Archives of Insect Biochemistry and Physiology最新文献

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.

Insect development is mainly controlled by juvenile hormone (JH) and ecdysone, and their hemolymph titer determines the insect direction; larva, pupa, or adult. The mediators of them are Krüppel homolog 1 (Kr-h1), Broad-Complex (BR-C), and E93. They activate genes that characterize larval, pupal, and adult feature, which gives rise to the metamorphosis. Before individual ecdysis, these master factors activate target genes to produce larva, pupa, or adult. Prothoracicotropic hormone (PTTH) from the brain activates prothoracic gland (PG), resulted in the ecdysis. Other factors that activate ecdysteroid production are reported. The produced ecdysteroid was observed early stages of the last larval instar of Bombyx mori, where the ecdysteroid titer is different from previous stage. Two stages are different in JH and ecdysone titer, and the interaction of the JH and ecdysone production determines their titer. Ecdysone brings about the prominent change, which needs many gene transcriptions and the interaction of ecdysone-responsive transcription factors (ERTFs). Their target genes are successively expressed, which brings about the metamorphosis. For the activation of genes, ecdysone gives rise to chromatin remodeling and histone modification. Ecdysone and other factors bring about cell division of the wing disc of the last larval instar; for the proliferation and differentiation, which gives rise to the growth and differentiation of the wing disc for the metamorphosis. In addition, hormone-responsive miRNAs work, several ERTFs function for one gene, and the suppressive TF function along with metamorphosis. Thus, several attractive things underly around the insect metamorphosis. We will be near the understanding of the metamorphosis through these things.

A neuropeptide, the CAPA, and its cognate receptor have been diversely characterized in different orders of class Insecta. CAPA peptides are synthesized in the abdominal neurohemal system and activate their corresponding receptor, CAPA receptor (CAPA-R), a type of G protein-coupled receptor (GPCR), to initiate cellular signals for diverse physiological functions in insects. Activation of the CAPA-R in Malpighian tubules results in ion-water homeostasis via antidiuresis in the majority of insect species; however, diuresis and myotropic activities are also known to result. Antidiuretic activity of CAPA peptides has been reported from mosquitoes, assassin bugs, spotted wing drosophila, and more; hence, this group of peptides also holds importance as potential targets when it comes to medical and agricultural entomology. GPCRs form a diverse family of cell membrane receptors responsible for signal transduction across the cell membrane in humans as well as in insects. With the advances in knowledge of human GPCRs, their physiological functions in agriculturally important insects have offered an opportunity for designing and implementing GPCR-targeting compounds in integrated pest management programs. In this review, we present a comprehensive view on physiological factors and peptides responsible for the diuresis/anti-diuresis in insects with special reference to the CAPA peptide-receptor interaction. The major focus is on the role of CAPA peptides in fluid and energy homeostasis, stress tolerance, muscle functioning, regulation of reproduction, and diapause-related processes. We end by outlining the significance of insect excretion with respect to the capa-r gene silencing and pest management.

Goji berry is an important economic crop, yet pest infestations pose a significant threat to its yield and quality. Traditional pest identification mainly relies on manual inspection by experts with specialized knowledge, which is subjective, time-consuming, and labor-intensive. To address these issues, this experiment proposes an improved convolutional neural network (CNN) for accurate identification of 17 types of goji berry pests. Firstly, the original data set is augmented using a multi-graph-occlusion data augmentation method. Subsequently, the augmented data set is imported into the improved CNN for training. Based on the original ResNet18 model, a new CNN, named GojiNet, is constructed by embedding multi-attention fusion modules at appropriate locations. Experimental results demonstrate that GojiNet achieves an average recognition accuracy of 95.35%, representing a 2.60% improvement over the ResNet18 network. Notably, compared to the original network, the training time of this model increases only slightly, while its size is reduced, and the recognition accuracy is enhanced. The experiment verifies the performance of the GojiNet model through a series of evaluation indicators. This study confirms the tremendous potential and application prospects of deep learning in pest identification, providing a referential solution for intelligent and precise pest identification.

The diversity of herbivorous insects is associated with host plant diversity. The determination of dietary profile is a central topic in insect ecology. DNA barcoding, that is, taxon identification using a standardized DNA region, have been important to the recent advances in food web understandings. In this study, three commonly plant barcoding loci (i.e., rbcL, matK, and trnH-psbA) were chosen for screening of ingested plant DNA in 207 specimens of 18 leaf-grazing katydid species representing 4 subfamilies in China. The obtained sequences were queried against the Barcode of Life Database (BOLD) and GenBank for taxa identification. The results of identification were as follow: 3 Conocephalinae species consumed 10 plant families, with preference for Poaceae; 1 Mecopodinae species consumed 18 plant families, with preference for Fabaceae and Vitaceae; 11 Phaneropterinae species consumed 43 plant families, with preference for Juglandaceae; 3 species Pseudophyllinae species consumed 9 plant families, with preference for Balsaminaceae. Among these, only 81 out of 207 samples were identified at the species level when compares with NCBI and BOLD database. Our study added a significant amount of dietary information for leaf-grazing katydids in China. It is crucial to fully understand coevolution of katydids and plant, katydids diet resource requirements, and best practices for habitat conservation.

Pardosa astrigera is a species of spider that plays an important role in controlling crops pests but is at risk due to human agricultural practices. To optimize laboratory rearing, we developed specialized diets and rearing containers for both mother spiders and spiderlings. The maximum survival to adulthood was achieved with a diet of Drosophila melanogaster, Acyrthosiphon pisum and Aphis gossypii. Spiderlings fed an artificial milk diet, consisting of milk, egg yolk, and honey, had a 33% survival rate until the 5th life stage. Increasing the rearing space using 250 mL plastic cups improved survival (66%) compared to 50 mL jars (38%). The findings of this study offer pivotal technical support for delving deeper into the biological traits, dietary necessities, and reproductive processes of spiders. Furthermore, these insights can serve as a valuable reference for the artificial cultivation of other beneficial insects, thereby facilitating the enhancement of biological control strategies.

Understanding gene expression in specific tissues and their modulation under environmental stimuli, such as nutritional deficiency, reveals the key physiological regulatory mechanisms of an organism. This study examined the tissue-specific expression of insulin-like peptide (ILP) genes (BmX and BmZ) in Bombyx mori larvae and their responses to hyperglycaemia, food deprivation and hormonal (20-hydroxyecdysone and bovine insulin) treatments. mRNA expression levels of BmX and BmZ were analyzed in the brain, fat body, midgut and ovary. The results revealed that BmX was highly expressed in the fat body, while both genes were abundant in the ovary. Hyperglycaemia increased BmX mRNA expression level in the midgut (3.07-fold) and brain (7.53-fold), while BmZ mRNA expression level was increased in all tissues except the midgut. Nutrient deficiency upregulated BmX mRNA expression level (1.36-fold) in the fat body while reducing it (−0.53-fold) in the midgut. Food deprivation progressively increased (0.77-fold at 24 h and 2.34-fold at 72 h) BmX mRNA expression level in the fat body, while both BmX and BmZ transcripts declined in the midgut. Insulin suppressed BmX (−0.25-fold) and BmZ (−0.91-fold) mRNA expression levels in food-deprived larvae in the fat body, whereas 20E consistently downregulated BmX, BmZ, and BmInR (insulin receptor) mRNA expression levels in all the conditions. These findings revealed the complex interaction of gene expression, tissue specificity, and environmental factors in B. mori larvae and provided insights into adaptive responses to nutritional stress and hormonal regulation in the insect with potential applications in sericulture and agricultural biotechnology.