the susceptibility against pathogens in honeybees in a dose-dependent manner

Recently, concerns regarding the impact of agrochemical pesticides on non-target organisms have increased. The effect of atrazine, the second-most widely used herbicide in commercial farming globally, on honeybees remains poorly understood. Here, we evaluated how atrazine impacts the survival of honeybees and pollen and sucrose consumption, investigating the morphology and mRNA expression levels of midgut tissue, along with bacterial composition (relative abundance) and load (absolute abundance) in the whole gut. Atrazine did not affect mortality, but high exposure (37.3 mg/L) reduced pollen and sucrose consumption, resulting in peritrophic membrane dysplasia. Sodium channels and chitin synthesis were considered potential atrazine targets, with the expression of various genes related to lipid metabolism, detoxification, immunity, and chemosensory activity being inhibited after atrazine exposure. Importantly, 37.3 mg/L atrazine exposure substantially altered the composition and size of the gut microbial community, clearly reducing both the absolute and relative abundance of three core gram-positive taxa, Lactobacillus Firm-5, Lactobacillus Firm-4, and Bifidobacterium asteroides. With altered microbiome composition and a weakened immune system following atrazine exposure, honeybees became more susceptible to infection by the opportunistic pathogen Serratia marcescens. Thus, considering its scale of use, atrazine could negatively impact honeybee populations worldwide, which may adversely affect global food security.

The effects of glyphosate, pure or in herbicide formulation, on bumble bees and their gut microbial communities

The widespread use of glyphosate-based formulations to eliminate unwanted vegetation has increased concerns regarding their effects on non-target organisms, such as honey bees and their gut microbial communities. These effects have been associated with both glyphosate and co-formulants, but it is still unknown whether they translate to other bee species. In this study, we tested whether glyphosate, pure or in herbicide formulation, can affect the gut microbiota and survival rates of the eastern bumble bee, Bombus impatiens. We performed mark-recapture experiments with bumble bee workers from four different commercial colonies, which were exposed to field relevant concentrations of glyphosate or a glyphosate-based formulation (0.01 mM to 1 mM). After a 5-day period of exposure, we returned the bees to their original colonies, and they were sampled at days 0, 3 and 7 post-exposure to investigate changes in microbial community and microbiota resilience by 16S rRNA amplicon sequencing and quantitative PCR. We found that exposure to glyphosate, pure or in herbicide formulation, reduced the relative abundance of a beneficial bee gut bacterium, Snodgrassella, in bees from two of four colonies when compared to control bees at day 0 post-exposure, but this reduction became non-significant at days 3 and 7 post-exposure, suggesting microbiota resilience. We did not find significant changes in total bacteria between control and exposed bees. Moreover, we observed an overall trend in decreased survival rates in bumble bees exposed to 1 mM herbicide formulation during the 7-day post-exposure period, suggesting a potential negative effect of this formulation on bumble bees.

Research Progresses on the Function and Detection Methods of Insect Gut Microbes

The insect gut is home to an extensive array of microbes that play a crucial role in the digestion and absorption of nutrients, as well as in the protection against pathogenic microorganisms. The variety of these gut microbes is impacted by factors such as age, diet, pesticides, antibiotics, sex, and caste. Increasing evidence indicates that disturbances in the gut microbiota can lead to compromised insect health, and that its diversity has a far-reaching impact on the host's health. In recent years, the use of molecular biology techniques to conduct rapid, qualitative, and quantitative research on the host intestinal microbial diversity has become a major focus, thanks to the advancement of metagenomics and bioinformatics technologies. This paper reviews the main functions, influencing factors, and detection methods of insect gut microbes, in order to provide a reference and theoretical basis for better research utilization of gut microbes and management of harmful insects.

Gut microbiota composition and gene expression changes induced in the Apis cerana exposed to acetamiprid and difenoconazole at environmentally realistic concentrations alone or combined

Apis cerana is an important pollinator of agricultural crops in China. In the agricultural environment, A. cerana may be exposed to acetamiprid (neonicotinoid insecticide) and difenoconazole (triazole fungicide), alone or in combination because they are commonly applied to various crops. At present, our understanding of the toxicological effects of acetamiprid and difenoconazole on honey bee gut microbiomes is limited. The primary objective of this study was to explore whether these two pesticides affect honey bees' gut microbiota and to analyze the transcriptional effects of these two pesticides on honey bees' head and gut. In this study, adults of A. cerana were exposed to acetamiprid and/or difenoconazole by contaminated syrup at field-realistic concentrations for 10 days. Results indicated that acetamiprid and/or difenoconazole chronic exposure did not affect honey bees' survival and food consumption, whereas difenoconazole decreased the weight of honey bees. 16S rRNA sequencing suggested that difenoconazole and the mixture of difenoconazole and acetamiprid decreased the diversity index and shaped the composition of gut bacteria microbiota, whereas acetamiprid did not impact the gut bacterial community. The ITS sequence data showed that neither of the two pesticides affected the fungal community structure. Meanwhile, we also observed that acetamiprid or difenoconazole significantly altered the expression of genes related to detoxification and immunity in honey bees' tissues. Furthermore, we observed that the adverse effect of the acetamiprid and difenoconazole mixture on honey bees' health was greater than that of a single mixture. Taken together, our study demonstrates that acetamiprid and/or difenoconazole exposure at field-realistic concentrations induced changes to the honey bee gut microbiome and gene expression.

Mixture toxic effects of thiacloprid and cyproconazole on honey bees (Apis mellifera L.)

Pesticide exposure remains one of the main factors in the population decline of insect pollinators. It is urgently necessary to assess the effects of mixtures on pollinator risk assessments because they are often exposed to numerous agrochemicals. In the present study, we explored the mixture toxic effects of thiacloprid (THI) and cyproconazole (CYP) on honey bees (Apis mellifera L.). Our findings revealed that THI possessed higher acute toxicity to A. mellifera (96-h LC₅₀ value of 216.3 mg a.i. L^-1) than CYP (96-h LC₅₀ value of 601.4 mg a.i. L^-1). It's worth noting that the mixture of THI and CYP exerted an acute synergistic effect on honey bees. At the same time, the activities of detoxification enzyme cytochrome P450s (CYP450s) and neuro target enzyme Acetylcholinesterase (AChE), as well as the expressions of seven genes (CRBXase, CYP306A1, CYP6AS14, apidaecin, defensing-2, vtg, and gp-93) associated with detoxification metabolism, immune response, development, and endoplasmic reticulum stress, were significantly altered in the combined treatment compared with the corresponding individual exposures of THI or CYP. These data indicated that a mixture of THI and CYP could disturb the physiological homeostasis of honey bees. Our study provides a theoretical basis for in-depth studies on the impacts of pesticide mixtures on the health of honey bees. Our study also provides important guidance for the rational application of pesticide mixtures to protect pollinators in agricultural production effectively.

Characterization of childhood exposure to environmental contaminants using stool in a semi-urban middle-class cohort from eastern Canada

Children are exposed to various environmental organic and inorganic contaminants with effects on health outcomes still largely unknown. Many matrices (e.g., blood, urine, nail, hair) have been used to characterize exposure to organic and inorganic contaminants. The sampling of feces presents several advantages; it is non-invasive and provides a direct evaluation of the gut microbiome exposure to contaminants. The gut microbiome is a key factor in neurological development through the brain-gut axis. Its composition and disturbances can affect the neurodevelopment of children. Characterization of children exposure to contaminants is often performed on vulnerable populations (e.g., from developing countries, low-income neighborhoods, and large urban centers). Data on the exposure of children from middle-class, semi-urban, and mid-size populations to contaminants is scarce despite representing a significant fraction of the population in North America. In this study, 73 organics compounds from different chemical classes and 22 elements were analyzed in 6 years old (n = 84) and 10 years old (n = 119) children's feces from a middle-class, semi-urban, mid-size population cohort from Eastern Canada. Results show that 67 out of 73 targeted organics compounds and all elements were at least detected in one child's feces. Only caffeine (97% & 80%) and acetaminophen (28% & 48%) were detected in more than 25% of the children's feces, whereas all elements besides titanium were detected in more than 50% of the children.

Strategies and techniques to mitigate the negative impacts of pesticide exposure to honey bees

In order to support food, fiber, and fuel production around the world, billions of kilograms of pesticides are applied to crop fields every year to suppress pests, plant diseases and weeds. These fields are often home to the most important commercial pollinators, honey bees (Apis spp.), which improve yield and quality of many agricultural products. The pesticides applied to support crop health can be detrimental to honey bee health. The conflict of pesticide use and reliance on honey bees contributes to significant honey bee colony losses across the world. Recommendations for reducing impact on honey bees are generally suggested in literature, pesticide regulations, and by crop consultants, but without a considerable discussion of the realistic limitations of protecting honey bees. New techniques in farming and beekeeping can reduce pesticide exposure through reduction in bee exposure, reduced toxicity of pesticides, and remedies that can be in response to exposure. However, lack of assessment of those new techniques under a systematical, comprehensive framework may overestimate or underestimate these techniques' potential to protect honey bees from pesticide damage. In this review, we summarize the current and arising strategies and techniques with the goal to inspire the development and adoption of pesticide mitigation practices for both agriculture and apiculture.

Effects of spinetoram and glyphosate on physiological biomarkers and gut microbes in Bombus terrestris

The sublethal effects of pesticide poisoning will have significant negative impacts on the foraging and learning of bees and bumblebees, so it has received widespread attention. However, little is known about the physiological effects of sublethal spinetoram and glyphosate exposure on bumblebees. We continuously exposed Bombus terrestris to sublethal (2.5 mg/L) spinetoram or glyphosate under controlled conditions for 10 days. The superoxide dismutase, glutathione-S-transferase, carboxylesterase, prophenoloxidase, α-amylase and protease activities, and changes in gut microbes were measured to understand the effects of sublethal pesticide exposure on the physiology and gut microbes of bumblebees. Sublethal pesticide exposure to significantly increased superoxide dismutase activity and significantly decreased gut α-amylase activity in bumblebees but had no significant effect on glutathione-S-transferase, carboxylesterase or gut protease activities. In addition, glyphosate increased the activity of prophenoloxidase. Interestingly, we observed that neither of the two pesticides had a significant effect on dominant gut bacteria, but glyphosate significantly altered the structure of the dominant gut fungal community, and reduced the relative abundance of Zygosaccharomyces associated with fat accumulation. These results suggest that sublethal spinetoram and glyphosate do not significantly affect the detoxification system of bumblebees, but may affect bumblebee health by inhibiting energy acquisition. Our results provide information on the sublethal effects of exposure to low concentrations of glyphosate and spinetoram on bumblebees in terms of physiology and gut microbes.

Disinfectant dodecyl dimethyl benzyl ammonium chloride (DDBAC) disrupts gut microbiota, phospholipids, and calcium signaling in honeybees (Apis mellifera) at an environmentally relevant level

One of the impacts of the Coronavirus disease 2019 (COVID-19) pandemic has been a profound increase in the application amounts of disinfectants. Dodecyl dimethyl benzyl ammonium chloride (DDBAC) is a widely used disinfectant, yet its hazards to non-target species remain largely unknown. We are unaware of any studies assessing DDBAC's impacts on honeybee, a pollinator species that is a useful indicator of environmental pollution essential for many forms of agricultural production. Here, we assessed the potentially negative effects of DDBAC on honeybees. After conducting a formal toxicity evaluation of DDBAC on honeybee mortality, we detected an accumulation of DDBAC in the honeybee midgut. We subsequently studied the midgut tissues of honeybees exposed to sub-lethal concentrations of DDBAC: histopathological examination revealed damage to midgut tissue upon DDBAC exposure, microbiome analysis showed a decreased abundance of beneficial midgut microbiota, lipidomics analysis revealed a significant reduction in cell membrane phospholipids with known functions in signal transduction, and a transcriptome analysis detected altered expression of genes involved in calcium signaling pathways (that variously function in calcium absorption, muscle contraction, and neurotransmission). Thus, our study establishes that DDBAC impacts honeybee midgut functions at multiple levels. Our study represents an early warning about the hazards of DDBAC and appeals for the proper stewardship of DDBAC to ensure the protection of our ecological environment.

Current Knowledge on Bee Innate Immunity Based on Genomics and Transcriptomics

As important pollinators, bees play a critical role in maintaining the balance of the ecosystem and improving the yield and quality of crops. However, in recent years, the bee population has significantly declined due to various pathogens and environmental stressors including viruses, bacteria, parasites, and increased pesticide application. The above threats trigger or suppress the innate immunity of bees, their only immune defense system, which is essential to maintaining individual health and that of the colony. In addition, bees can be divided into solitary and eusocial bees based on their life traits, and eusocial bees possess special social immunities, such as grooming behavior, which cooperate with innate immunity to maintain the health of the colony. The omics approach gives us an opportunity to recognize the distinctive innate immunity of bees. In this regard, we summarize innate bee immunity from a genomic and transcriptomic perspective. The genetic characteristics of innate immunity were revealed by the multiple genomes of bees with different kinds of sociality, including honeybees, bumblebees, wasps, leaf-cutter bees, and so on. Further substantial transcriptomic data of different tissues from diverse bees directly present the activation or suppression of immune genes under the infestation of pathogens or toxicity of pesticides.

Acaricide flumethrin-induced sublethal risks in honeybees are associated with gut symbiotic bacterium Gilliamella apicola through microbe-host metabolic interactions

Flumethrin is one of the few acaricides that permit the control of Varroa disease or varroosis in bee colonies. However, flumethrin accumulates in hive products. We previously discovered that sublethal doses of flumethrin induce significant physiological stress in honeybees (Apis mellifera L.), however its potential impacts on the honeybee gut microenvironment remains unknown. To fill this gap, honeybees were exposed to a field-relevant concentration of flumethrin (10 μg/L) for 14 d and its potential impacts on gut system were evaluated. The results indicated that flumethrin triggered immune responses in the gut but had limited effects on survival and gut microbial composition. However, survival stress drastically increased in bees exposed to antibiotics, suggesting that the gut microbiota is closely related to flumethrin-induced dysbiosis in the bee gut. Based on a non-targeted metabolomics approach, flumethrin at 10 μg/L considerably altered the composition of intestinal metabolites, and we discovered that this metabolic stress was closely linked with a reduction of gut core bacterial endosymbiont Gilliamella spp. through a combination of microbiological and metabolomics investigations. Finally, an in vitro study showed that while flumethrin does not directly inhibit the growth of Gilliamella apicola isolates, it does have a significant impact on the glycerophospholipid metabolism in bacteria cells, which was also observed in host bees. These findings indicated that even though flumethrin administered at environmental relevant concentrations does not significantly induce death in honeybees, it still alters the metabolism balance between honeybees and the gut symbiotic bacterium, G. apicola. The considerable negative impact of flumethrin on the honeybee gut microenvironment emphasizes the importance of properly monitoring acaricide to avoid potential environmental concerns, and further studies are needed to illustrate the mode of action of bee health-gut microbiota-exogenous pesticides.

Toxic effects of detected pyrethroid pesticides on honeybee (Apis mellifera ligustica Spin and Apis cerana cerana Fabricius)

To obtain the presence of environmental contaminants in honeybee and compare the toxicity of the detected pesticides to Apis mellifera ligustica Spin and Apis cerana cerana Fabricius. In this work, 214 honeybee samples were collected to simultaneous monitoring 66 pesticides between 2016 and 2017 in China. A modified QuEChERS extraction method coupled with multi-residue analytical methods by Ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and Gas chromatography-mass spectrum (GC–MS). Among, four pyrethroid pesticides were selected to test and compare the acute oral toxicities of two honeybees. And the survival risk of beta-cypermethrin was analyzed to them. Using this method, 21 compounds were detected, including 3 neonicotinoids, 5 pyrethroids, 5 organophosphorus and 8 others. Importantly, detected frequencies of pyrethroid pesticides were accounted for 53.3%. Among, acute toxicity values (LD₅₀) of four pyrethroid pesticides to the A.m. ligustica were higher than of that the A.c. cerana. When they were exposed to the same concentration of beta-cypermethrin (0.2906 mg/L), the survival rate of the A.m. ligustica (40.0%) was higher than the A.c. cerana (18.9%). Our work is valuable to analyze multiple pesticide residues of honeybees and evaluate the survival risk of two honeybee species, which also provides a basis for the risk assessment.

Reciprocal interactions between anthropogenic stressors and insect microbiota

Insects play many important roles in nature due to their diversity, ecological role, and impact on agriculture or human health. They are directly influenced by environmental changes and in particular anthropic activities that constitute an important driver of change in the environmental characteristics. Insects face numerous anthropogenic stressors and have evolved various detoxication mechanisms to survive and/or resist to these compounds. Recent studies highligted the pressure exerted by xenobiotics on insect life-cycle and the important role of insect-associated bacterial microbiota in the insect responses to environmental changes. Stressor exposure can have various impacts on the composition and structure of insect microbiota that in turn may influence insect biology. Moreover, bacterial communities associated with insects can be directly or indirectly involved in detoxification processes with the selection of certain microorganisms capable of degrading xenobiotics. Further studies are needed to assess the role of insect-associated microbiota as key contributor to the xenobiotic metabolism and thus as a driver for insect adaptation to polluted habitats.

Biofilm formation as an extra gear for Apilactobacillus kunkeei to counter the threat of agrochemicals in honeybee crop

The alteration of a eubiosis status in honeybees' gut microbiota is directly linked to the occurrence of diseases, and likely to the honeybees decline. Since fructophilic lactobacilli were suggested as symbionts for honeybees, we mechanistically investigated their behaviour under the exposure to agrochemicals (Roundup, Mediator and Reldan containing glyphosate, imidacloprid and chlorpyrifos-methyl as active ingredients respectively) and plant secondary metabolites (nicotine and p-coumaric acid) ingested by honeybees as part of their diet. The effects of exposure to agrochemicals and plant secondary metabolites were assessed both on planktonic cells and sessile communities of three biofilm-forming strains of Apilactobacillus kunkeei. We identified the high sensitivity of A. kunkeei planktonic cells to Roundup and Reldan, while cells embedded in mature biofilms had increased resistance to the same agrochemicals. However, agrochemicals still exerted a substantial inhibitory/control effect if the exposure was during the preliminary steps of biofilm formation. The level of susceptibility resulted to be strain-specific. Exopolysaccharides resulted in the main component of extracellular polymeric matrix (ECM) in biofilm, but the exposure to Roundup caused a change in ECM production and composition. Nicotine and p-coumaric acid had a growth-promoting effect in sessile communities, although no effect was found on planktonic growth.

Surfactant affects the tool use behavior of foraging ants

Surfactants are commonly used in detergents, soaps and agrichemical products. After use, the residual surfactants can be dispersed into environmental compartments, directly or indirectly affecting aquatic and terrestrial organisms. Ants are one of the few insects that are able to make and use tools when foraging for liquid food. However, this unique behavior of ants may be greatly affected by environmental pollutants. Here, we hypothesized that surfactants have adversarial impacts on ant foraging behavior, and tested this hypothesis by investigating the effect of TWEEN 80 (a common nonionic surfactant) on the tool use behavior of black imported fire ants (Solenopsis richteri) when foraging for liquid food (sugar water). Natural pine needles and man-made sponges were provided as tools for ants. The results revealed increasing surfactant concentration induced ants to deposit more tools and caused a higher drowning rate of ants. S. richteri tended to deposit more pine needles and tools of smaller size when exposed to surfactant. Interactions between tool type and surfactant concentration showed significant effects on tool deposition and drowning rate of ants. Addition of surfactant into sugar water increased the drowning rate and reduced the foraging activity and food collection of ant workers, suggesting that surfactant in liquid food can affect the foraging efficiency of ants. However, availability of tools reduced drowning rate and increased sugar water collected compared to without tools. Our results demonstrated that ants can adjust their tool use strategies to manage the foraging risk caused by environmental surfactant, such as increasing the amount and selecting appropriate size of the tools and assembling tools of different structures. Therefore, long-term exposure to surfactants may alter foraging behavior of ants and contribute to evolve new foraging strategy.

Bee foraging preferences, microbiota and pathogens revealed by direct shotgun metagenomics of honey

Honeybees (Apis mellifera) continue to succumb to human and environmental pressures despite their crucial role in providing essential ecosystem services. Owing to their foraging and honey production activities, honeybees form complex relationships with species across all domains, such as plants, viruses, bacteria and other hive pests, making honey a valuable biomonitoring tool for assessing their ecological niche. Thus, the application of honey shotgun metagenomics (SM) has paved the way for a detailed description of the species honeybees interact with. Nevertheless, SM bioinformatics tools and DNA extraction methods rely on resources not necessarily optimized for honey. In this study, we compared five widely used taxonomic classifiers using simulated species communities commonly found in honey. We found that Kraken 2 with a threshold of 0.5 performs best in assessing species distribution. We also optimized a simple NaOH-based honey DNA extraction methodology (Direct-SM), which profiled species seasonal variability similarly to an established column-based DNA extraction approach (SM). Both approaches produce results consistent with melissopalinology analysis describing the botanical landscape surrounding the apiary. Interestingly, we detected a strong stability of the bacteria constituting the core and noncore gut microbiome across seasons, pointing to the potential utility of honey for noninvasive assessment of bee microbiota. Finally, the Direct-SM approach to detect Varroa correlates well with the biomonitoring of mite infestation observed in hives. These observations suggest that Direct-SM methodology has the potential to comprehensively describe honeybee ecological niches and can be tested as a building block for large-scale studies to assess bee health in the field.

Genotoxicity, oxidative stress and transcriptomic effects of Nitenpyram on human bone marrow mesenchymal stem cells

Despite of the global contamination and ubiquitous exposure to nitenpyram (NIT), little knowledge is available on the adverse effects to human health, with some evidence referring to its genotoxic potency to non-target organisms and esophageal squamous papilloma in rats. Human bone marrow mesenchymal stem cells (hBMSCs) was employed as an in vitro model more relevant to humans to assess the potential genotoxicity of NIT and to understand the underlying mechanisms at cellular and molecular levels. Noncytotoxic concentrations of NIT, 50-2500 μg/mL, dose-dependently elevated MNs and nuclear buds frequencies to 8.7-29‰ and 15-35‰, respectively. Additional metabolism by rat liver S9 fraction decreased chromosome impairment by 27-52% on MN frequencies and 63-76% on NB frequencies. A commercial NIT product, containing 20% of NIT and 60% of pymetrozine, caused higher cytotoxicity and chromosome impairment in comparison with NIT alone. Expressions of genes responses to DNA damage, ATM, ATR, p53, p21, Bax, H2AX, and GADD45A were disturbed by NIT treatment. Reactive oxygen species (ROS) amount and superoxide dismutase (SOD) activity were enhanced by NIT. Comet assay showed that lower concentrations of NIT, 12.5-100 μg/mL, induced the DNA damage. Transcriptomic analysis identified 468 differentially expressed genes (p < 0.05, |log2(Foldchange)| ≥ 1), from which 22 pathways were enriched. Multiple affected pathways were related to cancer including viral carcinogenesis and bladder cancer. NIT may produce genotoxicity via inducing oxidative stress and deregulating PI3K/Akt, AMPK and mTOR signaling pathways, associated with carcinogenetic potency. While environmental levels of NIT alone may pose little risk to human health, attention should be paid to the health risk arose from the synergistic or additive effects that may exist among NEOs and other types of pesticides.

Endogenous Honeybee Gut Microbiota Metabolize the Pesticide Clothianidin

Including probiotics in honeybee nutrition represents a promising solution for mitigating diseases, and recent evidence suggests that various microbes possess mechanisms that can bioremediate environmental pollutants. Thus, the use of probiotics capable of degrading pesticides used in modern agriculture would help to both reduce colony losses due to the exposure of foragers to these toxic molecules and improve honeybee health and wellbeing globally. We conducted in vitro experiments to isolate and identify probiotic candidates from bacterial isolates of the honeybee gut (i.e., endogenous strains) according to their ability to (i) grow in contact with three sublethal concentrations of the pesticide clothianidin (0.15, 1 and 10 ppb) and (ii) degrade clothianidin at 0.15 ppb. The isolated bacterial strains were indeed able to grow in contact with the three sublethal concentrations of clothianidin. Bacterial growth rate differed significantly depending on the probiotic candidate and the clothianidin concentration used. Clothianidin was degraded by seven endogenous honeybee gut bacteria, namely Edwardsiella sp., two Serratia sp., Rahnella sp., Pantoea sp., Hafnia sp. and Enterobacter sp., measured within 72 h under in vitro conditions. Our findings highlight that endogenous bacterial strains may constitute the base material from which to develop a promising probiotic strategy to mitigate the toxic effects of clothianidin exposure on honeybee colony health.

Pesticide-induced disturbances of bee gut microbiotas

Social bee gut microbiotas play key roles in host health and performance. Worryingly, a growing body of literature shows that pesticide exposure can disturb these microbiotas. Most studies examine changes in taxonomic composition in Western honey bee (Apis mellifera) gut microbiotas caused by insecticide exposure. Core bee gut microbiota taxa shift in abundance after exposure but are rarely eliminated, with declines in Bifidobacteriales and Lactobacillus near melliventris abundance being the most common shifts. Pesticide concentration, exposure duration, season and concurrent stressors all influence whether and how bee gut microbiotas are disturbed. Also, the mechanism of disturbance-i.e. whether a pesticide directly affects microbial growth or indirectly affects the microbiota by altering host health-likely affects disturbance consistency. Despite growing interest in this topic, important questions remain unanswered. Specifically, metabolic shifts in bee gut microbiotas remain largely uninvestigated, as do effects of pesticide-disturbed gut microbiotas on bee host performance. Furthermore, few bee species have been studied other than A. mellifera, and few herbicides and fungicides have been examined. We call for these knowledge gaps to be addressed so that we may obtain a comprehensive picture of how pesticides alter bee gut microbiotas, and of the functional consequences of these changes.

Short exposure to nitenpyram pesticide induces effects on reproduction, development and metabolic gene expression profiles in Drosophila melanogaster (Diptera: Drosophilidae)

Although the toxicity of neonicotinoid insecticides has been demonstrated in several studies, the information on metabolism, behavior, and health risk remains limited and has raised concerns about its potential toxicity. Thus, in this study we assessed the effects of nitenpyram using different sublethal concentrations (one-third and one-tenth of the acute LC50 values) on various developmental and metabolic parameters from gene expression regulation in Drosophila melanogaster (model system used worldwide in ecotoxicological studies). As a result, nitenpyram sublethal concentrations prolonged the developmental time for both pupation and eclosion. Additionally, nitenpyram sublethal concentrations significantly decreased the lifespan, pupation rate, eclosion rate, and production of eggs of D. melanogaster. Moreover, the mRNA expression of genes relevant for development and metabolism was significantly elevated after exposure. Mixed function oxidase enzymes (Cyp12d1), (Cyp9f2), and (Cyp4ae1), hemocyte proliferation (RyR), and immune response (IM4) genes were upregulated, whereas lifespan (Atg7), male mating behavior (Ple), female fertility (Ddc), and lipid metabolism (Sxe2) genes were downregulated. These findings support a solid basis for further research to determine the hazardous effects of nitenpyram on health and the environment.

Honey bee Apis mellifera larvae gut microbial and immune, detoxication responses towards flumethrin stress

Mites are considered the worst enemy of honey bees, resulting in economic losses in agricultural production. In apiculture, flumethrin is frequently used to control mites. It causes residues of flumethrin in colonies which may threaten honey bees, especially for larvae. Still, the impact of flumethrin-induced dysbiosis on honey bees larval health has not been fully elucidated, and any impact of microbiota for decomposing flumethrin in honey bees is also poorly understood. In this study, 2-day-old larvae were fed with different flumethrin-sucrose solutions (0, 0.5, 5, 50 mg/kg) and the dose increased daily (1.5, 2, 2.5 and 3 μL) until capped, thereafter the expression level of two immune genes (hymenoptaecin, defensin1) and two detoxication-related genes (GST, catalase) were measured. Meanwhile, the effect of flumethrin on honey bee larvae (Apis mellifera) gut microbes was also explored via 16S rRNA Illumina deep sequencing. We found that flumethrin at 5 mg/kg triggered the over expression of immune-related genes in larvae, while the larval detoxification-related genes were up-regulated when the concentrations reached 50 mg/kg. Moreover, the abundance and diversity of microbes in flumethrin-treated groups (over 0.5 mg/kg) were significantly lower than control group, but it increased with flumethrin concentrations among the flumethrin-treated groups. Our results revealed that microbes served as a barrier in the honey bee gut and were able to protect honey bee larvae to a certain extent, and reduce the stress of flumethrin on honey bee larvae. In addition, as the concentration of flumethrin increases, honey bee larvae activate their immune system then detoxification system to defend against the potential threat of flumethrin. This is the first report on the impact of flumethrin on gut microbiota in honey bees larvae. The findings revealed new fundamental insights regarding immune and detoxification of host-associated microbiota.

Imbalance of intestinal microbial homeostasis caused by acetamiprid is detrimental to resistance to pathogenic bacteria in Bombyx mori

The neonicotinoid insecticide acetamiprid is widely applied for pest control in agriculture production, and its exposure often results in adverse effects on a non-target insect, Bombyx mori. However, only few studies have investigated the effects of exposure to sublethal doses of neonicotinoid insecticides on gut microbiota and susceptibility to pathogenic bacteria. In this study, we aimed to explore the possible mechanisms underlying the acetamiprid-induced compositional changes in gut microbiota of silkworm and reduced host resistance against detrimental microbes. This study indicated that sublethal dose of acetamiprid activated the dual oxidase-reactive oxygen species (Duox-ROS) system and induced ROS accumulation, leading to dysregulation of intestinal immune signaling pathways. The evenness and structure of bacterial community were altered. Moreover, after 96 h of exposure to sublethal dose of acetamiprid, several bacteria, such as Pseudomonas sp (Biotype A, DOP-1a, XW34) and Staphylococcus sp (RCB1054, RCB314, X302), invaded the silkworm hemolymph. The survival rate and bodyweight of the acetamiprid treated silkworm larvae inoculated with Enterobacter cloacae (E. cloacae) were significantly lower than the acetamiprid treatment group, suggesting that acetamiprid reduced silkworm resistance against pathogens. These findings indicated that acetamiprid disturbed gut microbial homeostasis of Bombyx mori, resulting in changes in gut microbial community and susceptibility to detrimental microbes.

Local Actions to Tackle a Global Problem: A Multidimensional Assessment of the Pollination Crisis in Chile

In the last decades, pollinators have drastically declined as a consequence of anthropogenic activities that have local and global impacts. The food industry has been expanding intensive agriculture crops, many of them dependent on animal pollination, but simultaneously reducing native pollinator habitats. Chile is a good example of this situation. Chile is becoming an agro-alimentary powerhouse in Latin America, where intensive agriculture expansion is performed at the expense of natural lands, posing a major threat to biodiversity. Here, we discussed the drivers responsible for the decline of pollinators (including habitat loss, pesticides, invasive species, and climate change) and its synergistic effects. This is particularly critical considering that Chile is a hotspot of endemic bee species locally adapted to specific habitats (e.g., Mediterranean-type ecosystems). However, there is a lack of data and monitoring programs that can provide evidence of their conservation status and contribution to crop yields. Based on our analysis, we identified information gaps to be filled and key threats to be addressed to reconcile crop production and biodiversity conservation. Addressing the local context is fundamental to undertake management and conservation actions with global impact.