Pesticide Biochemistry and Physiology最新文献

Abamectin (ABN) is an agricultural insecticide that is reported to damage various body organs including the heart. Velutin (VLN) is a plant-derived flavonoid that exhibits a wide range of medicinal properties. This study was planned to investigate the medicinal value of VLN against ABN induced cardiotoxicity in rats. Thirty-two male albino rats (Rattus norvegicus) were divided into four equal groups including the control, ABN (10 mg/kg), ABN (10 mg/kg) + VLN (20 mg/kg), and VLN (20 mg/kg) alone administrated group. The doses were administrated for 6 weeks orally. The results demonstrated that ABN intoxication promoted the gene expression of Nrf-2 and its associated antioxidant genes including glutathione reductase (GSR), heme‑oxygenase-1 (HO-1), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) while reducing the gene expression of Keap-1 as well as levels of ROS and MDA. Moreover, ABN exposure enhanced the gene expression of Janus kinase-1 (JAK1), Signal transducer and activator of transcription-3 (STAT3), NF-κB, TNF-α, C-reactive proteins, Interferon-gamma-induced protein 10 (IP-10), IL-1β, Monocyte chemoattractant protein-1 (MCP-1), IL-6 and COX-2. The concentrations of CK-MB, Brain natriuretic peptide (BNP), CPK, troponin-I, N-terminal pro b-type natriuretic peptide (NT-proBNP) and LDH were elevated after ABN administration. ABN intoxication abruptly upregulated the levels of Caspase-3, Caspase-9 and Bax while reducing the levels of Bcl-2 in cardiac tissues. Additionally, ABN exposure prompted various histopathological damages. Nevertheless, VLN treatment remarkably protected the cardiac tissues via regulating aforementioned disruptions. Lastly, molecular docking analysis was performed to determine the potential affinity of VLN and targeted protein i.e., Bax, NF-kB, Nrf-2/Keap1, JAK1 and STAT3. Our in-silico evaluation showed a strong binding affinitybetween VLN and the targeted proteins which further confirms its effectiveness as a cardioprotective agent.

Insect cuticle acts as a first line of defense and a physical protective barrier against entomopathogens. Chitin biosynthesis pathway plays a crucial role in chitin formation in the cuticle of insects. Glucosamine-6-phosphate N-acetyltransferase (GNA) is a key enzyme in insect chitin biosynthesis that regulate the chitin formation. However, how GNA-mediated cuticle metabolism influences virulence of entomopathogenic fungi is still unknown. In this study, CmGNA gene was cloned and characterized from the rice leaffolder Cnaphalocrocis medinalis. The CmGNA contains an open read frame (ORF) 600 nucleotides, encoding 199 amino acids with an isoelectric point of 8.65 and a molecular weight of 22.30 kDa. The expression profile showed that CmGNA was highly expressed in 4th instar larvae and in the cuticle. Here, we also reported the impact of CmGNA gene and entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana, on expression pattern of chitin biosynthesis genes, feeding behavior, survival rate and average body weight of infected larvae, phenotypic deformities, rate of pupation, and adult emergence. Our results showed that knockdown of CmGNA and application of M. anisopliae and B. bassiana three days after RNA interference (RNAi) significantly decreased the expression of CmGNA and other associated genes, reduced feeding efficiency and survival rate, and caused loss of average body weight, less rate of pupation and adult emergence of infected larvae. Knockdown of CmGNA gene also increased the lethality of larvae caused by M. anisopliae and B. bassiana and resulted in significantly phenotypic deformities of infected larvae. Our findings illustrated that RNAi-mediated CmGNA knockdown disturbed the chitin synthesis genes that led to enhancing the virulence of M. anisopliae and B. bassiana, which can provide us new insights to develop novel biocontrol strategies against C. medinalis.

Etofenprox is a pyrethroid insecticide that acts on the nervous system of insects. Due to its low toxicity to aquatic animals, it is permitted for use in controlling insect pests in rice fields. The brown planthopper (BPH), Nilaparvata lugens, a significant piercing-sucking pest feeding on rice exclusively, secretes various salivary components when feeding. Salivary proteins are essential for BPH feeding, but their response to etofenprox is not well understood. The application of etofenprox down-regulated the expression of 21 salivary protein genes, among which 9 genes (NlShpa, Salivap 3, CA, NlSEF1, Nl12, NlHSC70–3, NlSP1, NlG14, and NlDNAJB9) showed significant differences. Most differentially expressed genes are found important for BPH physiological processes, except Nl12. Here we found that silencing Nl12 impeded ovary development, thereby inhibiting oocyte formation. The potential explanation was that Nl12 was highly expressed in both salivary gland and ovary, and the ovary development abnormality may be due to the direct effect from expression reduction in ovary and/or indirect influence from expression reduction in salivary gland. Altogether, our findings provide a new insight into the mechanism of action of etofenprox on insect pests and explain part of the reason why etofenprox does not stimulate reproduction in BPH.

The application of Bacillus thuringiensis (Bt) has brought environmental benefits and delayed resistance development of pests. Most studies focus on the Bt insecticidal activity against pests, however, the molecular mechanism of Bt on impairing the growth and development of Spodoptera exigua remains unknown. Here, we show that juvenile hormone (JH) inhibits the lipogenesis mediated by fatty acid synthases (Fas) of S. exigua in response to Bt infection. The weight and lipid accumulation of S. exigua larvae post Bt infection were less than those of larvae without Bt infection. We further demonstrated that Bt infection causes the JH titer with a significant increase, which downregulates the expression of lipogenesis-related genes, SeFas3, SeFas4, and SeFas5, resulting in the delayed development of S. exigua larvae. In addition, the expression levels of SeFas genes were regulated by SeACC, indicating that SeFas genes were modulated by multiple pathways. Our findings reveal that novel insights into the molecular mechanisms underlying the impaired development caused by Bt infection which can inform the development of strategies for the sustainable pest control in the future.

The steroid 20-hydroxyecdysone (20E) is crucial in regulating ovarian development. However, the neuropeptidergic mechanisms underlying ovarian development via 20E are underexplored. In this study, we investigated myosuppressin (MS) signaling in the dominant fruit pest Grapholita molesta and revealed that MS signaling is necessary for 20E biosynthesis during ovarian maturation. Pharmacological and molecular docking analyses confirmed that the GmMS mature peptide could activate its receptor GmMSR. Additionally, transcript expression analyses of GmMS and GmMSR showed different distribution patterns in adults. Notably, GmMSR was also detected in the ovaries of sexually mature females. RNAi-mediated dysfunction of GmMS or GmMSR specifically decreased fertility in females. Furthermore, GmMS or GmMSR knockdown decreased vitellogenin synthesis and uptake, thereby delaying ovarian development. RNA-seq, gene expression validation, and hormone quantification further revealed that GmMS signaling depletion blocked 20E biosynthesis in the ovary. Finally, exogenous MS rescued most dsGmMS- or dsGmMSR-induced ovarian defects and 20E titers. These results suggest that MS/MSR-to-20E signaling regulates ovarian development through vitellogenesis, providing a new perspective on the development of neuroendocrine targets that suppress pest field populations.

The gray blight incited by Pestalotiopsis and allied genera is a prevalent disease affecting tea cultivation, and managing it with Trichoderma spp. is an alternative to synthetic fungicides. Plants modify their arsenal system against pathogens when they are exposed to Trichoderma spp., which produces proteins and enzymes associated with pathogenesis. Understanding the expression pattern of defense-related markers will help in developing gray blight resistance tea cultivars. Thus, this study intended to induce resistance against gray blight in tea by Trichoderma harzianum TIND02. For this, a total of eight Trichoderma isolates originated from organic tea rhizospheres were characterized and evaluated for their efficacy. Dual culture test revealed isolate TIND02 as the most potential candidate with 74.6% inhibitory activity against gray blight pathogen Pseudopestalotiopsis theae. Molecular characterization based on ITS and tef-1 alpha genes confirmed isolate TIND02 as T. harzianum. Scanning electron microscopic study showed the mycoparasitic nature of T. harzianum TIND02 (TH-TIND02) to Ps. theae. The ethyl acetate extract of TH-TIND02 at 100 and 200 μg mL⁻¹ showed potential inhibitory activity (>69.9%) against Ps. theae which confirmed the presence of higher volatile metabolites. Gas chromatography–Mass spectrometry study revealed that ethyl acetate extract of TH-TIND02 was composed of 21 major and minor volatile organic compounds with acetamide, 2, 2, 2-trifluoro-N, N-bis trimethyIsilyl–C (94.74%) as a major component. The isolate also produced chitinase, cellulase, β-1, 3 glucanase, and protease hydrolytic enzymes. Nursery experiments revealed that 2% and 5% doses (2 × 10⁶ CFU mL⁻¹) of TH-TIND02 significantly reduced respective 65.0% and 70.0% disease severity over control with improved plant growth. Besides, expressions of defense-related enzymes (chitinase, pHenolics, peroxidase, phenylalanine ammonia lyase, β-1, 3-glucanase, and polyphenol oxidase) and pathogenesis-related genes (chitinase and β-1, 3-glucanase) due to TH-TIND02 were determined. The secretion of defense-related enzymes was highly upregulated in plants applied with TH-TIND02 followed by Ps. theae inoculation compared to controls. The RT-qPCR analysis showed that the expression of both genes in co-inoculated plants was two-fold higher than in control after 21-day post incubation. These results suggest that TH-TIND02 application reduced gray blight severity by elevated enzyme activity and overexpressed pathogenesis-related genes in tea plants which offer for its eco-friendly and sustainable use as a bio-fungicide in tea gardens.

Isoxazoline insecticides have shown broad-spectrum insecticidal activity against a variety of insect pests. However, the high toxicity of isoxazoline compounds towards honeybees restricts their application in crop protection. To mitigate this issue, a series of isoxazoline derivatives containing 2-phenyloxazoline were designed and synthesized. Bioassays revealed that several compounds exhibited promising insecticidal activities against Plutella xylostella, with G28 showing particularly excellent insecticidal activity, reflected by an LC₅₀ value of 0.675 mg/L, which is comparable to that of fluxametamide (LC₅₀ = 0.593 mg/L). Furthermore, G28 also exhibited effective insecticidal activity against Solenopsis invicta. Importantly, bee toxicity experiments indicated that G28 had significantly lower acute oral toxicity (LD₅₀ = 2.866 μg/adult) compared to fluxametamide (LD₅₀ = 1.083 μg/adult) and fluralaner (LD₅₀ = 0.022 μg/adult), positioning it as a promising candidate with reduced toxicity to bees. Theoretical simulation further elucidated the reasons for the selective differences in the ability of isoxazoline to achieve higher insecticidal activity while maintaining lower bee toxicity. This research suggests that isoxazoline compounds containing 2-phenyloxazoline group hold potential as new insecticide candidates and offers insights into the development of novel isoxazoline insecticides with both high efficacy and environmental safety.

Bombyx mori is an insect species of great economic importance, and its silk gland is a vital organ for the synthesis and secretion of silk protein. However, long-term artificial domestication of B. mori has resulted in high sensitivity to chemical toxins, especially insecticides. Cyantraniliprole (Cya), a second-generation ryanodine receptor modulator insecticide, is widely utilized in agriculture for pest control. In this study, the impact of Cya toxicity on the development of silk glands in the 5th instar larvae of B. mori was assessed using Cya LC₅, LC₁₀ and LC₂₀, as well as a starvation treatment group for comparison. Short-term exposure (24 h) to different concentrations of Cya resulted in delayed development of silk glands in B. mori. Meanwhile, the body weight, silk gland weight, silk gland index and cocoon quality were significantly reduced in a concentration-dependent manner, except for the Cya LC₅ treatment. Histopathological and ultrastructural analysis revealed that Cya LC₁₀ induced disruption of the nuclear membrane and endoplasmic reticulum in the posterior silk gland (PSG) cells, leading to the formation of intracellular vacuoles. Transcriptome sequencing of PSGs identified 2152 genes that were differentially expressed after exposure to Cya LC₁₀, with 1153 down-regulated genes and 999 up-regulated genes. All differentially expressed genes were subjected to functional annotation using gene ontology and Kyoto encyclopedia of genes and genomes database, and it was found that protein synthesis-related pathways were significantly enriched, with the majority of genes being down-regulated. Furthermore, the transcription levels of genes involved in “protein processing in endoplasmic reticulum”, “protein export”, “proteasome” and “DNA replication” were quantified using qRT-PCR. Our findings suggested that short-term exposure to Cya LC₁₀ resulted in disruption of DNA replication, as well as protein transport, processing and hydrolysis in the PSG cells of B. mori. The results of this study provide a theoretical foundation for the safe utilization of Cya in sericulture production.

The black cutworm, Agrotis ipsilon (Lepidoptera: Noctuidae), is an important agricultural pest. Phoxim is an organophosphate insecticide that has been widely used to control A. ipsilon. The extensive application of phoxim has resulted in a reduction in phoxim susceptibility in A. ipsilon. However, the molecular mechanisms underlying phoxim tolerance in A. ipsilon remain unclear. In this work, we report the involvement of AiGSTz1, a zeta class glutathione S-transferase, in phoxim tolerance in A. ipsilon. Exposure to a sublethal concentration (LC₅₀) of phoxim dramatically upregulated the transcription level of the AiGSTz1 gene in A. ipsilon larvae, and this upregulation might be caused by phoxim-induced oxidative stress. The recombinant AiGSTz1 protein expressed in Escherichia coli was able to metabolize phoxim. Furthermore, AiGSTz1 displayed antioxidant activity to protect against oxidative stress. Knockdown of AiGSTz1 by RNA interference significantly increased the mortality rate of A. ipsilon larvae in response to phoxim. In addition, the transcription factor AiCncC can bind to the cap ‘n’ collar isoform C: muscle aponeurosis fibromatosis (CncC:Maf) binding site in the putative promoter of the AiGSTz1 gene. Silencing of AiCncC resulted in a dramatic downregulation of AiGSTz1. These results indicated that AiGSTz1 is involved in phoxim tolerance and is potentially regulated by AiCncC. These findings provide valuable insights into the defense mechanisms used by A. ipsilon against phoxim.

RNA interference (RNAi) is an effective pest management strategy through silencing the crucial genes in target organisms. However, the effectiveness of targeting a single gene is often limited by the silencing efficiency due to tissue or developmental stage-specific gene expression. Moreover, multiple pests often infest the same crop simultaneously under current ecological conditions. Therefore, a combined strategy of “targeting multiple genes” and “controlling multiple pests” is expected to yield better management results. In this study, homologous genes from two globally sap-sucking pests, the peach aphid (Myzus persicae) and the whitefly (Bemisia tabaci), were screened on a genome-wide scale. Subsequently, RNAi bioassays showed silencing the genes (MpAbd-A, MpH3, MpRpL27a, and MpScr) exhibited high mortalities in both species, which were further selected for designing fusion dsRNAs. These fusion dsRNAs resulted in higher mortalities in both pests than single gene silencing and posed a minimal off-target risk to the predator ladybeetle (Propylaea japonica) based on the sequence analysis. Finally, the tobacco plants expressing the fusion dsRNAs through virus-induced gene silencing (VIGS) technology enhanced the resistance to both pests. In conclusion, this study proposes a novel RNAi-based approach for managing two sap-sucking pests simultaneously.