Study on the Effect of Wing Bud Chitin Metabolism and Its Developmental Network Genes in the Brown Planthopper, Nilaparvata lugens, by Knockdown of TRE Gene

Stress Response of Aphid Population Under Combined Stress of Cadmium and Lead and Its Effects on Development of Harmonia axyridis

Heavy metal pollution is a serious global environmental issue. It threatens human and ecological health. Heavy metals can accumulate in the soil over extended periods and inevitably transfer through the food chain to herbivorous insects and their natural enemies, leading to various adverse effects. This study aimed to investigate the stress responses and biochemical metabolic changes of aphids and one of aphids' predators, ladybugs, under cadmium (Cd) and lead (Pb) stress by constructing a food chain of Vicia faba L., Megoura crassicauda, and Harmonia axyridis. The results showed that aphids and ladybugs had a notable accumulation of Cd2+ and Pb2+. Insects can adapt to heavy metal stress by regulating their energy metabolism pathways. Glycogen content in the first filial generation (F1) aphids decreased significantly, glucose content in the second filial generation (F2) to the fourth filial generation (F4) adult aphids significantly increased, and trehalose content in the F1 adult aphids increased significantly. Moreover, the relative expression levels of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) in the F1 adult aphids were significantly higher than those in the control group, and the expression levels of TPS genes in the second filial generation to the fifth filial generation (F2 to F5) aphids decreased, suggesting that insects can resist heavy metal stress by regulating trehalose metabolism. The fertility of female aphids in all treatment groups was reduced compared to the control group. Additionally, the relative expression level of vitellogenin (Vg) was down-regulated in all aphid generations except the F1 aphids. There was interaction between heavy metal concentration and aphid generation, and it significantly affected the number of aphids' offspring and the expression of the aphid Vg gene. The developmental duration of the ladybugs from the second to fourth instars was prolonged, and the weight decreased significantly from the prepupa to the adult stages. These results contribute to understanding the effects of Cd2+-Pb2+ accumulation on phytophagous insects and higher trophic levels' natural enemies, laying the foundation for protecting natural enemies and maintaining ecosystem stability.

The Role of TcCYP6K1 and TcCYP9F2 Influences Trehalose Metabolism under High-CO2 Stress in Tribolium castaneum (Coleoptera)

Cytochrome P450 monooxygenases (CYP), crucial detoxification enzymes in insects, are involved in the metabolism of endogenous substances as well as the activation and degradation of exogenous compounds. In this study, T. castaneum was utilized to investigate the roles of TcCYP6K1 and TcCYP9F2 genes influencing in the trehalose metabolism pathway under high-CO2 stress. By predicting the functional sequences of TcCYP6K1 and TcCYP9F2 genes and analyzing their spatiotemporal expression patterns, it was discovered that both genes belong to the CYP3 group and exhibit high expression levels during the larval stage, decreasing during the pupal stage, while showing high expression in the fatty body, intestine, and malpighian tubules. Furthermore, following the knockdown of TcCYP6K1 and TcCYP9F2 genes in combination with treating larvae with 75% CO2, it was observed that larval mortality increased, and glycogen content significantly decreased, while trehalose content increased significantly. Additionally, membrane-bound trehalase enzyme activity declined, TPS gene expression was significantly upregulated, GS gene expression was significantly downregulated, and ATP content showed a marked decrease. In conclusion, CYP genes are critical responsive genes of T. castaneum to high CO2 levels, potentially impacting the insect's resistance to carbon dioxide through their involvement in the synthesis or breakdown of the carbohydrate metabolism pathway. These findings could serve as a theoretical basis for the utilization of novel pesticides in low-oxygen grain storage techniques and offer new insights for environmentally friendly pest control strategies in grain storage.

Novel compounds ZK-PI-5 and ZK-PI-9 regulate the reproduction of Spodoptera frugiperda (Lepidoptera: Noctuidae), with insecticide potential

Trehalase inhibitors prevent trehalase from breaking down trehalose to provide energy. Chitinase inhibitors inhibit chitinase activity affecting insect growth and development. This is an important tool for the investigation of regulation of trehalose metabolism and chitin metabolism in insect reproduction. There are few studies on trehalase or chitinase inhibitors' regulation of insect reproduction. In this study, ZK-PI-5 and ZK-PI-9 were shown to have a significant inhibitory effect on the trehalase, and ZK-PI-9 significantly inhibited chitinase activity in female pupae. We investigated the reproduction regulation of Spodoptera frugiperda using these new inhibitors and evaluated their potential as new insecticides. Compounds ZK-PI-5 and ZK-PI-9 were injected into the female pupae, and the control group was injected with solvent (2% DMSO). The results showed that the emergence failure rate for pupae treated with inhibitors increased dramatically and aberrant phenotypes such as difficulty in wings spreading occurred. The oviposition period and longevity of female adults in the treated group were significantly shorter than those in the control group, and the ovaries developed more slowly and shrank earlier. The egg hatching rate was significantly reduced by treatment with the inhibitor. These results showed that the two new compounds had a significant impact on the physiological indicators related to reproduction of S. frugiperda, and have pest control potential. This study investigated the effect of trehalase and chitin inhibitors on insect reproduction and should promote the development of green and efficient insecticides.

Roles of GFAT and PFK genes in energy metabolism of brown planthopper, Nilaparvata lugens

Glutamine:fructose-6-phosphate aminotransferases (GFATs) and phosphofructokinase (PFKs) are the principal rate-limiting enzymes involved in hexosamine biosynthesis pathway (HBP) and glycolysis pathway, respectively. In this study, the NlGFAT and NlPFK were knocked down through RNA interference (RNAi) in Nilaparvata lugens, the notorious brown planthopper (BPH), and the changes in energy metabolism were determined. Knockdown of either NlGFAT or NlPFK substantially reduced gene expression related to trehalose, glucose, and glycogen metabolism pathways. Moreover, trehalose content rose significantly at 72 h after dsGFAT injection, and glycogen content increased significantly at 48 h after injection. Glucose content remained unchanged throughout the experiment. Conversely, dsPFK injection did not significantly alter trehalose, but caused an extreme increase in glucose and glycogen content at 72 h after injection. The Knockdown of NlGFAT or NlPFK significantly downregulated the genes in the glycolytic pathway, as well as caused a considerable and significant decrease in pyruvate kinase (PK) activity after 48 h and 72 h of inhibition. After dsGFAT injection, most of genes in TCA cycle pathway were upregulated, but after dsNlPFK injection, they were downregulated. Correspondingly, ATP content substantially increased at 48 h after NlGFAT knockdown but decreased to an extreme extent by 72 h. In contrast, ATP content decreased significantly after NlPFK was knocked down and returned. The results have suggested the knockdown of either NlGFAT or NlPFK resulted in metabolism disorders in BPHs, highlighting the difference in the impact of those two enzyme genes on energy metabolism. Given their influence on BPHs energy metabolism, developing enzyme inhibitors or activators may provide a biological control for BPHs.

Regulation of Vicia faba L. Response and Its Effect on Megoura crassicauda Reproduction under Zinc Stress

The heavy metal zinc (Zn) is known to be transmitted in the food chain; however, the effect of Zn stress on beans and herbivorous insects is largely unclear. This study aimed to investigate the resistance of broad bean plants to Zn stress and the consequent changes in their physiological and biochemical metabolism by simulating heavy metal pollution in soil. Simultaneously, the effects of aphid progeny treated with different Zn concentrations on the expression of carbohydrate and related genes were analyzed. The results showed that Zn had no effect on the germination rate of broad beans, but other effects mainly manifested as follows. (1) Chlorophyll content decreased. (2) The total soluble sugar and Zn content in stems and leaves increased with increasing Zn content. (3) The proline content first increased and then decreased with increasing Zn content. (4) The height of the seedlings indicates that low concentrations promote growth and high concentrations inhibit growth. In addition, only the first-generation fecundity decreased significantly when aphids fed on heavy metal broad beans. Continuous high Zn levels increase the trehalose content of aphid F1 and F2, while F3 decreases. These results can not only provide a theoretical basis for exploring the impact of soil heavy metal pollution on ecosystems but also preliminarily evaluate the possibility of broad beans as a means of pollution remediation.

Effects of insulin-like peptide 7 in Bemisia tabaci MED on tomato chlorosis virus transmission

BACKGROUND

Tomato chlorosis virus (ToCV) is a semi-persistent plant virus that is primarily transmitted by the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae). It causes a serious disease that lowers tomato yield. Insulin-like peptide (ILP), an insulin homolog, regulates trehalose metabolism in a variety of insects. In a previous study, we discovered that trehalose metabolism is required for whiteflies to transmit ToCV effectively. Furthermore, transcriptome sequencing revealed that the BtILP7 gene was highly expressed in B. tabaci infected with ToCV. Therefore, the whitefly ILP7 gene may facilitate the transmission of ToCV and be an attractive target for the control of whiteflies and subsequently ToCV.

RESULTS

The ToCV content in B. tabaci MED was found to be correlated with BtILP7 gene expression. Subsequent RNA interference (RNAi) of the BtILP7 gene had a significant impact on B. tabaci MED's trehalose metabolism and reproductive capacity, as well as ability to transmit ToCV.

CONCLUSIONS

These results indicate that the BtILP7 gene was closely related to ToCV transmission by regulating trehalose metabolism and reproduction behavior, thus providing a secure and environmentally friendly management strategy for the control of whiteflies and ToCV-caused disease. © 2022 Society of Chemical Industry.

Potential inhibitory effects of compounds ZK-PI-5 and ZK-PI-9 on trehalose and chitin metabolism in Spodoptera frugiperda (J. E. Smith)

Introduction:Spodoptera frugiperda is an omnivorous agricultural pest which is great dangerous for grain output.

Methods: In order to investigate the effects of potential trehalase inhibitors, ZK-PI-5 and ZK-PI-9, on the growth and development of S. frugiperda, and to identify new avenues for S. frugiperda control, we measured the content of the trehalose, glucose, glycogen and chitin, enzyme activity, and gene expression levels in trehalose and chitin metabolism of S. frugiperda. Besides, their growth and development were also observed.

Results: The results showed that ZK-PI-9 significantly reduced trehalase activity and ZK-PI-5 significantly reduced membraned-bound trehalase activity. Moreover, ZK-PI-5 inhibited the expression of SfTRE2, SfCHS2, and SfCHT, thus affecting the chitin metabolism. In addition, the mortality of S. frugiperda in pupal stage and eclosion stage increased significantly after treatment with ZK-PI-5 and ZK-PI-9, which affected their development stage and caused death phenotype (abnormal pupation and difficulty in breaking pupa).

Discussion: These results have provided a theoretical basis for the application of trehalase inhibitors in the control of agricultural pests to promote future global grain yield.

Targeting Aedes aegypti Metabolism with Next-Generation Insecticides

Aedes aegypti is the primary vector of dengue virus (DENV), zika virus (ZIKV), and other emerging infectious diseases of concern. A key disease mitigation strategy is vector control, which relies heavily on the use of insecticides. The development of insecticide resistance poses a major threat to public health worldwide. Unfortunately, there is a limited number of chemical compounds available for vector control, and these chemicals can have off-target effects that harm invertebrate and vertebrate species. Fundamental basic science research is needed to identify novel molecular targets that can be exploited for vector control. Next-generation insecticides will have unique mechanisms of action that can be used in combination to limit selection of insecticide resistance. Further, molecular targets will be species-specific and limit off-target effects. Studies have shown that mosquitoes rely on key nutrients during multiple life cycle stages. Targeting metabolic pathways is a promising direction that can deprive mosquitoes of nutrition and interfere with development. Metabolic pathways are also important for the virus life cycle. Here, we review studies that reveal the importance of dietary and stored nutrients during mosquito development and infection and suggest strategies to identify next-generation insecticides with a focus on trehalase inhibitors.

Knockdown of GFAT disrupts chitin synthesis in Hyphantria cunea larvae

Glutamine-fructose-6-phosphate transaminase (GFAT) has been reported to regulate the hexosamine biosynthetic pathway as the first rate-limiting enzyme. As a key enzyme that catalyzes the substrate of glycosylation modification, which has a wide-ranging effect on cellular functions. However, there are few studies on the relationship between GFAT and chitin metabolism in insects. In the present study, the GFAT gene from Hyphantria cunea was identified based on transcriptome and bioinformatic analysis. The role of HcGFAT in regulating development and chitin synthesis was analyzed by RNA interference (RNAi) in H. cunea larvae. The full-length HcGFAT gene (2028 bp) encodes a 676 amino acid (aa) polypeptide had typical structural features of the SIS and Gn_AT_II superfamily. Phylogenetic analyses showed that GFAT of H. cunea shares the highest homology and identity with GFAT of Ostrinia furnacalis. Expression profiles indicated that HcGFAT was expressed throughout larval, pupal and three tissues (midgut, fat body, epidermis), and highly expressed in the last instar of larvae and strongly expressed in epidermis among three tissues. Bioassay results showed that knockdown of HcGFAT repressed larval growth and development, resulting in a significant loss of larval body weight. Meanwhile, HcGFAT knockdown also significantly caused larval developmental deformity. Knockdown of HcGFAT regulated the expression of four other critical genes in the chitin synthesis pathway (HcGNA, HcPAGM, HcUAP, HcCHSA), and ultimately resulted in decreased chitin content in the epidermis. In summary, these findings indicated that GFAT plays a critical role in larval growth and development, as well as chitin synthesis in H. cunea.

Chitinase (CHI) of Spodoptera frugiperda affects molting development by regulating the metabolism of chitin and trehalose

Chitin is the main component of insect exoskeleton and midgut peritrophic membrane. Insect molting is the result of the balance and coordination of chitin synthesis and degradation in chitin metabolism under the action of hormones. In this study, a 678 bp dsRNA fragment was designed and synthesized according to the known CHI (Chitinase) sequence of Spodoptera frugiperda. It was injected into the larvae to observe the molting and development of S. frugiperda. At the same time, the activities of trehalase and chitinase, the contents of trehalose, chitin and other substances were detected, and the expression of related genes in the chitin synthesis pathway was determined. The results showed that CHI gene was highly expressed at the end of each instar, prepupa and pupal stage before molting; At 12 and 24 h after dsRNA injection of CHI gene of S. frugiperda, the expression of CHI gene decreased significantly, and the chitinase activity decreased significantly from 12 to 48 h. The expression of chitin synthase (CHSB) gene decreased significantly, and the chitin content increased significantly. Some larvae could not molt normally and complete development, leading to certain mortality. Secondly, after RNAi of CHI gene, the content of glucose and glycogen increased first and then decreased, while the content of trehalose decreased significantly or showed a downward trend. The activities of the two types of trehalase and the expression levels of trehalase genes decreased first and then increased, especially the trehalase activities increased significantly at 48 h after dsCHI injection. And trehalose-6-phosphate synthase (TPS), glutamine: fructose-6-phosphate amidotransferase (GFAT), UDP-N-acetylglucosamine pyrophosphorylases (UAP), hexokinase (HK), glucose-6-phosphate isomerase (G6PI) and phosphoacetylglucosamine mutase (PAGM) all decreased significantly at 24 h, and then increased or significantly increased at 48 h. These results indicated that when the expression of chitinase gene of S. frugiperda was inhibited, it affected the degradation of chitin in the old epidermis and the formation of new epidermis, and the content of chitin increased, which led to the failure of larvae to molt normally. Moreover, the chitin synthesis pathway and trehalose metabolism were also regulated. The relevant results provide a theoretical basis for screening target genes and developing green insecticides to control pests by using the chitin metabolism pathway.

Insulin-Like ILP2 Regulates Trehalose Metabolism to Tolerate Hypoxia/Hypercapnia in Tribolium castaneum

RNAi was used to downregulate the expression of insulin-like peptides (ILP2), with air-modulation, and high-concentration CO₂ stress, in the larvae of Tribolium castaneum. We assessed the changes in carbohydrate-related content, trehalase activity, and the expression levels of trehalose pathway genes. And pupation, adult emergence, pupation rate, and mortality were assessed. There was a significant change in the expression of ILPs in T. castaneum, at a certain concentration of CO₂. ILP2 RNAi did not alter the trehalose content significantly, however, the glycogen and glucose content increased significantly. High-concentration CO₂ stress altered the trehalose content and reduced the glycogen and glucose content. The expression levels of TPS and TRE2 were up-regulated by hypoxia/hypercapnia and dsILP2 combination, with the increase of CO₂ concentration, other trehalase genes begin to respond successively. ILP2 knockout raised the mortality and reduced the pupation rate and eclosion rate in CO₂. Understanding the insulin pathway responses to hypoxic stress induced by a high concentration of CO₂ would further elucidate the mechanisms underlying trehalose metabolism in insects.

C/EBPα Regulates PxTreh1 and PxTreh2 Trehalase-Related Bt Resistance in Plutella xylostella (L.)

Simple Summary

The diamondback moth (Plutella xylostella) is a major agricultural pest of cruciferous vegetables and crops worldwide, causing economic losses of up to USD 5 billion annually. The long-term use of insecticides leads to the rapid evolution of resistance in insects, which greatly increases the difficulty of controlling pests. Trehalase regulates energy metabolism in insects by converting trehalose into two glucose molecules. The existence of trehalase is critical for insect flight and larval stress resistance. However, whether trehalase participates in the development of pesticide resistance remains unclear. In this study, we found that the activity of trehalase and the levels of gene expression in Bt-resistant and field populations of P. xylostella were significantly higher than they were in the susceptible strains. By analyzing the promoter sequences of PxTreh1 and PxTreh2, we confirmed the interaction between C/EBPα and the PxTreh2 promoter. The findings of this study suggest that C/EBPα mediates the adaptability of P. xylostella to adverse environmental stressors by regulating the expression of trehalase.

Abstract

Trehalase regulates energy metabolism in insects by converting trehalose into two glucose molecules. High amounts of trehalase are critical for insect flight and larval stress resistance. However, whether trehalase participates in the development of pesticide resistance remains unclear. In this study, we explored this phenomenon and the mechanism that underlies the regulation of Trehalase transcription. We found that overexpression of PxTreh1 and PxTreh2 induced Bacillus thuringiensis (Bt) resistance in Plutella xylostella. The promoter sequences of PxTreh1 and PxTreh2 were also cloned and identified. The dual-luciferase reporter system and RNA interference technology revealed that the expression of PxTreh1 and PxTreh2 genes is possibly regulated by the CCAAT enhancer-binding protein (C/EBPα). A yeast one-hybrid experiment confirmed the interaction between C/EBPα and the PxTreh2 promoter. The findings of this study suggest that C/EBPα mediates the adaptability of P. xylostella to adverse environmental stressors by regulating the expression of trehalase.

Annotation of glycolysis, gluconeogenesis, and trehaloneogenesis pathways provide insight into carbohydrate metabolism in the Asian citrus psyllid

Citrus greening disease is caused by the pathogen Candidatus Liberibacter asiaticus and transmitted by the Asian citrus psyllid, Diaphorina citri. No curative treatment or significant prevention mechanism exists for this disease, which causes economic losses from reduced citrus production. A high-quality genome of D. citri is being manually annotated to provide accurate gene models to identify novel control targets and increase understanding of this pest. Here, we annotated 25 D. citri genes involved in glycolysis and gluconeogenesis, and seven in trehaloneogenesis. Comparative analysis showed that glycolysis genes in D. citri are highly conserved but copy numbers vary. Analysis of expression levels revealed upregulation of several enzymes in the glycolysis pathway in the thorax, consistent with the primary use of glucose by thoracic flight muscles. Manually annotating these core metabolic pathways provides accurate genomic foundation for developing gene-targeting therapeutics to control D. citri.

The vital hormone 20-hydroxyecdysone controls ATP production by upregulating binding of trehalase 1 with ATP synthase subunit α in Helicoverpa armigera

Trehalose is the major “blood sugar” of insects and it plays a crucial role in energy supply and as a stress protectant. The hydrolysis of trehalose occurs only under the enzymatic control of trehalase (Treh), which plays important roles in growth and development, energy supply, chitin biosynthesis, and abiotic stress responses. Previous reports have revealed that the vital hormone 20-hydroxyecdysone (20E) regulates Treh, but the detailed mechanism underlying 20E regulating Treh remains unclear. In this study, we investigated the function of HaTreh1 in Helicoverpa armigera larvae. The results showed that the transcript levels and enzymatic activity of HaTreh1 were elevated during molting and metamorphosis stages in the epidermis, midgut, and fat body, and that 20E upregulated the transcript levels of HaTreh1 through the classical nuclear receptor complex EcR-B1/USP1. HaTreh1 is a mitochondria protein. We also found that knockdown of HaTreh1 in the fifth- or sixth-instar larvae resulted in weight loss and increased mortality. Yeast two-hybrid, coimmunoprecipitation, and glutathione-S-transferase (GST) pull-down experiments demonstrated that HaTreh1 bound with ATP synthase subunit alpha (HaATPs-α) and that this binding increased under 20E treatment. In addition, 20E enhanced the transcript level of HaATPs-α and ATP content. Finally, the knockdown of HaTreh1 or HaATPs-α decreased the induction effect of 20E on ATP content. Altogether, these findings demonstrate that 20E controls ATP production by up-regulating the binding of HaTreh1 to HaATPs-α in H. armigera.

Trehalase inhibition by validamycin A may be a promising target to design new fungicides and insecticides

The introduction of insecticides and fungicides in agriculture has improved crop yields and, consequently, the quality of life for many people, especially in what is widely considered as the 'first world'. However, the indiscriminate use of dangerous chemical insecticides has led to pest resistance, human and animal poisoning and environmental pollution. Biochemical and genetic evidence concludes that the non-reducing disaccharide trehalose plays an essential role in the pathobiology of many insects and fungi. Both organisms share identical pathway for trehalose biosynthesis (the TPS/TPP pathway), while a high degree of homology in their trehalose hydrolysis capacity (trehalase activities) has also been demonstrated. In the search for new, effective and environmentally sustainable compounds, a set of trehalase inhibitors has emerged as a potentially interesting antifungal and insecticidal target. In particular, the trehalose analogue, Validamycin A, which has a strong inhibitory effect on several trehalases, has been successfully introduced for the treatment of various diseases caused by insects and fungi. Herein, we review the main features of the specific interaction between Validamycin A and trehalase as well as the expected advantages of the applications based on trehalase inhibition as insecticides and fungicides. © 2021 Society of Chemical Industry.

Characterization and functional analysis of chitinase family genes involved in nymph-adult transition of Sogatella furcifera

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 of SfCht7 in Sogatella furcifera. However, the number and function of chitinase genes in S. furcifera remain unknown. Here, we identified 12 full-length chitinase transcripts from S. furcifera, which included nine chitinase (Cht), two imaginal disc growth factor (IDGF), and one endo-β-N-acetylglucosaminidase (ENGase) genes. Expression analysis results revealed that the expression levels of eight genes (SfCht3, SfCht5, SfCht6-1, SfCht6-2, SfCht7, SfCht8, SfCht10, and SfIDGF2) 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 of SfCht5, SfCht10, and SfIDGF2 led to molting defects and lethality. RNAi inhibited the expressions of SfCht5, SfCht7, SfCht10, and SfIDGF2, which led to downregulated expressions of chitin synthase 1 (SfCHS1, SfCHS1a, and SfCHS1b) and four chitin deacetylase genes (SfCDA1, SfCDA2, SfCDA3, and SfCDA4), and caused a change in the expression level of two trehalase genes (TRE1 and TRE2). Furthermore, silencing of SfCht7 induced a significant decrease in the expression levels of three wing development-related genes (SfWG, SfDpp, and SfHh). In conclusion, SfCht5, SfCht7, SfCht10, and SfIDGF2 play vital roles in nymph-adult transition and are involved in the regulation of chitin metabolism, and SfCht7 is also involved in wing development; therefore, these genes are potential targets for control of S. furcifera.

Inhibition of trehalase affects the trehalose and chitin metabolism pathways in Diaphorina citri (Hemiptera: Psyllidae)

The Asian citrus psyllid, Diaphorina citri is the principal vector of huanglongbing, which transmits Candidatus Liberibacter asiaticus. Trehalase is a key enzyme involved in trehalose hydrolysis and plays an important role in insect growth and development. The specific functions of this enzyme in D. citri have not been determined. In this study, three trehalase genes (DcTre1-1, DcTre1-2, and DcTre2) were identified based on the D. citri genome database. Bioinformatic analysis showed that DcTre1-1 and DcTre1-2 are related to soluble trehalase, whereas DcTre2 is associated with membrane-bound trehalase. Spatiotemporal expression analysis indicated that DcTre1-1 and DcTre1-2 had the highest expression levels in the head and wing, respectively, and DcTre2 had high expression levels in the fat body. Furthermore, DcTre1-1 and DcTre1-2 expression levels were induced by 20-hydroxyecdysone and juvenile hormone Ⅲ, but DcTre2 was unaffected. The expression levels of DcTre1-1, DcTre1-2, and DcTre2 were significantly upregulated, which resulted in high mortality after treatment with validamycin. Trehalase activities and glucose contents were downregulated, but the trehalose content increased after treatment with validamycin. In addition, the expression levels of chitin metabolism-related genes significantly decreased at 24 and 48 h after treatment with validamycin. Furthermore, silencing of DcTre1-1, DcTre1-2, and DcTre2 reduced the expression levels of chitin metabolism-related genes and led to a malformed phenotype of D. citri. These results indicate that D. citri trehalase plays an essential role in regulating chitin metabolism and provides a new target for control of D. citri.

Characterization and Functional Analysis of trehalase Related to Chitin Metabolism in Glyphodes pyloalis Walker (Lepidoptera: Pyralidae)

Simple Summary

Sericulture has always been threatened by Glyphodes pyloalis Walker (G. pyloalis). Trehalase is an essential enzyme in chitin metabolism and energy supply. In this study, two trehalase genes in G. pyloalis (GpTre1 and GpTre2) were identified and functionally analyzed. Knockdown of the two genes led to the significant downregulation of chitin metabolism pathway-related genes, the difficulty in molting of larvae, and the deformation of adult wings. Moreover, the trehalase inhibitor, Validamycin A, treatment increased GpTre1 and GpTre2 expression and affected the expressions of chitin metabolism pathway-related genes. The inhibitor also caused a significantly increased cumulative mortality of larvae. The results suggested that GpTre1 and GpTre2 played a vital role on G. pyloalis development, which could be useful for providing information for insect pest control in the future.

Abstract

Glyphodes pyloalis Walker (G. pyloalis) is a serious pest on mulberry. Due to the increasing pesticide resistance, the development of new and effective environmental methods to control G. pyloalis is needed. Trehalase is an essential enzyme in trehalose hydrolysis and energy supply, and it has been considered a promising target for insect pest control. However, the specific function of trehalase in G. pyloalis has not been reported. In this study, two trehalase genes (GpTre1 and GpTre2) were identified from our previous transcriptome database. The functions of the trehalase in chitin metabolism were studied by injecting larvae with dsRNAs and trehalase inhibitor, Validamycin A. The open reading frames (ORFs) of GpTre1 and GpTre2 were 1,704 bp and 1,869 bp, which encoded 567 and 622 amino acid residues, respectively. Both of GpTre1 and GpTre2 were mainly expressed in the head and midgut. The highest expression levels of them were in 5th instar during different development stages. Moreover, knockdown both of GpTre1 and GpTre2 by the dsRNAs led to significantly decreased expression of chitin metabolism pathway-related genes, including GpCHSA, GpCDA1, GpCDA2, GpCHT3a, GpCHT7, GpCHSB, GpCHT-h, GpCHT3b, GpPAGM, and GpUAP, and abnormal phenotypes. Furthermore, the trehalase inhibitor, Validamycin A, treatment increased the expressions of GpTre1 and GpTre2, increased content of trehalose, and decreased the levels of glycogen and glucose. Additionally, the inhibitor caused a significantly increased cumulative mortality of G. pyloalis larvae on the 2nd (16%) to 6th (41.3%) day, and decreased the rate of cumulative pupation (72.3%) compared with the control group (95.6%). After the activities of trehalase were suppressed, the expressions of 6 integument chitin metabolism-related genes decreased significantly at 24 h and increased at 48 h. The expressions of GpCHSB and GpCHT-h, involved in chitin metabolism pathway of peritrophic membrane in the midgut, increased at 24 h and 48 h, and there were no changes to GpCHT3b and GpPAGM. These results reveal that GpTre1 and GpTre2 play an essential role in the growth of G. pyloalis by affecting chitin metabolism, and this provides useful information for insect pest control in the future.

GFAT and PFK genes show contrasting regulation of chitin metabolism in Nilaparvata lugens

Glutamine:fructose-6-phosphate aminotransferase (GFAT) and phosphofructokinase (PFK) are enzymes related to chitin metabolism. RNA interference (RNAi) technology was used to explore the role of these two enzyme genes in chitin metabolism. In this study, we found that GFAT and PFK were highly expressed in the wing bud of Nilaparvata lugens and were increased significantly during molting. RNAi of GFAT and PFK both caused severe malformation rates and mortality rates in N. lugens. GFAT inhibition also downregulated GFAT, GNPNA, PGM1, PGM2, UAP, CHS1, CHS1a, CHS1b, Cht1-10, and ENGase. PFK inhibition significantly downregulated GFAT; upregulated GNPNA, PGM2, UAP, Cht2-4, Cht6-7 at 48 h and then downregulated them at 72 h; upregulated Cht5, Cht8, Cht10, and ENGase; downregulated Cht9 at 48 h and then upregulated it at 72 h; and upregulated CHS1, CHS1a, and CHS1b. In conclusion, GFAT and PFK regulated chitin degradation and remodeling by regulating the expression of genes related to the chitin metabolism and exert opposite effects on these genes. These results may be beneficial to develop new chitin synthesis inhibitors for pest control.

RNA interference of trehalose-6-phosphate synthase and trehalase genes regulates chitin metabolism in two color morphs of Acyrthosiphon pisum Harris

Trehalose-6-phosphate synthase (TPS) and trehalase (TRE) directly regulate trehalose metabolism and indirectly regulate chitin metabolism in insects. Real-time quantitative PCR (RT-qPCR) and RNA interference (RNAi) were used to detect the expressions and functions of the ApTPS and ApTRE genes. Abnormal phenotypes were found after RNAi of ApTRE in the Acyrthosiphon pisum. The molting deformities were observed in two color morphs, while wing deformities were only observed in the red morphs. The RNAi of ApTPS significantly down-regulated the expression of chitin metabolism-related genes, UDP-N-acetyglucosamine pyrophosphorylase (ApUAP), chitin synthase 2 (Apchs-2), Chitinase 2, 5 (ApCht2, 5), endo-beta-N-acetylglucosaminidase (ApENGase) and chitin deacetylase (ApCDA) genes at 24 h and 48 h; The RNAi of ApTRE significantly down-regulated the expression of ApUAP, ApCht1, 2, 8 and ApCDA at 24 h and 48 h, and up-regulated the expression of glucose-6-phosphate isomerase (ApGPI) and Knickkopf protein (ApKNK) genes at 48 h. The RNAi of ApTRE and ApTPS not only altered the expression of chitin metabolism-related genes but also decreased the content of chitin. These results demonstrated that ApTPS and ApTRE can regulate the chitin metabolism, deepen our understanding of the biological functions, and provide a foundation for better understanding the molecular mechanism of insect metamorphosis.

Regulatory Functions of Nilaparvata lugens GSK-3 in Energy and Chitin Metabolism

Glucose metabolism is a biologically important metabolic process. Glycogen synthase kinase (GSK-3) is a key enzyme located in the middle of the sugar metabolism pathway that can regulate the energy metabolism process in the body through insulin signaling. This paper mainly explores the regulatory effect of glycogen synthase kinase on the metabolism of glycogen and trehalose in the brown planthopper (Nilaparvata lugens) by RNA interference. In this paper, microinjection of the target double-stranded GSK-3 (dsGSK-3) effectively inhibited the expression of target genes in N. lugens. GSK-3 gene silencing can effectively inhibit the expression of target genes (glycogen phosphorylase gene, glycogen synthase gene, trehalose-6-phosphate synthase 1 gene, and trehalose-6-phosphate synthase 2 gene) in N. lugens and trehalase activity, thereby reducing glycogen and glucose content, increasing trehalose content, and regulating insect trehalose balance. GSK-3 can regulate the genes chitin synthase gene and glucose-6-phosphate isomerase gene involved in the chitin biosynthetic pathway of N. lugens. GSK-3 gene silencing can inhibit the synthesis of chitin N. lugens, resulting in abnormal phenotypes and increased mortality. These results indicated that a low expression of GSK-3 in N. lugens can regulate the metabolism of glycogen and trehalose through the insulin signal pathway and energy metabolism pathway, and can regulate the biosynthesis of chitin, which affects molting and wing formation. The relevant research results will help us to more comprehensively explore the molecular mechanism of the regulation of energy and chitin metabolism of insect glycogen synthase kinases in species such as N. lugens.

Effects of long-term cadmium exposure on trehalose metabolism, growth, and development of Aedes albopictus (Diptera: Culicidae)

Trehalose is the major blood sugar in insects; it not only serves as an energy source but also plays important roles in physiological responses to adverse conditions. However, only a few studies have explored the effects of heavy metal exposure stress on trehalose metabolism in insects. Therefore, in this study, we examined the effects of cadmium stress on changes in trehalose metabolism in Aedes albopictus. Three concentrations of cadmium (0.005, 0.01, and 0.1 mg/L) were selected for evaluation of long-term stress in Ae. albopictus (from eggs to adults); Ae. albopictus in double-distilled water was used as the control group. The trehalose and glucose contents, trehalase activity, and trehalose metabolism-related gene expression were determined. The effects of long-term cadmium exposure on growth, development, and reproduction were also assessed. Trehalose contents were increased, whereas glucose contents and trehalase activity were decreased in Ae. albopictus following long-term exposure to low concentrations of cadmium compared with those in untreated individuals. Moreover, the expression of trehalose-6-phosphate synthase was upregulated, and that of trehalase was downregulated, indicating that Ae. albopictus may enhance trehalose synthesis to resist cadmium stress. Cadmium exposure also caused Ae. albopictus individuals to become smaller with a longer developmental duration, whereas both reproduction and hatching rates of the offspring were decreased compared with those in the control group. Our findings demonstrated that cadmium exposure affected the morphology, physiology, and biochemistry of Ae. albopictus. These findings also confirmed the role of trehalose in the response of Ae. albopictus to cadmium stress, providing insights into the effects of heavy metal stress on trehalose metabolism in an insect model.

Roles of the PTP61F Gene in Regulating Energy Metabolism of Tribolium castaneum (Coleoptera: Tenebrionidae)

Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator in the insulin signaling pathway. It belongs to a class of non-receptor phosphatases of protein tyrosine phosphatase and can catalyze the dephosphorylation of tyrosine to regulate cell differentiation, growth, and metabolism. However, few studies have focused on the role of PTP1B in regulating energy metabolism of insects. In this study, we investigated the expression profiles and the functions of a PTP1B gene (designated TcPTP61F) in the red flour beetle Tribolium castaneum. Quantitative real-time PCR analyzed showed that TcPTP61F was highly expressed in the pupal and adult stages. In adult tissues, TcPTP61F was prominently expressed in the tarsus and head. RNA interference-mediated silencing of TcPTP61F reduced the expression of eight genes in trehalose metabolic and glycolytic pathways. TcPTP61F depletion also caused a significant change in the distribution of trehalose, glucose, and glycogen. Additionally, knockdown of TcPTP61F inhibited the pyruvate kinase (PK) activity and significantly decreased the adenosine triphosphate (ATP) level. The results suggest that TcPTP61F is indispensible for trehalose and energy metabolism of T. castaneum.

Validamycin A Delays Development and Prevents Flight in Aedes aegypti (Diptera: Culicidae)

Trehalose is a disaccharide that is the major sugar found in insect hemolymph fluid. Trehalose provides energy, and promotes growth, metamorphosis, stress recovery, chitin synthesis, and insect flight. The hydrolysis of trehalose is under the enzymatic control of the enzyme trehalase. Trehalase is critical to the role of trehalose in insect physiology, and is required for the regulation of metabolism and glucose generation. Trehalase inhibitors represent a novel class of insecticides that have not been fully developed. Here, we tested the ability of trehalose analogues to function as larvacides or adulticides in an important disease vector-Aedes aegypti. We show that validamycin A, but not 5-thiotrehalose, delays larval and pupal development and prevents flight of adult mosquitoes. Larval mosquitoes treated with validamycin A were hypoglycemic and pupae had increased levels of trehalose. Treatment also skewed the sex ratio toward male mosquitoes. These data reveal that validamycin A is a mosquito adulticide that can impair normal development of an important disease vector.

RNA interference of a trehalose-6-phosphate synthase gene reveals its roles in the biosynthesis of chitin and lipids in Heortia vitessoides (Lepidoptera: Crambidae)

Trehalose-6-phosphate synthase (TPS), an enzyme that hydrolyzes two glucose molecules to yield trehalose, plays a pivotal role in various physiological processes. In this study, we cloned the trehalose-6-phosphate synthase gene (HvTPS) and investigated its expression patterns in various tissues and developmental stages in Heortia vitessoides Moore (Lepidoptera: Crambidae). HvTPS was highly expressed in the fat body and after pupation or before molting. We knocked down TPS in H. vitessoides by RNA interference and found that 3.0 μg of dsHvTPS resulted in optimal interference at 24 h and 36 h post-injection and caused a sharp decline in the survival rate during the 5th instar larval-pupal stage and obviously abnormal or lethal phenotypes. Additionally, compared to the controls, TPS activity and trehalose contents were significantly lower and the glucose content was significantly higher 24 h or 36 h after injection with 3.0 μg of dsHvTPS. Furthermore, the silencing of HvTPS suppressed the expression of six key genes in the chitin biosynthesis pathway and one key gene related to lipid catabolism. The expression levels of two genes associated with lipid biosynthesis were upregulated. These results strongly suggest that HvTPS is essential for the normal growth and development of H. vitessoides and provide a reference for further studies of the utility of key genes involved in chitin and lipid biosynthesis for controlling insect development.

miR-2703 regulates the chitin biosynthesis pathway by targeting chitin synthase 1a in Nilaparvata lugens

The chitin biosynthesis pathway is an important physiology process in arthropods. However, few microRNAs (miRNAs) involved in the regulation of the chitin biosynthesis pathway in insects have been reported until now. In this study, four groups of samples that either upregulated or downregulated the chitin biosynthesis pathway were collected for deep sequencing, and a total of 15 unique mature miRNAs with significantly different expression levels were found, including 11 known miRNAs and four novel miRNAs. Subsequently, we showed that miR-2703 and its new target gene chitin synthase 1a are important for ecdysone-induced chitin biosynthesis in Nilaparvata lugens, a serious insect pest of rice. The nymphs showed an obvious moulting defect phenotype, lower survival rate and significantly reduced chitin content after miR-2703 feeding or injection. Furthermore, we found that the transcription level of miR-2703 was not repressed by 20-hydroxyecdysone signalling after Broad-Complex (BR-C) double-stranded RNA (dsRNA) injection compared with the repressed levels after green fluorescent protein dsRNA injection, suggesting that the involvement of miR-2703 in the 20-hydroxyecdysone pathway contributes to BR-C activity. miR-2703 regulates the chitin biosynthesis pathway by targeting chitin synthase 1a in response to 20-hydroxyecdysone signalling.

Role of phosphoglucomutase in regulating trehalose metabolism in Nilaparvata lugens

Phosphoglucomutase (PGM) is a key enzyme in glycolysis and gluconeogenesis, regulating both glycogen and trehalose metabolism in insects. In this study, we explored the potential function of phosphoglucomutase (PGM) using RNA interference technology in Nilaparvata lugens, the brown planthopper. PGM1 and PGM2 were found highly expressed in the midgut of brown planthoppers, with different expression levels in different instar nymphs. The glycogen, glucose, and trehalose levels were also significantly increased after brown planthoppers were injected with dsRNA targeting PGM1 (dsPGM1) or PGM2 (dsPGM2). In addition, injection of dsPGM1 or dsPGM2 resulted in increased membrane-bound trehalase activity but not soluble trehalase activity. Furthermore, the expression of genes related to trehalose and glycogen metabolism decreased significantly after injection with dsPGM1 and dsPGM2. The expression levels of genes involved in chitin metabolism in the brown planthopper were also significantly decreased and the insects showed wing deformities and difficulty molting following RNAi. We suggest that silencing of PGM1 and PGM2 expression directly inhibits trehalose metabolism, leading to impaired chitin synthesis.

Evaluation of the Expression and Function of the TRE2-like and TRE2 Genes in Ecdysis of Harmonia axyridis

Harmonia axyridis is an important predatory insect and widely used in biological control of agricultural and forestry pests. Trehalose is directly involved in the energy storage of the H. axyridis and in the oxidative function of various physiological activities thereby providing an energy source for its growth and development. The aim of this study was to explore the potential function of membrane-bound-like trehalase (TRE2-like) and membrane-bound trehalase (TRE2) genes in H. axyridis by RNAi. In addition, the activity of soluble and membrane-bound trehalase and the expression of genes related to trehalose and glycogen metabolism were determined in the larvae injected with dsTRE2-like or dsTRE2. The results showed that wing abnormality and mortality appeared in adults, as well as the activity of soluble trehalase and glycogen contents increased when interfering with TRE2-like gene. However, the activity of membrane-bound trehalase, trehalose and glucose contents in the larvae decreased. The expression of glycogen synthase (GS) and glycogen phosphorylase (GP) genes were decreased after RNAi in the ecdysis stage. The expression of chitin synthase gene A (CHSA), chitin synthase gene B (CHSB), and trehalose-6-phosphate synthase genes (TPS) were decreased significantly after RNAi, especially in the ecdysis stage. These results indicated that RNA interference is capable of knocking down gene expression of TRE2-like and TRE2, thereby disrupting trehalose metabolism which affects the chitin synthesis pathway in turn and also leads to developmental defects, such as wing deformities. This study could provide some theoretical guidance for the function of TRE2 gene in other insects.

Knockdown of β-N-acetylglucosaminidase 2 Impairs Molting and Wing Development in Lasioderma serricorne (Fabricius)

β-N-acetylglucosaminidases (NAGs) are carbohydrate enzymes that degrade chitin oligosaccharides into N-acetylglucosamine monomers. This process is important for chitin degradation during insect development and metamorphosis. We identified and evaluated a β-N-acetylglucosaminidase 2 gene (LsNAG2) from the cigarette beetle, Lasioderma serricorne (Fabricius). The full-length open reading frame of LsNAG2 was 1776 bp and encoded a 591 amino acid protein. The glycoside hydrolase family 20 (GH20) catalytic domain and an additional GH20b domain of the LsNAG2 protein were highly conserved. Phylogenetic analysis revealed that LsNAG2 clustered with the group II NAGs. Quantitative real-time PCR analyses showed that LsNAG2 was expressed in all developmental stages and was most highly expressed in the late larval and late pupal stages. In the larval stage, LsNAG2 was predominantly expressed in the integument. Knockdown of LsNAG2 in fifth instar larvae disrupted larval-pupal molting and reduced the expression of four chitin synthesis genes (trehalase 1 (LsTRE1), UDP-N-acetylglucosamine pyrophosphorylase 1 and 2 (LsUAP1 and LsUAP2), and chitin synthase 1 (LsCHS1)). In late pupae, LsNAG2 depletion resulted in abnormal adult eclosion and wing deformities. The expression of five wing development-related genes (teashirt (LsTSH), vestigial (LsVG), wingless (LsWG), ventral veins lacking (LsVVL), and distal-less (LsDLL)) significantly declined in the LsNAG2-depleted beetles. These findings suggest that LsNAG2 is important for successful molting and wing development of L. serricorne.

Glucose Utilization in the Regulation of Chitin Synthesis in Brown Planthopper

Glucose-6-phosphatase (G6Pase) and hexokinase (HK) are two key enzymes in the glycolysis and gluconeogenesis pathways, which catalyze the synthesis and degradation of glucose in insects, respectively. G6Pase and HK play an important role in insect growth by regulating the metabolism of glucose, leading to the efficient metabolism of other macromolecules. However, it is unclear whether these genes could be investigated for pest control through their actions on chitin metabolism. We studied the potential functions of G6Pase and HK genes in the regulation of chitin metabolism pathways by RNAi technology. Interference with G6Pase expression did not affect trehalose and chitin metabolism pathways in brown planthopper, Nilaparvata lugens (Stål). However, knockdown of the HK gene resulted in a significant decrease of expression of genes associated with the trehalose metabolic pathway but had no significant effect on trehalase activity, trehalose content, or glucogen content. Additionally, HK knockdown resulting in downregulation of the genes involved in chitin metabolism in the brown planthopper. These insects also showed wing deformities and difficulty in molting to varying degrees. We suggest that the silencing of HK expression directly inhibited the decomposition of glucose, leading to impaired chitin synthesis.

Adipokinetic Hormone Receptor Mediates Trehalose Homeostasis to Promote Vitellogenin Uptake by Oocytes in Nilaparvata lugens

Adipokinetic hormones (AKHs) are well known to mobilize lipids and carbohydrates for energy-consuming activities in insects. These neuropeptides exert their functions by interacting with AKH receptors (AKHRs) located on the plasma membrane of fat body cells, which regulates energy mobilization by stimulating lipolysis of triacylglycerols (TAG) to diacylglycerols (DAG) and conversion of glycogen into trehalose. Here, we investigated the roles of AKH/AKHR signaling system in trehalose metabolism and vitellogenesis during female reproduction in the brown planthopper, Nilaparvata lugens. Knockdown of AKHR expression by RNA interference (RNAi) resulted in a decrease of the circulating trehalose in hemolymph and significantly increased levels of two trehalases in fat bodies, indicating that the modulation of hemolymph trehalose levels by AKHR may be mediated by regulating trehalose degradation. In addition, adult females that had been injected with double-stranded RNA (dsRNA) for AKHR exhibited delayed oocyte maturation, prolonged pre-oviposition period, as well as decline in egg number and reduction in fecundity. Considering that these phenotypes resulting from AKHR silencing are similar to those of vitellogenin receptor (VgR) RNAi, we further analyzed a possible connection between AKHR and vitellogenesis. Knockdown of AKHR showed no effects on the Vg synthesis in fat bodies, whereas it significantly reduced the levels of VgR in ovaries. With RNAi-females, we observed an increase of Vg accumulation in hemolymph and a decrease of Vg deposition in ovaries. Moreover, the decrease in VgR expression and Vg incorporation by developing oocytes could be partially rescued by injection of trehalose into AKHR RNAi females. The present study has implicated trehalose in the AKH/AKHR signaling-mediated control of reproduction and provided new insight into mechanisms of AKH/AKHR regulation of trehalose metabolism in insect vitellogenesis, oocyte maturation and fecundity.

Silencing of triazophos-induced Hexokinase-1-like reduces fecundity in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

Hexokinase is a rate-limiting enzyme that plays pivotal roles in glucose homeostasis and energy metabolism via glucose (Glc) phosphorylation and Glc signaling mediation. Previous investigations have revealed the modulatory role of Hexokinase (Hex) genes involved in proper glucose regulation during insect diapause and embryo development, whereas whether it functions in insect fecundity remains largely unknown. We aimed to explore the relationship between Triazophos (TZP)-induced Hex-1 and fecundity of female Nilaparvata lugens. In this study, Hex-1 expression were characterized at different developmental stages and in various tissues of N. lugens, with the highest expression registered in brain tissues and 5th instar nymph. The present findings indicated that TZP + dsHex-1 silencing significantly reduced protein synthesis, including the fat body and ovarian protein content of female adults. Meanwhile, the glycometabolism with respect to the soluble sugar, trehalose and glucose content in female adults were strikingly influenced as a result of Hex-1 knockdown. The relative transcript level of Hex-1, vitellogenin (NlVg) and vitellogenin receptor (NlVgR) considerably decreased in TZP + dsHex-1 treated females compared to TZP and TZP + dsGFP-treated groups. More importantly, TZP + dsHex-1 silencing led to reduced number of eggs laid and vitellogenin (Vg) accumulation as well as retarded ovary development compared with TZP-treated and TZP + dsGFP-treated groups. Taken together, it is proposed that Hex-1 implicates in N. lugens fecundity by exerting profound effects on glycometabolism, protein sythesis and NlVg expression.

A toxicological, metabonomic and transcriptional analysis to investigate the property of mulberry 1-deoxynojirimycin against the growth of Samia cynthia ricini

1-Deoxynojirimycin (DNJ) is a natural d-glucose analogue from mulberry with promising physiological activity in vivo. Up to the present, the antidiabetic effects of DNJ on lowering blood sugar and accelerating lipid metabolism in mammals were broadly reported, but the specific character of DNJ against insects was vastly ignored. In this study, a toxicological test of DNJ againgst eri-silkworm, Samia cynthia ricini was carried out to investigate the potential of DNJ in insect management. Further, a method of nuclear magnetic resonance (NMR) metabonomics and real-time qPCR (RT-qPCR) were performed to analyze the alteration in midgut of eri-silkworm caused by DNJ. The result of toxicology showed that 5% and 10% DNJ could significantly inhibit the development of third-instar larvae on day 1-5, and mass deaths happened in DNJ groups on day 3-5. The quantitative analysis of ¹H NMR in fifth-instar larvae showed that trehalose level increased in midgut of 0, 6 and 12 h DNJ groups, while the concentrations of glucose, lactate, alanine, pyruvate, α-ketoglutarate and fumarate were reduced in varying degrees. Meanwhile, principal component analysis (PCA) indicated that there were significant differences in the metabolic profiles among 12 h DNJ groups and the control group. In addition, RT-qPCR results displayed that four genes coding α-glucosidase, trehalase (THL) and lactate dehydrogenase (LDH) were lowered in expression of 12 h DNJ groups. Simultaneously, THL activity was significantly lowerd in 12 h DNJ groups. These mutually corroborated results indicated that the backbone pathways of energy metabolism, including hydrolysis of trehalose and glycogens, glycolysis and tricarboxylic acid (TCA) cycle were significantly inhibited by DNJ. Thus, the specific mechanism of DNJ efficiently suppressing the growth and energy metabolism of eri-silkworm was explored in this study, providing the potential of DNJ as to the production of botanical insecticide.