Insights into insecticide-resistance mechanisms in invasive species: Challenges and control strategies

Aegle marmelos-mediated zinc oxide nanoparticles for mosquito control, cancer therapy, and antibacterial applications

The study investigated the synthesis and characterization of zinc oxide nanoparticles (Am-ZnO-NPs) using Aegle marmelos leaves and their mosquitocidal, antioxidant, and anticancer efficacy. Am-ZnO-NPs were synthesized via combustion method under optimized conditions, including 5% plant extract, temperature of 70 °C, a contact time of 60 min, and pH of 10. The resulting nanoparticles were characterized using advanced analytical techniques. The Am-CuO-NPs were hexagonal wurtzite in shape and had an average particle size of 37.44 nm. The Am-CuO-NPs are highly stable with a surface charge of - 26.77 mV. Gas chromatography-mass spectrometry (GC-MS) analysis identified several compounds with insecticidal, antioxidant, and anticancer properties, including hexadecenoic acid, ethyl ester (25.61%), 9,12-octadecadienoic acid, ethyl ester (12.64%), and 9,12,15-octadecatrienoic acid, ethyl ester (6.31%). The aqueous extract of A. marmelos (100 µg/mL) demonstrated the highest larvicidal (57.33%) and pupicidal (42.67%) activities compared to other solvent extracts. In contrast, Am-ZnO-NPs exhibited relatively higher larvicidal activity (86.67%) and pupicidal (56.00%) at 10 µg/mL. The nanoparticles also inhibited the activities of acetylcholinesterase (AChE) and carboxylesterases and reduced the total protein (TP) levels in Ae. aegypti larvae. Further, both the aqueous leaf extract and Am-ZnO-NPs were effective in scavenging DPPH free radicals, achieving 76% and 94% inhibition, respectively, at a concentration of 125 µg/mL. Am-ZnO-NPs also exhibited cytotoxicity, induced cell cycle arrest, enhanced cell adhesion, and promoted apoptosis in L-132 lung cancer cell lines. Further, the Am-ZnO-NPs display potent antibacterial activity against clinical pathogens. These results highlight the role of phytochemicals in A. marmelos leaves for their effective biological activities.

Insights into garlic (Allium Sativum)'s nutrigenomics-associated fly-repellent potency in cattle

Despite effective control of flies using synthetic pesticides, fly resistance and environmental contamination have led to the inadequacy of this strategy. The use of integrated pest management approaches has since been advocated in contemporary research to sustainably control fly populations. Recent studies have found garlic (Allium Sativum) and its derivative bioactive compounds to possess insect-repellent attributes among other key health and production enhancing properties. This highlights the potential of garlic as a botanical pesticide to control flies in cattle. Moreover, the ability of cattle to naturally repel flies is influenced by animal genetic predisposition. The dietary garlic supplementation and gene interaction in disease resistance could also be an influential factor in repelling flies in cattle. Transcriptomics has emerged as a valuable tool in animal breeding and genetics which allows identification of trait-associated genes and understanding of complex interactions between dietary nutrients and animal genome expression. This paper explores the nutrigenomic effects of garlic supplementation on cattle and its contribution towards fly repellence efficacy in cattle. It was concluded that garlic supplementation in cattle diets could offer a sustainable approach to managing fly infestations in cattle farming. These findings underscore the importance of further research to validate these assertions and optimise the use of garlic to control flies in cattle under different production systems.

Nanoparticles alter locust development and behaviour

Locusts, among the world's most destructive migratory pests, threaten food security by devastating crops and pastures. Conventional chemical insecticides pose environmental and health risks, highlighting the need for sustainable alternatives. We demonstrate the efficacy of nickel ferrite (NiFe2O4) nanoparticles (36 ± 10 nm), as a safe, cost-effective insecticide for locust management. These NiFe2O4 nanoparticles disrupt locust development by impairing blastokinesis and growth, thus resulting in malformed nymphs with compacted abdomens and disorganised body structures - primarily arising from significantly lower heart rates (30 bpm for control vs. 20 bpm for embryos exposed to NiFe2O4) and changes to end-diastolic and end-systolic dimensions. Adult locusts retained ingested nanoparticles in their coelomic cavities, which could potentially be used as traceable markers for swarm tracking. Additionally, the nanoparticles were recoverable from soil with over 90% efficiency, minimising potential ecological impact. Our research therefore offers an innovative nanotechnology-based solution for sustainable and effective locust management.

With or Without You?-A Critical Review on Pesticides in Food

Pesticides are very important in modern agriculture, protecting crops against pests and diseases to ensure food safety. However, the use of pesticides in food production has raised significant concerns regarding their potential impacts on human health and the environment. This review provides comprehensive insights into the current status, future projections, and debates surrounding pesticides in food. Beginning with a historical overview of pesticide use in agriculture, the types of pesticides commonly used and the presence of their residues in food commodities are explored. The health and environmental impacts associated with pesticide exposure are examined, including both human health effects and ecological consequences. An analysis of the regulatory frameworks governing pesticide management at international and national levels is presented, along with emerging trends and future projections in pesticide technologies and agricultural practices. Strategies for mitigating pesticide risks, such as Integrated Pest Management and alternative approaches to conventional pesticide use, are discussed. Finally, the controversies surrounding pesticide use, including public perception, consumer concerns, and policy debates, are addressed. Through a critical examination of these issues, this review underscores a growing need for innovative solutions that can effectively balance agricultural demands with human health and the environment, enabling more resilient and sustainable food production.

Risk Assessment of Effects of Essential Oils on Honey Bees (Apis mellifera L.)

The toxicity of synthetic pesticides to non-target organisms has prompted a shift towards more environmentally friendly agricultural pest control methods, including the use of essential oils as possible biopesticides. Before these natural chemicals can be widely adopted for protecting food supplies and human health, it is crucial to evaluate their impacts on pollinators, such as honey bees. In this study, we examined the effects of one commercially available essential oil mixture (EcoTec+) and four essential oil components (β-bisabolene, cinnamaldehyde, 1,8-cineole, and eugenol) on honey bee workers using feeding or spray treatment. We then assessed the responses of esterase (EST), glutathione-S-transferase (GST), acetylcholine esterase (AChE), and P450. EcoTec+ increased the P450 transcript, while bisabolene inhibited EST and AChE, increased GST, and caused a mixed P450 response without being lethal. Cinnamaldehyde exhibited toxicity when ingested, suppressing P450 and eliciting a mixed response in AChE. Cineole inhibited EST but caused a mixed P450 response. Eugenol suppressed EST and AChE and was toxic on contact. We also assayed combinations of each compound with four synthetic formulations representative of the major pesticide categories, though no significant interactions were found. Overall, the essential oils tested did not cause acute lethal toxicity to honey bees; however, their biochemical effects varied, mostly remaining sublethal. These findings suggest that these essential oils could be considered safe for use around honey bees.

Toxicological investigations of biosynthesized nickel ferrites nanoparticles on midgut epithelium of Blaps polychresta as nanopesticides: Structural damages and oxidative stress

The development of eco-friendly insecticides with the ability to overcome insecticide resistance remains a thorny issue. This study therefore intends to evaluate the effectiveness of green synthesized nickel ferrite nanoparticles (NiFe2O4 NPs) as nanopesticides in this first report using darkling beetles, Blaps polychresta, as a model. The biosynthesized NiFe2O4 NPs were characterized employing various approaches, including FTIR, UV-Vis spectroscopy, XRD, XPS, and VSM. The morphological features and size of the nanoparticles were determined adopting SEM and TEM analyses, revealing that NiFe2O4 NPs have an average size of 24.59 nm with a quasi-spherical shape. The beetles treated with NiFe2O4 NPs showed their accumulation in midgut tissues, as evidenced by EDX analysis. Accumulation of NiFe2O4 NPs in midgut epithelium induced surplus reactive oxygen species (ROS) production, engendering elevated MDA level linked with increased expression of MT1 and HSP70. Besides, decreased GST, SOD, and GSH activities were also reported. These findings indicate antioxidant defense systems malfunction due to failure of NiFe2O4 NPs detoxification. Beyond that, comet assay and flow cytometry analysis exhibited noticeable amplifications of DNA impairment and cellular apoptosis, respectively, in beetles treated with NiFe2O4 NPs compared to untreated beetles. Pathohistological and ultrastructure investigations showed various aberrations in beetles exposed to NiFe2O4 NPs, including rapture of midgut epithelium and necrotic signs, substantiating the biochemical findings. These findings suggest that NiFe2O4 NPs could be implemented in agricultural practices as a sustainable insecticidal candidate to manage insect pests. Further studies are required to investigate NiFe2O4 NPs interaction with environmental conditions.

Automated video-tracking analysis of Agriotes obscurus wireworm behaviour before, during and after contact with thiamethoxam- and imidacloprid-treated wheat seeds

Limited studies have highlighted the importance of incorporating behavioural assessments into insecticide efficacy evaluations for wireworm pest control. "For this study, video tracking technology combined with a soil bioassay arena was employed to analyse the behaviour of Agriotes obscurus wireworms before, during, and after exposure to wheat seeds treated with the neonicotinoid insecticides thiamethoxam and imidacloprid at field-relevant concentrations. The analysis identified a set of behavioural key metrics for assessing the effects of these insecticides on wireworms. The results showed that these insecticides exhibited neutral attractancy towards wireworms. A brief period of feeding followed by rapid intoxication minimised damage to seeds. Furthermore, the wireworms demonstrated a specific form of behavioural resistance to neonicotinoids that did not rely on sensory input. In these insects, the rapid speed of intoxication, accompanied by drastic changes in behaviour, ensured that they received a sublethal rather than lethal dose of the insecticide. The wireworms fully recovered from all behavioural abnormalities within a week, and none died within 20 days following the exposure. In conclusion, this video tracking method provides a rapid and efficient means of assessing insecticides intended for wireworm management, offering valuable insights prior to more resource-intensive and costly field trials.

The importance of developing an integrated data-driven modelling platform for herbicide resistance research: A review

Herbicide-resistant weeds pose a global challenge, constraining agricultural practices worldwide. Despite efforts to establish an integrated, data-driven framework, understanding the varied risks of herbicide resistance (HR) across different agroecological zones remains elusive. This review paper advocates for an integrated approach that incorporates socioeconomic, environmental, adoption behavior, and physiological factors to uncover insights into HR drivers and develop tailored management strategies. HR not only escalates production costs but also necessitates alternative weed management tactics, highlighting the urgency for proactive environmental management to mitigate soil health degradation and biodiversity loss. While current initiatives prioritize integrated weed management (IWM) like crop rotation and herbicide mixtures, challenges persist in integrating socioeconomic factors into predictive models and promoting the universal adoption of sustainable practices. Advancements in big data analytics, spatial modeling, and remote sensing offer promising avenues for predicting and managing HR across landscapes. This study proposes a research framework to predict the emergence and management of HR in agri-food systems. Additionally, the study utilizes a novel text-mining technique to conduct a comprehensive literature review, highlighting gaps in the development of data-driven modeling platforms for predicting HR emergence. The text mining findings explored that while common terms like weeds, resistance, herbicides, crops, management, and control are prevalent, research often lacks focus on predictive data-driven approaches for HR. Therefore, urgent development of an integrated national-scale approach to predict HR emergence is imperative. Global cooperation is essential for sharing best practices, data, and responses to emerging resistance threats.

Jasmonic Acid (JA) Signaling Pathway in Rice Defense Against Chilo suppressalis Infestation

Jasmonic acid (JA) signaling plays a crucial role in rice defense against the striped stem borer, Chilo suppressalis, a notorious pest causing significant yield losses. This review explores the current understanding of JA-mediated defense mechanisms in rice, focusing on the molecular basis, regulatory elements, and practical implications for pest management. JA biosynthesis and signaling pathways are induced upon C. suppressalis infestation, leading to the activation of various defense responses. These include upregulation of JA-responsive genes involved in the production of proteinase inhibitors, volatile organic compounds, and other defensive compounds. The review also discusses the crosstalk between JA and other hormonal pathways, such as salicylic acid and ethylene, in fine-tuning defense responses. Structural modifications in rice plants, such as cell wall reinforcement and accumulation of secondary metabolites, have been highlighted as key components of JA-mediated defense against C. suppressalis. Furthermore, the practical applications of this knowledge in breeding insect-resistant rice varieties and developing sustainable pest management strategies were explored. Future research directions are proposed to further elucidate the complexities of JA signaling in rice-insect interactions and harness this knowledge to enhance crop protection.

De novo Transcriptomic analysis to unveil the deltamethrin induced resistance mechanisms in Callosobruchus chinensis (L.)

The use of synthetic insecticides has been crucial in the management of insect pests however the extensive use of insecticides can result in the development of resistance. Callosobruchus chinensis is a highly destructive pest of stored grains, it's a major feeder and infests a range of stored grains that are vital to both global food security and human nutrition. We extensively investigated gene expression changes of adults in response to deltamethrin to decipher the mechanism behind the insecticide resistance. The analysis of gene expression revealed 25,343 unigenes with a mean length of 1,435 bp. All the expressed genes were identified, and analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Exposure to deltamethrin (4.6 ppm) causes 320 differentially expressed genes (DEGs), of which 280 down-regulated and 50 up-regulated. The transcriptome analysis revealed that DEGs were found to be enriched in pathways related to xenobiotics metabolism, signal transduction, cellular processes, organismal systems and information processing. The quantitative real-time PCR was used to validate the DEGs encoding metabolic detoxification. To the best of our knowledge, these results offer the first toxicity mechanisms enabling a more comprehensive comprehension of the action and detoxification of deltamethrin in C. chinensis.

Laboratory and field efficacy of natural products against the invasive pest Halyomorpha halys and side effects on the biocontrol agent Trissolcus japonicus

The brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae), is an invasive pest causing major economic losses to crops. Since its outbreaks in North America and Europe, H. halys has been controlled with synthetic pesticides. More sustainable methods have been proposed, including biocontrol and use of natural products. Here, we conducted laboratory and field investigations to evaluate organically registered products for their effectiveness against H. halys and their non-target effect on the egg parasitoid, Trissolcus japonicus (Hymenoptera: Scelionidae). In the laboratory, azadirachtin, orange oil, potassium salts of fatty acids, kaolin, basalt dust, diatomaceous earth, zeolite, sulphur formulations, calcium polysulfide, and mixtures of sulphurs plus diatomaceous earth or zeolite demonstrated higher lethality against H. halys nymphs compared to control. Calcium polysulfide, azadirachtin and sulphur achieved more than 50% mortality. All treatments except azadirachtin and kaolin had negative effects on T. japonicus, with mortality exceeding 80% for calcium polysulfide and sulphur. Field experiments were conducted in 2021 and 2022 in pear orchards. Diatomaceous earth alone or alternated with sulphur or calcium polysulfide provided similar H. halys control, when compared to farm strategies based mostly on neonicotinoid (acetamiprid) treatments. Implications for H. halys control in integrated pest management are discussed.

Exploiting Trap Type and Color for Monitoring Macadamia Felted Coccid Acanthococcus ironsidei (Williams) and Associated Parasitic Wasps in Macadamia Orchards in Hawai'i

Acanthococcus ironsidei (Williams) (Hemiptera: Eriococcidae) is an invasive pest of macadamia, Macadamia integrifolia, in Hawai'i, causing death to macadamia trees and decreased nut productivity. Monitoring relies on wrapping double-sided sticky tapes over tree branches to trap dispersing crawlers (i.e., mobile immature stage), but this is tedious for growers, especially in large orchards. From September to November 2022 and December 2022 to February 2023, at two commercial macadamia orchards on Hawai'i Island, the use of colored sticky cards was assessed for improving the monitoring of A. ironsidei and to investigate the Hymenopteran parasitoid complex that inhabits macadamia canopies. At each study site, four different colored sticky cards (yellow, lime green, dark green, and white) were placed on the lower canopy of five trees, and on each tree, a transparent double-sided sticky tape was deployed. At bi-weekly intervals, the sticky cards were replaced and re-randomized on each tree, and the double-sided sticky tapes were replaced. The results showed that the sticky cards captured both A. ironsidei crawlers and (winged) male adults, while the double-sided sticky tapes captured only crawlers. The trap color did not have significant effects on the captures of A. ironsidei male adults at the sites, while the captures of crawlers on sticky cards were lowest on the dark green sticky traps at one site. The captures of A. ironsidei adult males on white sticky traps were generally correlated with the number of crawlers captured on the double-sided sticky tapes. The parasitoid complex captured had disparities in the attraction to color; however, the yellow, lime green and dark green colors were seemingly more effective for monitoring Encarsia lounsburyi (Berlese & Paoli), a reported parasitoid of A. ironsidei. These results have useful practical implications for improved monitoring of A. ironsidei crawlers, male adults and associated natural enemies.

P450 gene CYP321A8 is responsible for cross-resistance of insecticides in field populations of Spodoptera frugiperda

Continuous and long-term use of traditional and new pesticides can result in cross-resistance among pest populations in different fields. Study on the mechanism of cross-resistance and related genes will help resistance management and field pest control. In this study, the pesticide-resistance mechanism in Spodoptera frugiperda (FAW) was studied with field populations in 3 locations of South China. Field FAW populations were highly resistant to traditional insecticides, chlorpyrifos (organophosphate) and deltamethrin (pyrethroid), and had higher levels of cytochrome P450 activity than a non-resistant laboratory strain. Inhibition of P450 activity by piperonyl butoxide significantly increased the sensitivity of resistant FAW in 3 locations to chlorpyrifos, deltamethrin and chlorantraniliprole (amide), a new type of insecticide, suggesting that P450 detoxification is a critical factor for insecticide resistance in field FAW populations. Transcriptomic analysis indicated that 18 P450 genes were upregulated in the field FAW populations collected in 3 regions and in 2 consecutive years, with CYP321A8, the most significantly upregulated one. Knockdown of CYP321A8 messenger RNA by RNA interference resulted in an increased sensitivity to the 3 tested insecticides in the field FAW. Enzyme activity and molecular docking analyses indicated that CYP321A8 enzyme was able to metabolize the 3 tested insecticides and interact with 8 other types of insecticides, confirming that CYP321A8 is a key cross-resistance gene with a wide range of substrates in the field FAW populations across the different regions and can be used as a biomarker and target for management of FAW insecticide resistance in fields.

Insect Resistance to Insecticides: Causes, Mechanisms, and Exploring Potential Solutions

Insecticides play a crucial role as the primary means of controlling agricultural pests, preventing significant damage to crops. However, the misuse of these insecticides has led to the development of resistance in insect pests against major classes of these chemicals. The emergence of resistance poses a serious threat, especially when alternative options for crop protection are limited for farmers. Addressing this challenge and developing new, effective, and sustainable pest management approaches is not merely essential but also critically important. In the absence of alternative solutions, understanding the root causes behind the development of resistance in insects becomes a critical necessity. Without this understanding, the formulation of effective approaches to combat resistance remains elusive. With insecticides playing a vital role in global food security and public health, understanding and mitigating resistance are paramount. Given the growing concern over insect resistance to insecticides, this review addresses a crucial research gap by thoroughly examining the causes, mechanisms, and potential solutions. The review examines factors driving resistance, such as evolutionary pressure and excessive pesticide use, and provides a detailed analysis of mechanisms, including detoxifying enzyme overproduction and target site mutations. Providing an analysis of potential solutions, it discusses integrated pest management, strategic insecticide rotation, and the use of new pest control technologies and biological agents. Emphasizing the urgency of a multifaceted approach, the review provides a concise roadmap for sustainable pest management, guiding future research and applications.

Long-Term Exposure to Lambda-Cyhalothrin Reveals Novel Genes Potentially Involved in Aedes aegypti Insecticide Resistance

Insecticide resistance in Aedes aegypti populations hinders vector control programs. Many studies have focused on the classical mechanisms, kdr mutations, and metabolic enzymes to understand the development of insecticide resistance. In this study, we subjected a strain of Ae. aegypti to selective pressure for 13 consecutive generations to understand the development and extent of insecticide resistance. We delved into the transcriptomics of this pressured strain to gain insights into the molecular changes underlying insecticide resistance in Ae. aegypti. Our data suggest mosquito resistance is influenced by additional mechanisms that are difficult to explain using only classical mechanisms. The response by mosquitoes varies depending on the exposure time. Initially, when mosquitoes are in contact with insecticides, they modulate the expression of metabolic enzymes and gain some point mutations in the sodium channel genes. After long-term exposure, the mosquitoes respond to insecticides by expressing different proteins involved in the cuticle, energetic metabolism, and synthesis of proteases. We propose a model that includes these novel mechanisms found after prolonged insecticide exposure, which work in conjunction with established mechanisms (kdr and metabolic resistance) but have a different timeline in terms of expression and appearance.

Overexpression of multiple cytochrome P450 genes with and without knockdown resistance mutations confers high resistance to deltamethrin in Culex quinquefasciatus

BACKGROUND

The cytochrome P450s-mediated metabolic resistance and the target site insensitivity caused by the knockdown resistance (kdr) mutation in the voltage-gated sodium channel (vgsc) gene were the main mechanisms conferring resistance to deltamethrin in Culex quinquefasciatus from Thailand. This study aimed to investigate the expression levels of cytochrome P450 genes and detect mutations of the vgsc gene in deltamethrin-resistant Cx. quinquefasciatus populations in Thailand.

METHODS

Two field-collected strains of Cx. quinquefasciatus, Cq_SP and Cq_NiH, were selected with deltamethrin to generate the resistant strains Cq_SP-R and Cq_NiH-R, respectively. Bioassays were tested on larvae and adults of each strain according to WHO methods. Eight cytochrome P450 genes were analyzed for the expression level using quantitative real time-PCR. The cDNA of mosquitoes was amplified and sequenced for four fragments of vgsc gene. The kdr L1014F mutation and the haplotype of the CYP9M10 gene were detected in survivor and dead mosquitoes after exposure to the deltamethrin WHO test paper. Statistical analyses were performed using Fisher's exaction test.

RESULTS

Bioassay tests revealed a significantly higher resistance level in Cq_SP-R than in Cq_NiH-R strains in both larvae and adults. All eight cytochrome P450 genes were significantly overexpressed in larvae of Cq_NiH-R strain compared to the parent and susceptible Cq_Sus strains. The CYP6AA7 and CYP9J34 genes had the highest expression ratios, exceeding 24-fold in Cq_NiH-R larvae. In Cq_SP-R strain, the CYP4H34 and CYP9J34 genes were overexpressed in both stages. The kdr L1014F mutation was found in Cq_SP-R and its parent Cq_SP strains with a significantly higher mutant allele frequency in the survivor mosquitoes than in dead mosquitoes (P < 0.0001). The V240M and novel L925F mutations were found only in Cq_SP-R strain. Heterozygous genotype for the D-Cu( +)/Cu(-) of CYP9M10 gene was detected in Cq_NiH and Cq_NiH-R strains but other strains were mostly homozygous for the Cu(-)/Cu(-).

CONCLUSIONS

Overexpression of multiple cytochrome P450 genes alone has a relatively minor impact on resistance. The combined mechanisms of cytochrome P450- and kdr-mediated resistance result in significantly higher resistance to deltamethrin in Cx. quinquefasciatus. This study supports sustainable public health initiatives in Thailand to address the evolving challenges of insecticide resistance.

Differences in the abundance and diversity of endosymbiotic bacteria drive host resistance of Philodromus cespitum, a dominant spider of central European orchards, to selected insecticides

The ability of tissue endosymbionts to degrade and detoxify agrochemicals is increasingly recognized as a mechanism supporting the survival of arthropods in agroecosystems. Therefore, tissue endosymbionts have the potential to drive insecticide resistance in agrobiont spiders, i.e., in major generalist predators and pest control agents within agroecosystems. We hypothesized that the abundance and diversity of the endosymbiotic bacteria of Philodromus cespitum, a philodromid spider dominating central European apple orchards, vary with regard to differences in predation capacity and drive host insecticide resistance. We provisioned P. cespitum with diets of varying protein and lipid content and topically exposed them to field-relevant doses of commonly used insecticides, namely Mospilan (acetamiprid), Movento (spirotetramat), Gondola (sulfoxaflor), Decis (deltamethrin), Coragen (chlorantraniliprole), and Benevia (cyantraniliprole). The analyses were based on 16S rDNA profiles from lysates of the cephalothorax and legs of the tested spiders. The application of Benevia, Mospilan, and Movento was partially lethal. The spiders that were resistant to the treatments with Benevia, Mospilan, or Movento were associated with the increased relative abundance of Mycoplasmatota by more than one order of magnitude. Additionally, the abundance of other bacteria differed in Mospilan-resistant and Mospilan-sensitive individuals. In contrast, the diet regimens were not associated with any major differences in the microbiome diversity nor the diversity of endosymbionts. Philodromus cespitum hosts assemblages with unexpectedly high beta diversity of endosymbionts. The OTU identified as the alpha proteobacterium endosymbiont of Coelostomidia zealandica was an obligate endosymbiont of the analyzed P. cespitum population. Wolbachia, Rickettsia, and Spiroplasma endosymbionts were also highly prevalent and differed in their responses to the applied treatments. In conclusion, differences in the abundance and diversity of endosymbiotic bacteria drove the resistance of the spider host to selected insecticides.

The synergistic potential of polyethylene glycol 400 for the control of Hyphantria cunea larvae by Beauveria bassiana

The efficacy of entomopathogenic fungi as pest control agents is constrained by both their physiological state and external environmental factors. This study identified synergists capable of enhancing the insecticidal activity of Beauveria bassiana (Bb) and investigated the underlying synergistic mechanisms. Our results found that among 6 potential synergists, polyethylene glycol 400 (PEG) and trehalose significantly improved Bb's lethality against Hyphantria cunea larvae, with PEG demonstrating the most pronounced effect. PEG treatment markedly increased Bb spore adhesion and germination rates, while spore hydrophobicity and growth rates remained unaffected. Moreover, PEG-treated spores exhibited higher thermal tolerance compared to untreated ones. In the Bb + PEG treatment group, the hemocyte count, encapsulation and melanization activities, and the expression of related regulatory genes were significantly lower than those in the Bb treatment group. Additionally, pathogen recognition, signal transduction, and humoral immunity effector genes expression were markedly suppressed in the Bb + PEG group. A significant reduction in the content of total amino acids, free fatty acids, glucose, and trehalose, alongside decreased expression of key regulatory genes in the tricarboxylic acid cycle and glycolysis pathways, was observed in the Bb + PEG treatment group. Furthermore, PEG enhanced Bb-induced apoptosis in H. cunea larvae, as evidenced by the upregulation of apoptosis-related genes. Notably, PEG alone did not significantly impact the innate immunity, energy metabolism, or apoptosis in H. cunea larvae. Overall, PEG exhibits considerable potential in amplifying Bb's insecticidal activity by directly optimizing spore performance and indirectly modulating the larvae's innate immunity, energy metabolism, and apoptosis.

Integrated pest management adoption among citrus growers in Iran: an application of the protection motivation theory

BACKGROUND

Integrated pest management (IPM) is recognized as a sustainable approach to pest control. However, adoption rates among farmers in Iran have been observed to be low. This study investigates the adoption of IPM practices among citrus farmers in Iran and assesses the applicability of the protection motivation theory (PMT) in explaining farmers' behavior towards IPM.

RESULTS

Overall, farmers reported poor levels of IPM use, paying attention only to monitoring practices among the three groups of IPM practices examined (prevention, monitoring, and suppression). The perceived severity of the consequences of chemical pest control (β = 0.389, P < 0.001), the response efficacy of IPM practices (β = 0.254, P < 0.001), and the perceived self-efficacy of using IPM practices (β = 0.199, P < 0.001) positively predicted adoption of IPM practices, while response cost/barriers of IPM practices (β = -0.355, P < 0.001) negatively predicted adoption of IPM practices.

CONCLUSION

The PMT model presents a unique and interesting perspective to understand if and how IPM practices against the threat of pests are motivated. The perceived severity of the consequences of chemical pest control showed the strongest positive effect, whereas the response cost/barriers of IPM practices showed the strongest negative effect on IPM adoption. © 2024 Society of Chemical Industry.

Physiological and Molecular Mechanisms of Lepidopteran Insects: Genomic Insights and Applications of Genome Editing for Future Research

Lepidopteran insects are a major threat to global agriculture, causing significant crop losses and economic damage. Traditional pest control methods are becoming less effective due to the rapid evolution of insecticide resistance. This study explores the current status and genomic characteristics of 1315 Lepidopteran records, alongside an overview of relevant research, utilizing advanced functional genomics techniques, including RNA-seq and CRISPR/Cas9 gene-editing technologies to uncover the molecular mechanisms underlying insecticide resistance. Our genomic analysis revealed significant variability in genome size, assembly quality, and chromosome number, which may influence species' biology and resistance mechanisms. We identified key resistance-associated genes and pathways, including detoxification and metabolic pathways, which help these insects evade chemical control. By employing CRISPR/Cas9 gene-editing techniques, we directly manipulated resistance-associated genes to confirm their roles in resistance, demonstrating their potential for targeted interventions in pest management. These findings emphasize the value of integrating genomic data into the development of effective and sustainable pest control strategies, reducing reliance on chemical insecticides and promoting environmentally friendly integrated pest management (IPM) approaches. Our study highlights the critical role of functional genomics in IPM and its potential to provide long-term solutions to the growing challenge of Lepidopteran resistance.

Understanding the Influence of Secondary Metabolites in Plant Invasion Strategies: A Comprehensive Review

The invasion of non-native plant species presents a significant ecological challenge worldwide, impacting native ecosystems and biodiversity. These invasive plant species significantly affect the native ecosystem. The threat of invasive plant species having harmful effects on the natural ecosystem is a serious concern. Invasive plant species produce secondary metabolites, which not only help in growth and development but are also essential for the spread of these plant species. This review highlights the important functions of secondary metabolites in plant invasion, particularly their effect on allelopathy, defense system, interaction with micro soil biota, and competitive advantages. Secondary metabolites produced by invasive plant species play an important role by affecting allelopathic interactions and herbivory. They sometimes change the soil chemistry to make a viable condition for their proliferation. The secondary metabolites of invasive plant species inhibit the growth of native plant species by changing the resources available to them. Therefore, it is necessary to understand this complicated interaction between secondary metabolites and plant invasion. This review mainly summarizes all the known secondary metabolites of non-native plant species, emphasizing their significance for integrated weed management and research.

Evaluating foliar insecticides and economic thresholds for Tychius picirostris (Coleoptera: Curculionidae) management in Oregon white clover seed production

The clover seed weevil, Tychius picirostris Fabricius (Coleoptera: Curculionidae), is a major pest in Oregon white clover seed crops. Reliance on synthetic pyrethroid insecticides and limited availability of diverse modes of action (MoAs) has increased insecticide resistance selection in regional T. picirostris populations, emphasizing the need to evaluate novel chemistries and rotational strategies for effective insecticide resistance management (IRM). The efficacy of 8 foliar insecticide formulations for managing T. picirostris adult and larval life stages was determined in small and large-plot field trials across 2 crop years. In both years, bifenthrin (Brigade 2EC), the grower's standard, showed negligible adult and larval suppression. Insecticide formulations with isocycloseram and cyantraniliprole active ingredients reduced adult and larval populations when applied at BBCH 59-60 (prebloom) and BBCH 65-66 (full bloom) growth stages, respectively. While differences in T. picirostris abundance were observed among insecticide treatments, seed yield differences were not detected in large-plot trials. Larval abundance was correlated with reduced seed yield, and an economic threshold of ≥3 larvae per 30 inflorescences was determined as a conservative larval threshold to justify foliar applications of diamide insecticides. Additional commercial white clover seed fields were surveyed to compare larval scouting techniques, including a standard Berlese funnel and a grower's do-it-yourself funnel. Both larval extraction techniques were correlated and provided similar estimates of larval abundance. These findings demonstrate new MoAs, optimal insecticide application timing, and larval monitoring methods that can be incorporated into an effective T. picirostris IRM program in white clover seed crops.

Chirality in Insecticide Design and Efficacy

Chirality plays a crucial role in the design and efficacy of insecticides, significantly influencing their biological activity, selectivity, and environmental impact. Recent advancements in chiral insecticides have focused on enhancing their effectiveness, reducing toxicity to nontarget organisms, and improving environmental sustainability. This review provides a comprehensive overview of the current state of knowledge on chiral insecticides, including neonicotinoids, isoxazolines, and sulfiliminyls. We discuss the stereochemistry, synthetic development, mode of action, and environmental fate of these compounds. The review highlights the importance of chirality in optimizing insecticidal properties and underscores the need for continued research into novel chiral compounds and advanced synthesis technologies. By understanding the role of chirality, we can develop more effective and environmentally friendly insecticides for sustainable pest management.

Bioactive Insecticides from Chemometric Diverse Ant-Associated Symbionts Streptomyces novaecaesareae and Streptomyces nojiriensis against the Fall Armyworm Larvae

The Streptomyces genus has long been recognized as a prolific and valuable source of diverse secondary metabolites. These metabolites contribute significantly to the intricate chemical diversity exhibited by Streptomyces, making them an indispensable reservoir for drug discovery, agricultural applications, and industrial processes. Exploiting the potential of these natural compounds holds the promise of ushering in a new era in insect pest management, reducing reliance on synthetic chemicals and fostering ecologically sustainable solutions. This study dives into the realm of chemo diversity within isolates of Streptomyces nojiriensis and Streptomyces novaecaesareae, with a specific focus on the production of insecticidal compounds. We explored chromatographic techniques for the identification and isolation of insecticidal compounds, and two bioactive compounds were identified in extracts of S. novaecaesareae. Valinomycin was identified from hexanic extracts of strain Asp59, while naphthomycin from ethyl acetate extracts of strain Asp58. These compounds showed insecticidal activity against first instars of Spodoptera frugiperda (Asp59: LC50 = 10.82 µg/µL, LC90 = 26.25 µg/µL; Asp58: LC50 = 15.05 µg/µL, LC90 = 38.84 µg/µL). Notably, this is the first report of naphthomycin as an insecticidal compound. The present study suggests that valinomycin and naphthomycin may be a novel biological source for the control of Spodoptera frugiperda in early stages.

Omics approaches to unravel insecticide resistance mechanism in Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae)

Bemisia tabaci (Gennadius) whitefly (BtWf) is an invasive pest that has already spread worldwide and caused major crop losses. Numerous strategies have been implemented to control their infestation, including the use of insecticides. However, prolonged insecticide exposures have evolved BtWf to resist these chemicals. Such resistance mechanism is known to be regulated at the molecular level and systems biology omics approaches could shed some light on understanding this regulation wholistically. In this review, we discuss the use of various omics techniques (genomics, transcriptomics, proteomics, and metabolomics) to unravel the mechanism of insecticide resistance in BtWf. We summarize key genes, enzymes, and metabolic regulation that are associated with the resistance mechanism and review their impact on BtWf resistance. Evidently, key enzymes involved in the detoxification system such as cytochrome P450 (CYP), glutathione S-transferases (GST), carboxylesterases (COE), UDP-glucuronosyltransferases (UGT), and ATP binding cassette transporters (ABC) family played key roles in the resistance. These genes/proteins can then serve as the foundation for other targeted techniques, such as gene silencing techniques using RNA interference and CRISPR. In the future, such techniques will be useful to knock down detoxifying genes and crucial neutralizing enzymes involved in the resistance mechanism, which could lead to solutions for coping against BtWf infestation.

Distribution patterns of Phytoseiulus persimilis in response to climate change

BACKGROUND

The biological control agent Phytoseiulus persimilis is a commercialized specialist predator of two agricultural pest mite species Tetranychus urticae and Tetranychus evansi. Biocontrol of these pest species by P. persimilis has achieved success in biological control in some areas. However, the lack of precise information about the influence of global climate change on the worldwide distribution of this biocontrol agent hampers international efforts to manage pest mites with P. persimilis. With 276 occurrence records and 19 bioclimatic variables, this study investigated the potential global distribution of P. persimilis.

RESULTS

The results demonstrated that the Maximum Entropy (MaxEnt) model performed well, with the area under the curve being 0.956, indicating the high accuracy of this model. Two variables, the minimum temperature of the coldest month (Bio_6) and precipitation of the coldest quarter (Bio_19) were the most important environmental variables that influenced the distribution of P. persimilis, contributing more than 30% to the model, respectively. The suitable area currently occupies 21.67% of the world's land area, spanning latitudes between 60°S and 60°N. Under shared socio-economic pathway (SSP) 5-8.5 (high-carbon emissions), the low suitable area would increase by 1.31% until the 2050s.

CONCLUSION

This study successfully identified that south-eastern China, parts of countries in the Mediterranean coastal regions, including Libya, Algeria, Portugal, Spain, and France, are climatically favorable regions for P. persimilis, providing valuable information about the potential areas where it can be effectively exploited as biocontrol agents in classical biological control programs to manage pest spider mites environmentally friendly. © 2024 Society of Chemical Industry.

Insecticidal and Repellent Activity of Essential Oils from Copaifera reticulata, Citrus paradisi, Lavandula hybrida and Salvia sclarea Against Immature and Adult Stages of Ctenocephalides felis felis

PURPOSE

The flea Ctenocephalides felis (Siphonaptera: Pulicidae), parasitizes dogs and cats globally, acting as a vector for various pathogens affecting both animals and humans. Growing interest in environmentally friendly, plant-based products prompted this study. The aim of the study was to determine the chemical composition of essential oils (EOs) from Copaifera reticulata, Citrus paradisi, Lavandula hybrida and Salvia sclarea, assessing their insecticidal and repellent properties, determining lethal concentrations (LC50 and LC90), and evaluating residual efficacy in vitro against Ctenocephalides felis felis.

METHODS

Gas Chromatography with Flame Ionization Detector analyzed EO composition. In vitro tests involved preparing EO solutions at various concentrations. Ten specimens from each life stage (egg, larva, pupa, adult) were used for insecticidal activity assessment. Adulticidal activity was assessed using 10 cm2 filter paper strip, each treated with 0.200 mL of the test solution. Immature stages activities were evaluated using 23.76 cm2 discs of the same filter paper, each treated with 0.470 mL of the test solution. Mortality percentage was calculated using (number of dead insects × 100) / number of incubated insects. Probit analysis calculated LC50 values with a 95% confidence interval.

RESULTS

Major EO constituents were β-caryophyllene (EOCR), linalool (EOLH), linalyl acetate (EOSS), and limonene (EOCP). LC50 values were obtained for all stages except for the essential oil of C. paradisi. All oils showed repellent activity at 800 μg/cm2. OECR exhibited greater residual efficacy.

CONCLUSION

Each EO demonstrated superior insecticidal activity against specific C. felis felis stages.

Effectiveness and biochemical impact of ozone gas and silica nanoparticles on Culex pipiens (Diptera: Culicidae)

Culex pipiens (Diptera: Culicidae) is a vector of many serious human diseases, and its control by the heavy use of chemical insecticides has led to the evolution of insecticide resistance and high environmental risks. Many safe alternatives, such as ozone gas (O3) and silica nanoparticles (silica NPs) can reduce these risks. Therefore, O3 and silica NPs were applied to 3rd larval instars of Cx. pipiens at different concentrations (100, 200, and 400 ppm) for different exposure times (1, 2, 3, and 5 min for O3 and 24, 48, and 72 h for silica NPs). The activity of some vital antioxidant enzymes as well as scanning electron microscopy of the body surface were also investigated. A positive correlation was observed between larval mortality % and the tested concentrations of O3 and silica NPs. O3 was more effective than silica NPs, it resulted in 92% mortality at 400 ppm for a short exposure time (5 min). O3-exposed larvae exhibited a significant increase in glutathione peroxidase, glutathione S-transferase, and catalase activities as well as the total antioxidant capacity. Scanning electron microscopy showing disruptive effects on the body surface morphology of ozone and silica NPs treated larvae. These results provide evidence that O3 and silica NPs have the potential for use as alternative vector control tools against Cx. pipiens.

Molecular insights into the functional analysis of P450 CYP321A7 gene in the involvement of detoxification of lambda-cyhalothrin in Spodoptera frugiperda

Fall armyworm, Spodoptera frugiperda (J. E. Smith), is a widely recognized global agricultural pest that has significantly reduced crop yields all over the world. S. frugiperda has developed resistance to various insecticides. Insect cytochrome P450 monooxygenases (CYPs or P450s) play an important role in detoxifying insecticides, leading to increased resistance in insect populations. However, the function of the specific P450 gene for lambda-cyhalothrin resistance in S. frugiperda was unclear. Herein, the expression patterns of 40 P450 genes in the susceptible and lambda-cyhalothrin-resistant populations were analyzed. Among them, CYP321A7 was found to be overexpressed in the resistant population, specifically LRS (resistance ratio = 25.38-fold) derived from a lambda-cyhalothrin-susceptible (SS) population and FLRS (a population caught from a field, resistance ratio = 63.80-fold). Elevated enzyme activity of cytochrome P450 monooxygenases (P450s) was observed for LRS (2.76-fold) and the FLRS (4.88-fold) as compared to SS, while no significant differences were observed in the activities of glutathione S-transferases and esterases. Furthermore, the knockdown of CYP321A7 gene by RNA interference significantly increased the susceptibility to lambda-cyhalothrin. Remarkably, the knockdown of CYP321A7 reduced the enzymatic activity of P450 by 43.7%, 31.9%, and 22.5% in SS, LRS, and FLRS populations, respectively. Interestingly, fourth-instar larvae treated with lambda-cyhalothrin at the LC30 dosage had a greater mortality rate due to RNA interference-induced suppression of CYP321A7 (with increases of 61.1%, 50.0%, and 45.6% for SS, LRS, and FLRS populations, respectively). These findings suggest a link between lambda-cyhalothrin resistance and continual overexpression of CYP321A7 in S. frugiperda larvae, emphasizing the possible importance of CYP321A7 in lambda-cyhalothrin detoxification in S. frugiperda.

Antibiotic feeding changes the bacterial community of Chilo suppressalis and thereby affects its pesticide tolerance

BACKGROUND

Owing to the widespread use of chemical pesticides to control agricultural pests, pesticide tolerance has become a serious problem. In recent years, it has been found that symbiotic bacteria are related to pesticides tolerance. To investigate the potential role of microorganisms in the pesticide tolerance of Chilo suppressalis, this study was conducted.

RESULTS

The insect was fed with tetracycline and cefixime as the treatment group (TET and CFM, respectively), and did not add antibiotics in the control groups (CK). The 16S rDNA sequencing results showed that antibiotics reduced the diversity of C. suppressalis symbiotic microorganisms but did not affect their growth and development. In bioassays of the three C. suppressalis groups (TET, CFM, and CK), a 72 h LC50 fitting curve was calculated to determine whether long-term antibiotic feeding leads to a decrease in pesticide resistance. The CK group of C. suppressalis was used to determine the direct effect of antibiotics on pesticide tolerance using a mixture of antibiotics and pesticides. Indirect evidence suggests that antibiotics themselves did not affect the pesticide tolerance of C. suppressalis. The results confirmed that feeding C. suppressalis cefixime led to a decrease in the expression of potential tolerance genes to chlorantraniliprole.

CONCLUSIONS

This study reveals the impact of antibiotic induced changes in symbiotic microorganisms on the pesticide tolerance of C. suppressalis, laying the foundation for studying the interaction between C. suppressalis and microorganisms, and also providing new ideas for the prevention and control of C. suppressalis and the creation of new pesticides.

Insights into the role of non-coding RNAs in the development of insecticide resistance in insects

Pest control heavily relies on chemical pesticides has been going on for decades. However, the indiscriminate use of chemical pesticides often results in the development of resistance in pests. Almost all pests have developed some degree of resistance to pesticides. Research showed that the mechanisms of insecticide resistance in insects encompass metabolic resistance, behavioral resistance, penetration resistance and target-site resistance. Research on the these mechanisms has been mainly focused on the cis-regulatory or trans-regulatory for the insecticide resistance-related genes, with less attention paid to non-coding RNAs (ncRNAs), such as microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA). There has been increased studies focus on understanding how these ncRNAs are involved in post-transcriptional regulation of insecticide resistance-related genes. Besides, the formatted endogenous RNA (ceRNA) regulatory networks (lncRNA/circRNA-miRNA-mRNA) has been identified as a key player in governing insect resistance formation. This review delves into the functions and underlying mechanisms of miRNA, lncRNA, and circRNA in regulating insect resistance. ncRNAs orchestrate insect resistance by modulating the expression of detoxification enzyme genes, insecticide target genes, as well as receptor genes, effectively regulating both target-site, metabolic and penetration resistance in insects. It also explores the regulatory mechanisms of ceRNA networks in the development of resistance. By enhancing our understanding of the mechanisms of ncRNAs in insecticide resistance, it will not only provide valuable insights into the new mechanisms of insecticide resistance but also help to enrich new directions in ncRNAs gene regulation research.

Compatibility of Bioinsecticides with Parasitoids for Enhanced Integrated Pest Management of Drosophila suzukii and Tuta absoluta

Drosophila suzukii and Tuta absoluta are successful biological invaders of agroecosystems. Their integrated pest management (IPM) programs involve the release and/or conservation of natural enemies. Among these, Ganaspis kimorum is a major Asian parasitoid of D. suzukii and has been introduced as a classical biological control agent of this pest in Europe and North America, while Necremnus tutae is a key fortuitous parasitoid of T. absoluta in the Mediterranean region. Bioinsecticides represent key alternatives to chemicals for controlling both pests. This study investigated the potential compatibility of both parasitoids with Beauveria bassiana, Bacillus thuringiensis, garlic essential oil (EO), and spinosad, in comparison to two synthetic insecticides, cyantraniliprole and chlorantraniliprole. The results showed that combining each of the tested insecticides with G. kimorum slightly increased pest mortality compared to the insecticide alone. Necremnus tutae had a significant additive effect on host mortality when combined with insecticides. Beauveria bassiana and B. thuringiensis were most compatible with both parasitoid species. Both garlic EO and chlorantraniliprole impaired the survival of immature N. tutae and showed sublethal toxicity on the reproductive and non-reproductive behaviors of N. tutae. Spinosad exhibited high acute toxicity on both juvenile and adult parasitoids of both species. Overall, these findings provide useful insights into insecticide selectivity toward two key parasitoids and offer new knowledge on the potential of combining natural enemies and bioinsecticides for optimized IPM.

The P450-Monooxygenase Activity and CYP6D1 Expression in the Chlorfenapyr-Resistant Strain of Musca domestica L

The house fly Musca domestica L. is one of the most common insects of veterinary and medical importance worldwide; its ability to develop resistance to a large number of insecticides is well known. Many studies support the involvement of cytochrome P-450-dependent monooxygenases (P450) in the development of resistance to pyrethroids, neonicotinoids, carbamates, and organophosphates among insects. In this paper, the monooxygenase activity and expression level of CYP6D1 were studied for the first time in a chlorfenapyr-resistant strain of house fly. Our studies demonstrated that P450 activity in adults of the susceptible strain (Lab TY) and chlorfenapyr-resistant strain (ChlA) was 1.56-4.05-fold higher than that in larvae. In females of the Lab TY and ChlA strains, this activity was 1.53- and 1.57-fold higher, respectively (p < 0.05), than that in males, and in contrast, the expression level of CYP6D1 was 21- and 8-fold lower, respectively. The monooxygenase activity did not vary between larvae of the susceptible strain Lab TY and the chlorfenapyr-resistant strain ChlA. Activity in females and males of the ChlA strain exceeded that in the Lab TY strain specimens by 1.54 (p = 0.08) and 1.83 (p < 0.05) times, respectively, with the same level of CYP6D1 expression. PCR-RFLP analysis revealed a previously undescribed mutation in the promoter region of the CYP6D1 gene in adults of the Lab TY and ChlA strains, and it did not affect the gene expression level. The obtained results show that the development of resistance to chlorfenapyr in M. domestica is accompanied by an increase in P450-monooxygenase activity without changes in CYP6D1 expression.

Microbiome toxicology - bacterial activation and detoxification of insecticidal compounds

Insect gut bacteria have been implicated in a myriad of physiological processes from nutrient supplementation to pathogen protection. In fact, symbiont-mediated insecticide degradation has helped explain sudden control failure in the field to a range of active ingredients. The mechanisms behind the loss of susceptibility are varied based on host, symbiont, and insecticide identity. However, while some symbionts directly break down pesticides, others modulate endogenous host detoxification pathways or involve reciprocal degradation of insecticidal and bactericidal compounds both inspiring new questions and requiring the reexamination of past conclusions. Good steward of the chemical pesticide arsenal requires consideration of these ecological interactions from development to deployment.

Trichoplusia ni Transcriptomic Responses to the Phytosaponin Aglycone Hederagenin: Sex-Related Differences

Many plant species, particularly legumes, protect themselves with saponins. Previously, a correlation was observed between levels of oleanolic acid-derived saponins, such as hederagenin-derived compounds, in the legume Medicago truncatula and caterpillar deterrence. Using concentrations that reflect the foliar levels of hederagenin-type saponins, the sapogenin hederagenin was not toxic to 4th instar caterpillars of the cabbage looper Trichoplusia ni nor did it act as a feeding deterrent. Female caterpillars consumed more diet than males, presumably to obtain the additional nutrients required for oogenesis, and are, thus, exposed to higher hederagenin levels. When fed the hederagenin diet, male caterpillars expressed genes encoding trypsin-like proteins (LOC113500509, LOC113501951, LOC113501953, LOC113501966, LOC113501965, LOC113499659, LOC113501950, LOC113501948, LOC113501957, LOC113501962, LOC113497819, LOC113501946, LOC113503910) as well as stress-responsive (LOC113503484, LOC113505107) proteins and cytochrome P450 6B2-like (LOC113493761) at higher levels than females. In comparison, female caterpillars expressed higher levels of cytochrome P450 6B7-like (LOC113492289). Bioinformatic tools predict that cytochrome P450s could catalyze the oxygenation of hederagenin which would increase the hydrophilicity of the compound. Expression of a Major Facilitator Subfamily (MFS) transporter (LOC113492899) showed a hederagenin dose-dependent increase in gene expression suggesting that this transporter may be involved in sapogenin efflux. These sex-related differences in feeding and detoxification should be taken into consideration in insecticide evaluations to minimize pesticide resistance.

Insecticide resistance in social insects: assumptions, realities, and possibilities

Insecticide resistance is an evolved ability to survive insecticide exposure. Compared with nonsocial insects, eusocial insects have lower numbers of documented cases of resistance. Eusocial insects include beneficial and pest species that can be incidentally or purposely targeted with insecticides. The central goal of this review is to explore factors that either limit resistance or the ability to detect it in eusocial insects. We surveyed the literature and found that resistance has been documented in bees, but in other pest groups such as ants and termites, the evidence is more sparse. We suggest the path forward for better understanding eusocial resistance should include more tractable experimental models, comprehensive geographic sampling, and targeted testing of the impacts of social, symbiont, genetic, and ecological factors.

miRNA Dynamics for Pest Management: Implications in Insecticide Resistance

Utilizing chemical agents in pest management in modern agricultural practices has been the predominant approach since the advent of synthetic insecticides. However, insecticide resistance is an emerging issue, as pest populations evolve to survive exposure to chemicals that were once effective in controlling them, underlining the need for advanced and innovative approaches to managing pests. In insects, microRNAs (miRNAs) serve as key regulators of a wide range of biological functions, characterized by their dynamic expression patterns and the ability to target genes. Recent studies are increasingly attributed to the significance of miRNAs in contributing to the evolution of insecticide resistance in numerous insect species. Abundant miRNAs have been discovered in insects using RNA sequencing and transcriptome analysis and are known to play vital roles in regulation at both the transcriptional and post-transcriptional levels. Globally, there is growing research interest in the characterization and application of miRNAs, especially for their potential role in managing insecticide resistance. This review focuses on how miRNAs contribute to regulating insecticide resistance across various insect species. Furthermore, we discuss the gain and loss of functions of miRNAs and the techniques for delivering miRNAs into the insect system. The review emphasizes the application of miRNA-based strategies to studying their role in diminishing insecticide resistance, offering a more efficient and lasting approach to insect management.

Mixed insect pest populations of Diaspididae species under control of oligonucleotide insecticides: 3'-end nucleotide matters

Diaspididae are one of the most serious small herbivorous insects with piercing-sucking mouth parts and are major economic pests as they attack and destroy perennial ornamentals and food crops. Chemical control is the primary management approach for armored scale infestation. However, chemical insecticides do not possess selectivity in action and not always effective enough for the control of armored scale insects. Our previous work showed that green oligonucleotide insecticides (olinscides) are highly effective against armored and soft scale insects. Moreover, olinscides possess affordability, selectivity in action, fast biodegradability, and a low carbon footprint. Insect pest populations undergo microevolution and olinscides should take into account the problem of insecticide resistance. Using sequencing results, it was found that in the mixed populations of insect pests Dynaspidiotus britannicus Newstead and Aonidia lauri Bouche, predominates the population of A. lauri. Individuals of A. lauri comprised for 80% of individuals with the sequence 3'-ATC-GTT-GGC-AT-5' in the 28S rRNA site, and 20% of the population comprised D. britannicus individuals with the sequence 3'-ATC-GTC-GGT-AT-5'. We created olinscides Diasp80-11 (5'-ATG-CCA-ACG-AT-3') and Diasp20-11 (5'-ATA-CCG-ACG-AT-3') with perfect complementarity to each of the sequences. Mortality of insects on the 14th day comprised 98.19 ± 3.12% in Diasp80-11 group, 64.66 ± 0.67% in Diasp20-11 group (p < 0.05), and 3.77 ± 0.94% in the control group. Results indicate that for maximum insecticidal effect it is necessary to use an oligonucleotide insecticide that corresponds to the dominant species. Mortality in Diasp80-11 group was accompanied with significant decrease in target 28S rRNA concentration and was 8.44 ± 0.14 and 1.72 ± 0.36 times lower in comparison with control (p < 0.05) on the 10th and 14th days, respectively. We decided to make single nucleotide substitutions in Diasp20-11 olinscide to understand which nucleotide will play the most important role in insecticidal effect. We created three sequences with single nucleotide transversion substitutions at the 5'-end - Diasp20(5')-11 (A to T), 3'-end - Diasp20(3')-11 (T to A), and in the middle of the sequence - Diasp20(6)-11 (6th nitrogenous base of the sequence; G to C), respectively. As a result, mortality of mixed population of the field experiment decreased and comprised 53.89 ± 7.25% in Diasp20(5')-11 group, 40.68 ± 4.33% in Diasp20(6)-11 group, 35.74 ± 5.51% in Diasp20(3')-11 group, and 3.77 ± 0.94% in the control group on the 14th day. Thus, complementarity of the 3'-end nucleotide to target 28S rRNA was the most important for pronounced insecticidal effect (significance of complementarity of nucleotides for insecticidal effect: 5' nt < 6 nt < 3' nt). As was found in our previous research works, the most important rule to obtain maximum insecticidal effect is complete complementarity to the target rRNA sequence and maximum coverage of target sequence in insect pest populations. However, in this article we also show that the complementarity of 3'-end is a second important factor for insecticidal potential of olinscides. Also in this article we propose 2-step DNA containment mechanism of action of olinscides, recruiting RNase H. The data obtained indicate the selectivity of olinscides and at the same time provide a simple and flexible platform for the creation of effective plant protection products, based on antisense DNA oligonucleotides.

Analysis of insecticide resistance and de novo transcriptome assembly of resistance associated genes in the European grapevine moth, Lobesia botrana (Lepidoptera: Tortricidae)

The European grapevine moth Lobesia botrana (Denis & Shiffermüller 1776) is an economically important pest of the vine-growing areas worldwide. Chemical insecticides have been used for its control; however, its resistance status is largely unknown in many regions. We monitored the susceptibility of several L. botrana populations from Greece and Turkey. In addition, based on RNAseq transcriptome analysis, we identified and phylogenetically classify the cytochrome P450 genes of L. botrana, as well as analysed target site sequences and looked for the presence of known resistance mutations. Resistance against chlorantraniliprole, alpha-cypermethrin, spinetoram, etofenprox, and acetamiprid was very low (below 2.5-fold in all cases, compared to a reference strain from Greece) in all populations from Greece that were included in the study. However, resistance against indoxacarb (4-30-fold), spinosad (5-59-fold), and deltamethrin (18-30 fold) was detected in the L. botrana populations from Turkey, compared to a reference population from Turkey. De novo transcriptome assembly and manual annotation, and subsequent PCR-based analysis of insecticide target sequences (i.e. voltage-gated sodium channel - VGSC: target of pyrethroids and oxadiazines; nicotinic acetylcholine receptor subunit a6 - nAChR_α6: target of spinosad; ryanodine receptor - RyR: target of diamides; glutamate-gated chloride channel - GluCl: target of avermectins and; acetylcholinesterase - AChE: target of organophosphates) showed the absence of known resistance mutations in all specimens from both countries. Finally, the L. botrana CYPome (116 genes) was manually analysed and phylogenetically characterised, to provide resources for future studies that will aim the analysis of metabolic resistance.

kdr mutations and deltamethrin resistance in house flies in Abu Dhabi, UAE

BACKGROUND

The house fly, Musca domestica, is a significant carrier of diseases that can impact public health. Repeated use of pyrethroid insecticides may act as a selection pressure for mutations and amino acid substitutions in the house fly voltage-sensitive sodium channel (VSSC), which ultimately confers resistance. The objectives of this study were to determine the presence of knockdown resistance (kdr) mutations using molecular tools and to set up a CDC bottle bioassay specific for house flies in the United Arab Emirates (UAE) to screen for deltamethrin resistance.

METHODS

Adult flies were collected from 19 locations in Abu Dhabi, UAE, and DNA was extracted, followed by PCR amplification of specific alleles (PASA) and conventional PCR using several primers to amplify regions of the VSSC gene. Sanger sequencing was performed on PCR products. We also designed primers that detect four kdr mutations using complementary DNA (cDNA) in reverse transcriptase (RT)-PCR followed by Sanger sequencing. Additionally, a CDC bottle bioassay was set up for detecting deltamethrin resistance in adult house flies.

RESULTS

In PASA, the primers successfully amplified the target bands (480, 280 and 200 bp). The kdr allele was found in flies collected from 18 of the 19 locations, at the highest and lowest prevalence of 46.9% and 9.4%, respectively. Resistant homozygous (RR) insects constituted 5.0% of the tested populations, and heterozygous (RS) insects accounted for 36.5%. The RR genotype was prevalent in house flies collected at 10 of 19 sampling locations. House fly populations were mostly in Hardy-Weinberg equilibrium, except in three locations. In addition to verifying the presence of the previously identified kdr mutation L1014F, in this study we detected two kdr mutations, L1014H and T929I, that have not previously been reported in the UAE. Also, for the first time in the UAE, a CDC bottle bioassay for deltamethrin resistance was used, which found that 60 min and 4.5 µg/ml were the diagnostic time and dose, respectively. Using this assay, we detected deltamethrin resistance in house flies from two of 16 locations, with a resistance level of 12.5%.

CONCLUSIONS

Using DNA sequencing, we confirmed the presence of a known kdr mutation and uncovered two new kdr mutations in house flies from Abu Dhabi. Additionally, we detected deltamethrin resistance in these flies using a CDC bottle bioassay. Further research is recommended to comprehensively identify more kdr mutations in UAE house fly populations and assess their impacts on control strategies.

Present status of insecticide impacts and eco-friendly approaches for remediation-a review

Insecticides are indispensable for modern agriculture to ensuring crop protection and optimal yields. However, their excessive use raises concerns regarding their adverse effects on agriculture and the environment. This study examines the impacts of insecticides on agriculture and proposes remediation strategies. Excessive insecticide application can lead to the development of resistance in target insects, necessitating higher concentrations or stronger chemicals, resulting in increased production costs and disruption of natural pest control mechanisms. In addition, non-target organisms, such as beneficial insects and aquatic life, suffer from the unintended consequences of insecticide use, leading to ecosystem imbalances and potential food chain contamination. To address these issues, integrated pest management (IPM) techniques that combine judicious insecticide use with biological control and cultural practices can reduce reliance on chemicals. Developing and implementing selective insecticides with reduced environmental persistence is crucial. Promoting farmer awareness of responsible insecticide use, offering training and resources, and adopting precision farming technologies can minimize overall insecticide usage.

The role of P450 enzymes in malaria and other vector-borne infectious diseases

Vector-borne infectious diseases are still an important global health problem. Malaria is the most important among them, mainly pediatric, life-threatening disease. Malaria and other vector-borne disorders caused by parasites, bacteria, and viruses have a strong impact on public health and significant economic costs. Most vector-borne diseases could be prevented by vector control, with attention to the ecological and biodiversity conservation aspects. Chemical control with pesticides and insecticides is widely used as a measure of prevention although increasing resistance to insecticides is a serious issue in vector control. Metabolic resistance is the most common mechanism and poses a big challenge. Insect enzyme systems, including monooxygenase CYP P450 enzymes, are employed by vectors mainly to metabolize insecticides thus causing resistance. The discovery and application of natural specific inhibitors/blockers of vector P450 enzymes as synergists for commonly used pesticides will contribute to the "greening" of insecticides. Besides vector CYPs, host CYP enzymes could also be exploited to fight against vector-borne diseases: using mostly their detoxifying properties and involvement in the immune response. Here, we review published research data on P450 enzymes from all players in vector-borne infections, that is, pathogens, vectors, and hosts, regarding the potential role of CYPs in disease. We discuss strategies on how to exploit cytochromes P450 in vector-borne disease control.

Function of Cytochrome P450s and Gut Microbiome in Biopesticide Adaptation of Grapholita molesta on Different Host Diets

Insects that feed on various host plants possess diverse xenobiotic adaptations; however, the underlying mechanisms are poorly understood. In the present study, we used Grapholita molesta, which shifts feeding sites from peach shoots to apple fruits, as a model to explore the effects of shifts in host plant diet on the profiles of cytochrome P450s and the gut bacteria microbiome, as well as their effects on biopesticide adaptation. We found that the sensitivity of the fruit-feeding G. molesta to emamectin benzoate biopesticide was significantly lower than that of the shoot-feeding larvae. We also found that the P450 enzyme activity and the expression of nine cytochrome P450s were enhanced in G. molesta fed on Fuji apples compared to those fed on peach shoots. The survival rates of G. molesta exposed to emamectin benzoate significantly decreased as each of three of four emamectin benzoate-inducted cytochrome P450 genes were silenced. Furthermore, we discovered the gut bacteria dynamics of G. molesta changed with the host shift and the structure of the gut bacteria microbiome was determined by the final diet ingested; additionally, the dysbiosis of the gut microbiota induced by antibiotics could significantly increase the sensitivity to emamectin benzoate. Taken together, our results suggest that the expression of P450s and the composition of the gut bacteria microbiome promote adaptation to emamectin benzoate in G. molesta, providing new insights into the molecular mechanisms underlying xenobiotic adaptation in this notorious pest.

Enthralling genetic regulatory mechanisms meddling insecticide resistance development in insects: role of transcriptional and post-transcriptional events

Insecticide resistance in insects severely threatens both human health and agriculture, making insecticides less compelling and valuable, leading to frequent pest management failures, rising input costs, lowering crop yields, and disastrous public health. Insecticide resistance results from multiple factors, mainly indiscriminate insecticide usage and mounted selection pressure on insect populations. Insects respond to insecticide stress at the cellular level by modest yet significant genetic propagations. Transcriptional, co-transcriptional, and post-transcriptional regulatory signals of cells in organisms regulate the intricate processes in gene expressions churning the genetic information in transcriptional units into proteins and non-coding transcripts. Upregulation of detoxification enzymes, notably cytochrome P450s (CYPs), glutathione S-transferases (GSTs), esterases [carboxyl choline esterase (CCE), carboxyl esterase (CarE)] and ATP Binding Cassettes (ABC) at the transcriptional level, modification of target sites, decreased penetration, or higher excretion of insecticides are the noted insect physiological responses. The transcriptional regulatory pathways such as AhR/ARNT, Nuclear receptors, CncC/Keap1, MAPK/CREB, and GPCR/cAMP/PKA were found to regulate the detoxification genes at the transcriptional level. Post-transcriptional changes of non-coding RNAs (ncRNAs) such as microRNAs (miRNA), long non-coding RNAs (lncRNA), and epitranscriptomics, including RNA methylation, are reported in resistant insects. Additionally, genetic modifications such as mutations in the target sites and copy number variations (CNV) are also influencing insecticide resistance. Therefore, these cellular intricacies may decrease insecticide sensitivity, altering the concentrations or activities of proteins involved in insecticide interactions or detoxification. The cellular episodes at the transcriptional and post-transcriptional levels pertinent to insecticide resistance responses in insects are extensively covered in this review. An overview of molecular mechanisms underlying these biological rhythms allows for developing alternative pest control methods to focus on insect vulnerabilities, employing reverse genetics approaches like RNA interference (RNAi) technology to silence particular resistance-related genes for sustained insect management.

Failure of methanol detoxification in pests confers broad spectrum insect resistance in PME overexpressing transgenic cotton

Methanol is noxious to insect pests, but most plants do not make enough of it to shield themselves from encroaching insects. Methanol emission is known to increase in the instance of herbivory. In the current study, we showed that Aspergillus niger pectin methylesterase over-expression increases methanol emission and confers resistance to polyphagous insect pests on transgenic cotton plants by impeding the possible methanol detoxification pathways. Transgenic plants emitted ∼11 fold higher methanol displaying insect mortality of 96% and 93% in Helicoverpa armigera and Spodoptera litura, respectively. The larvae were unable to survive and finish their life cycle and the surviving larvae exhibited severe growth retardation. Insects try to detoxify methanol via catalase, carboxylesterase and cytochrome P450 monooxygenase enzymes, amongst which cytochrome P450 plays a major role in oxidizing methanol to formaldehyde and formaldehyde to formic acid, which is broken down into carbon dioxide and water. In our study, catalase and esterase enzymes were found to be upregulated, but cytochrome P450 monooxygenase levels were not much affected. Leaf disc assays and In-planta bioassays also showed 50-60% population reduction in the sap sucking pests, such as Bemisia tabaci and Phenacoccus solenopsis. These findings imply that elevated methanol emissions confer resistance in plants against chewing and sap-sucking pests by tampering the methanol detoxification pathways. Such mechanism will be useful in imparting expansive resistance against pests in plants.