Archives of Insect Biochemistry and Physiology最新文献

Sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) plays a critical role in maintaining intracellular Ca²⁺ homeostasis by transporting excess Ca²⁺ into the endoplasmic reticulum (ER) calcium reservoir. Calcium is essential for regulating key biological processes in Bombyx mori, including development, metamorphosis, and reproduction. To explore the role of BmSERCA in the proliferation of the B. mori ovary cell line (BmN), intracellular Ca²⁺ levels were measured following BmSERCA interference. At 48 h post-interference, intracellular Ca²⁺ levels increased significantly by 1.38 times. Moreover, transcript levels of genes involved in cell proliferation and division exhibited notable changes. Phenotypic assessments further demonstrated that BmSERCA interference significantly accelerated the proliferation and migration of BmN cells, with a marked increase in EdU-positive cells. Additionally, flow cytometry analysis revealed that BmSERCA interference notably affected the cell cycle by inducing G2/M phase accumulation and elevating the expression of G2/M phase regulators, including BmCyclinB and BmCDK1. Collectively, these findings suggested that BmSERCA interference disrupted intracellular Ca²⁺ homeostasis, thereby promoting BmN cell proliferation. This study provided a valuable foundation for understanding the role of BmSERCA in BmN cell proliferation.

The growth and development of insects are mainly governed by juvenile hormone (JH) and molting hormone, which play essential roles in metamorphosis, reproductive control, and signal transduction. However, it remains uncertain whether E74, a crucial transcription factor within the 20- hydroxyecdysone (20E) signaling pathway, is involved in regulating chitin biosynthesis in Lasioderma serricorne. In this study, the E74 gene was identified in L. serricorne, a damaging and prevalent pest of stored products. The E74 gene features an open reading frame of 1, 266 bp that encodes a protein of 421 amino acids, characterized by a typical Ets domain structure. Phylogenetic analysis indicated that E74 is most closely related to Onthophagus taurus. Analysis of temporal expression patterns revealed that E74 is expressed throughout all developmental stages of L. serricorne, with peak expression occurring during the prepupal stage. Tissue-specific expression studies showed high levels of E74 in the epidermis and head. RNA interference (RNAi) assays demonstrated that silencing E74 led to a mortality rate of 68.33%. Experiments involving hormone treatment confirmed that E74 expression is upregulated by 20E and downregulated by JH analog methoprene. Furthermore, the knockdown of E74 significantly decreased the expression of genes associated with the chitin biosynthesis pathway, which was corroborated by a notable reduction in chitin levels following E74 knockdown. In conclusion, this study established that E74 is not only vital for the growth and development of L. serricorne but also plays a role in regulating chitin biosynthesis. This study enhances the understanding of E74's functional role across various species and offers insights for identifying potential targets for pest control.

Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) are essential for host-seeking behaviors in herbivorous and predatory insects. However, limited studies have examined differences in the OBP and CSP profiles between herbivores and predators. Mirid bugs, which ancestrally were predatory, provide an ideal model to investigate these differences because some of mirid species have evolved to develop herbivorous capacities. In this study, we compared compared OBP and CSP profiles among transcriptome analysis of one zoophytophagous and four phytozoophagous mirid bugs, identifying a total of 146 OBPs and 69 CSPs. The number of OBPs was similar between phytozoophagous (26 in Adelphocoris fasciaticollis, 29 in Adelphocoris lineolatus, 28 in Apolygus lucorum, and 32 in Adelphocoris suturalis) and zoophytophagous (31 in Nesidiocoris tenuis) species. However, the zoophytophagous specie had more CSPs than the phytozoophagous species. Phylogenetic analysis revealed two types of OBPs in mirid bugs, with classic OBPs being more abundant than plus-C OBPs. Transcriptome revealed that the number of OBPs with high expressions was higher in the phytozoophagous species (18) than in the zoophytophagous species (14). By contrast, more CSPs (10) exhibited high expressions in the zoophytophagous mirid bug compared with those in the phytozoophagous species (≤ 7). These results suggest that differences in the number and expression levels of OBPs and CSPs between zoophytophagous and phytozoophagous mirid bugs affect host-selection processes. In conclusion, the findings provide a basis for developing novel pest management strategies, including the use of natural enemies or behavioral regulation of mirid bugs through OBP and CSP gene manipulation.

The omega glutathione S-transferases (GSTOs) are a class of cytosolic GSTs and play important roles in antioxidant defense in insects. However, the functions of some GSTOs remain unclear. Here, we performed functional analysis of a GSTO2 in Tribolium castaneum (TcGSTO2). Sequence alignment indicated that this gene was conserved among insects. During development, TcGSTO2 was highly expressed in the late stage of larva and pupa and the hemolymph, fat body, malpighian tubules of late larva. After treatment with various insecticides such as DDV, KBV, phoxim, and lambda-cyhalothrin, the expression level of TcGSTO2 was significantly increased, and knockdown of TcGSTO2 reduced the resistance to the insecticides. Exposure to various types of oxidative stress, including heat, cold, UV, and pathogenic microbes, largely induced TcGSTO2 expression, and overexpression of TcGSTO2 in E. coli increased the resistance to oxidative stress induced by paraquat and cumene hydroperoxide. Our study showed that TcGSTO2 participated in the cellular detoxification and antioxidant defense, deepening our understanding of the functional diversity of GSTOs in insects.

Argonaute (Ago) proteins are integral components of the RNA-induced silencing complex (RISC), regulate gene expression through RNAi, and are essential for embryogenesis and cellular morphogenesis in insects. However, today, little is known about their role in the molting development of insects. In this study, we have used the white-backed planthopper (Sogatella furcifera) as an important model and pest in agriculture, and we characterized and investigated the role of Ago-1 and Ago-2. In essence, the respective cDNA sequences of SfAgo1 and SfAgo2 contained 2823 and 3446 bp, and the respective encoded amino acids were 940 and 829. RT-qPCR revealed that Ago1 and Ago2 were expressed in all life stages as the nymphs that undergo molting, also in all tissues as the integument that is involved in new cuticle synthesis and chitin metabolism. Following RNAi, the lethal phenotypes showed molting failure, and typically, the expression levels of the chitin metabolic pathway genes and Dicer were significantly reduced. Similarly, transcriptome analysis revealed considerable enrichment of the GO terms structural constituent of cuticle, chitin catabolic progress, chitin binding, amino sugar and nucleotide sugar metabolism, and aminoglycan catabolic process upon RNAi of Ago1 and Ago2. Altogether, our findings indicate that Ago-1 and Ago-2 play a pivotal role in molting and new cuticle formation of insects. The data are discussed in relation to potential mechanisms and the use of RNAi in pest insect control.

Aedes aegypti (Ae. aegypti)-mediated transmission of arboviral diseases is posing a great concern globally. The challenge to traditional vector control methods is heightened by the increasing resistance of mosquitoes to chemical pesticides. In the present study, adulticide susceptibility tests against the pyrethroid insecticides—Permethrin and Deltamethrin were conducted using standard protocols, subsequently characterizing the partial segments of the voltage-gated sodium channel (VGSC) gene for Ae. aegypti populations sampled across ten districts of West Bengal, India. The mean mortalities for Permethrin and Deltamethrin were found to be 86.87 ± 2.36 and 92.03 ± 1.54, respectively, with significant differences between the regional populations. The knockdown time, KDT90 (min.), ranges between 61.85–314.68 and 74.49–298.92, respectively. Analysis of segment 6 from the partial domains II, III, and IV of the VGSC gene indicated amino acid substitutions at specific positions: S to P at 989, V to G at 1016, A to T at 1022, T to I at 1520, and F to C at 1534. The F1534C is the most frequent mutation (0.41) observed amongst the resistant population. Analysis of Molecular Variance (AMOVA) revealed significant genetic variation within and among the regional populations (F = 0.453 p < 0.001). Though the allele frequencies lied within the 95% confidence interval of the Hardy–Weinberg parabola, slight deviation of the allele frequencies from the equilibrium is indicative of operational selection pressure favouring the kdr mutants. Haplotype map shows the phylogeographical pattern with two distinct haplogroups diverging by 32 mutational steps. Thus, the study identified the resistance profile of Ae. aegypti mosquitoes across districts, aiding the selection of region-specific pesticides.

Fatty acid elongase (ELO) serves as the rate-limiting condensing enzyme in the initial step of the fatty acid elongation process. Among the ELO family members in the brown planthopper (Nilaparvata lugens), NlELO10 is essential for the development and physiology of N. lugens. However, the specific role and regulatory mechanisms of NlELO10 in lipid metabolism in N. lugens remain poorly understood. This study aimed to elucidate the effects of NlELO10 on lipid metabolism by employing RNA interference (RNAi) to silence the NlELO10 and utilizing lipidomics to analyze lipid composition and content changes following gene silencing. Lipidomic analysis revealed 32 differentially expressed lipid metabolites in N. lugens after NlELO10 knockdown. Among these, the levels of 3 phosphatidylcholines (PCs), 8 phosphatidylethanolamines (PEs), and 1 diacylglycerol (DG) were significantly elevated, whereas the levels of 20 triacylglycerols (TG) decreased significantly. The synthesis and metabolism of these differential lipid metabolites involve the coordinated action of multiple key enzymes, including acyl-CoA synthetase (FACS), diacylglycerol acyltransferase (DGAT), and phosphatidic acid phosphatase (PAP). To further validate the lipidomic findings, we performed real-time quantitative polymerase chain reaction (RT-qPCR) to examine the expression levels of genes encoding these metabolic enzymes. The gene expression patterns were consistent with the lipidomic data, supporting the involvement of these enzymes in the observed metabolic alterations. In conclusion, the silencing of NlELO10 disrupted the lipid composition and metabolism of N. lugens, potentially impairing physiological processes and leading to growth anomalies or mortality. These findings provide valuable insights into the functional role of NlELO10 in lipid metabolism and offer a theoretical foundation for identifying key lipid synthesis genes as targets for pest management strategies.

Cotesia ruficrus (Cr; Braconidae) can parasitize young Mythimna separata (Ms) larvae, but not 6th (final) instar Ms larvae. In the late instar, parasitization fails because Cr eggs suffer melanization and encapsulation. However, when multiple Cr parasitized a single Ms larva through superparasitization, the successful parasitization rate increased with higher superparasitization frequency. To induce immunosuppression, Cr parasitized 6th instar Ms larvae that were artificially injected with Cr venom (V) and/or polydnavirus (PDV). Successful parasitization rate of Cr improved with an increased amount of PDV injection, but there was no change only with V. When Cr monoparasitized, 92% of the parasitoid eggs suffered melanization and encapsulation. However, when the amount of PDV from four additional wasps was increased, the number of Cr eggs suffered melanization and encapsulation decreased to less than 10%. The number of hyperspread cells (HSCs), necessary for melanization and encapsulation also decreased in Ms larvae. The C-type lectin Cky811 of Cotesia kariyai inhibits the function of Mys-IML, a C-type lectin required for adhesion of HSCs to foreign substances in Ms. This study suggests that Crf111, a Cr PDV-produced C-type lectin with high amino acid homology to Cky811, may inhibit Mys-IML function. Crf111 expression was significantly higher in hemocytes of 6th instar Ms larvae injected with 4 µL of PDV alongside Cr monoparasitization. These results suggest that when Cr parasitizes 6th instar Ms larvae, the amount of injected PDV is insufficient, resulting in low Crf111 expression, which fails to regulate the host's immune response, and thus, parasitization is unsuccessful.