Archives of Insect Biochemistry and Physiology最新文献

At present, there is no clear consensus on the impact of carbohydrate feeds on bee colony health, and comprehensive research and evaluation in this context is lacking. To comprehensively and objectively examine the health status of honeybees after consuming those carbohydrates from multiple perspectives, experimental techniques, including high-throughput sequencing of the transcriptome, proboscis extension reflex (PER), and measuring bee growth parameters were employed. This study showed that compared with honey, feeding high fructose syrup (HFS) resulted in a decrease in the survival rate and body weight of bees, while sucrose decreased the learning and memory ability of bees. After feeding on honey, the main antimicrobial peptides including abaecin, apidaecin1, hymenoptin, and defensin in bees, are all upregulated in expression. The 14 DEGs significantly enriched in the axonal regeneration pathway were all downregulated in the sucrose group and HFS group. This study demonstrated that the expression of multiple genes involved in oxidative phosphorylation was downregulated in bees fed with HFS, moreover, HFS also affected the biosynthesis of unsaturated fatty acids. These effects may lead to energy and metabolic disorders (including fatty acids), thereby inhibiting the growth and development of bees. Sucrose can decrease the learning and memory ability of bees, which may be due to the downregulation of genes related to learning and memory in the axonal regeneration pathway. Honey can upregulate antimicrobial peptides and other immune-related proteins, activating the bee's immune system and boosting bees' immunity to pathogens.

The discovery that infections of viruses are pervasive among insects has considerable potential for future applications, such as new strategies for pest control through the manipulation of virus-host interactions. However, few studies can be found that aim to minimize (for beneficial insects) or maximize (for pests) virus impact or virulence. Viruses generally employ molecular mechanisms that deviate from the cells’ to increase their replication efficiency and to avoid the immune response. In this research, a screening system is presented for the detection of molecules that interfere with the internal ribosomal entry site (IRES) of Cricket paralysis virus (Dicistroviridae) which has been well characterized in previous research. Over-expression and RNAi experiments identified the importance of eIF4A, a component of the cap-dependent translation initiation complex, to modify the activity of IRES-mediated translation. Application of Rocaglamide A (RocA), a natural product from Aglaia plants and inhibitor of eIF4A, resulted in strong stimulation of IRES-mediated translation in reporter assays as well as increased CrPV genome replication and virion production in lepidopteran Hi5 cells. At 100 nM of RocA, dsRNA molecules accumulated in infected cells, corresponding to full-length genome (9.5 kb) and a smaller fragment (0.8 kb) with unknown function. Treatment of silkworm larvae with RocA by injection or topically was highly toxic while no strong stimulation of CrPV infection could be observed. The prospect of the use of rocaglamates as insecticides and enhancers of CrPV infection is discussed together with its potential impact on mammalian cells.

RNA interference (RNAi) is a promising technology for controlling insect pests of agriculture. This technology is mediated through the application of double-stranded RNAs (dsRNAs), which are processed within the insect cells into small interfering RNAs (siRNAs). These molecules then target and reduce the expression of the insect-specific genes that can kill or reduce the performance of the pest. The application of these RNA biopesticides generally falls under two methods: foliar sprays and expression of RNAi constructs within transgenic plants. Here, we provide evidence supporting feasibility of using transgenic plants to deliver RNAi-based biopesticides against their aphid pests. Our findings suggest that, under the Cucumis melo galactinol synthase 1 promoter, the companion cells of transformed Arabidopsis thaliana plants express dsRNAs but not siRNAs at detectable levels. Further, oral application of either siRNAs or dsRNAs is equally effective in reducing the expression of transcripts of the integral membrane protein aquaporin 1 in Acyrthosiphon pisum pea aphids. We did not find any dsRNAs or siRNAs remaining in the insects or honeydew 48 h post-exposure, suggesting a low risk of contamination of these molecules beyond the target phloem-piercing insect pests.

The plant defense against insects is multiple layers of interactions. They defend through direct defense and indirect defense. Direct defenses include both physical and chemical barriers that hinder insect growth, development, and reproduction. In contrast, indirect defenses do not affect insects directly but instead suppress them by releasing volatile compounds that attract the natural enemies of herbivores. Insects overcome plant defenses by deactivating biochemical defenses, suppressing defense signaling through effectors, and altering their behavior through chemical regulation. There is always a genetic war between plants and insects. In this genetic war, plant–insect co-evolution act as both weapons and messengers. Because plants always look for new strategies to avoid insects by developing adaptation. There are molecular processes that regulate the interaction between plants and insect. Here, we examine the genes and proteins involved in plant–insect interactions and explore how their discovery has shaped the current model of the plant genome's role. Plants detect damage-associated and herbivore-associated molecular patterns through receptors, which trigger early signaling pathways involving Ca²⁺, reactive oxygen species, and MAP kinases. The specific defense mechanisms are activated through gene signaling pathways, including phytohormones, secondary metabolites, and transcription factors. Expanding plant genome approaches to unexplored dimensions in fending off insects should be a future priority in order to develop management strategies.

Instant and refrigerated acid soaking are commonly used in cocoon production to prevent or break diapause, and provide developable silkworm eggs for sericulture, while their mechanisms have not been fully understood. This study aims to investigate the mechanisms by which hydrochloric acid (HCl) or dimethyl sulfoxide (DMSO) promotes embryonic development in silkworm Bombyx mori, focusing on the chloride ion (Cl⁻) related gene expression profiles. Our results revealed that the HCl treatment of up to 6 min enhanced hatchability in freshly picked and cold-stored eggs, whereas a slight decrease in hatchability was observed in those treated with DMSO for 40 min. The genes encoding chloride ion channel proteins were cloned and transcriptionally analyzed by quantitative real-time PCR in B. mori 932 strain. Bioinformatics analysis showed that BmCLIC, BmGluCl, and Bmγ-Cl mainly clustered with Lepidopteran insect homologs, while there existed a relatively low conservation from B. mori to mammals. We further explored the mRNA levels of BmCLIC, BmGluCl, and Bmγ-Cl in different egg processing conditions and embryonic developmental stages following HCl or DMSO treatments. Our results revealed that the mRNA expression profiles of BmCLIC, BmGluCl, and Bmγ-Cl increased in 20 h post-egg oviposition and refrigerated eggs after acid soaking. Moreover, the relative expression level of BmCLIC and BmGluCl gene was the highest on the first day, and maximum relative expression level of Bmγ-Cl gene presented on the second day in diapause eggs after treatment, and then it showed diversity. The expression profiles of the candidate genes seem like the same trend of changes during the development of eggs treated with instant acid soaking or DMSO treatment. In general, in the production practice of soaking silkworm eggs with HCl or DMSO, Cl⁻ channel is likely to play an important subsidiary role to promot the relieving of diapause.

Zeugodacus cucurbitae (Coquillett) is an important migratory vegetable pest. Previous research has demonstrated that short-term high temperatures induce differential expression of the vitellogenin receptor (ZcVgR) gene, reducing the number of eggs laid and the lifespan of female Z. cucurbitae. In this paper, we used Tandem Mass Tags (TMT) quantitative proteomics and Illumina high-throughput sequencing to determine the proteomic and transcriptomic information of female Z. cucurbitae after siRNA-mediated silencing of the target gene (ZcVgR) to gain a comprehensive understanding of the molecular mechanism of this gene in the regulation of reproduction and lifespan. The findings demonstrated that following the target gene's silencing, the ZcVgR gene's transcriptional expression was significantly downregulated, and there was no significant difference in protein level. The transcriptome and proteome had a low correlation; when the ZcVgR gene was silenced, vitellogenin-1 (ZcVg1), juvenile hormone epoxide hydrolase (JHEH), troponin C (TnC), heat shock protein 70 (HSP70), and other related genes were downregulated at the transcriptional level. By silencing the ZcVgR gene, transcriptionally level immune-related pathways were activated and energy metabolism-related pathways were inhibited; protein-level glycometabolism and phagosome pathways were activated, while phototransduction-fly and autophagy-animal pathways were inhibited. The findings of this study might offer a theoretical foundation for integrated management of Z. cucurbitae in the summertime.

C-type lectin S (CTL-S) plays a crucial role in pathogen recognition and the activation of immune response. In comparison, the proportion of CTL-S was relatively high in insects, but the study was much smaller than the proportion observed. In this study, we cloned and characterized one CTL-S, TcCTL4, from Tribolium castaneum. Our analysis revealed that TcCTL4 was highly expressed during the early pupal stage, with expression levels exhibiting a tendency to change with developmental stages. Additionally, tissue expression analysis showed a high expression of TcCTL4 in the central nervous system (CNS). Moreover, we observed a significant increase in TcCTL4 transcripts after bacterial challenge. The RNA interference (RNAi) of TcCTL4 before bacterial treatment resulted in a significant reduction in the transcripts of immune factors (IFs) and antimicrobial peptides (AMPs), indicating that TcCTL4 may regulate AMP expression through the activation of the immune signaling pathway. Furthermore, our investigation revealed that the recombinant protein TcCTL4 (rTcCTL4) not only recognized bacteria but also agglutinated bacteria in a Ca²⁺-dependent manner. Enzyme activity analysis suggested that rTcCTL4 could enhance phenoloxidase activity, implying its potential involvement in the prophenoloxidase activation pathway. In conclusion, these results indicate that TcCTL4 is involved in the immunity of T. castaneum, providing valuable insights into insect CTLs.

Cuckoo wasps, also known as jewel or gold wasps (Hymenoptera: Chrysididae), are kleptoparasites and parasitoids that impose their offspring on the breeding efforts of other wasp species. Chrysidids oviposit in the nests of predatory wasps, and the hatched larva kills the host's larva and consumes the resources collected by the host. When a cuckoo wasp is detected by the host wasp, the host may abandon the nest or take other measures to prevent the development of the kleptoparasite. Chemical camouflage, particularly involving cuticlar hydrocarbons (CHCs), is crucial for cuckoo wasp females. There is a conflict because females need chemical signals that are easily detectable by males but not by the host wasps. It was demonstrated that virgin females of Chrysis angustula, Chrysis fulgida, and Chrysis iris contain CHCs that stimulate behavioral reactions in conspecific males. Coupled gas chromatography-electroantennogram detection analysis revealed 16 hydrocarbons with carbon chain lengths of C23-27 in virgin females: 6 in C. angustula, 8 in C. fulgida, and 13 in C. iris. A specific ratio of CHC compounds, including putative sex pheromones, was established for these three chrysidid species. Observations of re-mating refusals led to the hypothesis that virgin females of cuckoo wasps cease production of some unsaturated CHCs, functioning as sex pheromones, following mating. This change could reduce the risk of detection of CHCs traces left while entering the host's nest.

We evaluated the possible roles of five cytochrome P450 transcripts in the susceptibility of both adults and larvae of Aedes aegypti to three pyrethroids using RNA interference (RNAi) coupled with insecticide bioassays. RNAi by feeding larvae with chitosan/dsRNA nanoparticles led to reductions of CYP6AA5, CYP6AL1, CYP9J32, CYP4J16A, and CYP4J16B transcripts by 38.7%, 46.0%, 46.52%, 44.0%, and 41.0%, respectively, and increased larval mortality by 46.0% to permethrin when CYP9J32 was silenced and by 41.2% to cypermethrin when CYP6AA5 was silenced. RNAi by injecting dsRNA in adults led to reductions of CYP6AA5, CYP6AL1, and CY4J16A transcripts by 77.9%, 80.0%, and 87.1% (p < 0.05), respectively, at 96 h and reduction of CYP9J32 transcript by 46.5% at 24 h after injection. In contrast, CYP4J16B was repressed by 78.2% at 72 h after injection. Exposure of the adults injected with CYP6AA5 dsRNA resulted in 1.5- to 2.0-fold increased susceptibility to cypermethrin as compared with the control. Homology modeling of CYP6AA5 followed by ligand docking showed that distances between the heme iron and the putative aromatic hydroxylation site were 9.2, 7.2, and 9.1 Å for permethrin, cypermethrin, and deltamethrin, respectively. For the aliphatic hydroxylation site, these distances were 5.3, 4.9, and 3.1 Å. These results supported that CYP6AA5 may be able to metabolize cypermethrin preferentially by aliphatic hydroxylation as indicated by the close interaction with the heme iron. Our study also suggests that the detoxification roles of cytochrome P450 genes in A. aegypti may vary according to the mosquito developmental stages, cytochrome P450 genes, and insecticides.