Search Results (48)

To elucidate the effect of cold stress on Dendroctonus valens larvae, a study was conducted under controlled laboratory conditions to examine the physiological and biochemical mechanisms associated with cold stress, coupled with transcriptome sequencing. Physiological and biochemical assessments indicated stable water content in larvae during cold stress initiation, with triglycerides and fats serving as primary energy reserves that decreased over cold stress progression. Glycogen and trehalose were identified as energy sources for larval energy metabolism, with their levels increasing as cold stress duration extended. Superoxide dismutase (SOD) activity exhibited an initial decline followed by an increase, while peroxidase (POD) activity initially rose before decreasing over induction time, and catalase (CAT) activity decreased during cold stress induction. Transcriptome sequencing at various time points revealed 4630 upregulated and 1554 downregulated genes, predominantly involved in metabolic pathways such as carbohydrate, amino acid, and lipid metabolism. Quantitative polymerase chain reaction (qPCR) results validated the transcriptome data accuracy. This investigation delineated the physiological, biochemical, and transcriptome alterations during cold stress, offering a theoretical framework for the rational prediction of Dendroctonus valens outbreaks. Full article

Kefiran, the extracellular polysaccharide produced by Generally Recognized as Safe (GRAS) bacteria found in kefir grains, is a promising biopolymer with multiple applications in agri-food and biomedical fields. Besides its characteristics and potential applications, the factors that affect its production remain a prime subject of interest. Lactic acid bacteria synthesize polysaccharides to protect their cells from adverse conditions. Therefore, low-temperature storage (4 °C) of kefir grains inoculated into Ultra-High-Temperature (UHT) milk at two different concentrations (5% and 30%) was studied as a factor for increasing kefiran production in the medium. The cryoprotectant disaccharide trehalose, which comprises a carbon and energy source for many microorganisms, was also evaluated for its effectiveness in enhancing kefiran production. The pH, the increase in kefir grain mass, the amount of kefiran produced, and the rheological properties of the acidified milk were determined during two distinct storage periods, depending on kefir grain concentration. For comparison, kefir grains were also fermented at 25 °C and 30 °C. Low-temperature storage at a kefir grain concentration of 30% resulted in an increase in the amount of polysaccharide produced beyond that obtained through fermentation. Fermentation of a 5% grain inoculum at 30 °C resulted in the lowest kefiran production. In the presence of trehalose, prolonged low-temperature storage favored an increase in the biosynthesis of kefiran, especially at a 30% kefir grain inoculum. Trehalose, however, was not a significant factor in the fermentation experiments. Proper selection of low-temperature storage time is required to avoid a reduction in kefiran concentration due to the metabolic activity of the microorganisms in kefir grains. The acidified milk (low-temperature storage) and kefir (fermentation) samples both exhibited increased elasticity and apparent viscosity with increasing kefir grain concentration. However, the rheological behavior of acidified milk was greatly affected by protein degradation during low-temperature storage. As shown by the findings of the present study, low-temperature storage (4 °C) of a 30% kefir grain inoculum in the presence of trehalose (3% w/w) until a final pH of 4.2 proves to favor kefiran production in the medium the most. Full article

The free-living infective juveniles of entomopathogenic nematodes (EPNs) are critical biological control agents against insect pests. The field efficacy of EPNs is largely determined by their tolerance to low-humidity stress, a trait closely linked to the mobilization of their energy reserves. This study aims to investigate how varying levels of humidity stress influence energy reserve dynamics in two EPNs, Steinernema kraussei 0657L and Heterorhabditis brevicaudis 0641TY, and their relationship with the survival rate and pathogenicity. The results demonstrated that lipids were the predominant energy reserve, followed by proteins and sugars. Notably, neutral lipid constituted approximately 3% of the total lipid content. Among sugars, soluble sugar levels were the highest, followed by glycogen and trehalose. Exposure to low-humidity stress resulted in increased levels of protein, total lipid, glycogen, and trehalose in nematodes. These increases were more pronounced in S. kraussei 0657L, a highly drought-resistant strain, compared to H. brevicaudis 0641TY. Furthermore, the accumulation of protein, total lipid, and trehalose was negatively correlated with survival rate and pathogenicity. However, positive correlations were observed between trehalose and both total lipids and soluble sugars. Furthermore, transcriptome analysis revealed that under low-humidity stress, S. kraussei 0657L exhibited an enrichment of differentially expressed genes (DEGs) involved in glycolysis/gluconeogenesis, fatty acid metabolism, and glycerophospholipid metabolism pathways. This indicates that S. kraussei 0657L regulated energy metabolism to adapt to low-humidity stress. These findings provide insights into the mechanisms underlying drought resistance in EPNs and offer an experimental basis for their application in arid environments. Full article

Nilaparvata lugens is a migratory pest with high fecundity and outstanding drug resistance, which poses a devastating danger to rice production. This study investigated the reproductive regulation mechanism of N. lugens, specifically silencing the trehalose-6-phosphate synthase gene (TPS) via RNAi to elucidate how TPS governs the trehalose metabolic network through modulation of trehalose biosynthesis. Insect fecundity hinges on the synchronized progression of oogenesis and the tightly controlled expression of vitellogenin (Vg). In N. lugens, this coordination is orchestrated by an integrated molecular network that converges juvenile hormone signaling (JH), 20-hydroxyecdysone pathways (20E), insulin/IGF signaling (IIS), and the target of rapamycin cascade (TOR), collectively dictating the reproductive output of the species. Using TPS knockdown as the entry point, this study dissects the lipid-metabolic circuitry of N. lugens and uncovers how hormonal signaling cascades orchestrate reproduction by precisely modulating vitellogenin (Vg) and its cognate receptor VgR. Synthesized double-stranded terpene synthase genes (dsTPSs) can degrade mRNA, inhibit protein translation, and ultimately lead to the silencing of TPS genes, simultaneously crippling energy provision and hormonal signaling to orchestrate a multi-pronged suppression of reproduction. This dual-action intervention offers a promising molecular target for environmentally friendly management of N. lugens. Full article

Organ functions generally decline with age, but the ovary is a prototypical organ that undergoes functional loss over time. Autophagy plays a crucial role in maintaining organ homeostasis, and age-related upregulation of the autophagy inhibitor protein, Rubicon, has been linked to cellular and tissue dysfunction. This review describes how granulosa cell autophagy supports follicular growth and oocyte selection and maturation by regulating cellular energy metabolism and protein quality control. We then introduce the role of selective autophagy, including mitophagy or lipophagy, in steroidogenesis and cellular remodeling during luteinization. In aged ovaries, Rubicon accumulation suppresses autophagic flux, leading to diminished oxidative-stress resilience and enhanced DNA damage. Moreover, impaired autophagy drives the accumulation of ATP citrate lyase, which correlates with poor oocyte quality and reduced ovarian reserve. Following fertilization, oocytes further upregulate autophagy to provide the energy required for blastocyst transition. Conversely, in infertility-related disorders, such as premature ovarian insufficiency, endometriosis, and polycystic ovary syndrome, either deficient or excessive autophagy contributes to disease pathogenesis. Both autophagy inhibitors (e.g., Rubicon) and activators (e.g., Beclin1) could be emerging as promising biomarkers for assessing ovarian autophagy status. Therapeutically, Rubicon inhibition by trehalose in aged ovaries and autophagy suppression by agents such as hydroxychloroquine in polycystic ovary syndrome and endometriosis hold potential. Establishing robust methods to evaluate ovarian autophagy will be essential for translating these insights into targeted treatments. Full article

Trehalose, a disaccharide consisting of two D-glucose molecules, is present in a variety of organisms, including bacteria, yeast, fungi, insects, and plants. In plants, it functions as a source of energy and carbon, and in yeast and plants, it serves as a signaling molecule, influencing metabolic pathways and growth regulation. Additionally, it plays a role in protecting proteins and cell membranes from stress-induced damage. This study aims to assess the optimal level of trehalose supplementation in the diets of layer hens aged 34 to 49 weeks, addressing the limited existing literature on its effects on productivity. Experimental diets, designed in accordance with nutritional recommendations, were formulated to contain six different levels of trehalose (0, 0.05, 0.10, 0.30, 0.60, and 1.00%). The study was conducted over five 21-day periods, during which various performance parameters were evaluated. The results indicated that trehalose supplementation at levels of 0.05%, 0.10%, and 0.30% led to increased feed intake (FI) compared to the 1.00% level (p < 0.05). Furthermore, the highest trehalose level (1.00%) significantly reduced the feed conversion ratio by egg mass (FCRem) compared to both the control group and the other supplementation levels; however, the feed conversion ratio by dry matter (FCRDz) remained consistent across all treatments. The levels of 0.05%, 0.10%, and 0.30% exhibited superior FCREm and FCRDz compared to the 1.00% level. Egg weight (EW) was higher in the trehalose-supplemented groups compared to the control group. Additionally, the 1.00% trehalose treatment was found to be the most effective in terms of relative weights of shells (RWS), and egg mass (EM) was higher at all trehalose levels compared to the control group. The antioxidant status, as measured by malondialdehyde (MDA) levels, indicated that supplementation with 0.30% and 0.60% trehalose had a protective effect against oxidative stress, although the 1.00% level resulted in increased MDA levels. Total weight (TW) was highest in the 0.30% treatment group, and bone strength (BS) improved in the groups supplemented with 0.10% and 1.00% trehalose. Other parameters, including lipid content (L), dry matter (DM), phosphorus (P), and calcium (Ca), did not show any significant differences among the treatment groups. In conclusion, supplementation with 1.00% trehalose enhances feed efficiency, egg weight, and quality, with minimal impact on lipid peroxidation, while potentially providing benefits for gut health and egg quality. Full article

Estrogen-related receptors (ERRs) are important transcription factors within the nuclear receptor family that regulate cellular energy storage and consumption by binding to estrogen-related receptor response elements (ERREs) on gene promoters. While ERRs’ role in vertebrates is well-studied, their molecular mechanisms in insect metabolism and development remain unclear. This study systematically summarizes the functions of ERRs in insects, focusing on silkworms by analyzing gene functions and comparing databases. ERRE-like elements were identified in the 2000 bp upstream promoter regions of 69 metabolism-related silkworm genes. Furthermore, electrophoretic mobility shift assays (EMSAs) revealed that ERREs within the promoters of 15 genes related to sugar, fat, and protein metabolism specifically bind to ERR. Notably, an ERRE in the promoter of the trehalose transporter 1 gene (BmTret1), crucial for trehalose homeostasis in insect hemolymph, exhibited significantly enhanced activity in ERR-overexpressing cells. These findings suggest that ERR is a potential regulatory factor in silkworm metabolism and refine its metabolic regulatory network. This study highlights the broader and more critical role of ERR in insects than that previously recognized, contributing to a deeper understanding of insect metabolism and its potential applications in related fields. Full article

Fatty acid synthase (FAS) is a pivotal gene in the lipid synthesis pathway and plays a crucial role in insect energy metabolism. Locusta migratoria, as one of the major agricultural pests, requires identification of new targets to control or reduce its reproductive capacity for effective locust pest management strategies. In this study, we focused on L. migratoria and identified FAS2 as a potential target gene with functional significance in lipid metabolism and reproduction based on sequence characteristics analysis and tissue-expression patterns of five FAS genes. Subsequently, through RNA interference (RNAi) targeting FAS2 expression, we assessed alterations in lipid and carbohydrate metabolism-related gene expression levels, lipid and carbohydrate contents, ovarian development, and reproductive capacity using experimental techniques such as RT-qPCR, ELISA, and morphological observations. Our findings revealed that interference with FAS2 upregulated genes involved in lipid degradation, including Lsd-1, Lsd-2, Lipase3, and Brummer, while significantly decreasing the TAG content and fat accumulation. At the level of carbohydrate metabolism, FAS2 silencing led to significant upregulation of key genes TPS and GS in the synthesis pathway, resulting in increased glycogen and trehalose content. In addition, FAS2 interference resulted in a significant reduction of Vg mRNA expression level sand protein content in L. migratoria, followed by delayed ovarian development and reduced egg production. This further confirms that impaired FAS2 function prompts L. migratoria to enhance lipid degradation and sugar storage to maintain the energy balance, while reducing the energy investment into reproduction. Collectively, the results of this study suggest that FAS2 can serve as a novel molecular target for controlling L. migratoria. Full article

Due to the intensification of human activities, the ecosystems are being polluted by heavy metals. The pollution of heavy metals in agricultural systems has become a serious issue of global concern. This study detected the bioaccumulation of cadmium (Cd) in broad beans and aphids through continuous exposure to varying concentrations of Cd pollution (0, 3.125, 6.25, 12.5, 25, 50 mg/L) and subsequently examined its effects on aphid energy metabolism and reproductive ability. The results showed that Cd can be transmitted and accumulated between Vicia faba L. and aphids along the food chain, and the amount of accumulation was related to the Cd treatment concentration. Quantitative real-time PCR results showed that the expression levels of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) in F1 were significantly upregulated, and those of vitellogenin (Vg) were varied across the five generations of aphids after Cd treatment, which were up-regulated, and others down-regulated. Compared with the control group, the glycogen content and two types of trehalase activities of the first-generation Cd-treatment aphids were decreased, while trehalose content increased; there was no significant change in the carbohydrate content and trehalase activity of the fourth and fifth generations of aphids. In addition, the reproduction of female aphids was inhibited. This research is helpful for studying the toxic effects of heavy metals on insects and the adaptation mechanisms of insects to extreme environments. It also provides a theoretical basis for further exploring the molecular mechanisms of Cd homeostasis in plants and insects under Cd stress. Full article

FoxO is a downstream target gene of cellular nutrient and growth factors, oxidative stress responses, and insulin signaling pathways. It play a crucial role in insect growth, development, and reproduction. Locusta migratoria is a significant agricultural pest; therefore, the identification of novel control targets for its management is of significant importance. After injecting dsRNA to interfere with FoxO expression, we observed changes in the reproduction-related gene expression and ovary development through RT-qPCR and morphological observation. Simultaneously, the trehalose and glycogen contents were measured following RNAi. The results demonstrate that interference with FoxO significantly downregulates key genes in the Hippo pathway and Notch gene expression. In terms of carbohydrate metabolism, the trehalose content decreases significantly while the glycogen content increases markedly after FoxO silencing. Additionally, FoxO silencing considerably inhibits reproductive-related gene expression, resulting in delayed ovarian development. These findings indicate that FoxO regulates L. migratoria reproduction through the Hippo signaling pathway: when impaired, the reproductive capacity function declines. In addition, FoxO-mediated energy mobilization is involved in the regulation of egg production. These results indicate that the RNAi of FoxO may be a useful control strategy against L. migratoria. Full article

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. Full article

Insects’ growth and development are highly dependent on energy supply, with sugar metabolism playing a pivotal role in maintaining homeostasis and regulating physiological processes. The present study investigated the effects of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on the growth, development, glycolysis, and energy metabolism of fourth-instar larvae of the fall webworm, Hyphantria cunea. We determined the impact of exendin-4 on larval growth and nutritional indices, analyzed the responses of glycolytic and metabolic pathways, and revealed the underlying regulatory mechanisms. Exendin-4 treatment significantly decreased growth and nutritional indices, influenced the activity of digestive enzymes, and induced changes in metabolite profiles, particularly affecting energy substance metabolism. We observed an increase in the glycogen content and a decrease in glucose and trehalose levels in the hemolymph, suggesting a regulatory effect on blood sugar homeostasis. Furthermore, exendin-4 promoted glycolysis by enhancing the activities and expressions of key glycolytic enzymes, leading to an increase in pyruvate production. This was accompanied by a reduction in ATP levels and the activation of AMP-activated protein kinase (AMPK), which may underlie the growth arrest in larvae. Our findings provide novel insights into the effects of exendin-4 on insect responses from an energy metabolism perspective and may contribute to the development of GLP-1R agonists for pest management. Full article

An increasing body of research has underscored the significant impact of non-consumptive effects on the dynamics of prey pests, encompassing growth, development, reproduction, and metabolism across various vertebrate and invertebrate taxa, rivaling the influence of consumption effects. In our investigation, we delved into the non-consumptive effects exerted by the natural predatory enemy Harmonia axyridis on the reproductive capacity and metabolism of Spodoptera frugiperda adults. Our findings revealed a substantial decrease in the reproductive ability of S. frugiperda adults when exposed to the non-consumptive effects of H. axyridis. Concurrently, we observed an elevation in hydrogen peroxide (H₂O₂) content and the activities of antioxidant enzymes such as superoxide dismutases (SODs), catalases (CATs), and peroxidases (PODs). Furthermore, notable alterations were detected in energy metabolism, characterized by heightened triglyceride levels and diminished glycogen and trehalose concentrations. These outcomes underscored the adaptive response of the pest aimed at mitigating non-consumptive adverse effects by augmenting antioxidant enzyme activity to counteract oxidative stress and minimize cellular damage. Nonetheless, this defensive mechanism entails a significant expenditure of energy resources, resulting in shifts in energy utilization. Elevated triglyceride levels and reduced glycogen and trehalose concentrations diminish available resources for reproductive processes, such as egg laying, ultimately culminating in decreased fecundity. This study contributes novel insights into the non-consumptive effects observed in insects, while also furnishing valuable insights into the mechanisms underlying insect stress responses. Full article

The aphidophagous gall midge, Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae), a dominant natural enemy of aphids, has been used as a biological control agent in many countries to control aphids in greenhouses. To identify key factors that induce diapause in A. aphidimyza, we evaluated the effects of photoperiod and temperature on the incidence of diapause in A. aphidimyza under laboratory conditions. The results showed that temperature and photoperiod had significant impacts on development and diapause in A. aphidimyza. Low temperatures and a short photoperiod inhibited development, while high temperatures and a long photoperiod promoted development. Temperatures above 20 °C and a photoperiod greater than 14 h prevented diapause in A. aphidimyza. However, the highest diapause rate was recorded at under 15 °C and 10L:14D photoperiod conditions. At 15 °C, the first to third larvae were sensitive to a short photoperiod at any stage, and a short photoperiod had a cumulative effect on diapause induction. The longer the larvae received short light exposure, the higher the diapause rate appeared to be. Transcriptome sequencing analysis at different stages of diapause showed that differentially expressed genes were mainly enriched in the glucose metabolism pathway. Physiological and biochemical analyses showed that diapausing A. aphidimyza reduced water content; accumulated glycogen, trehalose, sorbitol, and triglycerides; and gradually reduced trehalose and triglyceride contents in the body with the extension of diapause time. Glycogen may be used as a source of energy, but sorbitol is usually used as a cryoprotectant. This study provided results on aspects of diapause in A. aphidimyza, providing data and theoretical support for promoting its commercial breeding and in-depth research on the molecular mechanisms underlying diapause regulation. Full article

The pea aphid, Acyrthosiphon pisum, is a major pest of legume crops, exhibiting distinct polymorphism in terms of wings and body color. We found that, under crowded conditions, the red morph A. pisum produced more winged offspring than the green morph. The signaling pathways involved in aphid wing determination, like insulin and ecdysone, also play important roles in regulating growth, development, and metabolism. Thus, here, we examined the association between the wing-producing ability and the growth rate, development time, reproductive capacity, and energy metabolism in these two color morphs. The growth rate of red morphs was significantly higher than that of green morphs, whereas green morphs produced more offspring during the first 6 days of the adult stage. Red morphs accumulated higher levels of glycogen and triglycerides and consumed more triglycerides during starvation; however, green aphids consumed more trehalose during food deprivation. Red aphids exhibited stronger starvation tolerance, possibly due to their higher triglyceride catabolic activity. Furthermore, the expression levels of genes involved in the insulin pathway, glycolysis, and lipolysis in red aphids were higher than those in green aphids. These results suggest that the wing-producing ability of the pea aphid may be associated with its growth and metabolism, which may be due to the shared regulatory signaling pathways. Full article