High nitrogen application in maize enhances insecticide tolerance of the polyphagous herbivore Spodoptera litura by induction of detoxification enzymes and intensification of cuticle.

Nitrogen (N) is one of the most intensively used fertilizers in cropping system and could exert a variety of bottom-up effects on the ecological fitness of herbivores. However, the effects of increased N inputs on insect pesticide tolerance have not been comprehensively understood. Bioassays showed that high N (HN) applied to maize plants significantly increased larval tolerance of Spodoptera litura to multiple insecticides. Activities of detoxification enzymes were significantly higher in the larvae fed on maize plants supplied with HN. RNA-seq analysis showed that numerous GST and cuticle-related genes were induced in the larvae fed on HN maize. RT-qPCR analysis further confirmed four GST genes and larval-specific cuticle gene LCP167. Furthermore, when injected with dsRNA specific to GSTe1, GSTs5, and LCP167, the mortality of larvae treated with methomyl was about 3-fold higher than that of dsGFP-injected larvae. Electron microscope observation showed that cuticle of the larvae fed on HN maize was thicker than the medium level of N. These findings suggest that increased application of N fertilizer enhances insecticide tolerance of lepidopteran pests via induction of detoxification enzymes and intensification of cuticle. Thus, overuse of N fertilizer may increase pest insecticide tolerance and usage of chemical insecticides.

Integration of transcriptome and metabolome analyses reveals the role of OsSPL10 in rice defense against brown planthopper.

KEY MESSAGE: OsSPL10 is a negative regulator of rice defense against BPH, knockout of OsSPL10 enhances BPH resistance through upregulation of defense-related genes and accumulation of secondary metabolites. Rice (Oryza sativa L.), one of the most important staple foods worldwide, is frequently attacked by various herbivores, including brown planthopper (BPH, Nilaparvata lugens). BPH is a typical monophagous, phloem-sucking herbivore that has been a substantial threat to rice production and global food security. Understanding the regulatory mechanism of defense responses to BPH is essential for improving BPH resistance in rice. In this study, a SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 10 (OsSPL10) transcription factor was found to play a negative role in the defenses of rice against BPH. To gain insights into the molecular and biochemical mechanisms of OsSPL10, we performed combined analyses of transcriptome and metabolome, and revealed that knockout of OsSPL10 gene improved rice resistance against BPH by enhancing the direct and indirect defenses. Genes involved in plant hormone signal transduction, MAPK signaling pathway, phenylpropanoid biosynthesis, and plant-pathogen interaction pathway were significantly upregulated in spl10 mutant. Moreover, spl10 mutant exhibited increased accumulation of defense-related secondary metabolites in the phenylpropanoid and terpenoid pathways. Our findings reveal a novel role for OsSPL10 gene in regulating the rice defense responses, which can be used as a potential target for genetic improvement of BPH resistance in rice.

Tracking Adaptive Pathways of Invasive Insects: Novel Insight from Genomics.

Despite the huge human and economic costs of invasive insects, which are the main group of invasive species, their environmental impacts through various mechanisms remain inadequately explained in databases and much of the invasion biology literature. High-throughput sequencing technology, especially whole-genome sequencing, has been used as a powerful method to study the mechanisms through which insects achieve invasion. In this study, we reviewed whole-genome sequencing-based advances in revealing several important invasion mechanisms of invasive insects, including (1) the rapid genetic variation and evolution of invasive populations, (2) invasion history and dispersal paths, (3) rapid adaptation to different host plant ranges, (4) strong environmental adaptation, (5) the development of insecticide resistance, and (6) the synergistic damage caused by invasive insects and endosymbiotic bacteria. We also discussed prevention and control technologies based on whole-genome sequencing and their prospects.

Astrocytes promote the proliferation of oligodendrocyte precursor cells through connexin 47-mediated LAMB2 secretion in exosomes.

BACKGROUND: Oligodendrocyte precursor cells (OPCs) can proliferate and differentiate into oligodendrocytes, the only myelin-forming cells in the central nervous system. Proliferating OPCs promotes remyelination in neurodegenerative diseases. Astrocytes (ASTs) are the most widespread cells in the brain and play a beneficial role in the proliferation of OPCs. Connexin 47 (Cx47) is the main component of AST-OPC gap junctions to regulate OPC proliferation. Nonetheless, the specific mechanism remains unclear. METHODS AND RESULTS: This study investigates the proliferation mechanism of OPCs connected to ASTs via Cx47. Cx47 siRNA significantly inhibited OPCs from entering the proliferation cycle. Transcriptome sequencing of OPCs and gene ontology enrichment analysis revealed that ASTs enhanced the exosome secretion by OPCs via Cx47. Transmission electron microscopy, Western blot, and nanoparticle tracking analysis indicated that the OPC proliferation was related to extracellular exosomes. Cx47 siRNA decreased the OPC proliferation and exosome secretion in AST-OPC cocultures. Exogenous exosome supplementation alleviated the inhibitory effect of Cx47 siRNA and significantly improved OPC proliferation. Mass spectrometry revealed that LAMB2 was abundant in exosomes. The administration of exogenous LAMB2 induced DNA replication in the S phase in OPCs by activating cyclin D1. CONCLUSIONS: Collectively, ASTs induce the secretion of exosomes that carry LAMB2 by OPCs via Cx47 to upregulate cyclin D1 thereby accelerating OPC proliferation.

The metabolic resistance of Nilaparvata lugens to chlorpyrifos is mainly driven by the carboxylesterase CarE17.

The involvement of carboxylesterases (CarEs) in resistance to chlorpyrifos has been confirmed by the synergism analysis in Nilaparvata lugens. However, the function of specific CarE gene in chlorpyrifos resistance and the transcriptional regulatory mechanism are obscure. Herein, the expression patterns of 29 CarE genes in the susceptible and chlorpyrifos-resistant strains were analyzed. Among them, CarE3, CarE17 and CarE19 were overexpressed in the resistant strain, and knockdown of either CarE gene by RNA interference significantly increased the susceptibility to chlorpyrifos. Remarkably, knockdown of CarE17 reduced the enzymatic activity of CarE by 88.63 % and showed a much greater effect on increasing chlorpyrifos toxicity than silencing other two CarE genes. Overexpression of CarE17 in Drosophila melanogaster decreased the toxicity of chlorpyrifos to transgenic fruit flies. Furthermore, the region between - 205 to + 256 of CarE17 promoter sequence showed the highest promoter activity, and 16 transcription factors (TFs) were predicted from this region. Among these TFs, Lim1ß and C15 were overexpressed in the resistant strain. Knockdown of either TF resulted in reduced CarE17 expression and a decrease in resistance of N. lugens to chlorpyrifos. These results indicate that the constitutive overexpression of Lim1ß and C15 induces CarE17 expression thus conferring chlorpyrifos resistance in N. lugens.

Activation of the NR2E nuclear receptor HR83 leads to metabolic detoxification-mediated chlorpyrifos resistance in Nilaparvata lugens.

Increased production of detoxification enzymes appears to be the primary route for insecticide resistance in many crop pests. However, the mechanisms employed by resistant insects for overexpression of detoxification genes involved in insecticide resistance remain obscure. We report here that the NR2E nuclear receptor HR83 plays a critical role in chlorpyrifos resistance by regulating the expression of detoxification genes in the brown planthopper (BPH), Nilaparvata lugens. HR83 was highly expressed in the fat body and ovary of adult females in chlorpyrifos-resistant BPHs. Knockdown of HR83 by RNA interference showed no effect on female fecundity, whereas caused a decrease of resistance to chlorpyrifos. This treatment also led to a dramatic reduction in the expression of multiple detoxification genes, including four UDP-glycosyltransferases (UGTs), three cytochrome P450 monooxygenases (P450s) and four carboxylesterases (CarEs). Among these HR83-regulated genes, UGT-1-3, UGT-2B10, CYP6CW1, CYP4CE1, CarE and Esterase E4-1 were over-expressed both in the fat body and ovary of the resistant BPHs. Functional analyses revealed that UGT-2B10, CYP4CE1, CarE and Esterase E4-1 are essential for the resistance of BPH to chlorpyrifos. Generally, this study implicates HR83 in the metabolic detoxification-mediated chlorpyrifos resistance and suggests that the regulation of detoxification genes may be an ancestral function of the NR2E nuclear receptor subfamily.

Identification of a cytochrome P450 CYP6AB60 gene associated with tolerance to multi-plant allelochemicals from a polyphagous caterpillar tobacco cutworm (Spodoptera litura).

Generalist phytophagous insects adapt to adventurous chemical environment in a wide variety of host plants by extraordinary detoxifying metabolic abilities. However, how polyphagous insect cope with the diversity of plant defenses remains largely unknown and only a few counter-defense genes detoxifying a wide range of toxic secondary metabolites have been well characterized. Here, we identify a cytochrome P450 gene (CYP6AB60) from tobacco cutworm (Spodoptera litura) in response to three different plant's defense metabolites. After being exposed to artificial diet supplemented with coumarin (COU), xanthotoxin (XAN) or tomatine (TOM), activities of P450 and CYP6AB60 transcript levels in both midgut and fat body tissues were significantly increased. Developmental expression analysis revealed that CYP6AB60 was expressed highly during the larval stages, and tissue distribution analysis showed that CYP6AB60 was expressed extremely high in the midgut, which correspond to the physiological role of CYP6AB60 from S. litura larvae in response to plant allelochemicals. Furthermore, when larvae are injected with double-stranded RNA (dsRNA) specific to CYP6AB60, levels of this transcript in the midgut and fatbody decrease and the negative effect of plant's defense metabolites on larval growth is magnified. These data demonstrate that the generalist insect S. litura might take advantage of an individual detoxificative gene CYP6AB60 to toxic secondary metabolites from different host plants. The CYP6AB60 can be a potential gene to carry out RNAi-mediated crop protection against the major polyphagous pest S. litura in the future.

Regulation of NlE74A on vitellogenin may be mediated by angiotensin converting enzyme through a fecundity-related SNP in the brown planthopper, Nilaparvata lugens.

The major yolk protein precursors (YPP) gene, vitellogenin (Vg), usually considered as a reproductive indicator and molecular marker for evaluating insect fecundity, is controlled by insect hormone (mainly ecdysteroids and juvenile hormone), transcription factors and many other fecundity-related genes. To better understand the underlying molecular regulation mechanisms of the NlVg in the brown planthopper Nilaparvata lugens (N. lugens), the correlation between one early ecdysone response gene E74 and one important fecundity-related gene angiotensin converting enzyme (ACE) on the regulation of Vg gene expression, was investigated. We first showed that the mRNA expression level of NlACE were significantly higher in a high-fecundity population (HFP) than a low-fecundity population (LFP) at different development stages, and knockdown of NlACE expression by RNA interference (RNAi) results in a reduced level of NlVg expression and N. lugens fecundity. Subsequently, we analyzed the promoter of NlACE and found an E74A binding site, which was also differentially expressed in HFP and LFP. Then a gene putatively encoding E74A, namely NlE74A, predominant in the ovary and fat body was cloned and characterized. Furthermore, the developmental profile during female adult and the tissue-specific expression pattern of NlACE and NlE74A were similar to the expression pattern of NlVg gene, implying that both NlACE and NlE74A may be involved in regulating the expression of NlVg. Finally, after injecting the dsRNA of NlE74A, the NlACE expression levels were significantly reduced simultaneously at 24 h and 48 h post-injection, and the NlVg expression level was significant reduced at 24 h post-injection and the downswing was more significant at 48 h post-injection. These results imply that regulation of NlE74A on NlVg transcription might be mediated by NlACE through the E74 binding site at the NlACE promoter region in N. lugens.

Discovery of novel non-steroidal reverse indole mineralocorticoid receptor antagonists.

Reported herein are a series of reverse indoles that represent novel non-steroidal mineralocorticoid receptor (MR) antagonists. The key structure-activity relationships (SAR) are presented below. This reverse indole series is exemplified by a compound that demonstrated efficacy in an acute natriuresis rodent model comparable to marketed MR antagonists, spironolactone and eplerenone.

Comparative study of the gut microbial community structure of Spodoptera frugiperda and Spodoptera literal (Lepidoptera).

Background: Spodoptera frugiperda, the fall armyworm is a destructive invasive pest, and S. litura the tobacco cutworm, is a native species closely related to S. frugiperda. The gut microbiota plays a vital role in insect growth, development, metabolism and immune system. Research on the competition between invasive species and closely related native species has focused on differences in the adaptability of insects to the environment. Little is known about gut symbiotic microbe composition and its role in influencing competitive differences between these two insects. Methods: We used a culture-independent approach targeting the 16S rRNA gene of gut bacteria of 5th instar larvae of S. frugiperda and S. litura. Larvae were reared continuously on maize leaves for five generations. We analyzed the composition, abundance, diversity, and metabolic function of gut microbiomes of S. frugiperda and S. litura larvae. Results: Firmicutes, Proteobacteria, and Bacteroidetes were the dominant bacterial phyla in both species. Enterococcus, ZOR0006, Escherichia, Bacteroides, and Lactobacillus were the genera with the highest abundance in S. frugiperda. Enterococcus, Erysipelatoclostridium, ZOR0006, Enterobacter, and Bacteroides had the highest abundance in S. litura. According to α-diversity analysis, the gut bacterial diversity of S. frugiperda was significantly higher than that of S. litura. KEGG analysis showed 15 significant differences in metabolic pathways between S. frugiperda and S. litura gut bacteria, including transcription, cell growth and death, excretory system and circulatory system pathways. Conclusion: In the same habitat, the larvae of S. frugiperda and S. litura showed significant differences in gut bacterial diversity and community composition. Regarding the composition and function of gut bacteria, the invasive species S. frugiperda may have a competitive advantage over S. litura. This study provides a foundation for developing control strategies for S. frugiperda and S. litura.

Study on the prediction method of grasshopper occurrence risk in Inner Mongolia based on the maximum entropy model during the growing period.

Grasshoppers represent a significant biological challenge in Inner Mongolia's grasslands, severely affecting the region's animal husbandry. Thus, dynamic monitoring of grasshopper infestation risk is crucial for sustainable livestock farming. This study employed the Maxent model, along with remote sensing data, to forecast Oedaleus decorus asiaticus occurrence during the growing season, using grasshopper suitability habitats as a base. The Maxent model's predictive accuracy was high, with an AUC of 0.966. The most influential environmental variables for grasshopper distribution were suitable habitat data (34.27%), the temperature-vegetation dryness index during the spawning period (18.81%), and various other meteorological and vegetation factors. The risk index model was applied to calculate the grasshopper distribution across different risk levels for the years 2019-2022. The data indicated that the level 1 risk area primarily spans central, eastern, and southwestern Inner Mongolia. By examining the variable weights, the primary drivers of risk level fluctuation from 2019 to 2022 were identified as accumulated precipitation and land surface temperature anomalies during the overwintering period. This study offers valuable insights for future O. decorus asiaticus monitoring in Inner Mongolia.

Screening and functional validation of the core detoxification genes conferring broad-spectrum response to insecticides in Spodoptera frugiperda.

BACKGROUND: Fall armyworm, Spodoptera frugiperda, a formidable agricultural pest, has developed resistance to various synthetic insecticides. However, how S. frugiperda utilizes its limited energy and resources to deal with various insecticides remains largely unexplored. RESULTS: We utilized transcriptome sequencing to decipher the broad-spectrum adaptation mechanism of S. frugiperda to eight insecticides with distinct modes-of-action. Analysis of the Venn diagram revealed that 1014 upregulated genes and 778 downregulated genes were present in S. frugiperda treated with at least five different insecticides, compared to the control group. Exposure to various insecticides led to the significant upregulation of eight cytochrome P450 monooxygenases (P450s), four UDP glucosyltransferases (UGTs), two glutathione-S-transferases (GSTs) and two ATP-binding cassette transporters (ABCs). Among them, the sfCYP340AD3 and sfCYP4G74 genes were demonstrated to respond to stress from six different insecticides in S. frugiperda, as evidenced by RNA interference and toxicity bioassays. Furthermore, homology modeling and molecular docking analyses showed that sfCYP340AD3 and sfCYP4G74 possess strong binding affinities to a variety of insecticides. CONCLUSION: Collectively, these findings showed that S. frugiperda utilizes a battery of core detoxification genes to cope with the exposure of synthetic insecticides. This study also sheds light on the identification of efficient insecticidal targets gene and the development of resistance management strategies in S. frugiperda, thereby facilitating the sustainable control of this serious pest. © 2024 Society of Chemical Industry.

Dual-crosslinking gelatin-hyaluronic acid methacrylate based biomimetic PDAC desmoplastic niche enhances tumor-associated macrophages recruitment and M2-like polarization.

The tumor microenvironment (TME) of pancreatic ductal adenocarcinoma (PDAC) is characterized by deposition of desmoplastic matrix (including collagen and hyaluronic acid). And the interactions between tumor-associated macrophages (TAMs) and tumor cells play a crucial role in progression of PDAC. Hence, the appropriate model of tumor cell-macrophage interaction within the unique PDAC TME is of significantly important. To this end, a 3D tumor niche based on dual-crosslinking gelatin methacrylate and hyaluronic acid methacrylate hydrogels was constructed to simulate the desmoplastic tumor matrix with matching compressive modulus and composition. The bionic 3D tumor niche creates an immunosuppressive microenvironment characterized by the downregulation of M1 markers and upregulation of M2 markers in TAMs. Mechanistically, RNA-seq analysis revealed that the PI3K-AKT signaling pathway might modulate the phenotypic balance and recruitment of macrophages through regulating SELE and VCAM-1. Furthermore, GO and GSEA revealed the biological process of leukocyte migration and the activation of cytokine-associated signaling were involved. Finally, the 3D tumor-macrophage niches with three different ratios were fabricated which displayed increased M2-like polarization and stemness. The utilization of the 3D tumor niche has the potential to provide a more accurate investigation of the interplay between PDAC tumor cells and macrophages within an in vivo setting.

Proteomic and transcriptomic analyses of fecundity in the brown planthopper Nilaparvata lugens (Stål).

As an r-strategy insect species, the brown planthopper (BPH) Nilaparvata lugens (Stål) is a serious pest of rice crops in the temperate and tropical regions of Asia and Australia, which may be due to its robust fecundity. Here we combined 2-DE comparative proteomic and RNA-seq transcriptomic analyses to identify fecundity-related proteins and genes. Using high- and low-fecundity populations as sample groups, a total of 54 and 75 proteins were significantly altered in the third and sixth day brachypterous female stages, respectively, and 39 and 54 of these proteins were identified by MALDI-TOF/TOF MS. In addition, 71,966 unigenes were quantified by Illumina sequencing. On the basis of the transcriptomic analysis, 7408 and 1639 unigenes demonstrated higher expression levels in the high-fecundity population in the second day brachypterous female adults and the second day fifth instar nymphs, respectively, and 411 unigenes were up-regulated in both groups. Of these dozens of proteins and thousands of unigenes, five were differentially expressed at both the protein and mRNA levels at all four time points, suggesting that these genes may regulate fecundity. Glutamine synthetase (GS) was chosen for further functional studies. RNAi knockdown of the GS gene reduced the fecundity of N. lugens by 64.6%, disrupted ovary development, and inhibited vitellogenin (Vg) expression. Our results show that a combination of proteomic and transcriptomic analyses provided five candidate proteins and genes for further study. The knowledge gained from this study may lead to a more fundamental understanding of the fecundity of this important agricultural insect pest.

Insecticide Susceptibility and Detoxification Enzyme Activity of Frankliniella occidentalis under Three Habitat Conditions.

Frankliniella occidentalis is a highly destructive and invasive agricultural pest that has developed resistance to a variety of insecticide classes. Different planting structures and insecticide use frequency can directly affect the resistance development of F. occidentalis. In this study, the susceptibility of three field strains of F. occidentalis, collected over one year (April to November) from three habitat conditions (facility agriculture area, FA; open field crop area, OF; agroforestry intersection area, AI), to spinetoram, spinosad, emamectin benzoate, chlorfenapyr, acetamiprid, and imidacloprid were monitored and compared. At the same time, the detoxification enzyme activity of F. occidentalis in different habitats was determined. The results showed that the susceptibility of the F. occidentalis population in FA was significantly lower than that of populations from OF and AI. Among them, the F. occidentalis population in FA had developed low levels of resistance to spinetoram (RR = 9.18-fold), emamectin benzoate (RR = 5.47-fold), chlorfenapyr (RR = 6.67-fold), and acetamiprid (RR = 7.49-fold), and had developed moderate level resistance to imidacloprid (RR = 11.67-fold), while still being relatively sensitive to spinosad. The population of F. occidentalis from OF had developed low level resistance to spinetoram (RR = 5.24-fold) but was still relatively sensitive to the other five insecticides. The resistance of F. occidentalis from AI to six insecticides was at relatively sensitive levels. The results of the enzyme activities of detoxification enzymes, including carboxylesterase (CarE), glutathione S-transferase (GST), acetylcholinesterase (AChE), and the cytochrome P450 enzyme system (CYP450), revealed that the activities of the FA population of F. occidentalis were significantly higher than those of the other two populations. The change of CarE activity in F. occidentalis was consistent with that of spinetoram resistance, indicating that CarE may be involved in the metabolic resistance of F. occidentalis to spinetoram. Among the three populations, the resistance and detoxification enzyme activities of F. occidentalis of the FA population to six insecticides were higher than those of the other two populations. Our findings, along with other strategies, are expected to help with the resistance management of F. occidentalis in different habitats.

Effects of Septoglomus constrictum and Bacillus cereus on the competitive growth of Ageratina adenophora.

Beneficial microorganisms play a pivotal role in the invasion process of exotic plants, including arbuscular mycorrhizal fungi (AMF) and Bacillus. However, limited research exists on the synergistic influence of AMF and Bacillus on the competition between both invasive and native plants. In this study, pot cultures of Ageratina adenophora monoculture, Rabdosia amethystoides monoculture, and A. adenophora and R. amethystoides mixture were used to investigate the effects of dominant AMF (Septoglomus constrictum, SC) and Bacillus cereus (BC), and the co-inoculation of BC and SC on the competitive growth of A. adenophora. The results showed that inoculation with BC, SC, and BC + SC significantly increased the biomass of A. adenophora by 14.77, 112.07, and 197.74%, respectively, in the competitive growth between A. adenophora and R. amethystoides. Additionally, inoculation with BC increased the biomass of R. amethystoides by 185.07%, while inoculation with SC or BC + SC decreased R. amethystoides biomass by 37.31 and 59.70% compared to the uninoculated treatment. Inoculation with BC significantly increased the nutrient contents in the rhizosphere soil of both plants and promoted their growth. Inoculation with SC or SC + BC notably increased the nitrogen and phosphorus contents of A. adenophora, therefore enhancing its competitiveness. Compared with single inoculation, dual inoculation with SC and BC increased AMF colonization rate and Bacillus density, indicating that SC and BC can form a synergistic effect to further enhance the growth and competitiveness of A. adenophora. This study reveals the distinct role of S. constrictum and B. cereus during the invasion of A. adenophora, and provide new clues to the underlying mechanisms of interaction between invasive plant, AMF and Bacillus.

Analysis of Spatiotemporal Variation in Habitat Suitability for Oedaleus decorus asiaticus Bei-Bienko on the Mongolian Plateau Using Maxent and Multi-Source Remote Sensing Data.

O. decorus asiaticus is a major grasshopper species that harms the development of agriculture on the Mongolian Plateau. Therefore, it is important to enhance the monitoring of O. decorus asiaticus. In this study, the spatiotemporal variation in the habitat suitability for O. decorus asiaticus on the Mongolian Plateau was assessed using maximum entropy (Maxent) modeling along with multi-source remote sensing data (meteorology, vegetation, soil, and topography). The predictions of the Maxent model were accurate (AUC = 0.910). The key environmental variables affecting the distribution of grasshoppers and their contribution were grass type (51.3%), accumulated precipitation (24.9%), altitude (13.0%), vegetation coverage (6.6%), and land surface temperature (4.2%). Based on the assessment results of suitability by Maxent model, the model threshold settings, and the formula for calculating the inhabitability index, the 2000s, 2010s, and 2020s inhabitable areas were calculated. The results show that the distribution of suitable habitat for O. decorus asiaticus in 2000 was similar to that in 2010. From 2010 to 2020, the suitability of the habitat for O. decorus asiaticus in the central region of the Mongolian Plateau changed from moderate to high. The main factor contributing to this change was accumulated precipitation. Few changes in the areas of the habitat with low suitability were observed across the study period. The results of this study enhance our understanding of the vulnerability of different regions on the Mongolian Plateau to plagues of O. decorus asiaticus and will aid the monitoring of grasshopper plagues in this region.

Genome-Wide Scanning Loci and Differentially Expressed Gene Analysis Unveils the Molecular Mechanism of Chlorantraniliprole Resistance in Spodoptera frugiperda.

Chlorantraniliprole has been widely used to controlSpodoptera frugiperda, but it has led to the development of chlorantraniliprole resistance. Multiomics analysis of strains with two extreme traits helps to elucidate the complex mechanisms involved. Herein, following genome resequencing and application of the Euclidean distance algorithm, 550 genes within a 16.20-Mb-linked region were identified from chlorantraniliprole-resistant (Ch-R) and chlorantraniliprole-susceptible (Ch-Sus) strains. Using transcriptome sequencing, 2066 differentially expressed genes were identified between Ch-R and Ch-Sus strains. Through association analysis, three glutathione S-transferase family genes and four trehalose transporter genes were selected for functional verification. Notably, SfGSTD1 had the strongest binding ability with chlorantraniliprole and is responsible for chlorantraniliprole tolerance. The Ch-R strain also increased the intracellular trehalose content by upregulating the transcription of SfTret1, thereby contributing to chlorantraniliprole resistance. These findings provide a new perspective to reveal the mechanism of resistance of agricultural pests to insecticides.

CYP321A Subfamily P450s Contribute to the Detoxification of Phytochemicals and Pyrethroids in Spodoptera litura.

Although the induction of cytochrome P450 monooxygenases involved in insect detoxification has been well documented, the underlying regulatory mechanisms remain obscure. In Spodoptera litura, CYP321A subfamily members were effectively induced by exposure to flavone, xanthotoxin, curcumin, and λ-cyhalothrin, while knockdown of the CYP321A genes increased larval susceptibility to these xenobiotics. Homology modeling and molecular docking analyses showed that these four xenobiotics could stably bind to the CYP321A enzymes. Furthermore, two transcription factor genes, CncC and MafK, were significantly induced by the xenobiotics. Knockdown of CncC or MafK reduced the expression of four CYP321A genes and increased larval susceptibility to the xenobiotics. Dual-luciferase reporter assays showed that cotransfection of reporter plasmids carrying the CYP321A promoter with CncC and/or MafK-expressing constructs significantly magnified the promoter activity. These results indicate that the induction of CYP321A subfamily members conferring larval detoxification capability to xenobiotics is mediated by the activation of CncC and MafK.

Assessment on Potential Suitable Habitats of the Grasshopper Oedaleus decorus asiaticus in North China based on MaxEnt Modeling and Remote Sensing Data.

Grasshopper populations can quickly grow to catastrophic levels, causing a huge amount of damage in a short time. Oedaleus decorus asiaticus (Bey-Bienko) (O. d. asiaticus) is the most serious species in Xilingol League of the Inner Mongolia Autonomous Region. The region is not only an important grassland but also a site of agricultural heritage systems in China. Therefore, projecting the potential geographic distribution of O. d. asiaticus to provide an early warning is vital. Here, we combined temperature, precipitation, soil, vegetation, and topography with remote sensing data to screen the predictors that best characterize the current geographical distribution of O. d. asiaticus. A MaxEnt model approach was applied to project the potential suitable distribution of O. d. asiaticus in Xilingol League (the Inner Mongolia Autonomous Region of China) combined with a set of optimized parameters. The modeling results indicated that there were six main habitat factors that determined the suitable distribution of O. d. asiaticus such as the soil type (ST), grassland type (GT), elevation, precipitation during the growing period (GP), precipitation during the spawning period (SP), and normalized difference vegetation index during the overwintering period (ONDVI). The simulated result was good, with average AUC and TSS values of 0.875 and 0.812, respectively. The potential inhabitable areas of grasshoppers were 198,527 km2, distributed mainly in West Urumqi, Xilinhot City, East Urumqi, Abaga Banner, and Xianghuang Banner of Xilingol League. This study is valuable to guide managers and decision-makers to prevent and control the occurrence of O. d. asiaticus early on and this study may facilitate meaningful reductions in pesticide application.