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In addition to the acute lethal toxicity, insecticides might affect population dynamics of insect pests by inducing life history trait changes under low concentrations, however, the underlying mechanisms remain not well understood. Here we examined systemic impacts on development and reproduction caused by low concentration exposures to cyantraniliprole in the fall armyworm (FAW), Spodoptera frugiperda, and the putative underlying mechanisms were investigated. The results showed that exposure of third-instar larvae to LC 10 and LC 30 of cyantraniliprole significantly extended larvae duration by 1.46 and 5.41 days, respectively. Treatment with LC 30 of cyantraniliprole significantly decreased the pupae weight and pupation rate as well as the longevity, fecundity and egg hatchability of female adults. Consistently, we found that exposure of FAW to LC 30 cyantraniliprole downregulated the mRNA expression of four ecdysteroid biosynthesis genes including SfNobo , SfShd , SfSpo and SfDib and one ecdysone response gene SfE75 in the larvae as well as the gene encoding vitellogenin (SfVg) in the female adults. We also found that treatment with LC 30 of cyantraniliprole significantly decreased the whole body levels of glucose, trehalose, glycogen and triglyceride in the larvae. Our results indicate that low concentration of cyantraniliprole inhibited FAW development by disruption of ecdysteroid biosynthesis as well as carbohydrate and lipid metabolism, which have applied implications for the control of FAW. [Display omitted] • Low concentrations of cyantraniliprole negatively affected the fitness of S. frugiperda. • LC 30 cyantraniliprole downregulated the mRNA expression of ecdysteroid biosynthesis genes. • LC 30 cyantraniliprole treatment led to disruption of carbohydrate and lipid metabolism. [ABSTRACT FROM AUTHOR]

Abstract Glutamate-gated chloride channels (GluCls) mediate fast inhibitory neurotransmission in invertebrate nervous systems, and are of considerable interest in insecticide discovery. The full length cDNA encoding CsGluCl was cloned from the rice stem borer Chilo suppressalis (Walker). Multiple cDNA sequence alignment revealed three variants of CsGluCl generated by alternative splicing of exon 3 and exon 9. While all the transcripts were predominantly expressed in both nerve cord and brain, the expression patterns of these three variants differed among other tissues and developmental stages. Specifically, the expression level of CsGluCl C in cuticle was similar to that in nerve cord and brain, and was the predominant variant in late pupae and early adult stages. Both injection and oral delivery of dsGluCl significantly reduced the mRNA level of CsGluCl. Increased susceptibility to abamectin and reduced larvae growth and pupation rate were observed in dsGluCl-treated larvae. Thus, our results provide the evidence that in addition to act as the target of abamectin, GluCls also play important physiological roles in the development of insects. Graphical abstract Unlabelled Image Highlights • Three variants of CsGluCl were generated by alternative splicing of exon 3. • CsGluCl C showed high expression in cuticle and was the predominant variant in late pupae and early adult stages. • Increased susceptibility to abamectin and reduced larvae growth and pupation rate were observed in dsGluCl -treated larvae. [ABSTRACT FROM AUTHOR]

Abstract The γ-aminobutyric acid (GABA) receptor is a primary neurotransmitter receptor in both vertebrate and invertebrate nervous systems. Multiple RDL subunits have been found in insects including the rice stem borer, Chilo suppressalis , however, comparative characterization of duplicated RDL genes in insects is still limited. In this study, comparison of the genomic sequences and the cDNA sequences revealed that both CsRDL1 and CsRDL2 consisted of 10 exons and 9 introns, and their exon-intron boundaries occur in the same position with respect to the coding sequences. Expression profiling showed that both CsRDL1 and CsRDL2 were predominantly expressed in nervous system, and had low expression levels in the gut and integument. The transcript level of CsRDL2 dramatically increased from the prepupae to late pupae and were much higher than that of CsRDL1 in adult stages. Notably, dietary ingestion of dsRDL1 and dsRDL2 significantly decreased the larval susceptibility to abamectin. These results suggest that CsRDL1 and CsRDL2 might play both physiological roles in development and toxicological roles in action of abamectin in C. suppressalis. Graphical abstract Unlabelled Image Highlights • The genomic sequences of CsRDL1 and CsRDL2 were compared. • CsRDL1 and CsRDL2 were predominantly expressed in nervous system. • The transcript level of CsRDL2 dramatically increased from the prepupae to late pupae. • Knockdown of dsRDL1 and dsRDL2 significantly decreased the larval susceptibility to abamectin. [ABSTRACT FROM AUTHOR]

Abstract To understand the role of target site insensitivity in abamectin resistance in the western flower thrips (WFT), Frankliniella occidentalis (Pergande), cDNAs encoding gamma-aminobutyric acid receptor subunit (FoRdl) and glutamate-gated chloride channel (FoGluCl) were cloned from WFT, and both single nucleotide polymorphisms (SNPs) and mRNA expression levels of FoRdl and FoGluCl were detected in a susceptible strain (ABA-S) and a laboratory selected strain (ABA-R) displaying 45.5-fold resistance to abamectin. Multiple cDNA sequence alignment revealed three alternative splicing variants of FoRdl and two alternative splicing variants of FoGluCl generated by alternative splicing of exon 3. While sequence comparison of FoRdl and FoGluCl in ABA-S and ABA-R strains identified no resistance-associated mutations, the expression level of FoGluCl in ABA-R strain was 2.63-fold higher than that in ABA-S strain. Thus, our preliminary results provide the evidence that the increased mRNA expression of FoGluCl could be an important factor in FoGluCl -mediated target site insensitivity in WFT. Graphical abstract Unlabelled Image Highlights • The insecticide target genes FoRdl and FoGluCl were cloned from Frankliniella occidentalis. • Three variants of FoRdl and two variants of FoGluCl were generated by alternative splicing of exon 3. • The single nucleotide polymorphisms (SNPs) of FoRdl and FoGluCl were detected in abamectin-resistant strain (ABA-R). • mRNA expression levels of FoRdl and FoGluCl were detected in ABA-R and the susceptible strain ABA-S. [ABSTRACT FROM AUTHOR]

It is well known that sublethal dose of insecticides induces life history trait changes of both target and non-target insect species, however, the underlying mechanisms remain not well understood. In this study, the effects of low concentrations of the anthranilic diamide insecticide chlorantraniliprole on the development and reproduction of the fall armyworm (FAW), Spodoptera frugiperda , were evaluated, and the underlying mechanisms were explored. The results showed that exposure of FAW to LC 10 and LC 30 chlorantraniliprole prolonged the larvae duration, decreased the mean weight of the larvae and pupae, and lowered the pupation rate as well as emergence rate. The fecundity of female adults was also negatively affected by treatment with low concentrations of chlorantraniliprole. Consistently, we found that exposure of FAW to LC 30 chlorantraniliprole downregulated the mRNA expression of juvenile hormone (JH) esterase (SfJHE), leading to the increase of JH titer in larvae. We also found that treatment with low concentrations of chlorantraniliprole suppressed the expression of ribosomal protein S6 kinase1 (SfS6K1) in female adults, resulting in the downregulation of the gene encoding vitellogenin (SfVg). These results provided insights into the mechanisms underlying the effects of low concentrations of insecticides on insect pests, and had applied implications for the control of FAW. [Display omitted] • LC 10 and LC 30 chlorantraniliprole negatively affected the fitness of S. frugiperda. • LC 30 chlorantraniliprole increased the juvenile hormone titer in the larvae. • The mRNA level of SfJHE was downregulated after exposure to LC 30 chlorantraniliprole. • Low concentrations of chlorantraniliprole downregulated SfS6K1 and SfVg. [ABSTRACT FROM AUTHOR]

Prothioconazole (PTC) is a widely used agricultural fungicide. In recent years, studies have confirmed that it exerts adverse effects on various species, including aquatic organisms, mammals, and reptiles. However, the toxicological effects of PTC on soil organisms are poorly understood. Here, we investigated the toxic effects, via oxidative stress and metabolic responses, of PTC on earthworms (Eisenia fetida). PTC exposure can induce significant changes in oxidative stress indicators, including the activities of superoxide dismutase (SOD) and catalase (CAT) and the content of glutathione (GSH), which in turn affect the oxidative defense system of earthworms. In addition, metabolomics revealed that PTC exposure caused significant changes in the metabolic profiles of earthworms. The relative abundances of 16 and 21 metabolites involved in amino acids, intermediates of the tricarboxylic acid (TCA) cycle and energy metabolism were significantly altered after 7 and 14 days of PTC exposure, respectively. Particularly, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that multiple different metabolic pathways could be disturbed after 7 and 14 days of PTC exposure. Importantly, these alterations in oxidative stress and metabolic responses in earthworms reveal that the effects of PTC on earthworms were time dependent, and vary with exposure time. In conclusion, this study highlights that the effects of PTC on soil organisms are of serious concern. [Display omitted] • PTC could affect the oxidative defense system of earthworms. • PTC could induce disturbance of metabolic profiles in earthworms. • Toxic effects of PTC on earthworms were time-dependent. [ABSTRACT FROM AUTHOR]

Control of Bemisia tabaci has depended primarily and heavily on insecticides, especially neonicotinoids. The novel sulfoximine insecticide sulfoxaflor exhibits high potency against a broad range of sap-feeding insect species, including those resistant to neonicotinoids. The resistance levels of Q-biotype B. tabaci field strains collected from 8 locations in eastern China to neonicotinoids and sulfoxaflor were investigated, and single nucleotide polymorphisms (SNPs) of nicotinic acetylcholine receptor β1 subunit gene ( Btβ1 ) were detected. Compared with the reference strain, the field strains had developed low to moderate levels of resistance to imidacloprid and nitenpyram with the resistance ratios (RR) ranging between 4.07 and 21.75-fold and 3.37 and 16.14-fold, respectively. While YZ strain exhibited high resistance (RF 40.38) to thiamethoxam, only low levels of resistance to thiamethoxam (RF 3.50–8.58) was observed in other strains. All strains were relatively susceptible to both dinotefuran (RF 0.50–2.55) and sulfoxaflor (RF 0.40–3.07). Sequence analysis of Btβ1 cDNA fragments revealed 23 SNPs representing 19 amino acid replacements in these strains. Notably, a 45 bp fragment deletion was detected in JY strain, which encodes 15 amino acid residues (positions 66–80) containing arginine at position 79 (R79) corresponding to the R81T mutation in Loop D of nAChR β1 subunit in Myzus persicae resistant to neonicotinoids. The lack of cross-resistance indicates that both dinotefuran and sulfoxaflor could play an important role in the control of B. tabaci already resistant to the first and second generation neonicotinoids. [ABSTRACT FROM AUTHOR]

Chlorantraniliprole (CAP), a representative bisamide insecticide, is widely used in rice fields around the world, posing potential toxicity risks to aquatic organisms. In this study, we examined the effects of exposure to CAP on growth and metabolic phenotype of zebrafish (Danio rerio) and oxidative stress and apoptosis in the liver of zebrafish (Danio rerio). First, we identified that CAP had a low bioaccumulation in zebrafish. Subsequently, growth phenotype analysis revealed that CAP could significantly increase liver weight and liver index in zebrafish. In addition, we found that CAP exposure could cause significant changes in indicators of oxidative stress, resulting in a significant increase in the content of malondialdehyde (MDA), causing oxidative stress in the liver of zebrafish. Meanwhile, the expression levels of apoptosis-related genes were also significantly changed and apoptosis was promoted in the liver of zebrafish with CAP exposure. Importantly, the results of metabolomics analysis shown that CAP exposure could significantly disrupt the metabolic phenotype of zebrafish, interfering with multiple metabolic pathways, mainly including valine, leucine and isoleucine biosynthesis and degradation, alanine, aspartate and glutamate metabolism and d -glutamine and D-glutamate metabolism. Last but not least, correlation analysis identified strong links between changes in liver function involving oxidative stress and apoptosis and changes in metabolic phenotype of zebrafish following CAP exposure. In brief, these results indicate that potential environmental risks of CAP to aquatic organisms should receive more attention. [Display omitted] • CAP had a low bioaccumulation in zebrafish. • CAP could cause oxidative stress and apoptosis in the liver of zebrafish. • CAP could disrupt the metabolic phenotypes of zebrafish. [ABSTRACT FROM AUTHOR]

Metabolism of insecticides is an energy-consuming process. As an important component of the intracellular energy buffering system, arginine kinase (AK) plays an important role in insect cellular energy homeostasis and environmental stress response, but the involvement of AKs in the response to chemical stressors (insecticides) remains largely unknown. In this study, using Tribolium castaneum as a model organism, we found that deltamethrin treatment significantly upregulated the expression of TcAK1 and TcAK2 and decreased the whole body ATP content. The knockdown of TcAK1 or TcAK2 significantly enhances the deltamethrin-induced ATP depletion and increase the susceptibility of T. castaneum to deltamethrin. In addition, pretreatment with two AK inhibitors, rutin and quercetin, significantly decreased the lifespan of beetles treated with deltamethrin. These results suggest that AKs might be involved in detoxification of insecticides by regulating cellular energy balance. [Display omitted] • Exposure of Tribolium castaneum to deltamethrin led to ATP depletion and upregulation of TcAK1 and TcAK2. • RNAi of TcAK1 and TcAK2 increased the susceptibility of T. castaneum to deltamethrin. • Rutin and quercetin act as synergists to deltamethrin in T. castaneum. [ABSTRACT FROM AUTHOR]

The glutathione S -transferases (GSTs) are a kind of metabolic enzymes and participate in the detoxification metabolism of xenobiotics in various organisms. In insects, GSTs play important roles in the development of insecticide resistance and antioxidant protection. The rice stem borer Chilo suppressalis is one of the most damaging pests in rice and has developed high levels of resistance to abamectin in many areas of China, whereas the potential resistance mechanisms of C suppressalis to abamectin are still unclear. In the present study, a total of 23 CsGSTs genes were identified from the C. suppressalis transcriptome and genome, including 21 cytosolic and two microsomal CsGSTs. The cytosolic CsGSTs were further classified into seven categories based on phylogenetic analysis, and their sequence characteristics and genome structures were also analyzed. Synergism study revealed that the susceptibility of C. suppressalis to abamectin was increased significantly when the CsGSTs were inhibited by diethyl maleate (DEM). Sixteen CsGSTs genes were up-regulated in C. suppressalis larvae after treatment with abamectin, among which four CsGSTs genes including CsGSTe2 , CsGSTe4 , CsGSTo4 and CsGSTu1 were significantly induced in the midgut and fat body tissues. These results indicated that CsGSTs were associated with the detoxification of C. suppressalis to abamectin, and CsGSTe2 , CsGSTe4 , CsGSTo4 and CsGSTu1 might play important roles in the insecticide detoxification or antioxidant protection in C. suppressalis. Our present study provides valuable information on C. suppressalis GSTs, and are helpful in understanding the contributions of GSTs in abamectin detoxification in C. suppressalis and other insects. [Display omitted] • A total of 23 CsGSTs were identified from the C. suppressalis. • The susceptibility of C. suppressalis to abamectin was increased after treatment with GSTs inhibitor DEM. • Four CsGSTs genes were induced in the midgut and fat body of larvae post-treatment with abamectin. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ryanodine receptors (RyRs) are the targets of novel diamide insecticides. [•] We obtained full-length RyR cDNA sequence (HaRyR) from Helicoverpa armigera. [•] All hallmarks of ryanodine receptor proteins are conserved in the HaRyR. [•] Developmental and anatomical regulation of HaRyR transcription was observed. [Copyright &y& Elsevier]

Abstract: Voltage-gated sodium channels are the targets of several important classes of synthetic insecticides including pyrethroids, indoxacarb and metaflumizone. The rice leaffolder, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), is an important rice insect pest throughout Southeast Asia. In this study, we report the cDNA sequence (named as CmNav) of C. medinalis sodium channel α-subunit homologous to the para gene from Drosophila melanogaster. The 5643-bp contiguous CmNav gene sequence encoded 1877 amino acid residues, which spans the 5′ UTR and covers the open reading frame from the start codon to beyond the last transmembrane segment of transmembrane domain IV (IV S6). The deduced amino acid sequence of CmNav shares 79% identity with Drosophila para. All hallmarks of sodium channel proteins are conserved in the CmNav including an overall organization of four large hydrophobic domains and the sodium channel’s DEKA selectivity filter motif. In addition, two conserved alternative splicing sites were identified in the CmNav gene, which form the optional exon B and the mutually exclusive exon K/L, respectively. Diagnostic PCR showed that the inclusion frequencies of alternative exons differed between developmental stages or adult anatomical regions. [Copyright &y& Elsevier]

Abstract: Abamectin resistance was selected in the western flower thrips [Frankliniella occidentalis (Pergande)] under the laboratory conditions, and cross-resistance patterns and possible resistance mechanisms in the abamectin-resistant strain (ABA-R) were investigated. Compared with the susceptible strain (ABA-S), the ABA-R strain displayed 45.5-fold resistance to abamectin after 15 selection cycles during 18 generations. Rapid reversion of abamectin resistance was observed in the ABA-R strain in the absence of the insecticide selection pressure. Moderate and low levels of cross-resistance to chlorpyrifos (RR 11.4) and lambda-cyhalothrin (3.98) were observed in the ABA-R strain, but no significant cross-resistance was found to spinosad (2.00), acetamiprid (1.47) and chlorfenapyr (0.26). Our studies also showed that the esterase inhibitor S,S,S-tributyl phosphorotrithioate (DEF) and glutathione S-transferase inhibitor diethyl maleate (DEM) were not able to synergize the toxicity of abamectin, whereas the oxidase inhibitor piperonyl butoxide (PBO) conferred a significant synergism on abamectin in the ABA-R strain (SR 3.00). Biochemical analysis showed that cytochrome P450 monooxygenase activity of the ABA-R strain was 6.66-fold higher than that of the ABA-S strain. It appears that enhanced oxidative metabolism mediated by cytochrome P450 monooxygenases was a major mechanism for abamectin resistance in the western flower thrips. [Copyright &y& Elsevier]

The sulfuryl transfer reaction catalyzed by cytosolic sulfotransferase (SULT) is one of the major conjugating pathways responsible for the detoxification and subsequent elimination of xenobiotics, however, functional characterization of insect SULTs is still limited. In this study, cDNA encoding a cytosolic sulfotransferase, named TcSULT1 , was cloned from the red flour beetle, Tribolium castaneum. Sequence analysis revealed that TcSULT1 had the conserved signature sequences of SULTs, and shared moderate amino acid identities with Bombyx mori and Drosophila SULTs. Analysis of the transcription level showed that TcSULT1 was highly expressed in head, epidermis and malpighian tube, and upregulated at 4 h after exposure to deltamethrin. Knockdown of TcSULT1 significantly increased the susceptibility of beetles to deltamethrin. Both RNAi and dual-luciferase assay revealed that the transcription factor TcCncC regulates the expression of TcSULT1. These data provides insights into the function and regulatory mechanism of insect SULTs. [Display omitted] • cDNA encoding a cytosolic sulfotransferase, TcSULT1 , was cloned from Tribolium castaneum. • RNAi of TcSULT1 increased the susceptibility of T. castaneum to deltamethrin. • TcCncC upregulates the expressions of TcSULT1. [ABSTRACT FROM AUTHOR]

The insect voltage-gated sodium channel is the primary target of pyrethroids and novel efficient insecticides such as indoxacarb and metaflumizone. In this study, we cloned and characterized two putative sodium channel genes, TcNav1 and TcNav2, in Tribolium castaneum. The composite TcNav1 and TcNav2 encode a protein of 2045 and 2037 amino acid residues, sharing 76.1% and 75.5% amino acid identity with Drosophila para , respectively. Comparative analysis of genomic organization showed that TcNav1 and TcNav2 contain 26 and 27 exons, respectively. Analysis of the expression patterns showed that the mRNA levels of TcNav1 and TcNav2 were predominantly expressed in the head. RNAi-mediated knockdown of both TcNav1 and TcNav2 adversely affected adult emergence and significantly decreased sensitivity to deltamethrin. Significantly reduced pupation rate and sensitivity to beta-cypermethrin were observed after injection of siRNA targeting TcNav1 but not TcNav2. Taken together, we provide evidence that sodium channel gene has undergone duplication in T. castaneum , resulting in diversified developmental and toxicological functions. [Display omitted] • Two voltage-gated sodium channel genes, TcNav1 and TcNav2, were cloned from Tribolium castaneum. • Knockdown of TcNav1 or TcNav2 adversely affected adult emergence and decreased sensitivity to deltamethrin. • Reduced pupation rate and sensitivity to beta-cypermethrin were observed when knockdown of TcNav1 but not TcNav2. [ABSTRACT FROM AUTHOR]