摘要: Rice stripe virus (RSV) is the causative agent of rice stripe disease and is completely dependent on insect vectors for its plant-to-plant transmission.Laodelphax striatellusis the major insect vector for RSV. In this study, we explored the interactions between RSV infection andL. striatellusautophagy, a potential intrinsic antiviral mechanism in insects. We found thatL. striatellusautophagic activity did not affect RSV infection; however, the autophagy-related-8 (Atg8) gene significantly enhanced virus infection. During RSV initial infection within theL. striatellusmidgut, silencing ofAtg8expression significantly decreased the phosphorylation of c-Jun N-terminal kinase (p-JNK); however, when RSV infection is absent, silencing of Atg8 did not alterp-JNK levels. These results indicated that Atg8 might activate the JNK machinery by allowing more virus infection into cells. We further revealed thatAtg8-deficiency significantly decreased RSV accumulation on the surface of the insect midgut epithelial cells, suggesting a receptor trafficking function of the gamma-aminobutyric acid receptor-associated protein family. Using the RSV ovary entry as a model, in which vitellogenin receptor (VgR) mediates RSV cell entry, we clarified thatAtg8-deficiency decreased the abundance of VgR localizing on the cytomembrane and disturbed the attachment of RSV in the germarium zones. Collectively, these results revealed an autophagy-independent function ofL. striatellusAtg8 that enhances RSV initial infection by increasing virus attachment on the infection sites.

摘要: The evolutionary success of phytophagous insects depends on their ability to efficiently exploit plants as a source of energy for survival. Herbivorous insects largely depend on the efficiency, flexibility, and diversity of their digestive physiology and sophistication of their detoxification system to use chemically diverse host plants as food sources. The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a polyphagous pest of many commercially important crops. To elucidate the ability of this insect pest to adapt to host plant mechanisms, we evaluated the impact of primary (corn) and alternate (rice) host plants after 11 generations on gut digestive enzymatic activity and expression profiles of related genes. Results indicated that the total protease and class-specific trypsin- and chymotrypsin-like protease activity of S. frugiperda significantly differed among host plant treatments. The class-specific protease profiles greatly differed in S. frugiperda midguts upon larval exposure to different treatments with inhibitors compared with treatments without inhibitors. Similarly, the single and cumulative effects of the enzyme-specific inhibitors TLCK, TPCK, and E-64 significantly increased larval mortality and reduced larval growth/mass across different plant treatments. Furthermore, the quantitative reverse transcription polymerase chain reaction results revealed increased transcription of two trypsin (SfTry-3, SfTry-7) and one chymotrypsin gene (Sfchym-9), which indicated that they have roles in host plant adaptation. Knockdown of these genes resulted in significantly reduced mRNA expression levels of the trypsin genes. This was related to the increased mortality observed in treatments compared with the dsRED control. This result indicates possible roles of S. frugiperda gut digestive enzymes and related genes in host plant adaptation.

摘要: Chitinase degrades chitin in the old epidermis or peritrophic matrix of insects, which ensures normal development and metamorphosis. In our previous work, we comprehensively studied the function ofSfCht7inSogatella furcifera. However, the number and function of chitinase genes inS.furciferaremain unknown. Here, we identified 12 full-length chitinase transcripts fromS.furcifera, which included nine chitinase (Cht), two imaginal disc growth factor (IDGF), and one endo-beta-N-acetylglucosaminidase (ENGase) genes. Expression analysis results revealed that the expression levels of eight genes (SfCht3,SfCht5,SfCht6-1,SfCht6-2,SfCht7,SfCht8,SfCht10, andSfIDGF2) with similar transcript levels peaked prior to molting of each nymph and were highly expressed in the integument. Based on RNA interference (RNAi), description of the functions of each chitinase gene indicated that the silencing ofSfCht5,SfCht10, andSfIDGF2led to molting defects and lethality. RNAi inhibited the expressions ofSfCht5,SfCht7,SfCht10, andSfIDGF2, which led to downregulated expressions of chitin synthase 1 (SfCHS1,SfCHS1a, andSfCHS1b) and four chitin deacetylase genes (SfCDA1,SfCDA2,SfCDA3, andSfCDA4), and caused a change in the expression level of two trehalase genes (TRE1andTRE2). Furthermore, silencing ofSfCht7induced a significant decrease in the expression levels of three wing development-related genes (SfWG,SfDpp, andSfHh). In conclusion,SfCht5,SfCht7,SfCht10, andSfIDGF2play vital roles in nymph-adult transition and are involved in the regulation of chitin metabolism, andSfCht7is also involved in wing development; therefore, these genes are potential targets for control ofS.furcifera.

摘要: Odorant binding proteins (OBPs) are a group of soluble proteins functioning as odorant carriers in insect antennae, mouth parts and other chemosensory organs. However, multiple insect OBPs have been detected in other tissues and various functions have been proposed. Therefore, a detailed expression profile including stages, tissues and sexes where OBPs are expressed will assist in building the links to their potential functions, enhancing the functional studies of insect OBPs. Here, we identified 39 putative OBP genes from its genome and transcriptome sequences of diamondback moth (DBM),Plutella xylostella. The expression patterns of identified PxylOBPs were further investigated from eggs, larvae, pupae, virgin adults, mated adults, larval midgut, larval heads, adult antennae, adult heads and adult tarsi. Moreover,P. xylostellalarvae and adults with and without host plants for 5 h were utilized to study the interactions between OBP expression and host plants. The results showed that most PxylOBPs were highly expressed in male and female adult antennae. The expression levels of certain PxyOBPs could be regulated by mating activities and feeding host plants. This study advances our knowledge ofP. xylostellaOBPs, which may help develop new strategies for more environmentally sustainable management ofP. xylostella.

摘要: Cuticular hydrocarbons form a barrier that protects terrestrial insects from water loss via the epicuticle. Lipophorin loads and transports lipids, including hydrocarbons, from one tissue to another. In some insects, the lipophorin receptor (LpR), which binds to lipophorin and accepts its lipid cargo, is essential for female fecundity because it mediates the incorporation of lipophorin by developing oocytes. However, it is unclear whether LpR is involved in the accumulation of cuticular hydrocarbons and its precise role in aphid reproduction remains unknown. We herein present the results of our molecular characterization, phylogenetic analysis, and functional annotation of the pea aphid (Acyrthosiphon pisum) LpR gene (ApLpR). This gene was transcribed throughout theA. pisumlife cycle, but especially during the embryonic stage and in the abdominal cuticle. Furthermore, we optimized the RHA interference (RNAi) parameters by determining the ideal dose and duration for gene silencing in the pea aphid. We observed that the RNAi-basedApLpRsuppression significantly decreased the internal and cuticular hydrocarbon contents as well as adult fecundity. Additionally, a deficiency in cuticular hydrocarbons increased the susceptibility of aphids to desiccation stress, with decreased survival rates under simulated drought conditions. Moreover,ApLpRexpression levels significantly increased in response to the desiccation treatment. These results confirm thatApLpRis involved in transporting hydrocarbons and protecting aphids from desiccation stress. Furthermore, this gene is vital for aphid reproduction. Therefore, theApLpRgene ofA. pisummay be a novel RNAi target relevant for insect pest management.