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1.
Food Chem ; 400: 134049, 2023 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-36067689

RESUMO

Novel insecticide cyetpyrafen is frequently used in various crops, however, knowledge of its fate in crops and environments is largely unexplored. In this study, an effective method was firstly established for simultaneous determination of cyetpyrafen and its metabolites (M-309 and M-391) in 13 matrices (e.g., plants and soils) to explore their fate. Mean recoveries of the three compounds ranged from 73.1 % to 118.7 % with the relative standard deviations (RSDs) less than 17.9 %. Further, after 28 days of exposure in a field soil-strawberry system, cyetpyrafen and M-309 exhibited great accumulations in strawberry leaves by foliar spray while both compounds were predominately accumulated in roots by root irrigation, where cyetpyrafen was poorly translocated within plant. An equal amount of M-309 was measured in both strawberry plants and soils indicates the extensive transformation of cyetpyrafen in soil-strawberry system. Therefore, metabolism of cyetpyrafen in foods need to be considered for its better risk assessment.


Assuntos
Produtos Agrícolas/química , Fragaria , Praguicidas/análise , Solo/química , Água/análise , Produtos Agrícolas/metabolismo , Inseticidas/análise , Inseticidas/metabolismo , Praguicidas/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Água/metabolismo
2.
Pestic Biochem Physiol ; 187: 105173, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36127039

RESUMO

Declines of the monarch butterfly population have prompted large-scale plantings of milkweed to restore the population. In North America, there are >73 species of milkweed to choose from for these nationwide plantings. However, it is unclear how different milkweed species affect monarch caterpillar physiology, particularly detoxification enzyme activity and gene expression, given the highly variable cardenolide composition across milkweed species. Here, we investigate the effects of a high cardenolide, tropical milkweed species and a low cardenolide, swamp milkweed species on pyrethroid sensitivity as well as detoxification enzyme activity and expression in monarch caterpillars. Caterpillars fed on each species through the fifth-instar stage and were topically treated with bifenthrin after reaching this final-instar stage. Esterase, glutathione S-transferase, and cytochrome P450 monooxygenase activities were quantified as well as the expression of selected esterase, glutathione S-transferase, ABC transporter, and cytochrome P450 monooxygenase transcripts. There were no significant differences in survival 24 h after treatment with bifenthrin. However, bifenthrin significantly increased glutathione S-transferase activity in caterpillars feeding on tropical milkweed and significantly decreased esterase activity in caterpillars feeding on tropical and swamp milkweed. Significant differential expression of ABC transporter, glutathione S-transferase, and esterase genes was observed for caterpillars feeding on tropical and swamp milkweed and not receiving bifenthrin treatment. Furthermore, significant differential expression of glutathione S-transferase and esterase genes was observed for bifenthrin-treated and -untreated caterpillars feeding on tropical milkweed relative to swamp milkweed. These results suggest that feeding on different milkweed species can affect detoxification and development mechanisms with which monarch caterpillars rely on to cope with their environment.


Assuntos
Asclepias , Borboletas , Inseticidas , Piretrinas , Transportadores de Cassetes de Ligação de ATP , Animais , Asclepias/metabolismo , Borboletas/genética , Cardenolídeos/metabolismo , Esterases/genética , Esterases/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Inseticidas/metabolismo , Inseticidas/toxicidade , Oxigenases de Função Mista/metabolismo , Piretrinas/metabolismo , Piretrinas/toxicidade
3.
Toxins (Basel) ; 14(9)2022 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-36136584

RESUMO

Xenorhabdus nematophila HB310 secreted the insecticidal protein toxin complex (Tc). The chi60 and chi70 chitinase genes are located on the gene cluster encoding Tc toxins. To clarify the insecticidal activity of chitinases and their relationship with Tc toxins, the insecticidal activity of the chitinases was assessed on Helicoverpa armigera. Then, the chi60 and chi70 genes of X. nematophila HB310 were knocked out by the pJQ200SK suicide plasmid knockout system. The insecticidal activity of Tc toxin from the wild-type strain (WT) and mutant strains was carried out. The results demonstrate that Chi60 and Chi70 had an obvious growth inhibition effect against the second instar larvae of H. armigera with growth-inhibiting rates of 81.99% and 90.51%, respectively. Chi70 had a synergistic effect with the insecticidal toxicity of Tc toxins, but Chi60 had no synergistic effect with Tc toxins. After feeding Chi60 and Chi70, the peritrophic membrane of H. armigera became inelastic, was easily broken and leaked blue dextran. The Δchi60, Δchi70 and Δchi60-chi70 mutant strains were successfully screened. The toxicity of Tc toxins from the WT, Δchi60, Δchi70 and Δchi60-chi70 was 196.11 µg/mL, 757.25 µg/mL, 885.74 µg/mL and 20,049.83 µg/mL, respectively. The insecticidal activity of Tc toxins from Δchi60 and Δchi70 was 3.861 and 4.517 times lower than that of Tc toxins from the WT, respectively, while the insecticidal activity of Tc toxins from the Δchi60-chi70 mutant strain almost disappeared. These results indicate that the presence of chi60 and chi70 is indispensable for the toxicity of Tc toxins.


Assuntos
Quitinases , Inseticidas , Mariposas , Toxinas Biológicas , Xenorhabdus , Animais , Proteínas de Bactérias/farmacologia , Proteínas de Bactérias/toxicidade , Quitinases/genética , Quitinases/metabolismo , Humanos , Inseticidas/metabolismo , Inseticidas/farmacologia , Larva , Toxinas Biológicas/metabolismo , Xenorhabdus/genética
4.
Front Immunol ; 13: 849620, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36159828

RESUMO

Cry toxins produced by Bacillus thuringiensis (Bt) are well known for their insecticidal activities against Lepidopteran, Dipteran, and Coleopteran species. In our previous work, we showed that trypsin-digested full-length Cry7Ab4 protoxin did not have insecticidal activity against Plutella xylostella larvae but strongly inhibited their growth. In this paper, we expressed and purified recombinant active Cry7Ab4 toxic core from Escherichia coli for bioassay and identified its binding proteins. Interestingly, Cry7Ab4 toxic core exhibited activity to delay the pupation of P. xylostella larvae. Using protein pull-down assay, several proteins, including basic juvenile hormone-suppressible protein 1-like (BJSP-1), were identified from the midgut juice of P. xylostella larvae as putative Cry7Ab4-binding proteins. We showed that feeding P. xylostella larval Cry7Ab4 toxic core upregulated the level of BJSP-1 mRNA in the hemocytes and fat body and decreased the free juvenile hormone (JH) level in larvae. BJSP-1 interacted with Cry7Ab4 and bound to free JH in vitro. A possible mechanism of Cry7Ab4 in delaying the pupation of P. xylostella larvae was proposed.


Assuntos
Inseticidas , Mariposas , Animais , Proteínas de Bactérias/metabolismo , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Hormônios Juvenis/metabolismo , Larva/metabolismo , Mariposas/metabolismo , RNA Mensageiro/metabolismo , Tripsina/metabolismo
5.
J Environ Manage ; 322: 115989, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36055090

RESUMO

Flupyradifurone (FLU) has great application potential in agricultural production as a new generation of neonicotinoid insecticide after imidacloprid. Nevertheless, the toxic effects of FLU on non-target soil organisms remain unclear, resulting in considerable environmental risks. We evaluated the acute and subchronic toxicities of FLU to earthworms. The results of acute toxicity show that the median lethal concentration (LC50) values (14 d) of FLU were 186.9773 mg kg-1 for adult earthworms and 157.6502 mg kg-1 for juveniles, respectively. The subchronic toxicity of FLU that focused on the activities of antioxidant and detoxication enzymes showed the superoxide dismutase (SOD), catalase (CAT), and glutathione-S transferase (GST) activities in earthworms increased while the peroxidase (POD) and acetylcholinesterase (AChE) activities decreased after exposure to FLU. Oxidative damage analyses revealed that the reactive oxygen species (ROS) level and malonaldehyde (MDA) content in earthworms were increased by FLU, resulting in DNA damage. Transcriptomics and RT-qPCR confirmed that FLU influenced the expression of genes related to antioxidant response and detoxification of earthworms. Ultimately detoxification metabolism, environmental information processing, cell processes, and immune system pathways are significantly enriched to respond jointly to FLU. Our study fills the gaps in the toxicity of FLU to earthworms, providing a basis for its risk assessment of soil ecosystems and non-target biological toxicity.


Assuntos
Inseticidas , Oligoquetos , Poluentes do Solo , 4-Butirolactona/análogos & derivados , Acetilcolinesterase/metabolismo , Acetilcolinesterase/farmacologia , Animais , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Catalase/genética , Catalase/metabolismo , Catalase/farmacologia , Ecossistema , Glutationa/metabolismo , Glutationa/farmacologia , Inseticidas/metabolismo , Malondialdeído/metabolismo , Malondialdeído/farmacologia , Neonicotinoides/metabolismo , Neonicotinoides/toxicidade , Oligoquetos/metabolismo , Estresse Oxidativo , Piridinas , Espécies Reativas de Oxigênio , Solo , Poluentes do Solo/metabolismo , Superóxido Dismutase/metabolismo , Transferases/metabolismo , Transferases/farmacologia
6.
Pestic Biochem Physiol ; 186: 105178, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35973767

RESUMO

Spodoptera exigua (Lepidoptera, Noctuidae) has been responsible for causing considerable and widespread agricultural losses worldwide. Owing to strong selective pressure, S. exigua showed increased resistance to Lufenuron (LUF). Consequently, RNA interference (RNAi)-based insecticides had more benefits than chemical insecticides. Therefore, to enhance the insecticidal activity of LUF to S. exigua, in the present study, we aimed to elucidate the impact of double-stranded RNAs (dsRNAs) on S. exigua larval susceptibility to LUF. First, the transcriptome of S. exigua was sequenced following the treatment with LUF. By comparing the upregulated and downregulated GO enrichment, chitin binding and chitin metabolic processes were the significantly enriched pathways. According to transcriptome sequencing, 8 genes associated with chitin biosynthesis, 8 chitin degradation genes, and 17 cuticle protein genes were obtained. UDP-N-acetylglucosamine pyrophosphorylase (UAP) and Chitin synthase A (CHSA) showed significantly downregulated expression after treatment with different sublethal doses of LUF. Downregulation of UAP increased mortality from 31.97% to 47.91% when the larvae were exposed to LUF. A significant increase in the mortality of S. exigua from 30.63% to 50.19% was observed following LUF administration after dsCHSA. In addition, the expression analysis of genes associated with chitin biosynthesis was significantly changed after LUF treatment, dsRNAs-RNAi, and their combination (LUF-dsRNAs). Significant differences were observed in the chitin content between the control group at 72 h after treatments. Results of the present study can help further elucidate the understanding of the combined effects of RNAi and LUF on S. exigua. Additionally, this research provides a suitable foundation for future studies with the aim to develop an efficient method of delivery for large-scale pest control in the fields.


Assuntos
Quitina Sintase , Inseticidas , Animais , Benzamidas , Quitina/farmacologia , Quitina Sintase/genética , Quitina Sintase/metabolismo , Fluorcarbonetos , Inseticidas/metabolismo , Inseticidas/farmacologia , Larva/genética , Larva/metabolismo , Nucleotidiltransferases , RNA de Cadeia Dupla/farmacologia , Spodoptera
7.
Indoor Air ; 32(8): e13090, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-36040288

RESUMO

Permethrin is one of the most widely used active ingredients in spray-type home insecticides. However, indoor permethrin exposure resulting from the use of home insecticides is not well-characterized, as measured permethrin concentrations in indoor environmental and biological media with a known application rate are scarce. We conducted an intervention study with four participants for seven days. We conducted personal air monitoring and collected 24-h urine samples in which we quantified time-weighted average (TWA) permethrin concentrations in indoor air (Cair ) and urinary concentrations of two permethrin metabolites, 3-phenoxybenzoic acid (3-PBA) and cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis/trans-DCCA). We also estimated (1) TWA Cair using a simple indoor air model and (2) urinary excreted (UE) mass using a simple excretion model with both estimated and measured TWA Cair . Measurements of TWA Cair from personal air monitoring were lower than those estimated from the indoor model by a factor of 2.9 to 49.4. The ratio of estimated to measured UE mass ranged 3.5-18.2 when using estimated TWA Cair and 1.1-2.9 when using measured TWA Cair . Smaller ratios in estimating internal permethrin exposure from personal air monitoring suggest that personal air monitoring could reduce uncertainties in permethrin exposure assessment resulting from the use of spray-type insecticides.


Assuntos
Poluição do Ar em Ambientes Fechados , Inseticidas , Piretrinas , Biomarcadores , Monitoramento Ambiental , Humanos , Inseticidas/metabolismo , Permetrina/metabolismo , Piretrinas/metabolismo
8.
Environ Sci Technol ; 56(17): 12494-12505, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36006007

RESUMO

Neonicotinoid insecticides have attracted worldwide attention due to their ubiquitous occurrence and detrimental effects on aquatic organisms, yet their impacts on fish reproduction during long-term exposure remain unknown. Here, zebrafish (F0) were exposed to a neonicotinoid, acetamiprid, at 0.19-1637 µg/L for 154 d. Accumulation and biotransformation of acetamiprid were observed in adult fish, and the parent compound and its metabolite (acetamiprid-N-desmethyl) were transferred to their offspring. Acetamiprid caused slight survival reduction and significant feminization in F0 fish even at the lowest concentration. Hormone levels in F0 fish were remarkedly altered, that is, gonad 17ß-estradiol (E2) significantly increased, while androstenedione decreased. The corresponding transcription of steroidogenic genes (ar, cyp19b, fshß, gnrh2, gnrh3, and lhß) were significantly upregulated in the brain and gonad of the females but downregulated in the males. The vtg1 gene expression in the liver of male fish was also upregulated. In addition to F0 fish, parental exposure to acetamiprid decreased hatchability and enhanced malformation of F1 embryos. Chronic exposure to acetamiprid at environmentally relevant concentrations altered hormone production and the related gene expression of the hypothalamic-pituitary-gonad (HPG) axis in a sex-dependent way, caused feminization and reproductive dysfunction in zebrafish, and impaired production and development of their offspring.


Assuntos
Inseticidas , Poluentes Químicos da Água , Animais , Bioacumulação , Feminino , Feminização/induzido quimicamente , Feminização/metabolismo , Gônadas , Humanos , Inseticidas/metabolismo , Inseticidas/toxicidade , Masculino , Neonicotinoides/toxicidade , Reprodução , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/metabolismo
9.
Environ Res ; 214(Pt 3): 113940, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35952736

RESUMO

As a common pyrethroid insecticide, allethrin is widely used for various purposes in agriculture and home applications. At present, allethrin residues have been frequently detected worldwide, yet little is known about the kinetics and degradation mechanisms of this insecticide. In this study, a highly efficient allethrin-degrading bacterium, Bacillus megaterium strain HLJ7, was obtained through enrichment culture technology. Strain HLJ7 can remove 96.5% of 50 mg L-1 allethrin in minimal medium within 11 days. The first-order kinetic analysis of degradation demonstrated that the half-life of allethrin degradation by strain HLJ7 was 3.56 days, which was significantly shorter than the 55.89 days of the control. The Box-Behnken design of the response surface method optimized the degradation conditions for strain HLJ7: temperature 32.18 °C, pH value 7.52, and inoculation amount 1.31 × 107 CFU mL-1. Using Andrews equation, the optimal concentration of strain HLJ7 to metabolize allethrin was determined to be 21.15 mg L-1, and the maximum specific degradation rate (qmax), half-rate constant (Ks) and inhibition coefficient (Ki) were calculated to be 1.80 d-1, 1.85 mg L-1 and 68.13 mg L-1, respectively. Gas chromatography-mass spectrometry identified five intermediate metabolites, suggesting that allethrin could be degraded firstly by cleavage of its carboxylester bond, followed by degradation of the five-carbon ring and subsequent metabolism. The results of soil remediation experiments showed that strain HLJ7 has excellent bioremediation potential in the soils. After 15 days of treatment, about 70.8% of the initial allethrin (50 mg kg-1) was removed and converted into nontoxic intermediate metabolites, and its half-life was significantly reduced in the soils. Taken together, these findings shed light on the degradation mechanisms of allethrin and also highlight the promising potentials of B. megaterium HLJ7 in bioremediation of allethrin-comtaminated environment.


Assuntos
Bacillus megaterium , Inseticidas , Poluentes do Solo , Aletrinas , Bacillus megaterium/metabolismo , Biodegradação Ambiental , Inseticidas/metabolismo , Cinética , Solo/química , Microbiologia do Solo , Poluentes do Solo/metabolismo , Água
10.
J Agric Food Chem ; 70(36): 11192-11200, 2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36043880

RESUMO

Functions of insect CYP2 clan P450s in insecticide resistance are relatively less reported. In Spodoptera litura, a gene from the CYP2 clan (CYP304F1) was validated to be up-regulated significantly in a pyrethroid- and organophosphate-resistant population (QJ) than a susceptible population by RNA-Seq and qRT-PCR. Spatial-temporal expression indicated the high expression of CYP304F1 in the fourth, fifth, and sixth instar larvae and the metabolism-related tissue fat body and malpighian tubules. CYP304F1 was knocked out by CRISPR/Cas9, and a homozygous population (QJ-CYP304F1) with a G-base deletion at exon 2 was obtained after selection. Bioassay results showed that the LD50 values to ß-cypermethrin and chlorpyrifos in the QJ-CYP304F1 population decreased significantly, and the resistance ratio was both 1.81-fold in the QJ population compared with that in the QJ-CYP304F1 population. The toxicity of fenvalerate, cyhalothrin, or phoxim showed no significant change. These results suggested that CYP304F1 is involved in ß-cypermethrin and chlorpyrifos resistance in S. litura.


Assuntos
Clorpirifos , Inseticidas , Piretrinas , Animais , Sistemas CRISPR-Cas , Clorpirifos/metabolismo , Clorpirifos/farmacologia , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Inseticidas/farmacologia , Larva/genética , Piretrinas/metabolismo , Piretrinas/farmacologia , Spodoptera
11.
Ecotoxicol Environ Saf ; 242: 113847, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35809399

RESUMO

Insecticides harm the beneficial organisms, such as predatory spiders, through direct killing or regulation of the development and reproduction. In this study, the bioassay showed that the treatment of juvenile hormone (JH) analogue fenoxycarb delayed the moulting of Pardosa pseudoannulata, a dominant predatory spider in paddy fields. In order to figure out the regulatory mechanism of fenoxycarb on the spider development, we systematically analyzed JH biosynthesis in P. pseudoannulata. All genes involved in JH biosynthesis pathway were retrieved from the genome of P. pseudoannulata, except for CYP15A1. The absence of CYP15A1 was in agreement with the identification of methyl farnesoate (MF) rather than JH III in the spider. The delayed moulting and decreased expression of JH biosynthesis-related genes in the MF-applied spiderlings supported that MF was an active JH. Fenoxycarb treatment significantly upregulated the transcriptional level of JH biosynthesis-related genes and consequently delayed the spiderling moulting. In the spider development, ecdysteroid played the opposite role, in contrast to MF, to accelerate the development, as our previous study. Here we found that the treatment of ecdysteroid analogue tebufenozide accelerated P. pseudoannulata spiderling moulting, which resulted from the expressional suppression of ecdysteroid biosynthesis-related genes. In total, the JH and ecdysteroid analogues affected the development of P. pseudoannulata by the expressional regulation of biosynthesis-related genes, which would be helpful for the evaluation of hormone analogue insecticides in environmental safety, and useful for the protection and application of P. pseudoannulate and related spider species.


Assuntos
Inseticidas , Aranhas , Animais , Ecdisteroides/metabolismo , Inseticidas/metabolismo , Hormônios Juvenis/farmacologia , Comportamento Predatório , Aranhas/metabolismo
12.
Toxins (Basel) ; 14(7)2022 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-35878162

RESUMO

Abamectin, produced by the soil-dwelling actinomycete Streptomyces avermitilis, belongs to the macrocyclic lactones class of pesticides, has nematocidal, acaricidal, and insecticidal activity, and is highly effective when used against targeted species. Bemisia tabaci, the tobacco whitefly, is a highly destructive insect to agricultural production worldwide, and various insecticide-resistant strains have been identified in China. Here, we monitored levels of resistance to abamectin in twelve field-collected B. tabaci populations from northern China, and confirmed that, compared with the lab reference strain, six field populations exhibited strong abamectin resistance, while the other six exhibited low-to-medium resistance. Among these, the Xinzheng (XZ) population displayed about a 40-fold increased resistance to abamectin, and experienced significant cross-resistance to chlorpyrifos and imidacloprid. The abamectin resistance of XZ was found to be autosomal and incompletely dominant. Metabolic enzyme and synergism tests were conducted, and two metabolic enzymes, glutathione S-transferase and P450 monooxygenase, were found to be conducive to the field-developed abamectin resistance of the XZ population. The above results provide valuable information that can be used in identifying new pest control strategies and delaying the evolution of resistance to abamectin in field populations of whiteflies.


Assuntos
Hemípteros , Inseticidas , Animais , China , Resistência a Inseticidas , Inseticidas/metabolismo , Inseticidas/farmacologia , Ivermectina/análogos & derivados , Ivermectina/farmacologia
13.
Toxins (Basel) ; 14(7)2022 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-35878191

RESUMO

Afidopyropen, a newly identified chemical, is a derivative of pyripyropene A, which is produced by the filamentous fungus Penicillium coprobium. It is a promising novel pesticide applied against whiteflies in agriculture. In this study, the reversion and selection, cross-resistance patterns, synergistic effects, and fitness costs of afidopyropen resistance were studied in a field-developed resistant population of B. tabaci. Compared to a reference MED-S strain, the field-developed resistant Haidian (HD) population showed 36.5-fold resistance to afidopyropen. Significant reversion of resistance to afidopyropen was found in the HD population when it was kept with no selective pressure of the insecticide. The HD-Afi strain, developed from the HD population with afidopyropen pressure, developed 104.3-fold resistance to afidopyropen and significant cross-resistance to sulfoxaflor. Piperonyl butoxide (PBO) largely inhibited afidopyropen resistance in the HD-Afi strain, which indicates that P450 monooxygenase could be involved in the resistance. Significant fitness costs associated with afidopyropen resistance were observed in HD-Afi. This study indicates that a rotation of afidopyropen with other chemical control agents could be useful for impeding afidopyropen resistance in B. tabaci. In addition, we expanded upon the understanding of resistance to afidopyropen, offering evidence suggesting the importance of devising better strategies for the management of whiteflies.


Assuntos
Hemípteros , Inseticidas , Animais , Compostos Heterocíclicos de 4 ou mais Anéis , Resistência a Inseticidas , Inseticidas/metabolismo , Inseticidas/farmacologia , Lactonas/metabolismo
14.
Sci Rep ; 12(1): 12529, 2022 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-35869123

RESUMO

The insecticidal crystalline proteins (Crys) are a family of insect endotoxin functioning in crop protection. As insects keep evolving into tolerance to the existing Crys, it is necessary to discover new Cry proteins to overcome potential threatens. Crys possess three functional domains at their N-termini, and the most active region throughout evolution was found at the domain-III. We swapped domain-IIIs from various Cry proteins and generated seven chimeric proteins. All recombinants were expressed in Escherichia coli and their toxicity was assessed by dietary exposure assays. Three of the seven Crys exhibited a high toxicity to Asian corn borer over the controls. One of them, Cry1Ab-Gc, a chimeric Cry1Ab being replaced with the domain-III of Cry1Gc, showed the highest toxicity to rice stem borer when it was over-expressed in Oryza sativa. Furthermore, it was also transformed into maize, backcrossed into commercial maize inbred lines and then produced hybrid to evaluate their commercial value. Transgenic maize performed significant resistance to the Asian corn borer without affecting the yield. We further showed that this new protein did not have adverse effects on the environment. Our results indicated that domain III swapped of Crys could be used as an efficient method for developing new engineered insecticidal protein.


Assuntos
Bacillus thuringiensis , Inseticidas , Oryza , Animais , Bacillus thuringiensis/genética , Bacillus thuringiensis/metabolismo , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Endotoxinas/metabolismo , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Insetos/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Oryza/genética , Oryza/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Proteínas Recombinantes/metabolismo , Zea mays/genética , Zea mays/metabolismo
15.
Microb Biotechnol ; 15(10): 2607-2618, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35830334

RESUMO

Vip3 proteins are produced by Bacillus thuringiensis and are toxic against lepidopterans, reason why the vip3Aa gene has been introduced into cotton and corn to control agricultural pests. Recently, the structure of Vip3 proteins has been determined and consists of a tetramer where each monomer is composed of five structural domains. The transition from protoxin to the trypsin-activated form involves a major conformational change of the N-terminal Domain I, which is remodelled into a tetrameric coiled-coil structure that is thought to insert into the apical membrane of the midgut cells. To better understand the relevance of this major change in Domain I for the insecticidal activity, we have generated several mutants aimed to alter the activity and remodelling capacity of this central region to understand its function. These mutants have been characterized by proteolytic processing, negative staining electron microscopy, and toxicity bioassays against Spodoptera exigua. The results show the crucial role of helix α1 for the insecticidal activity and in restraining the Domain I in the protoxin conformation, the importance of the remodelling of helices α2 and α3, the proteolytic processing that takes place between Domains I and II, and the role of the C-t Domains IV and V to sustain the conformational change necessary for toxicity.


Assuntos
Bacillus thuringiensis , Inseticidas , Animais , Bacillus thuringiensis/genética , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/toxicidade , Endotoxinas/genética , Endotoxinas/metabolismo , Endotoxinas/toxicidade , Inseticidas/metabolismo , Inseticidas/farmacologia , Spodoptera/metabolismo , Tripsina/química , Tripsina/metabolismo
16.
Pest Manag Sci ; 78(11): 4579-4588, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35837767

RESUMO

BACKGROUND: Due to the development of insecticide resistance in mosquitoes, with worldwide mosquito-borne diseases resurgence in recent years, recent advances in proteome technology have facilitated a proteome-wide analysis of insecticide resistance-associated proteins in mosquitoes. Understanding the complexity of the molecular basis of insecticide resistance mechanisms employed by mosquitoes will help in designing the most effective and sustainable mosquito control methods. RESULTS: After 30 generations, insecticide-selected strains showed elevated resistance levels to the cypermethrin used for selection. Proteome data allowed the detection of 2892 proteins, of which 2885 differentially expressed proteins (DEPs) achieved quantitative significances in four stages (egg, larvae, pupae, adult) of Culex pipiens pallens cypermethrin-resistant strain as compared to the susceptible strain. Among them, a significant enrichment of proteins, including cuticular proteins, enzymes involved in the detoxification (cytochrome P450, glutathione S-transferases, esterase, ATP-binding cassette) and some biological pathways (oxidative phosphorylation, hippo signalling) that are potentially involved in cypermethrin resistance, was observed. Thirty-one representative DEPs (cytochrome P450, glutathione S-transferase, cuticle protein) during Cx. pipiens pallens developmental stages were confirmed by a parallel reaction monitoring strategy. CONCLUSIONS: The present study confirmed the power of isobaric tags for relative and absolute quantification for identifying concomitantly quantitative proteome changes associated with cypermethrin in Cx. pipiens pallens. Proteome analysis suggests that proteome modifications can be selected rapidly by cypermethrin, and multiple resistance mechanisms operate simultaneously in cypermethrin-resistance of Cx. pipiens pallens, Our results interpret that an up-regulated expression of proteins and enzymes like cytochrome P450, glutathione S-transferases, esterase etc. has an impact in insecticide resistance. Previously neglected penetration resistance (cuticular proteins) may play an important role in the adaptive response of Cx. pipiens pallens to insecticides. This information may serve as a basis for future work concerning the possible role of these proteins in cypermethrin resistance in mosquito Cx. pipiens pallens. © 2022 Society of Chemical Industry.


Assuntos
Culex , Inseticidas , Piretrinas , Trifosfato de Adenosina/metabolismo , Trifosfato de Adenosina/farmacologia , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Esterases/metabolismo , Glutationa/metabolismo , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Proteínas de Insetos/metabolismo , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Inseticidas/farmacologia , Proteoma/metabolismo , Piretrinas/metabolismo , Piretrinas/farmacologia , Transferases/metabolismo , Transferases/farmacologia
17.
Pest Manag Sci ; 78(11): 4599-4607, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35841135

RESUMO

BACKGROUND: Pest management requires continual identification of new physiological targets and strategies to control pests affecting agriculture and public/animal health. We propose the muscarinic system as a target for agrochemicals because of its physiological importance. Unlike the muscarinic system, gamma-amino butyric acid (GABA) receptors are an established insecticide target. Here, we investigated target-site synergism using small molecule probes (agonist and antagonist) against the muscarinic system and their ability to enhance the toxicity of GABAergic insecticides in Drosophila melanogaster (Meigen). RESULTS: Oral delivery of pilocarpine (muscarinic agonist) enhanced the toxicity of dieldrin, fipronil, and lindane, resulting in synergist ratios (SRs) between 4-32-fold (orally delivered) or between 2-67-fold when insecticides were topically applied. The synergism between pilocarpine and the GABA-insecticides was greater than the synergism observed with atropine (muscarinic antagonist), and was greater, or comparable, to the synergism observed with the metabolic inhibitor piperonyl butoxide. In addition to lethality, pilocarpine increased the knockdown of lindane. The mechanism of synergism was also investigated in the central nervous system using extracellular electrophysiology, where pilocarpine (3 µmo/L) lowered the half-maximal inhibitory concentration (IC50 ) of lindane from 1.3 (0.86-1.98) µmol/L to 0.17 (0.14-0.21) µmol/L and fipronil's IC50 from 2.2 (1.54-3.29) µmol/L to 0.56 (0.40-0.77) µmol/L. CONCLUSION: Convergence of the cellular function between the muscarinic and GABAergic systems enhanced the insecticidal activity of GABA receptor blocking insecticides through the modulation of the central nervous system (CNS). The future impact of the findings could be the reduction of the active ingredient needed in a formulation with the development of muscarinic synergists. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Inseticidas , Animais , Derivados da Atropina/metabolismo , Canais de Cloreto/metabolismo , Dieldrin/metabolismo , Dieldrin/farmacologia , Drosophila melanogaster , Hexaclorocicloexano/metabolismo , Inseticidas/metabolismo , Inseticidas/farmacologia , Agonistas Muscarínicos/metabolismo , Agonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/metabolismo , Antagonistas Muscarínicos/farmacologia , Pilocarpina/metabolismo , Pilocarpina/farmacologia , Butóxido de Piperonila , Receptores de GABA/genética , Receptores de GABA/metabolismo , Receptores Muscarínicos/metabolismo , Ácido gama-Aminobutírico/metabolismo , Ácido gama-Aminobutírico/farmacologia
18.
Pest Manag Sci ; 78(11): 4802-4808, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35904889

RESUMO

BACKGROUND: The selective aphicide flonicamid is known to cause symptoms in aphids that are like those of chordotonal organ TRPV channel modulator insecticides such as pymetrozine, pyrifluquinazon and afidopyropen. Flonicamid is classified by the Insecticide Resistance Action Committee as a chordotonal organ modulator with an undefined target site. However, although it has been shown not to act on TRPV channels, flonicamid's action on chordotonal organs has not been documented in the literature. RESULTS: Flonicamid causes locusts to extend their hindlegs, indicating an action on the femoral chordotonal organ. In fruit flies, it abolishes negative gravitaxis behavior by disrupting transduction and mechanical amplification in antennal chordotonal neurons. Although flonicamid itself only weakly affects locust chordotonal organs, its major animal metabolite 4-trifluoromethylnicotinamide (TFNA-AM) potently stimulates both locust and fly chordotonal organs. Like pymetrozine, TFNA-AM rapidly increases Ca2+ in antennal chordotonal neurons in wild-type flies, but not iav1 mutants, yet the effect is nonadditive with the TRPV channel agonist. CONCLUSIONS: Flonicamid is a pro-insecticide form of TFNA-AM, a potent chordotonal organ modulator. The functional effects of TFNA-AM on chordotonal organs of locusts and flies are indistinguishable from those of the TRPV agonists pymetrozine, pyrifluquinazon and afidopyropen. Because our previous results indicate that TFNA-AM does not act directly on TRPV channels, we conclude that it acts upstream in a pathway that leads to TRPV channel activation. © 2022 Society of Chemical Industry.


Assuntos
Gafanhotos , Inseticidas , Animais , Drosophila , Compostos Heterocíclicos de 4 ou mais Anéis/farmacologia , Inseticidas/metabolismo , Inseticidas/farmacologia , Lactonas/farmacologia , Niacinamida/análogos & derivados
19.
Toxins (Basel) ; 14(8)2022 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-35893749

RESUMO

To control the fall armyworm (FAW), Spodoptera frugiperda (Smith), a serious threat to maize production in China, the Chinese government has issued biosafety certificates for transgenic insect-resistant maize expressing Bt (Bacillus thuringiensis) toxins including Bt-Cry1Ab maize (crop event DBN9936), Bt-Vip3Aa maize (event DBN9501), Bt-(Cry1Ab+Vip3Aa) maize with superimposed traits (event DBN9936 × DBN9501) and Bt-(Cry1Ab+Vip3Aa) maize with superimposed traits (event Bt11 × MIR162), but the susceptibility baselines of geographically distinct FAW populations to these events, which form the basis for managing resistance development in the pest to these events, are not clear. We used the diet-incorporated bioassays method to detect the susceptibilities of the seven FAW populations collected from Yunnan, Henan and Hubei provinces in China in 2021 to the insecticidal proteins of the four Bt maize events. The result showed that the susceptibilities of different geographical populations to Bt insecticidal proteins were significantly different. In the seven populations, the range in median lethal concentrations (LC50) of Cry1Ab expressed in DBN9936 was 0.87-2.63 µg/g, 0.14-0.30 µg/g for Vip3Aa expressed in DBN9501, 0.78-1.86 µg/g for Cry1Ab+Vip3Aa expressed in DBN9936 × DBN9501, and 0.36-1.42 µg/g for CryAb+Vip3Aa expressed in Bt11 × MIR162. The growth inhibition responses also showed that the susceptibilities varied with the different median growth inhibitory concentration (GIC50) ranges (0.38-1.22, 0.08-0.28, 0.28-0.87, and 0.24-0.78 µg/g, respectively). The variations in the ranges of the susceptibility baselines of the geographical populations of fall armyworm in China to the insecticidal proteins expressed in the four events provide a scientific basis for monitoring FAW population resistance to Bt maize and managing the populations using different Bt maize events.


Assuntos
Inseticidas , Zea mays , Animais , Toxinas de Bacillus thuringiensis , Proteínas de Bactérias/farmacologia , Proteínas de Bactérias/toxicidade , China , Endotoxinas/genética , Endotoxinas/metabolismo , Endotoxinas/farmacologia , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Proteínas Hemolisinas/farmacologia , Resistência a Inseticidas/genética , Inseticidas/metabolismo , Inseticidas/farmacologia , Larva/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Spodoptera/metabolismo , Zea mays/metabolismo
20.
Int J Mol Sci ; 23(13)2022 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-35806039

RESUMO

The plant Tanacetum coccineum (painted daisy) is closely related to Tanacetum cinerariifolium (pyrethrum daisy). However, T. cinerariifolium produces large amounts of pyrethrins, a class of natural insecticides, whereas T. coccineum produces much smaller amounts of these compounds. Thus, comparative genomic analysis is expected to contribute a great deal to investigating the differences in biological defense systems, including pyrethrin biosynthesis. Here, we elucidated the 9.4 Gb draft genome of T. coccineum, consisting of 2,836,647 scaffolds and 103,680 genes. Comparative analyses of the draft genome of T. coccineum and that of T. cinerariifolium, generated in our previous study, revealed distinct features of T. coccineum genes. While the T. coccineum genome contains more numerous ribosome-inactivating protein (RIP)-encoding genes, the number of higher-toxicity type-II RIP-encoding genes is larger in T. cinerariifolium. Furthermore, the number of histidine kinases encoded by the T. coccineum genome is smaller than that of T. cinerariifolium, suggesting a biological correlation with pyrethrin biosynthesis. Moreover, the flanking regions of pyrethrin biosynthesis-related genes are also distinct between these two plants. These results provide clues to the elucidation of species-specific biodefense systems, including the regulatory mechanisms underlying pyrethrin production.


Assuntos
Chrysanthemum cinerariifolium , Inseticidas , Piretrinas , Tanacetum , Chrysanthemum cinerariifolium/genética , Chrysanthemum cinerariifolium/metabolismo , Genômica , Inseticidas/metabolismo , Piretrinas/metabolismo , Tanacetum/metabolismo
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