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BACKGROUND: Cuticular proteins (CPs) play essential roles in forming cuticular structures in insects. However, the specific functions and regulatory mechanisms of CPs remain largely unexplored. In this study, the Larval cuticular protein 17 (HcLCP‐17) gene was identified from Hyphantria cunea, a highly destructive and polyphagous forest pest. To investigate the role of HcLCP‐17 in cuticular function and transcriptional regulation mediated by 20E‐responsive transcription factors (ERTFs), we employed RNA interference (RNAi) and yeast one‐hybrid assay techniques. Additionally, we examined the molecular mechanism by which chlorbenzuron, a type of benzoylphenylurea (BPU) that functions as a chitin synthesis inhibitor (CSI), affects the 20E signaling pathway and ultimately regulates HcLCP‐17 expression. RESULTS: HcLCP‐17 encodes a polypeptide consisting of 393 amino acids, which includes a chitin‐binding domain. Silencing HcLCP‐17 resulted in a disturbance in the structural organization of the larval cuticle and a notable reduction in chitin levels. HcLCP‐17 expression was controlled by the interaction between Broad‐Complex (Br‐C) and beta Fushi Tarazu Factor‐1 (βFTZ‐F1) with its promoter fragment. Furthermore, the inhibitory effect of chlorbenzuron on HcLCP‐17 expression was found to be potentially mediated by Br‐C and βFTZ‐F1. CONCLUSION: The study presents a novel mode of action for the 20E signaling pathway in regulating the expression of CPs and reveals the potential mode‐of‐action of BPUs in insect cuticles. These findings provide a theoretical basis for future utilization of LCP‐17 as a pesticide target making a significant contribution to the development of effective pest management strategies. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Poplar in China has long been plagued by the fall webworm Hyphantria cunea. Enhancing plant immunity using chemical elicitors is an environmentally friendly approach to pest control. The phytohormone methyl jasmonate (MeJA) can stimulate the chemical defenses of poplars against herbivores but has been shown to have limited efficacy in practice. Here, we studied the effects of a MeJA and mesoporous silica nanoparticle (MSN) complex (MeJA@MSN) regarding the induction of poplar resistance to H. cunea, which may provide strategies for the effective use of MeJA. RESULTS: The silicon‐based phytohormone complex (MeJA@MSNs) exhibited excellent biological and physiochemical properties, such as excellent biocompatibility and plant tissue transportability. The changes in metabolites in poplar leaves induced by MeJA, MSNs, and MeJA@MSNs were investigated by metabolic analysis. MeJA@MSNs led to highly potent induced resistance along with elevated salicylaldehyde content, which increased with the dose administered. The salicylaldehyde metabolite showed a strong antifeedant effect on H. cunea larvae at a dosage of 1 μg, with the 50% lethal dose being 20.4 μg/mg. Furthermore, transcriptional analysis showed that MeJA@MSNs upregulated key genes in biosynthetic pathways more than MeJA and MSNs. CONCLUSION: Our results show that MeJA and MSNs interact positively in poplar, leading to salicylaldehyde accumulation and increased induced resistance to H. cunea, providing new insights into the underlying resistance mechanisms induced by MeJA@MSNs. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Dietary generalist herbivorous insects are widespread and often occur in a variety of environments. Across their geographic range, herbivorous insects may encounter variable plant traits as they feed on high‐quality or low‐quality plants. Herbivorous insect larvae experience both bottom‐up (host plant) and top‐down (parasitoid) factors that affect survival. Host plant quality may affect larval growth and survival in that larvae feeding on low‐quality plants often suffer reduced fitness. However, herbivores on different host plants are also subject to different levels of parasitism. High‐quality plants confer stronger larval performance (higher survival, more offspring), but larvae may also face higher parasitism. In some herbivore species, diet mediates larval immune response. The generalist insect herbivore fall webworm (FW), Hyphantria cunea Drury (Lepidoptera: Erebidae), is a moth native to North America, and its larvae have considerable variance in their performance when reared on different host plants. We investigated whether diet affects the immune response in FW larvae when they are reared on different host plant species known to vary in food quality. We measured immune response by melanization of a nylon filament. We found significant differences in immune response across host plants, indicating that diet mediates immune response in FW larvae. Our study helps elucidate the factors that cause variation in immune response in a generalist herbivore. [ABSTRACT FROM AUTHOR]

BACKGROUND: Sensing dietary components in the gut is important to ensure an appropriate hormonal response and metabolic regulation after food intake. The fall webworm, Hyphantria cunea, is a major invasive pest in China and has led to significant economic losses and ecosystem disruption. The larvae's broad host range and voracious appetite for leaves make H. cunea a primary cause of serious damage to both forests and crops. To date, however, the gustatory receptors (Grs) of H. cunea and their regulatory function remain largely unknown. RESULTS: We identified the fall webworm gustatory receptor HcGr76 as a fructose and chlorogenic acid receptor using Ca2+ imaging and determination of intracellular Ca2+ concentration by a microplate reader. Moreover, reverse transcription–quantitative polymerase chain reaction (RT–qPCR) analysis revealed that HcGr76 is highly expressed in the anterior and middle midgut. Knockdown of HcGr76 caused a significant reduction in the expression of neuropeptide F 1 (NPF1) and CCHamide‐2, and led to a decrease in carbohydrate and lipid levels in the hemolymph. CONCLUSION: Our studies provide circumstantial evidence that HcGr76 expressed in the midgut is involved in sensing dietary components, and regulates the expression of relevant peptide hormones to alter metabolism in H. cunea larvae, thus providing a promising molecular target for the development of new insect‐specific control products. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Populus cathayana × canadansis ‘Xinlin 1’ (‘P.‘xin lin 1’) with the characteristics of rapid growth and high yield, is frequently attacked by herbivorous insects. However, little is known about how it defenses against Hyphantria cunea (H. cunea) at molecular and biochemical levels. Differences in the transcriptome and metabolome were analyzed after ‘P. ‘xin lin 1’ leaves were fed to H. cunea for 0h, 2h, 4h, 8h, 16h and 24h. In the five comparison groups including 2h vs. CK, 4h vs. CK, 8h vs. CK, 16h vs. CK, and 24h vs. CK, a total of 8925 genes and 842 metabolites were differentially expressed. A total of 825 transcription factors (TFs) were identified, which encoded 56 TF families. The results showed that the top four families with the highest number of TFs were AP2/ERF, MYB, C2C2, bHLH. Analyses of leaves which were fed to H. cunea showed that the differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) were significantly enriched in plant hormone signal transduction pathway, MAPK signaling pathway, flavonoid, flavone and flavonol and anthocyanin biosynthesis pathway. Additionally, there were a number of genes significantly up-regulated in MAPK signaling pathway. Some compounds involved in plant hormone signal transduction and flavonoid/flavone and flavonol/ anthocyanin pathways such as jasmonic acid (JA), jasmonoyl-L-Isoleucine (JA-Ile), kaempferol and cyanidin-3-O-glucoside were induced in infested ‘P.‘xin lin 1’. This study provides a new understanding for exploring the dynamic response mechanism of poplar to the infestation of H. cunea. [ABSTRACT FROM AUTHOR]

Abstract Populus cathayana × canadansis ‘Xinlin 1’ (‘P.‘xin lin 1’) with the characteristics of rapid growth and high yield, is frequently attacked by herbivorous insects. However, little is known about how it defenses against Hyphantria cunea (H. cunea) at molecular and biochemical levels. Differences in the transcriptome and metabolome were analyzed after ‘P. ‘xin lin 1’ leaves were fed to H. cunea for 0h, 2h, 4h, 8h, 16h and 24h. In the five comparison groups including 2h vs. CK, 4h vs. CK, 8h vs. CK, 16h vs. CK, and 24h vs. CK, a total of 8925 genes and 842 metabolites were differentially expressed. A total of 825 transcription factors (TFs) were identified, which encoded 56 TF families. The results showed that the top four families with the highest number of TFs were AP2/ERF, MYB, C2C2, bHLH. Analyses of leaves which were fed to H. cunea showed that the differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) were significantly enriched in plant hormone signal transduction pathway, MAPK signaling pathway, flavonoid, flavone and flavonol and anthocyanin biosynthesis pathway. Additionally, there were a number of genes significantly up-regulated in MAPK signaling pathway. Some compounds involved in plant hormone signal transduction and flavonoid/flavone and flavonol/ anthocyanin pathways such as jasmonic acid (JA), jasmonoyl-L-Isoleucine (JA-Ile), kaempferol and cyanidin-3-O-glucoside were induced in infested ‘P.‘xin lin 1’. This study provides a new understanding for exploring the dynamic response mechanism of poplar to the infestation of H. cunea.

Hyphantria cunea is a significant invasive pest characterized by its polyphagous nature and robust reproductive capabilities. In the present study, the interaction between Morus alba seedlings and H. cunea larvae was revealed by combining the induced chemical defense of M. alba with the adaptive strategies of H. cunea larvae. Larval feeding damage swiftly triggers both local and systemic chemical defenses in M. alba, involving nutrients (amino acids, proteins, soluble sugars), secondary metabolites (total phenol, total flavone, tannin, lignin), and flavonoid synthesis pathways. Mild damage induced defense responses in M. alba that persisted until day 21, inhibiting the growth of a subsequent batch of H. cunea larvae after 7 days of continuous feeding. Conversely, at moderate damage levels, these induced defenses diminished by day 21, temporarily failing to affect the larval growth. In response to these defenses, H. cunea larvae significantly up-regulated the expression of most detoxification enzyme genes, which remained active throughout. Initially, some trypsin and lipase genes in the larvae were significantly up-regulated, but with prolonged feeding, gene expression shifted towards the α-amylase family. Feeding by H. cunea larvae can stimulate the induced chemical defense of M. alba. The H. cunea larvae can adapt to the M. alba chemical defense by modulating their digestive and metabolic detoxification mechanisms. [ABSTRACT FROM AUTHOR]

Simple Summary: Poplar forests are significantly threatened by Hyphantria cunea in China. Although previous studies have identified variations in resistance among the different poplar clones to this pest, the induced mechanisms behind the resistance are not yet well understood. This research investigated the dynamic changes in the defensive enzymes and metabolic profiles in resistant '2KEN8' and susceptible 'Nankang' with or without feeding by H. cunea. The findings suggested that the resistant poplar clone initiated an earlier and stronger accumulation of defensive enzymes, and metabolites such as phenolic compounds, flavonoids, and unsaturated fatty acids than the susceptible one after infestation. These changes might contribute to inhibition of larva development in '2KEN8'. The present results are helpful for revealing the mechanisms of poplar resistance to H. cunea and breeding resistant varieties. Poplar trees are significant for both economic and ecological purposes, and the fall webworm (Hyphantria cunea Drury) poses a major threat to their plantation in China. The preliminary resistance assessment in the previous research indicated that there were differences in resistance to the insect among these varieties, with '2KEN8' being more resistant and 'Nankang' being more susceptible. The present study analyzed the dynamic changes in the defensive enzymes and metabolic profiles of '2KEN8' and 'Nankang' at 24 hours post-infestation (hpi), 48 hpi, and 96 hpi. The results demonstrated that at the same time points, compared to susceptible 'Nankang', the leaf consumption by H. cunea in '2KEN8' was smaller, and the larval weight gain was slower, exhibiting clear resistance to the insect. Biochemical analysis revealed that the increased activity of the defensive enzymes in '2KEN8' triggered by the feeding of H. cunea was significantly higher than that of 'Nankang'. Metabolomics analysis indicated that '2KEN8' initiated an earlier and more intense reprogramming of the metabolic profile post-infestation. In the early stages of infestation, the differential metabolites induced in '2KEN8' primarily included phenolic compounds, flavonoids, and unsaturated fatty acids, which are related to the biosynthesis pathways of phenylpropanoids, flavonoids, unsaturated fatty acids, and jasmonates. The present study is helpful for identifying the metabolic biomarkers for inductive resistance to H. cunea and lays a foundation for the further elucidation of the chemical resistance mechanism of poplar trees against this insect. [ABSTRACT FROM AUTHOR]

Insects rely on olfaction for mating, finding oviposition sites, and locating hosts. Hyphantria cunea is a serious pest that severely damages forests. Differential expression analysis of olfactory-related genes between males and females is the basis for elucidating the functions of olfactory-related proteins in H. cunea. In this study, Illumina HiSeqTM 4000 high-throughput sequencing technology was used to perform transcriptome sequencing of the antennal tissues of adult male and female H. cunea. Functional annotation was conducted using the NR, Swiss-Prot, KOG, KEGG, and GO databases, and the results showed that the antennal transcriptome of adult H. cunea contained 50,158 unigenes. Differential expression analysis identified 3923 genes that were significantly differentially expressed between male and female antennae. A total of 221 olfactory-related genes were annotated, and 96 sex-biased genes were identified, including 13 odorant receptors (ORs), 48 odorant binding proteins (OBPs), 7 chemosensory proteins (CSPs), 10 ionotropic receptors (IRs), 10 sensory neuron membrane proteins (SNMPs), 2 gustatory receptors (GRs), and 6 odorant-degrading enzymes (ODEs), indicating that there were differences in olfaction between male and female H. cunea. Quantitative real-time PCR was used to verify the expression levels of 21 putative general odorant receptor genes in male and female antennae. HcunOR4 and HcunOR5 showed female-biased expression; HcunOR48, HcunOR49 and HcunOR50 showed male-biased expression. The results were consistent with the transcriptome differential analysis. The screening of male-biased odorant receptor genes might provide a theoretical basis for the functional characterization of odorant receptors for recognizing sex pheromones in H. cunea. [ABSTRACT FROM AUTHOR]

Poplar is an important greening and timber tree species in China, which has great economic and ecological values. However, the spread of Hyphantria cunea has become increasingly serious in recent years, resulting in huge economic loss of poplar production. Exploring the molecular mechanism of poplar reponse to H. cunea stress has significant implications for future development of new insectresistant poplar varieties using genetic engineering technology. In this study, a total of 1039 differentially expressed genes (DEGs), 106 differentially expressed proteins (DEPs) and 212 differentially expressed metabolites (DEMs) were screened from Populus simonii × P. nigra leaves under H. cunea stress by transcriptome, proteomics and metabolomics analysis, respectively. GO and KEGG analysis showed that the DEGs and DEPs are associated with endopeptidase inhibitor activity, stress response, α-linolenic acid metabolism, phenylpropanoid biosynthesis and metabolic pathways, cysteine and methionine metabolism pathways and MAKP signaling pathway. Metabolomics analysis showed the most of DEMs were lipids and lipid molecules, and the pathways associated with transcriptome mainly include plant hormone signal transduction, α-linolenic acid metabolic pathway, amino sugar and nucleotide sugar metabolism, and phenylpropanoid biosynthesis. In particular, multi-omics analysis showed that several pathways such as α-linolenic acid metabolic, phenylpropanoid biosynthesis and metabolic pathway and cysteine and methionine metabolic pathway were significantly enriched in the three omics, which may play an important role in the resistance to pests in poplar. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigated the influence of exendin-4, a glucagon-like peptide-1 receptor (GLP-1R) agonist, on fall webworm Hyphantria cunea larvae. We found that exendin-4 induced growth arrest by regulating sugar metabolism, affecting digestive enzyme activities, and altering metabolite profiles. Specifically, it decreased glucose and trehalose levels while increasing the glycogen content, indicating a regulatory effect on blood sugar. Exendin-4 also promoted glycolysis and reduced ATP levels, potentially through the activation of AMPK. These findings enhance our understanding of the physiological effects of GLP-1R agonists in insects and could inform pest management strategies. 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. [ABSTRACT FROM AUTHOR]

In recent years, the situation of the Hyphantria cunea (Drury) (Lepidoptera: Erebidae), infestation in China has been serious and has a tendency to continue to spread. A comprehensive analysis was carried out to examine the spatial distribution trends and influencing factors of H. cunea. This analysis involved integrating administrative division and boundary data, distribution data of H. cunea, and environmental variables for 2021. GeoDetector and gravity analysis techniques were employed for data processing and interpretation. The results show that H. cunea exhibited high aggregation patterns in 2021 and 2022 concentrated mainly in eastern China. During these years, the focal point of the infestation was in Shandong Province with a spread towards the northeast. Conditions such as high vegetation density in eastern China provided favorable situations for growth and development of H. cunea. In China, the spatial distribution of the moth is primarily influenced by two critical factors: precipitation during the driest month and elevation. These play a pivotal role in determining the spread of the species. Based on these results, suggestions are provided for a multifaceted approach to prevention and control of H. cunea infestation. [ABSTRACT FROM AUTHOR]

Adaptive evolution following colonization can affect the impact of invasive species. The fall webworm (FWW) invaded China 40 years ago through a single introduction event involving a severe bottleneck and subsequently diverged into two genetic groups. The well‐recorded invasion history of FWW, coupled with a clear pattern of genetic divergence, provides an opportunity to investigate whether there is any sign of adaptive evolution following the invasion. Based on genome‐wide SNPs, we identified genetically separated western and eastern groups of FWW and correlated spatial variation in SNPs with geographical and climatic factors. Geographical factors explained a similar proportion of the genetic variation across all populations compared with climatic factors. However, when the two population groups were analysed separately, environmental factors explained more variation than geographical factors. SNP outliers in populations of the western group had relatively stronger response to precipitation than temperature‐related variables. Functional annotation of SNP outliers identified genes associated with insect cuticle protein potentially related to desiccation adaptation in the western group and genes associated with lipase biosynthesis potentially related to temperature adaptation in the eastern group. Our study suggests that invasive species may maintain the evolutionary potential to adapt to heterogeneous environments despite a single invasion event. The molecular data suggest that quantitative trait comparisons across environments would be worthwhile. [ABSTRACT FROM AUTHOR]

The Masculinizer gene, Masc, encodes a lepidopteran‐specific novel CCCH‐type zinc finger protein, which controls sex determination and dosage compensation in Bombyx mori. Considering the potential application of it in pest control, it is necessary to investigate the function of Masc gene in Hyphantria cunea, a globally invasive forest pest. In the present study, we identified and functionally characterized the Masc gene, HcMasc, in H. cunea. Sequence analysis revealed that HcMASC contained the conserved CCCH‐type zinc finger domain, nuclear localization signal, and male determining domain, in which the last was confirmed to be required for its masculinization in BmN cell line. However, expression data showed that unlike male‐biased expression in B. mori, HcMasc gene expresses in main all developmental stages or tissues in both sexes. Clustered regularly interspaced palindromic repeats (CRISPR) / CRISPR‐associated protein 9‐based disruption of the common exons 1 and 3 of the HcMasc gene resulted in imbalanced sex ratio and abnormal external genitalia of both sexes. Our results suggest that the HcMasc gene is required for both male and female sexual differentiation and dosage compensation in H. cunea and provide a foundation for developing better strategies to control this pest. [ABSTRACT FROM AUTHOR]

Abstract Plants play an important role in interactions between insect herbivores and their pathogens. The ability of host plants to modify the infectivity of entomopathogens in herbivorous insects has been widely documented. However, the plants’ nutrients have always been neglected as a factor contributing to variation in the susceptibility of insect herbivores to entomopathogens. The fall-webworm (FWW), Hyphantria cunea Drury, is a typical polyphagous caterpillar, and the Hyphantria cunea nucleopolyhedrovirus (HycuNPV) is a distinctly specialized baculovirus for the FWW, which is safe for other organisms and has been effectively used as a biological insecticide against H. cunea in China. In this study, we investigated the nutrient components of four host plant species, i.e., Prunus serrulate, Cerasus serrulate, Camptotheca acuminata, and Populus deltoides, and their effects on the susceptibility of H. cunea larvae to HycuNPV. The HycuNPV-infected larvae fed on P. deltoides leaves exhibited higher survival rates, longer survival times, more food intake, and gained larger body size. These biological parameters were positively correlated with the nitrogen components of host plant leaves. Moreover, the larval antioxidant enzymes exhibited different responses to HycuNPV. HycuNPV infection significantly triggered the catalase (CAT) and prophenoloxidase (PPO) enzyme activity levels of H. cunea larvae. The uninfected larvae fed on poplar leaves induced a robust increase in the POD activity, which could scavenge extra reactive oxygen species and provide a protective effect against the HycuNPV. In conclusion, the plant-mediated effects of HycuNPV on the FWW have been investigated in this study. The nitrogen content in dietary was an essential factor in determining the insect herbivore susceptibility to entomopathogenic viruses, and it helped explain variations in the susceptibility of pests to the entomopathogenic viruses and aid in developing more robust tolerance monitoring assays in the lab that reflect the performance of pests in the field. Graphical Abstract

In recent decades, ecological niche models (ENMs) have been widely used to predict suitable habitats for species. However, for invasive organisms, the prediction accuracy is unclear. In this study, we employed the most widely used maximum entropy (MaxEnt) model and ensemble model (EM) Biomod2 and verified the practical effectiveness of the ENM in predicting the distribution areas of invasive insects based on the true occurrence of Hyphantria cunea in China. The results showed that when only limited data of invasive areas were used, the two ENMs could not effectively predict the distribution of suitable habitats of H. cunea, although the use of global data can greatly improve the prediction accuracy of ENMs. When analyzing the same data, Biomod2's prediction accuracy was significantly better than that of MaxEnt. For long‐term predictions, the area of suitable habitat predicted by the ENMs was much greater than the occurrence area; for short‐term predictions, the accuracy of the predicted area was significantly improved. Under the current conditions, the area of suitable habitat for H. cunea in China is 118 × 104 km2, of which 59.32% is moderately or highly suitable habitat. Future climate change could significantly increase the suitable habitat area of H. cunea in China, and the predicted area of suitable habitats in all climate scenarios exceeded 355 × 104 km2, accounting for 36.98% of the total land area in China. This study demonstrates the use of ENMs to study invasive insects and provides a reference for the management of H. cunea in China. [ABSTRACT FROM AUTHOR]

Carya illinoinensis (Wangenh.) K. Koch (Pecan), a deciduous tree native to North America, faces significant challenges from pests. This study investigated the insecticidal efficacy and food safety of using the broad-spectrum insecticide emamectin benzoate via trunk injection for potential pecan pest management. Injections were given at dosages of 0.4, 0.8, 1.6, and 2.4 mL/cm of tree diameter at breast height (DBH), and leaf samples were collected at 10, 30, 60, and 100 days post-injection, while fruit samples were obtained during the swelling, ripening, and harvest stages. We established an analytical method for the determination and quantification of emamectin benzoate content in pecans using ultra-performance liquid chromatography–mass spectrometry (UPLC-MS). Leaf emamectin benzoate content was significantly higher compared to nuts (p ≤ 0.036). The content in leaves following the four dosage treatments decreased over time and at 100 days was 0.1943/0.2799 mg/kg (upper crown/lower crown), 0.1910/0.3957 mg/kg, 0.3663/0.6235 mg/kg, and 1.3988/1.9123 mg/kg, respectively. The pesticide residues of 0.4 mL/cm and 0.8 mL/cm treatment groups in kernels at harvest time were 0.0016 mg/kg and 0.0039 mg/kg, respectively, below the latest European Union Regulation (0.005 mg/kg). All four dosage treatments (0.4, 0.8, 1.6, and 2.4 mL/cm of tree diameter at DBH) in the leaf feeding test caused significant mortalities of the fourth instar Hyphantria cunea (Drury) larvae. The mortality rates at 10 days post-injection were 64.7%, 73.3%, 79.3%, and 84.7%, respectively, while at 60 days post-injection, the rates were 26.0%, 47.3%, 53.7%, and 81.7%, respectively. In summary, this study successfully established a sensitive analytical method for the detection and quantification of trunk-injected emamectin benzoate residues in pecans and demonstrates its safety and effectiveness as a chemical control option against foliar pecan pest insects. [ABSTRACT FROM AUTHOR]

Simple Summary: The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Erebidae, Arctiidae), is a major invasive pest of China. Although it has spread from Dandong City (about 40° N) in Liaoning Province to Nanjing City (about 32° N) in Jiangsu Province and other areas, the effects of temperature changes associated with its geographical spread on its life-history traits and adult fecundity are still unknown. Thus, the current study investigated the effects of larval-rearing temperature on the developmental duration and body mass of larvae, body size, body mass, and energy reserves of pupae, as well as the body size and fecundity of adults. We found that higher larval-rearing temperatures shortened the larval developmental period and increased larval and pupal body mass as well as pupal and adult body size. Higher larval-rearing temperatures also decreased the lipid and carbohydrate content of the pupae but increased their soluble protein content and adult egg production. These results suggest that the life-history traits and fecundity of H. cunea are plastic. This information is crucial for better understanding the dispersal adaptation strategies of H. cunea and for improving the prediction of population dynamics of this species according to environmental temperatures in different years. Temperature is an important environmental factor influencing the life-history traits of ectotherms. This study investigated the effects of larval-rearing temperature (21, 23, 25, and 27 °C) on the life-history traits and adult fitness of the fall webworm, Hyphantria cunea, an economically important invasive pest of China. With the increase in temperature during the larval stage, the larval developmental duration was significantly shortened, and the body mass was significantly increased, as was that of the body mass and size of pupae. The carbohydrate and lipid content of pupae significantly decreased with increasing larval-rearing temperature, whereas the protein content significantly increased. Adult body size and egg production increased significantly with increasing larval-rearing temperature, whereas there was no significant difference in egg diameter. These results indicate that H. cunea demonstrates life-history traits plasticity. In addition, the increase in fecundity would maintain a stable population size of H. cunea under higher temperatures. Such characteristics could enable H. cunea to spread to the more southern, warmer areas of China, posing an increased risk to the forestry industry in these regions. [ABSTRACT FROM AUTHOR]

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Heavy metal contamination has been regarded as an environmental variable that affects the efficiency of pest biological control, but the parasitic fitness of parasitoids under heavy metal stress is poorly understood. Herein, the effect of Cd exposure through the host pupa of Hyphantria cunea on the parasitic fitness of Chouioia cunea was investigated, and the mechanism by which Cd exposure affects the interaction between H. cunea and C. cunea from the perspective of innate immunity in host insect and the oxidative status in the parasitoid offspring was explored. Our results indicated that Cd can be transferred from the H. cunea pupae to the parasitoid offspring, and the transfer coefficient reflected biological amplification. There were no significant differences in the rates of parasitism success and offspring emergence between the untreated and Cd-treated groups. However, after parasitizing Cd-accumulated pupae, the parasitic fitness of offspring wasps (e.g., the number, individual size and life span) decreased significantly. Under Cd exposure, the cellular and humoral immunity of H. cunea pupae decreased significantly. Compared with the untreated group, the H2O2 content of parasitoid offspring in the Cd-treated group was significantly increased. Cd exposure significantly inhibited superoxide dismutase activity in parasitoid offspring, but the contents of ascorbic acid and glutathione were significantly increased by Cd stress. Taken together, these results indicate that Cd exposure reduces the cyclic utilization efficiency of C. cunea on H. cunea pupae. The oxidative status of parasitoid offspring triggered by Cd exposure could be responsible for the reduced parasitic fitness of C. cunea on Cd-accumulated H. cunea pupae.

Poplar trees are significant for both economic and ecological purposes, and the fall webworm (Hyphantria cunea Drury) poses a major threat to their plantation in China. The preliminary resistance assessment in the previous research indicated that there were differences in resistance to the insect among these varieties, with ‘2KEN8’ being more resistant and ‘Nankang’ being more susceptible. The present study analyzed the dynamic changes in the defensive enzymes and metabolic profiles of ‘2KEN8’ and ‘Nankang’ at 24 hours post-infestation (hpi), 48 hpi, and 96 hpi. The results demonstrated that at the same time points, compared to susceptible ‘Nankang’, the leaf consumption by H. cunea in ‘2KEN8’ was smaller, and the larval weight gain was slower, exhibiting clear resistance to the insect. Biochemical analysis revealed that the increased activity of the defensive enzymes in ‘2KEN8’ triggered by the feeding of H. cunea was significantly higher than that of ‘Nankang’. Metabolomics analysis indicated that ‘2KEN8’ initiated an earlier and more intense reprogramming of the metabolic profile post-infestation. In the early stages of infestation, the differential metabolites induced in ‘2KEN8’ primarily included phenolic compounds, flavonoids, and unsaturated fatty acids, which are related to the biosynthesis pathways of phenylpropanoids, flavonoids, unsaturated fatty acids, and jasmonates. The present study is helpful for identifying the metabolic biomarkers for inductive resistance to H. cunea and lays a foundation for the further elucidation of the chemical resistance mechanism of poplar trees against this insect.

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.

Abstract In recent decades, ecological niche models (ENMs) have been widely used to predict suitable habitats for species. However, for invasive organisms, the prediction accuracy is unclear. In this study, we employed the most widely used maximum entropy (MaxEnt) model and ensemble model (EM) Biomod2 and verified the practical effectiveness of the ENM in predicting the distribution areas of invasive insects based on the true occurrence of Hyphantria cunea in China. The results showed that when only limited data of invasive areas were used, the two ENMs could not effectively predict the distribution of suitable habitats of H. cunea, although the use of global data can greatly improve the prediction accuracy of ENMs. When analyzing the same data, Biomod2's prediction accuracy was significantly better than that of MaxEnt. For long‐term predictions, the area of suitable habitat predicted by the ENMs was much greater than the occurrence area; for short‐term predictions, the accuracy of the predicted area was significantly improved. Under the current conditions, the area of suitable habitat for H. cunea in China is 118 × 104 km2, of which 59.32% is moderately or highly suitable habitat. Future climate change could significantly increase the suitable habitat area of H. cunea in China, and the predicted area of suitable habitats in all climate scenarios exceeded 355 × 104 km2, accounting for 36.98% of the total land area in China. This study demonstrates the use of ENMs to study invasive insects and provides a reference for the management of H. cunea in China.

BACKGROUND: How parasitoids distinguish hosts from non‐hosts remains an unknown question. Chouioia cunea Yang (Eulophidae) is an important fall webworm parasitoid that attacks many forest and agricultural pests. To study the differences in the chemical clues used by C. cunea to distinguish host and non‐host plants, we used gas chromatography–mass spectrometry (GC–MS) to identify volatile compounds of two C. cunea hosts (Hyphantria cunea and Helicoverpa armigera) and two non‐hosts (Spodoptera exigua and Spodoptera frugiperda). Additionally, we used behavioral assays to compare the attraction of C. cunea to various compounds. RESULTS: The two natural host species were more attractive than the two non‐host species, in the following order: Hyphantria cunea > Helicoverpa armigera > S. exigua = S. frugiperda. The pupae of the natural hosts contained 1‐dodecene, which was not produced by the two natural non‐hosts. When the 'attractants' based on the difference between the species‐specific blend emitted by pupae and the optimal blend were sprayed onto the natural non‐host pupae, they significantly improved the attraction of C. cunea to the non‐host pupae. CONCLUSION: These results revealed that specific host‐produced volatile compounds guide C. cunea to distinguish between natural hosts and non‐hosts. Overall, this study provides a foundation for developing a behavior‐modifying strategy to re‐direct C. cunea attacks to control important non‐host pests. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Hyphantria cunea (Drury), a destructive polyphagous pest, has been spreading southward after invading northern China, which indicates that this insect species is facing a huge thermal challenge. Small heat shock proteins (sHSPs) function as ATP-independent molecular chaperones that protect insects from heat stress damage. In order to explore the role of sHSPs in the thermotolerance of H. cunea, five novel sHSP genes of H. cunea were cloned, including an orthologous gene (HcHSP21.4) and four species-specific sHSP genes (HcHSP18.9, HcHSP20.1, HcHSP21.5, and HcHSP29.8). Bioinformatics analysis showed that the proteins encoded by these five HcHSPs contained typical α-crystallin domains. Quantitative real-time PCR analysis revealed the ubiquitous expression of all HcHSPs across all developmental stages of H. cunea, with the highest expression levels in pupae and adults. Four species-specific HcHSPs were sensitive to high temperatures. The expression levels of HcHSPs were significantly up-regulated under heat stress and increased with increasing temperature. The expression levels of HcHSPs in eggs exhibited an initial up-regulation in response to a temperature of 40 °C. In other developmental stages, the transcription of HcHSPs was immediately up-regulated at 30 °C or 35 °C. HcHSPs transcripts were abundant in the cuticle before and after heat shock. The expression of HcHSP21.4 showed weak responses to heat stress and constitutive expression in the tissues tested. These results suggest that most of the HcHSPs are involved in high-temperature response and may also have functions in the normal development and reproduction of H. cunea. [ABSTRACT FROM AUTHOR]

There are a large number of microorganisms in the gut of insects, which form a symbiotic relationship with the host during the long-term co-evolution process and have a significant impact on the host's nutrition, physiology, development, immunity, stress tolerance and other aspects. However, the composition of the gut microbes of Hyphantria cunea remains unclear. In order to investigate the difference and diversity of intestinal microbiota of H. cunea larvae feeding on different host plants, we used PacBio sequencing technology for the first time to sequence the 16S rRNA full-length gene of the intestinal microbiota of H. cunea. The species classification, β diversity and function of intestinal microflora of the 5th instar larvae of four species of H. cunea feeding on apricot, plum, redbud and Chinese ash were analysed. The results showed that a total of nine phyla and 65 genera were identified by PacBio sequencing, amongst which Firmicutes was the dominant phylum and Enterococcus was the dominant genus, with an average relative abundance of 59.29% and 52.16%, respectively. PERMANOVA analysis and cluster heat map showed that the intestinal microbiomes of H. cunea larvae, fed on different hosts, were significantly different. LEfSe analysis confirmed the effect of host diet on intestinal community structure and PICRUSt2 analysis showed that most of the predictive functions were closely related to material transport and synthetic, metabolic and cellular processes. The results of this study laid a foundation for revealing the interaction between the intestinal microorganisms of H. cunea and its hosts and provided ideas for exploring new green prevention and control strategies of H. cunea.

BACKGROUND: General odor‐binding proteins (GOBPs) play critical roles in insect olfactory recognition of sex pheromones and plant volatiles. Therefore, the identification of GOBPs in Hyphantria cunea (Drury) based on their characterization to pheromone components and plant volatiles is remain unknown. RESULTS: In this study, two H. cunea (HcunGOBPs) genes were cloned, and their expression profiles and odorant binding characteristics were systematically analyzed. Firstly, the tissue expression study showed that both HcunGOBP1 and HcunGOBP2 were highly expressed in the antennae of both sexes, indicating their potential involvement in the perception of sex pheromones. Secondly, these two HcunGOBPs genes were expressed in Escherichia coli and ligand binding assays were used to assess the binding affinities to its sex pheromone components including two aldehydes and two epoxides, and some plant volatiles. HcunGOBP2 showed high binding affinities to two aldehyde components (Z9, Z12, Z15‐18Ald and Z9, Z12‐18Ald), and showed low binding affinities to two epoxide components (1, Z3, Z6‐9S, 10R‐epoxy‐21Hy and Z3, Z6‐9S, 10R‐epoxy‐21Hy), whereas HcunGOBP1 showed weak but significant binding to all four sex pheromone components. Furthermore, both HcunGOBPs demonstrated variable binding affinities to the plant volatiles tested. Thirdly, in silico studies of HcunGOBPs utilized homology, structure modeling, and molecular docking revealed critical hydrophobic residues might be involved in the binding of HcunGOBPs to their sex pheromone components and plant volatiles. CONCLUSION: Our study suggests that these two HcunGOBPs may serve as potential targets for future studies of HcunGOBPs ligand binding, providing insight in the mechanism of olfaction in H. cunea. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Despite the major role of benzoylureas (BPUs) in the control of pests in agricultural and forestry, their molecular mechanisms have in most cases remained elusive. BPUs cause molting impairments and were thought to interfere with chitin biosynthesis. Here, chlorbenzuron-treated Hyphantria cunea was subjected to extensive transcriptomic and proteomic analyses to investigate the toxicological mechanisms by which BPUs induce abortive molting and decrease chitin in insects. Following chlorbenzuron treatment, the transcriptomic analysis yielded 1973 differentially expressed genes (DEGs), while the proteomic analysis yielded 714 differentially expressed proteins (DEPs). The DEGs and DEPs were functionally annotated using Gene Ontology (GO) and analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database. Comprehensive transcript and protein analyses revealed that DEGs and DEPs were co-regulated in insect cuticle biosynthesis and detoxification metabolism. Of note, these genes and proteins, as well as their associated dysregulated pathways, could be promising targets for research into the precise action site of BPUs. This research provides large-scale omics data that can be used to better understand the overall mechanism of action of BPUs and the cause of death in insects. [ABSTRACT FROM AUTHOR]

Abstract Background The aim of this study was to develop an oil formulation from a local betabaculovirus. Hyphantria cunea Drury (Lepidoptera: Erebidae) granulovirus (HycuGV-Hc1) was isolated from the infected larvae to test its efficacy on the pest. The oil formulation was prepared by mixing the viral suspension with sunflower oil and some adjuvants and named HycuGV-TR61. Crude virus and the formulations were carried out on third instar H. cunea larvae using 1 × 104–8 OBs /ml concentrations and were exposed to temperatures (28, 35, and 42 °C) and UV-B light at different periods (0, 1, 3, 5 h). Results The mortality rate, which was 50% at the lowest concentration (1 × 104 OB/ml), reached 99.86% at the highest concentration (1 × 108 OB/ml). LC50 values of fresh and old forms were calculated as 0.64 × 104 and 0.87 × 104 OBs/ml, respectively. Application of shelf life showed that there was non-significant change in the pathogenic activity of the formulation with time. In the experiments, it was observed that the activity decreased as the temperature and time of exposure increased. Significantly difference in larval mortality was observed when fresh and old formulations were exposed to 0, 1, 3 and 5 h to UV-B, (old: 96.7, 86, 80 and 60%; fresh: 97.1, 90, 85 and 62%, respectively). Conclusions The results revealed superior aspects of HycuGV-TR61, which was developed as a local viral biopesticide, its resistance to abiotic factors and its potential to be used in pest control.

The steroid hormone 20‐hydroxyecdysone (20E) has been described to regulate fat body lipid metabolism in insects, but its accurate regulatory mechanism, especially the crosstalk between 20E‐induced lipid metabolism and gluconeogenesis remains largely unclear. Here, we specially investigated the effect of 20E on lipid metabolism and gluconeogenesis in the fat body of Hyphantria cunea larvae, a notorious pest in forestry. Lipidomics analysis showed that a total of 1 907 lipid species were identified in the fat body of H. cunea larvae assigned to 6 groups and 48 lipid classes. The differentially abundant lipids analysis showed a significant difference between 20E‐treated and control samples, indicating that 20E caused a remarkable alteration of lipidomics profiles in the fat body of H. cunea larvae. Further studies demonstrated that 20E accelerated fatty acid β‐oxidation, inhibited lipid synthesis, and promoted lipolysis. Meanwhile, the activities of pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose‐1,6‐bisphosphatase, and glucose‐6‐phosphatase were dramatically suppressed by 20E in the fat body of H. cunea larvae. As well, the transcriptions of genes encoding these 4 rate‐limiting gluconeogenic enzymes were significantly downregulated in the fat body of H. cunea larvae after treatment with 20E. Taken together, our results revealed that 20E disturbed fat body lipid homeostasis, accelerated fatty acid β‐oxidation and promoted lipolysis, but negatively regulated gluconeogenesis in H. cunea larvae. The findings might provide a new insight into hormonal regulation of glucose and lipid metabolism in insect fat body. [ABSTRACT FROM AUTHOR]

Hyphantria cunea (Drury) (Lepidoptera: Erebidae) is an invasive alien species that is widely distributed in northern China. H. cunea now occurs for the first time in the subtropical areas of China. Despite the importance of identifying oviposition host plants to control the spread of H. cunea, it is not clear whether H. cunea has a new oviposition preference for plant hosts in the new habitat after invading the subtropical region. At the same time, whether the presence of new plant volatiles of new hosts in new habitats influences the oviposition host preference of H. cunea has not been studied. In this study, we investigated the oviposition host plant preferences of H. cunea in the subtropical region of China. In the presence of multiple potential host plants, we found, for the first time, that H. cunea preferred Carya illinoinensis, Morus alba, and Carya cathayensis for oviposition. Through the effects on plant volatiles and on the oviposition, ten volatile compounds with significant differences in relative abundance between five plants with different fitness levels were significantly correlated with the oviposition preference of females. Cis-Hex-3-en-1-ol, (E)-3-Hexen-1-ol, cis-3-Hexenyl acetate 1, and 3-Pentadiene,4-methyl, had a significant positive correlation with the adult oviposition preference. Our results provide an important research basis for the study of green prevention and control strategies of subtropical H. cunea in China. [ABSTRACT FROM AUTHOR]

Simple Summary: Hyphantria cunea is a cosmopolitan quarantine pest that can sustain on a wide range of host plants. However, the role of the digestive physiology of H. cunea larvae in regulating its multi-host adaptation has not been reported. Herein, we found that α-amylase and trypsin played an important role in nutrient metabolism and host adaptation of H. cunea. Furthermore, H. cunea larvae had highly adaptable compensatory mechanisms for digestion in response to insect digestive enzyme inhibitors. The findings reveal that digestive physiology mediates the multi-host adaptation of H. cunea larvae. Digestive physiology mediates the adaptation of phytophagous insects to host plants. In this study, the digestive characteristics of Hyphantria cunea larvae feeding preferences on different host plants were investigated. The results showed that the body weight, food utilization, and nutrient contents of H. cunea larvae feeding on the high-preference host plants were significantly higher than those feeding on the low-preference host plants. However, the activity of larval digestive enzymes in different host plants presented an opposite trend, as higher α-amylase or trypsin activity was observed in the group feeding on the low-preference host plants than that feeding on the high-preference host plants. Upon treatment of leaves with α-amylase and trypsin inhibitors, the body weight, food intake, food utilization rate, and food conversion rate of H. cunea larvae significantly decreased in all host plant groups. Furthermore, the H. cunea comprised highly adaptable compensatory mechanisms of digestion involving digestive enzymes and nutrient metabolism in response to digestive enzyme inhibitors. Taken together, digestive physiology mediates the adaptation of H. cunea to multiple host plants, and the compensatory effect of digestive physiology is an important counter-defense strategy implemented by H. cunea to resist plant defense factors, especially the insect digestive enzyme inhibitors. [ABSTRACT FROM AUTHOR]

Background: The fall webworm, Hyphantria cunea, an invasive forest pest found worldwide, causes serious ecological and economic damage. Currently, the application of chemical pesticides is the most widely used strategy for H. cunea management. However, long‐term pesticide use leads to pest resistance, phytotoxicity, human poisoning, and environmental deterioration. RNA interference (RNAi) technology may provide an environmentally friendly and cost‐effective option for H. cunea control. However, effective RNAi targets and application methods for H. cunea are lacking. Results: We screened and obtained two highly effective RNAi targets, vATPase A (V‐type proton ATPase catalytic subunit A) and Rop (Ras opposite), from 23 candidate genes, using initial and repeat screening tests with the double‐stranded RNA (dsRNA) injection method. RNAi against these two genes was effective in suppressing each target messenger RNA level and interfering with larval growth, leading to significant larval mortality and pupal abnormality. For massive production of dsRNA and practical application of RNAi technology in H. cunea, transformed bacteria expressing dsRNAs of these two genes were prepared using the L4440 expression vector and HT115 strain of Escherichia coli. Oral administration of bacterially expressed dsRNA targeting vATPase A and Rop genes showed high mortality and the same malformed phenotype as the injection treatment. To further investigate the lethal effects of targeting these two genes on larval development, transcriptome sequencing (RNA‐seq) was performed on RNAi samples. The results demonstrated disorders in multiple metabolic pathways, and the expression levels of most genes related to insect cuticle metabolism were significantly different, which may directly threaten insect survival. In addition, some new findings were obtained via RNA‐seq analysis; for example, the progesterone‐mediated oocyte maturation and oocyte meiosis processes were significantly different after silencing vATPase A, and the insect olfactory protein‐related genes were significantly downregulated after dsHcRop treatment. Conclusion: vATPase A and Rop are two highly effective RNAi‐mediated lethal genes in H. cunea that regulate insect growth via multiple metabolic pathways. Oral delivery of bacterially expressed dsRNA specific to vATPase A and Rop can potentially be used for RNAi‐based H. cunea management. This is the first study to apply bacteria‐mediated RNAi for the control of this invasive pest, which is a major step forward in the application of the RNAi technology in H. cunea. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Temperature is an important environmental factor influencing the life-history traits of ectotherms. This study investigated the effects of larval-rearing temperature (21, 23, 25, and 27 °C) on the life-history traits and adult fitness of the fall webworm, Hyphantria cunea, an economically important invasive pest of China. With the increase in temperature during the larval stage, the larval developmental duration was significantly shortened, and the body mass was significantly increased, as was that of the body mass and size of pupae. The carbohydrate and lipid content of pupae significantly decreased with increasing larval-rearing temperature, whereas the protein content significantly increased. Adult body size and egg production increased significantly with increasing larval-rearing temperature, whereas there was no significant difference in egg diameter. These results indicate that H. cunea demonstrates life-history traits plasticity. In addition, the increase in fecundity would maintain a stable population size of H. cunea under higher temperatures. Such characteristics could enable H. cunea to spread to the more southern, warmer areas of China, posing an increased risk to the forestry industry in these regions.

Population density is an essential factor affecting the life history traits of insects and their trade-off relationships, as increasing density intensifies intraspecific competition. It decreases the average resources available to individuals within a population, affecting their morphology, physiology, behavior, and fitness. The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), has been an invasive pest of forest trees, ornamental plants, and fruit trees in China for many years. The larvae have a typical aggregation habit before the fourth instar and keep spitting silk to gather the damaged leaves into silk webs. However, the fitness of H. cunea in response to population density remains unclear. In this study, the critical biological parameters, food utilization, and population parameters of H. cunea in response to different rearing densities were investigated. The results showed that under high population density, H. cunea larvae showed better performance, with faster development, higher survival rates, and shorter generation time, but pupal weight and female fecundity decreased as population density increased. In contrast, for larvae raised in low density, the developmental period was prolonged, and mortality was increased, while higher food utilization, greater body size, and female fecundity were observed. Both males and females had similar development strategies in response to the density, but females may be more resistant to crowding than males. In conclusion, H. cunea could adopt different ecological strategies against the stress of density. High population densities result in shorter generation cycles and higher survival rates. Conversely, the low-density generation period becomes longer but with greater fecundity. The results may help determine the possible outbreak mechanism and develop effective population monitoring and forecasting measures for H. cunea.

The effects of competition can have far‐reaching consequences for individuals, populations, and communities and therefore we should strive toward a deeper understanding of competitive interactions. In some cases, dietary generalists may be predicted to experience weak competition effects because of their ability to use a wide range of host plants. However, competition between insects frequently occurs indirectly, which can hinder insects' abilities to avoid competitive interactions. Therefore, competition may be as strong among dietary generalists as among dietary specialists. Yet competition between insects that are dietary generalists is infrequently studied. We tested for evidence of competitive interactions between two common, temporally separated, generalist insects: the western tent caterpillar (Malacosoma californicum), which feeds early in the season, and the fall webworm (Hyphantria cunea), which feeds later in the season. Both species frequently use a common host plant species (chokecherry) as a preferred host at our field sites. We tested the relative strength of bottom‐up effects resulting from competitive interactions between these two generalists with laboratory‐rearing trials at the relevant time of year for each insect. We recorded three common fitness measures (development time, pupal mass, and survival) for caterpillars reared on chokecherry with no damage from either of our focal species, with tent caterpillar damage, and with fall webworm damage. To test the strength of top‐down pressures on fall webworm larval fitness and any potential interactions with bottom‐up effects, we reared larvae in the field either exposed to or protected from predators on host plants that either did or did not have tent caterpillars feeding on them earlier in the season. We found evidence of bottom‐up fitness effects on tent caterpillars and top‐down and bottom‐up fitness effects on fall webworms confirming that tent caterpillars and fall webworms compete indirectly. Tent caterpillars had lower pupal mass when reared on leaves from shrubs damaged by fall webworms. Fall webworms had lower pupal mass and longer development time when reared on leaves from shrubs damaged by tent caterpillars. In field trials, fall webworms reared on shrubs damaged by tent caterpillars had a lower survival and pupal mass. We show evidence of indirect competition in temporally separated generalists through leaf quality (bottom‐up effects) and natural enemies (top‐down effects). [ABSTRACT FROM AUTHOR]

Hyphantria cunea Drury (Lepidoptera: Erebidae) is a quarantine pest in China that can cause damage to hundreds of plants. As biological control agents, Nuclear Polyhedrosis Virus (NPV) and Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt) are commonly used to inhibit the prevalence of H. cunea. To investigate the role of midgut bacteria in the infection of NPV and Bt in H. cunea , we performed a series of tests, including isolating the dominant culturable bacteria in the midgut, eliminating intestinal bacteria, and respectively inoculating the dominant strains with NPV and Bt for bioassay. Two dominant bacteria, Klebsiella oxytoca Lautrop (Enterobacterales: Enterobacteriaceae) and Enterococcus mundtii Collins (Lactobacillales: Enterococcaceae), in the midgut of H. cunea were identified, and a strain of H. cunea larvae without intestinal bacteria was successfully established. In the bioassays of entomopathogen infection, K. oxytoca showed significant synergistic effects with both NPV and Bt on the death of H. cunea. In contrast, E. mundtii played antagonistic effects. This phenomenon may be attributed to the differences in the physico-chemical properties of the two gut bacteria and the alkaline environment required for NPV and Bt to infect the host. It is worth noting that the enhanced insecticidal activity of K. oxytoca on NPV and Bt provides a reference for future biological control of H. cunea by intestinal bacteria. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to develop an oil formulation from a local betabaculovirus. Hyphantria cunea Drury (Lepidoptera: Erebidae) granulovirus (HycuGV-Hc1) was isolated from the infected larvae to test its efficacy on the pest. The oil formulation was prepared by mixing the viral suspension with sunflower oil and some adjuvants and named HycuGV-TR61. Crude virus and the formulations were carried out on third instar H. cunea larvae using 1 × 104–8 OBs /ml concentrations and were exposed to temperatures (28, 35, and 42 °C) and UV-B light at different periods (0, 1, 3, 5 h). Results: The mortality rate, which was 50% at the lowest concentration (1 × 104 OB/ml), reached 99.86% at the highest concentration (1 × 108 OB/ml). LC50 values of fresh and old forms were calculated as 0.64 × 104 and 0.87 × 104 OBs/ml, respectively. Application of shelf life showed that there was non-significant change in the pathogenic activity of the formulation with time. In the experiments, it was observed that the activity decreased as the temperature and time of exposure increased. Significantly difference in larval mortality was observed when fresh and old formulations were exposed to 0, 1, 3 and 5 h to UV-B, (old: 96.7, 86, 80 and 60%; fresh: 97.1, 90, 85 and 62%, respectively). Conclusions: The results revealed superior aspects of HycuGV-TR61, which was developed as a local viral biopesticide, its resistance to abiotic factors and its potential to be used in pest control. [ABSTRACT FROM AUTHOR]

Hyphantria cunea is a globally distributed quarantine plant pest. In a previous study, the Cordyceps javanica strain BE01 with a strong pathogenic effect on H. cunea was identified, and overexpression of the subtilisin-like serine protease CJPRB of this strain was found to accelerate the death of H. cunea (previous research results). In this study, the active recombinant CJPRB protein was obtained through the Pichia pastoris expression system. It was found that CJPRB protein administration to H. cunea via infectation, feeding and injection was able to induce changes in protective enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and polyphenol oxidase (PPO), and the expression of immune defense-related genes in H. cunea. In particular, CJPRB protein injection induced a more rapid, widespread and intense immune response in H. cunea compared to the other two treatment methods. The results suggest that the CJPRB protein may play a role in eliciting a host immune response during infectation by C. javanica. [ABSTRACT FROM AUTHOR]

In China, Hyphantria cunea (Drury) is an invasive phytophagous pest; it attacks nearly all species of defoliated trees. To develop integrated pest management programs (IPM) for H. cunea , we need to ensure the availability of insects by mass-rearing them on artificial diets under laboratory conditions. This study compared the growth characteristics, nutritional indices, growth indices, and digestive enzyme activity of insects reared on Pterocarya stenoptera C.DC (Fagales: Juglandaceae), the Chinese wingnut, and an artificial diet. We also investigated the correlation between diet components and growth indices using principal components analysis and Pearson correlation analysis. We found that mass-rearing of H. cunea on an artificial diet was feasible. It led to a shorter developmental period, with heavier larvae and pupae than natural diets. The principal components analysis indicated that the growth indices and α-Amylase were significantly positively associated with PC1, which explained 82.45% of the total data variability. Pearson correlation analysis showed a significant correlation between digestion, absorption parameters, and growth. Developing a mass-rearing program to produce H. cunea on an artificial diet will be valuable for improving IPM strategies. Understanding the mechanism of the responses of phytophagous insect populations to anthropogenic diet regulation can provide new ideas and methods for pest control. [ABSTRACT FROM AUTHOR]

Background: The insulin signaling pathway is closely related to metabolism, growth, reproductive capacity and lifespan of insects. However, the physiological function of the insulin signaling pathway is little known in Hyphantria cunea. Results: Five insulin signaling pathway genes (HcInR, HcPI3K, HcAKT, HcFOXO and HcTOR) in H. cunea were identified and characterized in this study. The spatiotemporal expression profiles of the genes showed that HcInR, HcAKT, HcPI3K and HcTOR expressions were higher at the egg stage than those in other development stages, whereas HcFOXO was highly expressed in the adult stage; all of these genes were highly expressed in the larval digestive system, especially in the midgut and hindgut. After RNA interference (RNAi) of the five genes in 5th instar H. cunea larvae, weight gain and survival rate (except in the siHcAKT-injected group) were significantly decreased, and the developmental duration of larval and pupal stages were prolonged. In addition, knockdown of five genes in 7th instar larvae decreased the pupation rate, survival rate and oviposition capacity, and resulted in abnormal development during larval–pupal transition. Conclusion: Our findings indicate that the insulin signaling pathway plays essential roles in growth and development and the molting process in H. cunea, providing an important basis for developing new potentially molecular targets for RNAi-based pest control and understanding the mechanism of H. cunea outbreak. [ABSTRACT FROM AUTHOR]

Nutrient accumulation is crucial in insect diapause preparation because insufficient nutrient accumulation can shorten the diapause period, interfere with diapause development completion, and decrease the probability of surviving the overwintering period. The amounts of lipids and carbohydrates stored in diapausing pupae of Hyphantria cunea (Drury) (Lepidoptera: Erebidae, Arctiinae) are greater than those in the non‐diapausing pupae. In this study, we tested the hypothesis that diapause‐destined (DD) and non‐diapause‐destined (NDD) larvae of H. cunea have different nutrient accumulation patterns in penultimate and final instars. The body mass, as well as lipid, carbohydrate, and soluble protein contents, and the efficiency of converting digested food and ingested food into body matter were greater in the DD penultimate and final instars than in the NDD penultimate and final instars. Larger amounts of lipids, carbohydrates, and proteins were absorbed by DD penultimate and final instars and the final instar development period in the DD larvae was prolonged relative to NDD larvae. The activities of fatty acid synthase and glycogen synthase of DD penultimate and final instars were significantly higher than those of NDD larvae. These results suggest that the changes in nutrient accumulation patterns between DD and NDD larvae occur in penultimate and final instars, and that the DD larvae increase their nutrient accumulation during diapause preparation by the combined effect of extending their final‐instar development period and improving their digestive efficiency; they increase their lipid and carbohydrate stores by increasing the activities of fatty acid synthase and glycogen synthase in the fat body. [ABSTRACT FROM AUTHOR]

[Objectives] To clarify the toxicological effect of sublethal doses of avermectin on Hyphantria cunea, and thereby provide a theoretical basis for the rational use of this pesticide. [Methods] The growth and development of 4th to 6th instar H. cunea larvae were measured after these had consumed artificial diets containing sublethal concentrations of abamectin (LC10 or LC30) for 72 h. Control groups were fed an aqueous solution containing 0.1% dimethyl sulfoxide. The reproductive ability of adults obtained from these treatment groups was also measured. [Results] The 4th instar LC30 treatment group grew 22% less than the respective control group (P<0.05), whereas there were no significant differences in growth between the 5th and 6th instar LC30 treatment groups and their respective control groups (P>0.05). There was no significant difference in growth between the LC10 treatment groups and their respective control groups (P>0.05). Development of the 4th, 5th and 6th larval instars in the LC30 treatment groups (3.4, 2.2 and 1.7 days, respectively) was significantly prolonged relative to the respective control groups (P<0.05), but there was no significant difference in the duration of development of the LC10 treatment groups (P>0.05) and the respective control groups. Adult longevity in the LC10 and LC30 treatment groups (1-1.7 and 2.3-2.7 days, respectively) was significantly shorter than that of the respective control groups (P<0.05). The pupation rate, emergence rate, fecundity and hatching rate of the LC10 and LC30 treatment groups were also significantly shorter compared to the respective control groups (P<0.05). Pupation and emergence rates, fecundity, and hatching rate in the LC30 treatment group were 36%-56%, 33%-66%, 49%-78% and 45%-62%, respectively, those of the respective control groups. The fecundity and hatching rate of the LC10 treatment groups were 66-88% and 62-82%, respectively, those of the respective control groups. Only the feeding, larvae period, emergence rates and pupation rates of 4th instar larvae, the larvae period and emergence rates of 5th instar larvae, and the emergence rates and egg hatching rate of 6th instar larvae, were significantly less in the LC10 and LC30 treatment groups than in the respective control groups; the differences were greater for the LC30 treatment group than for the LC10 treatment group. [Conclusion] Exposure of H. cunea larvae to sublethal concentrations of abamectin (LC10 and LC30) inhibits both larval growth and development and the reproductive capacity of larvae that survive to adulthood. [ABSTRACT FROM AUTHOR]

[Objectives] To clarify the influence of sex, age (days) and temperature, on the flight ability of adult Hyphantria cunea, and there by provide information essential for monitoring, and predicting, the dispersal of this pest. [Methods] The effect of gender, age and temperature on the flight ability of adult H. cunea was measured in an insect flight mill. [Results] Males were significantly stronger fliers than females with a maximum flight distance of 17.87 km and cumulative flight time of 17.38 h. One day-old males had the longest cumulative flight distance; the average cumulative flight distance and average cumulative flight time of males decreased with age. The maximum female flight distance was 8.21 km and the longest cumulative flight time was 7.4 h. Female flight distance tended to first increase, then decrease, with age. Three day-old females had the maximum cumulative flight distance. A two-way ANOVA of the average cumulative flight distance, average cumulative flight time, and average flight speed, did not detect a significant interaction between sex and age. Male flight speed was significantly slower at a temperature of 16 °C. [Conclusion] Male H. cunea are stronger fliers than females. Male flight ability gradually decreases with age, whereas that of females tends to increase up to 3 days of age, then decrease. Low temperatures reduce the flight speed of H. cunea males. [ABSTRACT FROM AUTHOR]

[Objectives] To determine the optimal reproduction and storage conditions for the Hyphantria cunea nudeopolyhedrovirus (HcNPV) in order to provide a theoretical basis and technological support for the commercial production of this virus. [Methods] The effects of different larval instars, virus concentration, duration, temperature and population density, were analyzed to identify the optimal condition for HcNPV reproduction in vivo. Effects of different formulations, times, temperatures and adjuvants on the stability of HcNPV storage were also investigated to determine the optimal HcNPV bioactivity assay method. In feeding bioassays, the number of proliferating occlusion bodies (OB) were recorded with a hemocytometer, and the lethal time (LT50) was calculated to quantify the insecticidal activity of HcNPV Third instar larvae fed a diet with a HcNPV concentration of 1x106 OBmL-1 were used for follow-up experiments. [Results] OB proliferation in 5th instar larvae reared on an artificial diet containing HcNPV at a concentration of 1x106 OBmL-1 was significantly higher (1.16x1010 OB per larva) than in other treatments. The optimal temperature for HcNPV reproduction was 20 °C, which resulted in 5.06x109 OB per larva. The abundance of HcNPV virions significantly decreased from 3.42x109 OB per larva after feeding for 1 day to 0.97x109 OB per larva after feeding for 5 days. Larvae kept at a density of 100 larvae/box (0.05 larvae/cm²) had 4.94x109 OB per larva, which was significantly higher than that of those kept at densities of 200, 300, 400, 500 larvae/box. The LT50 of 3rd instar larvae infected from insect pulp and freeze-dried insect pulp was significantly lower than that of those infected from virus suspension and freeze-dried virus suspension. There was no significant change in the insecticidal activity of HcNPV when stored for less than 12 months and insecticidal activity did not change significantly over a range of storage temperatures from - 20 to 25 °C. The best preservatives were sucrose (50%) and sodium chloride (5%), which had in LT50 values of 4.94 days and 4.97 days, respectively. [Conclusion] The highest yield of HcNPV was achieved by giving 5th instar H. cunea larvae a single feed of an artificial diet containing HcNPV inoculum at a concentration of 1x106 OB mL-1 and keeping larvae at a density of 0.05 larvae/cm² at a temperature of 20 °C. Grinding the bodies of diseased larvae into a slurry, adding sucrose (50%) or sodium chloride (5%) as adjuvants, and storing the resultant homogenate in a refrigerator at - 20 °C, allowed HcNPV to be stored for up to 12 months with no loss in insecticidal activity. [ABSTRACT FROM AUTHOR]

Hyphantria cunea has many hosts, a broad distribution, caused serious economic damage, is difficult to control, and has seriously affected the development of forestry in China. Control of this pest mainly relies on a combination of chemical and biological methods, including the use of sex pheromones traps and monitoring population dynamics in combination with chemical and biological control. However, developing more sustainable and effective methods for controlling of H. cunea has always been a focus of research on this species. This paper reviews the current distribution of H. cunea in China, problems in the prevention and control of this pest, and progress in the application of ecological control. It also introduces new control technologies, such as genetically-modified sterile insect technology, RNAi and Bt transgenic insect-resistant tree species. Finally, it forecasts the future trends in the development of H. cunea control methods [ABSTRACT FROM AUTHOR]

[Objectives] To compare the insecticidal activity of four commonly used insecticides; emamectin benzoate, beta-cypermethrin, chlorobenzuron and matrine, on the larvae of Hyphantria cunea (Drury), in order to determine which have a significant synergistic interaction with the Hyphantria cunea nuclear polyhedrosis virus (HycuNPV). [Methods] Groups of 3rd instar larvae of H. cunea infected with HycuNPV were treated with one of the four chemical insecticides above using the artificial feed surface coating method. The synergistic interaction between each insecticide and HycuNPV was then evaluated using the co-toxicity factor method. Those insecticides with a significant synergistic effect were identified, and the optimal pesticide: virus ratio and concentration was determined. [Results] The relative toxicity of the four insecticides tested was: emamectin benzoate >beta-cypermethrin>chlorobenzuron>matrine, and their median lethal concentrations (LC50) were 0.021, 2.149, 4.522 and 70.255 mg-L-1, respectively. A combination of emamectin benzoate (0.021 mg-L-1) and HycuNPV(1.18x106 OBs mL-1) had a significant synergistic effect. A pesticide: virus volume ratio of 1-9 resulted in a 29.06 fold increase in mortality and a 2.89 day reduction in the median lethal time (LT50) compared to HycuNPV in isolation. [Conclusion] Among the insecticides tested, emamectin benzoate had both the highest toxicity to 3rd instar H. cunea larvae, and the greatest synergy with HycuNPV. Optimum toxicity was achieved at a concentration of 0.021 mg L-1 emamectin benzoate and 1.18x106 OBsmL-1 HycuNPV and a volume ratio of 1:9. [ABSTRACT FROM AUTHOR]