Pesticide Biochemistry and Physiology最新文献

Synthetic pyrethroids are widely used insecticides which may cause chronic diseases in non-target organisms upon long-term exposure. Microbial degradation offers a reliable method to remove them from the environment. This study focused on Brevibacillus parabrevis BCP-09 and its enzymes for degrading pyrethroids. The predicted deltamethrin-degrading genes phnA and mhpC were used to construct recombinant plasmids. These plasmids, introduced into Escherichia coli BL21(DE3) cells and induced with L-arabinose. The results indicated that the intracellular crude enzyme efficiently degraded deltamethrin by 98.8 %, β-cypermethrin by 94.84 %, and cyfluthrin by 73.52 % within 24 h. The hydrolytic enzyme MhpC possesses a catalytic triad Ser/His/Asp and a typical “Gly-X-Ser-X-Gly” conservative sequence of the esterase family. Co-cultivation of induced E. coli PhnA and E. coli MhpC resulted in degradation rates of 41.44 ± 3.55 % and 60.30 ± 4.55 %, respectively, for deltamethrin after 7 d. This study states that the degrading enzymes from B. parabrevis BCP-09 are an effective method for the degradation of pyrethroids, providing available enzyme resources for food safety and environmental protection.

The carmine spider mite, Tetranychus cinnabarinus (Boisduval), is an important agricultural arthropod pest. This study investigated acaricide susceptibility differences between sexes to determine the biochemical mechanisms potentially involved in these differences. The susceptibility of females and males to seven acaricides (pyridaben, cyflumetofen, abamectin, chlorpyrifos, propargite, profenofos and fenpropathrin) was compared with laboratory bioassays. Males were more susceptible than females for each acaricide. Differences in the lethal concentration 50 % (LC₅₀) values between the sexes were observed to range from 2.04-fold to 6.05-fold. The surface area was markedly greater for females than males (by 1.87-fold) and the weight was significantly greater for females compared to males (by 4.67-fold). The specific surface area of male was 2.61-fold higher than that of female. There were no differences in the cuticle structure, whereas the thickness of females was 1.63-fold than that of males. The penetration rate of males was statistically significantly higher than that of females, both in pyridaben and cyflumetofen. Synergism experiments and biochemical assays suggested the involvement of the three detoxification enzyme systems in the sexual susceptibility of T. cinnabarinus. The activities of cytochrome P450 monooxygenases (P450s) (p < 0.01), glutathione-S-transferase (GSTs) (p < 0.05) and carboxylesterase (CarEs) (p < 0.05) in females were significantly higher than that in males. The results reveal that the individual size (specific surface area), cuticle thickness, and detoxification enzyme activity were involved in the sexual susceptibility to acaricides of T. cinnabarinus.

The decline in postharvest citrus quality due to fungal infections necessitates innovative packaging solutions. This study presents a pullulan-based edible film (PBYFs) with biocontrol yeasts, designed to dissolve in both liquid and soil. This film is capable of enveloping entire citrus fruits, effectively managing postharvest diseases, and extending their shelf life. The formulation of PBYFs includes NaCl 0.1 M, Kloeckera apiculata 34–9 at 1.0 × 10⁷ CFU mL⁻¹, pullulan 3 % w/v, SA 0.5 % w/v, and glycerin 1 % w/v. Our experiments, conducted on eight citrus varieties, demonstrated that PBYFs significantly reduced the occurrence of green and blue molds, sour rot, and anthracnose in vivo. Moreover, PBYFs-coated fruits exhibited an extended shelf life without compromising the quality parameters such as weight loss, TSS (total soluble solids), TA (titratable acidity), VC (vitamin C), or the accumulation of off-flavor volatiles. This research presents a promising approach for creating scalable, cost-effective, and environmentally sustainable biodegradable antifungal packaging systems for citrus fruits.

Echinochloa crus-galli (L.) P. Beauv is a monocotyledonous weed that seriously infests rice fields. Florpyrauxifen-benzyl, a novel synthetic auxin herbicide commercialized in China in 2018, is an herbicide for controlling E. crus-galli. However, a suspected resistant population (R) collected in 2012 showed resistance to the previously unused florpyrauxifen-benzyl. Whole-plant dose-response bioassay indicated that the R population evolved high resistance to quinclorac and florpyrauxifen-benzyl. Pretreatment with P450 inhibitors did not influence the GR₅₀ of E. crus-galli to florpyrauxifen-benzyl. The expression of target receptor EcAFB4 was down-regulated in the R population, leading to the reduced response to florpyrauxifen-benzyl (suppresses over-production of ethylene and ABA). We verified this resistance mechanism in the knockout OsAFB4 in Oryza sativa L. The Osafb4 mutants exhibited high resistance to florpyrauxifen-benzyl and moderate resistance to quinclorac. Furthermore, DNA methylation in the EcAFB4 promoter regulated its low expression in the R population after florpyrauxifen-benzyl treatment. In summary, the low expression of the auxin receptor EcAFB4 confers target resistance to the synthetic auxin herbicide florpyrauxifen-benzyl in the R- E. crus-galli.

Insect growth-blocking peptides (GBPs) are a family of cytokines found in several insect orders and are known for their roles in regulating development, paralysis, cell proliferation, and immune responses. Despite their diverse functions, the potential of GBPs as biocontrol targets against the pest Spodoptera frugiperda (Lepidoptera: Noctuidae) has not been fully explored. In this study, S. frugiperda GBP (SfGBP) was identified and functionally characterized. SfGBP is synthesized as a 146 amino acid proprotein with a 24 amino acid C-terminal active peptide (Glu123-Gly146). Predominant expression of SfGBP occurs in fourth to sixth instar larvae and in the larval fat body, with significant upregulation in response to pathogens and pathogen-associated molecular patterns. Injection of the synthetic active peptide into larvae induced growth retardation, delayed pupation, and increased survival against Beauveria bassiana infection. Conversely, RNA interference-mediated knockdown of SfGBP resulted in accelerated growth, earlier pupation, and decreased survival against B. bassiana infection. Further analysis revealed that SfGBP promoted SF9 cell proliferation and spreading, enhanced bacteriostatic activity of larval hemolymph, and directly inhibited germination of B. bassiana conidia. In addition, SfGBP enhanced humoral responses, such as upregulation of immunity-related genes and generation of reactive oxygen species, and cellular responses, such as nodulation, phagocytosis, and encapsulation. These results highlight the dual regulatory role of SfGBP in development and immune responses and establish it as a promising biocontrol target for the management of S. frugiperda.

Fenitrothion (FNT) is a common organophosphorus pesticide that is widely used in both agricultural and domestic pest control. FNT has been frequently detected in various environmental media, including the human body, and is a notable contaminant. Epidemiological investigations have recently shown the implications of exposure to FNT in the incidence of various metabolic diseases, such as diabetes mellitus in humans, indicating that FNT may be a potential endocrine disruptor. However, the effects of FNT exposure on glucose homeostasis and their underlying mechanisms in model organisms remain largely unknown, which may limit our understanding of the health risks of FNT. In this study, FNT (4 5, 90, 180, and 4 50 μM) exposure model of rat hepatocytes (Buffalo Rat Liver, BRL cells) was established to investigate the effects and potential mechanisms of its toxicity on glucose metabolism. Several key processes of glucose metabolism were detected in this study. The results showed significantly increased glucose levels in the culture medium and decreased glycogen content in the FNT-exposed BRL cells. The results of quantitative real-time PCR and enzymology showed the abnormal expression of genes and activity/content of glucose metabolic enzymes involved in glucose metabolism, which might promote gluconeogenesis and inhibit glucose uptake, glycolysis, and glycogenesis. Furthermore, gluconeogenesis and glycolytic were carried out in the mitochondrial membrane. The abnormal of mitochondrial membrane potential may be a potential mechanism underlying FNT-induced glucose metabolism disorder. In addition, the mRNA and protein expression implicated that FNT may disrupt glucose metabolism by inhibiting the AMPKα and IRS1/PI3K/AKT signaling pathways. In conclusion, results provide in vitro evidence that FNT can cause glucose metabolism disorder, which emphasizes the potential health risks of exposure to FNT in inducing diabetes mellitus.

Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) have revolutionized pest control. However, the evolution of resistance by target pests poses a significant threat to the long-term success of Bt crops. Understanding the genetics and mechanisms underlying Bt resistance is crucial for developing resistance detection methods and management tactics. The T92C mutation in a tetraspanin gene (HaTSPAN1), resulting in the L31S substitution, is associated with dominant resistance to Cry1Ac in a major pest, Helicoverpa armigera. Previous studies using CRISPR/Cas9 technique have demonstrated that knockin of the HaTSPAN1 T92C mutation confers a 125-fold resistance to Cry1Ac in the susceptible SCD strain of H. armigera. In this study, we employed the piggyBac transposon system to create two transgenic H. armigera strains based on SCD: one expressing the wild-type HaTSPAN1 gene (SCD-TSPANwt) and another expressing the T92C mutant form of HaTSPAN1 (SCD-TSPANmt). The SCD-TSPANmt strain exhibited an 82-fold resistance to Cry1Ac compared to the recipient SCD strain, while the SCD-TSPANwt strain remained susceptible. The Cry1Ac resistance followed an autosomal dominant inheritance mode and was genetically linked with the transgene locus in the SCD-TSPANmt strain of H. armigera. Our results further confirm the causal association between the T92C mutation of HaTSPAN1 and dominant resistance to Cry1Ac in H. armigera. Additionally, they suggest that the piggyBac-mediated transformation system we used in H. armigera is promising for functional investigations of candidate Bt resistance genes from other lepidopteran pests.

Pyrethroid are the primary insecticides used for controlling of Bactricera dorsalis, a highly destructive and invasive fruit pest. Field populations have developed serious resistance, especially to β-cypermethrin. While mutations in the voltage-gated sodium channel (Vgsc) are a common mechanism of pyrethroid resistance, variations in BdVgsc associated with β-cypermethrin resistance remain unclear. Here, we reported the resistance levels of five field populations from China, with resistance ratio ranging from 1.54 to 21.34-fold. Cloning the full length of BdVgsc revealed no specific or known amino acid mutations between the most resistant population and the susceptible strain. However, three types of partial intron retention (IRE4–5, IRE19-f and IREL-24) were identified in BdVgsc transcripts, with these intron retentions containing stop codons. The expression of IRE4–5 transcripts and total BdVgsc showed different trends across developmental stages and tissues. Exposure to β-cypermethrin led to increased expression of IRE4–5. Comparison of genomic and transcriptional sequences reveled that IRE4–5 transcripts had two types (IRE4–5.5 T and IRE4–5.6 T) caused by genomic variations. Both field and congenic strains indicated that homozygotes for IRE4–5.5 T had lower IRE4–5 transcript levels than homozygotes for IRE4–5.6 T. However, congenic and field strains exhibited inconsistent results about the association of expression levels of IRE4–5 transcripts with sensitivity to β-cypermethrin. In summary, this study is the first to identify intron retention transcripts in the Vgsc gene from B. dorsalis and to examine their expression patterns across different developmental stages, tissues, and strains with varying sensitivities to β-cypermethrin. The potential role of the intron retentions of BdVgsc in insecticide toxicity is also discussed.

Plant growth-promoting rhizobacteria (PGPR) have been reported to suppress various diseases as potential bioagents. It can inhibit disease occurrence through various means such as directly killing pathogens and inducing systemic plant resistance. In this study, a bacterium isolated from soil showed significant inhibition of Valsa mali. Morphological observations and phylogenetic analysis identified the strain as Pseudomonas thivervalensis, named K321. Plate confrontation assays demonstrated that K321 treatment severely damaged V. mali growth, with scanning electron microscopy (SEM) observations showing severe distortion of hyphae due to K321 treatment. In vitro twigs inoculation experiments indicated that K321 had good preventive and therapeutic effects against apple Valsa canker (AVC). Applying K321 on apples significantly enhanced the apple inducing systemic resistance (ISR), including induced expression of apple ISR-related genes and increased ISR-related enzyme activity. Additionally, applying K321 on apples can activate apple MAPK by enhancing the phosphorylation of MPK3 and MPK6. In addition, K321 can promote plant growth by solubilizing phosphate, producing siderophores, and producing 3-indole-acetic acid (IAA). Application of 0.2% K321 increased tomato plant height by 53.71%, while 0.1% K321 increased tomato fresh weight by 59.55%. Transcriptome analysis revealed that K321 can inhibit the growth of V. mali by disrupting the integrity of its cell membrane through inhibiting the metabolism of essential membrane components (fatty acids) and disrupting carbohydrate metabolism. In addition, transcriptome analysis also showed that K321 can enhance plant resistance to AVC by inducing ISR-related hormones and MAPK signaling, and application of K321 significantly induced the transcription of plant growth-related genes. In summary, an excellent biocontrol strain has been discovered that can prevent AVC by inducing apple ISR and directly killing V. mali. This study indicated the great potential of P. thivervalensis K321 for use as a biological agent for the control of AVC.

The tomato leafminer, Tuta absoluta (Meyrick), one of the most economically destructive pests of tomato, causes severe yields losses of tomato production globally. Rapid evolution of insecticide resistance requires the development of alternative control strategy for this pest. RNA interference (RNAi) represents a promising, innovative control strategy against key agricultural insect pests, which has recently been licensed for Colorado Potato Beetle control. Here two essential genes, voltage-gated sodium channel (Na_v) and NADPH-cytochrome P450 reductase (CPR) were evaluated as targets for RNAi using an ex vivo tomato leaf delivery system. Developmental stage-dependent expression profiles showed TaNa_v was most abundant in adult stages, whereas TaCPR was highly expressed in larval and adult stages. T. absoluta larvae feeding on tomato leaflets treated with dsRNA targeting TaNa_v and TaCPR showed significant knockdown of gene expression, leading to reduction in adult emergence. Additionally, tomato leaves treated with dsRNA targeting these two genes were significantly less damaged by larval feeding and mining. Furthermore, bioassay with LC₃₀ doses of λ-cyholthin showed that silencing TaNa_v and TaCPR increased T. absoluta mortality about 32.2 and 17.4%, respectively, thus indicating that RNAi targeting TaNa_v and TaCPR could increase the susceptibility to λ-cyholthin in T. absoluta. This study demonstrates the potential of using RNAi targeting key genes, like TaNa_v and TaCPR, as an alternative technology for the control of this most destructive tomato pests in the future.