Archives of Insect Biochemistry and Physiology最新文献

The prevailing view has always been that insects only have innate immune defenses and do not have acquired immune defenses. However, recent studies have shown that some insects exhibit immune priming, which means they can initiate an effective immune response upon secondary pathogen infection, thereby protecting themselves from reinfection. Interestingly, this immune protection effect can not only be generated in the parent generation but also be transmitted to the offspring, thus protecting the offspring from the same pathogen infection. This phenomenon is known as transgenerational immune priming (TGIP). However, research on TGIP in insects is still in its infancy, and many unknown questions do not have perfect answers. In this review, we will systematically review the factors that induce TGIP in insects, analyze the molecular mechanisms that induce TGIP, and ultimately expect to provide theoretical support and development directions for the study of TGIP in insects.

Fatty acid desaturase (FAD) serves as a pivotal enzyme in the lipid synthesis pathway, regulating fatty acid unsaturation levels in insects through catalytic activity. While FAR, another crucial enzyme in the same pathway, has been demonstrated to influence the integument architecture of the brown planthopper (BPH), the functional role of FAD in this biological process remains insufficiently explored. In the present investigation, we systematically identified 10 NlFAD family genes through bioinformatics analysis and subsequently characterized their expression patterns using real-time quantitative polymerase chain reaction (RT-qPCR). Through integrated approaches combining RNA interference (RNAi), transmission electron microscopy (TEM), and targeted fatty acid metabolomics, we elucidated the regulatory effects of NlFAD silencing on both integument ultrastructure and fatty acid biosynthesis in BPH. Key findings revealed that NlFAD3 knockdown induced: Silencing of NlFAD3 resulted in a significant increase in the mortality rate of BPH, the highest percentage of moulting deaths, the phenomenon of significant disruption of its integument structure, and a significant increase in the content of BPH stearic acid. This study provides a new research idea for the search of effective target genes to realize the effective control of BPH.

In insects, heat shock proteins (HSPs) are crucial for protecting against environmental stressors, particularly insecticides. However, in the important agricultural pest Agrotis ipsilon, the specific protective function provided by HSPs against different insecticides remains unclear. Herein, we identified a small HSP (sHSP) gene in A. ipsilon: AisHSP19.6. Peak AisHSP19.6 expression occurred during the sixth-instar larval stage in the larval midgut. Treatment with phoxim (PHO), lambda-cyhalothrin (LCT), and chlorantraniliprole (CAP) causes oxidative stress in A. ipsilon larvae. Furthermore, PHO, LCT, and CAP exposure, as well as H₂O₂ injection, significantly elevated AisHSP19.6 transcription. Although AisHSP19.6 did not metabolize PHO, LCT, and CAP, it protected the cells from oxidative stress. Moreover, A. ipsilon larvae in which AisHSP19.6 was silenced using RNA interference (RNAi), exhibited a significantly higher mortality rate in response to PHO, LCT, and CAP exposure relative to AisHSP19.6-expressing larvae. This study provides new insights into sHSP-mediated insecticide susceptibility in A. ipsilon. These findings also provide a potential RNAi-based strategy for the management of this agricultural pest.

Proteins are essential for insect development, with methionine (Met) being crucial for protein synthesis. However, the roles of methionine and the methionine-rich storage protein 1 (HaSP1) in Helicoverpa armigera larvae remain unclear. In this study, casein removal (-casein) from the larval diet was employed to simulate protein deficiency. Compared with the normal diet control, the -casein group displayed significant reductions in larval body weight and pupation rate, along with markedly increased mortality. Additionally, the methionine content in the fat body and the expression of HaSP1 were both significantly reduced. During larval development, both methionine levels and HaSP1 expression peaked in the late final instar stage. Both 20-hydroxyecdysone (20E) and juvenile hormone (JH) upregulated HaSP1 in midgut. Further RNA interference (RNAi) experiments indicated that knockdown of HaSP1 resulted in decreased larval body weight, increased mortality, and reduced Met content than the Green Fluorescent Protein (dsGFP) control. Furthermore, Methoprene-tolerant 1 (HaMet1) and Hormone Receptor 3 (HaHR3) expression was significantly downregulated upon HaSP1 knockdown. This study revealed that Met was indispensable for larval development and that HaSP1 governed systemic Met levels, thereby playing a pivotal role in larval growth. The findings provide experimental evidence and a theoretical basis for developing green pest-control pesticides that target key genes in nutrient metabolism.

Silkworms (Bombyx Mori) are traditionally reared on mulberry leaves; however, artificial diets have been developed to enable year-round rearing and automation. The physiological performance and cocoon yield of silkworms fed artificial diets remain inferior to those reared on mulberry leaves. We compared growth and nutrient composition in larvae reared on mulberry leaves (ML) and antibiotic-free artificial diet (ADS), and profiled gut microbiota in ML, ADS, and antibiotic-supplemented artificial diet (ADSA) to assess dietary effects on host physiology and microbial ecology. Proximate analysis revealed that protein accumulation was greater in ML-fed larvae, while ADS-fed larvae showed relatively higher fat content at the late fifth instar. Amino acid profiling showed consistently higher silk-related residues (Gly, Ala, Ser) and the derived Silk Amino Acid Index in ML-fed larvae, indicating enhanced fibroin synthesis potential. Microbiome analysis using 16S rRNA amplicon sequencing demonstrated dominance of Enterococcus mundtii in ADS groups, resulting in reduced alpha diversity and uneven community structure. In contrast, ML-fed larvae harbored diverse taxa, including Methylorubrum and Methylobacterium, while ADSA groups exhibited intermediate profiles with occasional dominance of Bacillus cereus. These findings highlight that artificial diet alters host nutrient metabolism and drives dysbiosis of gut microbiota, underscoring the need for optimized formulations and microbiome-stabilizing strategies, such as probiotics or prebiotics.

Spiromesifen is a nonsystemic insecticide that has been primarily recognized for its efficacy against immature stages of whiteflies and mites. However, its activity against adult and egg stages has been less well characterized. In this study, we evaluated its sublethal effects on the reproduction and egg development of the Mediterranean (MED) cryptic species of Bemisia tabaci (Hemiptera: Aleyrodidae). Leaf-dipping bioassays demonstrated that spiromesifen causes significantly higher mortality in nymphs than in eggs and adults. Beyond direct lethality, adult exposure to spiromesifen-treated tomato leaves reduced oviposition rates and disrupted egg development, inducing abnormal egg morphologies in 39.2% and 58.5% of the eggs, respectively, compared with the untreated control. In addition, as the exposure duration increased, egg hatchability declined proportionally, reaching 50.2% compared with the untreated control. These results indicate that spiromesifen has both lethal and sublethal impacts on B. tabaci, combining direct mortality with reproductive suppression. Such dual effects highlight spiromesifen as a promising tool for integrated pest management (IPM) programs, provided it is used judiciously within resistance management frameworks.

In ectothermic species such as insects, temperature significantly influences development and survival. This study examines the effects of thermal stress on metabolic response of Spodoptera litura (Fabricius), a major agricultural pest, to understand how varying thermal conditions, intensified by climate change, affects its physiology. Eggs and larvae were subjected to 42°C and 46°C for 4 h and 1 h respectively in a single and multiple basis for 2 and 4 consecutive days for eggs and larvae respectively. The study measured water content, protein, carbohydrate, and glycogen levels in adults emerging from these heat stressed stages. Results indicated significant reductions in water content and increase in protein, carbohydrate, and glycogen levels under higher temperatures and repeated stress exposures. Females demonstrated higher resilience, evidenced by higher water and protein content compared to males. The findings suggest that S. litura's physiological adaptations to thermal stress involve complex metabolic adjustments, enhancing thermotolerance. This study provides insights into the potential impacts of climate change on S. litura populations and underscores the necessity for sustainable pest management strategies. Key findings include stage-specific differences in thermal sensitivity, with larvae showing greater susceptibility to heat stress, and the critical role of metabolic plasticity in insect resilience. Understanding these metabolic responses is crucial for predicting pest dynamics and developing effective control measures in a changing climate. This study contributes to the broader knowledge of ectothermic pest adaptation to environmental stressors, emphasizing the integration of physiological data into pest management framework.

High-humidity environments can inhibit the reproduction of faba bean aphids (Megoura crassicauda), reduce their moisture content, and induce the emergence of long-winged aphids. However, little is currently known about the molecular mechanisms through which M. crassicauda adapts to high-humidity stress. To better understand the adaptive mechanisms of M. crassicauda under high relative humidity (RH) conditions, we examined their gene expression under three different RH treatments (60%, 75%, and 90%). Differentially expressed genes (DEGs) and related biological processes were identified using transcriptome analysis. Based on the transcriptomic data, several genes with significant expression differences were identified, and their expression patterns under different humidity conditions were validated by qRT-PCR. In the comparisons of RH 60% versus RH 75%, RH 60% versus RH 90%, and RH 75% versus RH 90%, we observed 44, 552, and 268 upregulated genes, and 17, 1536, and 1075 downregulated genes, respectively. Three key pathways, specifically the PI3K/Akt, AMPK, and insulin signaling pathway, were found to be responsive to high-humidity stress, with a greater number of genes downregulated at RH 90%. Additionally, heat shock proteins (HSPs) and zinc finger proteins (ZFPs) were significantly differentially expressed under high humidity, highlighting their crucial roles in the stress response. These findings provide valuable insights into the genes and metabolic signaling pathways involved in high-humidity stress response, laying the foundation for future research on the molecular mechanisms of M. crassicauda adaptation and identifying potential target genes for pest control.