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Insect lytic polysaccharide monooxygenases (LPMO15s) are newly discovered copper‐dependent enzymes that promote chitin degradation in insect through oxidative cleavage of glycosidic bonds. They are potential pesticide targets due to their critical role for chitin turnover in the integument, trachea, and peritrophic matrix of the midgut during insect molting. However, the knowledge about whether and how LPMO15s participate in chitin turnover in other tissues is still insufficient. Here, using the orthopteran pest Locusta migratoria as a model, a novel alternative splicing site of LmLPMO15‐1 was discovered and it produces 2 variants, LmLPMO15‐1a and LmLPMO15‐1b. The transcripts of LmLPMO15‐1a and LmLPMO15‐1b were specifically expressed in the trachea and foregut, respectively. RNA interference targeting LmLPMO15‐1 (a common fragment shared by both LmLPMO15‐1a and LmLPMO15‐1b), a specific region of LmLPMO15‐1a or LmLPMO15‐1b all significantly reduced survival rate of nymphs and induced lethal phenotypes with developmental stasis or molt failure. Ultrastructure analysis demonstrated that LmLPMO15‐1b was specifically involved in foregut old cuticle degradation, while LmLPMO15‐1a was exclusively responsible for the degradation of the tracheal old cuticle. This study revealed LmLPMO15‐1 achieved tissue‐specific functional differentiation through alternative splicing, and proved the significance of the spliced variants during insect growth and development. It provides new strategies for pest control targeting LPMO15‐1. [ABSTRACT FROM AUTHOR]

RNA N6-methyladenosine (m6A), as the most abundant modification of messenger RNA, can modulate insect behaviors, but its specific roles in aggregation behaviors remain unexplored. Here, we conducted a comprehensive molecular and physiological characterization of the individual components of the methyltransferase and demethylase in the migratory locust Locusta migratoria. Our results demonstrated that METTL3, METTL14 and ALKBH5 were dominantly expressed in the brain and exhibited remarkable responses to crowding or isolation. The individual knockdown of methyltransferases (i.e., METTL3 and METTL14) promoted locust movement and conspecific attraction, whereas ALKBH5 knockdown induced a behavioral shift toward the solitary phase. Furthermore, global transcriptome profiles revealed that m6A modification could regulate the orchestration of gene expression to fine tune the behavioral aggregation of locusts. In summary, our in vivo characterization of the m6A functions in migratory locusts clearly demonstrated the crucial roles of the m6A pathway in effectively modulating aggregation behaviors. [ABSTRACT FROM AUTHOR]

Low-density lipoprotein receptor-related protein 2 (LRP2) is a multifunctional endocytic receptor expressed in epithelial cells. In mammals, it acts as an endocytic receptor that mediates the cellular uptake of cholesterol-containing apolipoproteins to maintain lipid homeostasis. However, little is known about the role of LRP2 in lipid homeostasis in insects. In the present study, we investigated the function of LRP2 in the migratory locust Locusta migratoria (LmLRP2). The mRNA of LmLRP2 is widely distributed in various tissues, including integument, wing pads, foregut, midgut, hindgut, Malpighian tubules and fat body, and the amounts of LmLRP2 transcripts decreased gradually in the early stages and then increased in the late stages before ecdysis during the nymphal developmental stage. Fluorescence immunohistochemistry revealed that the LmLRP2 protein is mainly located in cellular membranes of the midgut and hindgut. Using RNAi to silence LmLRP2 caused molting defects in nymphs (more than 60%), and the neutral lipid was found to accumulate in the midgut and surface of the integument, but not in the fat body, of dsLmLRP2-treated nymphs. The results of a lipidomics analysis showed that the main components of lipids (diglyceride and triglyceride) were significantly increased in the midgut, but decreased in the fat body and hemolymph. Furthermore, the content of total triglyceride was significantly increased in the midgut, but markedly decreased in the fat body and hemolymph in dsLmLRP2-injected nymphs. Our results indicate that LmLRP2 is located in the cellular membranes of midgut cells, and is required for lipid export from the midgut to the hemolymph and fat body in locusts.

Wings are an important flight organ of insects. Wing development is a complex process controlled by a series of genes. The flightless wing pad transforms into a mature wing with the function of migratory flight during the nymph-to-adult metamorphosis. However, the mechanism of wing morphogenesis in locusts is still unclear. This study analyzed the microstructures of the locust wing pads at pre-eclosion and the wings after eclosion and performed the comparative transcriptome analysis. RNA-seq identified 25,334 unigenes and 3,430 differentially expressed genes (DEGs) (1,907 up-regulated and 1,523 down-regulated). The DEGs mainly included cuticle development (LmACPs), chitin metabolism (LmIdgf4), lipid metabolism-related genes, cell adhesion (Integrin), zinc finger transcription factors (LmSalm, LmZF593 and LmZF521), and others. Functional analysis based on RNA interference and hematoxylin and eosin (H&E) staining showed that the three genes encoded zinc finger transcription factors are essential for forming wing cuticle and maintaining morphology in Locusta migratoria. Finally, the study found that the LmSalm regulates the expression of LmACPs in the wing pads at pre-eclosion, and LmZF593 and LmZF521 regulate the expression of LmIntegrin/LmIdgf4/LmHMT420 in the wings after eclosion. This study revealed that the molecular regulatory axis controls wing morphology in nymphal and adult stages of locusts, offering a theoretical basis for the study of wing development mechanisms in hemimetabolous insects.

Locust (Locusta migratoria) has a single striated muscle myosin heavy chain (Mhc) gene, which contains 5 clusters of alternative exclusive exons and 1 differently included penultimate exon. The alternative exons of Mhc gene encode 4 distinct regions in the myosin motor domain, that is, the N‐terminal SH3‐like domain, one lip of the nucleotide‐binding pocket, the relay, and the converter. Here, we investigated the role of the alternative regions on the motor function of locust muscle myosin. Using Sf9‐baculovirus protein expression system, we expressed and purified 5 isoforms of the locust muscle myosin heavy meromyosin (HMM), including the major isoform in the thorax dorsal longitudinal flight muscle (FL1) and 4 isoforms expressed in the abdominal intersegmental muscle (AB1 to AB4). Among these 5 HMMs, FL1‐HMM displayed the highest level of actin‐activated adenosine triphosphatase (ATPase) activity (hereafter referred as ATPase activity). To identify the alternative region(s) responsible for the elevated ATPase activity of FL1‐HMM, we produced a number of chimeras of FL1‐HMM and AB4‐HMM. Substitution with the relay of AB4‐HMM (encoded by exon‐14c) substantially decreased the ATPase activity of FL1‐HMM, and conversely, the relay of FL1‐HMM (encoded by exon‐14a) enhanced the ATPase activity of AB4‐HMM. Mutagenesis showed that the exon‐14a‐encoded residues Gly474 and Asn509 are responsible for the elevated ATPase activity of FL1‐HMM. Those results indicate that the alternative relay encoded by exon‐14a/c play a key role in regulating the ATPase activity of FL1‐HMM and AB4‐HMM. [ABSTRACT FROM AUTHOR]

This study investigated the influence of different linearly polarized spectrum lights on locusts polartactic response characteristics linearly polarized vector sensitivity mode and polartactic response) by using linearly polarized spectrum vector light module and experimental device. The objective was to clarify the vector sensitivity characteristics and functional effect of linearly polarized light spectrum intensity on locusts polartactic response, determine the influence specificity of linearly polarized spectrum illumination properties on locusts polarization-related behavior. When spectrum and illumination were constant, locusts polartactic response, presenting the response feature of sine and cosine function change specificity, was related to spectrum attribute. The visual acuity effect stimulated by violet spectrum was the best, whereas the optical distance modulation effect induced by orange spectrum was the strongest. When illumination was enhanced, locusts vector sensitivity mode shifted to present the specific sensitivity prompted by light intensity at long distance and inhibited by light intensity at short distance. Moreover, the regulating function of violet spectrum was the strongest, and the regulatory mutation effect of orange spectrum was the least significant. Simultaneously, locusts polartactic sensitivity to 300° vector at 100 lx, whereas to 240° vector at 1000 lx of linearly polarized violet light was the strongest. Locusts polartactic aggregation and visual tendency sensitivity to 90° vector at 100 lx, whereas to 270° vector at 1000 lx of linearly polarized violet light was the strongest. The heterogeneous regulation function of different linearly polarized spectrum couplings with light intensity led to significant variations in locusts vector sensitivity mode. This was derived from the antagonistic and specific tuning characteristics of locusts polartactic vision, reflecting the integrated output effect of locusts vector dependence regulated by linearly polarized spectrum intensity attribute. The findings were significant for the construction of pest polarization induction light sources and the investigation of the sensitive physiology pathway of locusts polarization vision. [ABSTRACT FROM AUTHOR]

Simple Summary: Fushi Tarazu Factor-1 (FTZ-F1) is a member of the nuclear receptor superfamily, which plays an important role in the molting process of insects. In this study, two FTZ-F1 transcripts (LmFTZ-F1-X1 and LmFTZ-F1-X2) were identified in Locusta migratoria, which were highly expressed in the cuticle. Then, the function of LmFTZ-F1-X1 and LmFTZ-F1-X2 in the molting process was explored using RNA interference. Silencing LmFTZ-F1-X1 and LmFTZ-F1-X2 separately did not affect the normal development of the nymph, but the simultaneous RNAi of LmFTZ-F1-X1 and LmFTZ-F1-X2 blocked the nymphal molting by regulating the genes involved in cuticle formation, chitin synthesis, and other key molting processes. Fushi-tarazu factor 1 (FTZ-F1) is a class of transcription factors belonging to the nuclear receptor superfamily and an important molting regulator in insects; however, its detailed function in the molting process of Locusta migratoria is still unclear. This study identified two FTZ-F1 transcripts (LmFTZ-F1-X1 and LmFTZ-F1-X2) in L. migratoria. The classical domains of FTZ-F1 were present in their protein sequences and distinguished based on their variable N-terminal domains. Reverse-transcription quantitative polymerase chain reaction analysis revealed that LmFTZ-F1-X1 and LmFTZ-F1-X2 were highly expressed in the integument. RNA interference (RNAi) was used to explore the function of LmFTZ-F1s in the molting of the third-instar nymph. Separate LmFTZ-F1-X1 or LmFTZ-F1-X2 silencing did not affect the normal development of third-instar nymphs; however, the simultaneous RNAi of LmFTZ-F1-X1 and LmFTZ-F1-X2 caused the nymphs to be trapped in the third instar stage and finally die. Furthermore, the hematoxylin-eosin and chitin staining of the cuticle showed that the new cuticles were thickened after silencing the LmFTZ-F1s compared to the controls. RNA-seq analysis showed that genes encoding four cuticle proteins, two chitin synthesis enzymes, and cytochrome P450 303a1 were differentially expressed between dsGFP- and dsLmFTZ-F1s-injected groups. Taken together, LmFTZ-F1-X1 and LmFTZ-F1-X2 are involved in the ecdysis of locusts, possibly by regulating the expression of genes involved in cuticle formation, chitin synthesis, and other key molting processes. [ABSTRACT FROM AUTHOR]

ABSTRACT Locusta migratoria is an important phytophagous pest, and its gut microbial communities play an important role in cellulose degradation. In this study, the gut microbial and cellulose digestibility dynamics of Locusta migratoria were jointly analyzed using high-throughput sequencing and anthrone colorimetry. The results showed that the gut microbial diversity and cellulose digestibility across life stages were dynamically changing. The species richness of gut bacteria was significantly higher in eggs than in larvae and imago, the species richness and cellulose digestibility of gut bacteria were significantly higher in early larvae (first and second instars) than in late larvae (third to fifth instars), and the diversity of gut bacteria and cellulose digestibility were significantly higher in imago than in late larvae. There is a correlation between the dynamics of gut bacterial communities and cellulose digestibility. Enterobacter, Lactococcus, and Pseudomonas are the most abundant genera throughout all life stages. Six strains of highly efficient cellulolytic bacteria were screened, which were dominant gut bacteria. Carboxymethyl cellulase activity (CMCA) and filter paper activity (FPA) experiments revealed that Pseudomonas had the highest cellulase enzyme activity. This study provides a new way for the screening of cellulolytic bacteria and lays the foundation for developing insects with significant biomass into cellulose-degrading bioreactors.IMPORTANCECellulose is the most abundant and cheapest renewable resource in nature, but its degradation is difficult, so finding efficient cellulose degradation methods is an urgent challenge. Locusta migratoria is a large group of agricultural pests, and the large number of microorganisms that inhabit their intestinal tracts play an important role in cellulose degradation. We analyzed the dynamics of Locusta migratoria gut microbial communities and cellulose digestibility using a combination of high-throughput sequencing technology and anthrone colorimetry. The results revealed that the gut microbial diversity and cellulose digestibility were dynamically changed at different life stages. In addition, we explored the intestinal bacterial community of Locusta migratoria across life stages and its correlation with cellulose digestibility. The dominant bacterial genera at different life stages of Locusta migratoria were uncovered and their carboxymethyl cellulase activity (CMCA) and filter paper activity (FPA) were determined. This study provides a new avenue for screening cellulolytic bacteria and lays the foundation for developing insects with significant biomass into cellulose-degrading bioreactors.

Fushi-tarazu factor 1 (FTZ-F1) is a class of transcription factors belonging to the nuclear receptor superfamily and an important molting regulator in insects; however, its detailed function in the molting process of Locusta migratoria is still unclear. This study identified two FTZ-F1 transcripts (LmFTZ-F1-X1 and LmFTZ-F1-X2) in L. migratoria. The classical domains of FTZ-F1 were present in their protein sequences and distinguished based on their variable N-terminal domains. Reverse-transcription quantitative polymerase chain reaction analysis revealed that LmFTZ-F1-X1 and LmFTZ-F1-X2 were highly expressed in the integument. RNA interference (RNAi) was used to explore the function of LmFTZ-F1s in the molting of the third-instar nymph. Separate LmFTZ-F1-X1 or LmFTZ-F1-X2 silencing did not affect the normal development of third-instar nymphs; however, the simultaneous RNAi of LmFTZ-F1-X1 and LmFTZ-F1-X2 caused the nymphs to be trapped in the third instar stage and finally die. Furthermore, the hematoxylin-eosin and chitin staining of the cuticle showed that the new cuticles were thickened after silencing the LmFTZ-F1s compared to the controls. RNA-seq analysis showed that genes encoding four cuticle proteins, two chitin synthesis enzymes, and cytochrome P450 303a1 were differentially expressed between dsGFP- and dsLmFTZ-F1s-injected groups. Taken together, LmFTZ-F1-X1 and LmFTZ-F1-X2 are involved in the ecdysis of locusts, possibly by regulating the expression of genes involved in cuticle formation, chitin synthesis, and other key molting processes.

Immunity and reproduction are vital functions for the survival and population maintenance of female insects. However, owing to limited resources, these two functions cannot be fulfilled simultaneously, resulting in an energy tradeoff between them. Notably, the mechanisms underlying this immune-reproductive trade-off, in which energy competition likely plays a central role, remain poorly understood. Fatty acid synthase (FAS), a key gene involved in lipid synthesis and insect energy metabolism, was investigated in this study using Locusta migratoria as the research subject. Bacterial infection and RNA interference (RNAi) technology were used to examine changes in the immunity, fecundity, and energy metabolism patterns of locusts under different treatments. The findings of this study demonstrate that infection with Micrococcus luteus triggers an immune response in locusts, significantly upregulates the expression of defensin 3 (DEF3) and Attacin , and enhances pHenoloxidase (PO) activity. Upon FAS2 silencing, bacterial attack upregulated DEF3 and Attacin expression to a lesser extent, leading to increased lysozyme activity instead of PO. Furthermore, bacterial infection results in a decrease in glycogen and glucose content in the fat body, accompanied by a significant increase in triacylglycerol (TAG) content. However, after FAS2 knockdown, both the lipid and carbohydrate contents were significantly reduced in the fat body. Compared with bacterial infection alone, low FAS2 expression further exacerbated fecundity impairment in locusts. The expression levels of vitellogenin A (VgA) and vitellogenin B (VgB) were significantly low, with severe ovarian atrophy observed. Notably, the ovarian weight was only 21 % compared to that of the control group. Moreover, females exhibited minimal egg-laying behavior. In summary, our findings suggest that following FAS2 gene silencing, there is a greater inclination toward immune stimulation energy activation in locusts, whereas reproductive investment is reduced. The outcomes of this study will contribute to the further exploration of the molecular mechanisms underlying the trade-off between immune and reproductive energy in locusts. [Display omitted] • M. luteus infection reduces the fecundity of locusts. • LmFAS2 plays an important role in lipid synthesis and reproduction. • dsFAS2 + M. luteus infection seriously impaired the fecundity of locusts. [ABSTRACT FROM AUTHOR]

Paranosema locustae is an environmentally friendly parasitic predator with promising applications in locust control. In this study, transcriptome sequencing was conducted on gonadal tissues of Locusta migratoria males and females infected and uninfected with P. locustae at different developmental stages. A total of 18,635 differentially expressed genes (DEGs) were identified in female ovary tissue transcriptomes, with the highest number of DEGs observed at 1 day post-eclosion (7141). In male testis tissue transcriptomes, a total of 32,954 DEGs were identified, with the highest number observed at 9 days post-eclosion (11,245). Venn analysis revealed 25 common DEGs among female groups and 205 common DEGs among male groups. Gene ontology and Kyoto Encyclopaedia of Genes and Genome analyses indicated that DEGs were mainly enriched in basic metabolism such as amino acid metabolism, carbohydrate metabolism, lipid metabolism, and immune response processes. Protein-protein interaction analysis results indicated that L. migratoria regulates the expression of immune- and reproductive-related genes to meet the body's demands in different developmental stages after P. locustae infection. Immune- and reproductive-related genes in L. migratoria gonadal tissue were screened based on database annotation information and relevant literature. Genes such as Tsf , Hex1 , Apolp-III , Serpin , Defense , Hsp70 , Hsp90 , JHBP , JHE , JHEH1 , JHAMT , and VgR play important roles in the balance between immune response and reproduction in gonadal tissues. For transcriptome validation, Tsf , Hex1 , and ApoLp-III were selected and verified by quantitative real-time polymerase chain reaction (qRT-PCR). Correlation analysis revealed that the qRT-PCR expression patterns were consistent with the RNA-Seq results. These findings contribute to further understanding the interaction mechanisms between locusts and P. locustae .

Energy metabolism is essential for insect development, reproduction and detoxification. Insects often reallocate energy and resources to manage external stress, balancing the demands of detoxification and reproduction. Glucose transport 4 (Glut4), a glucose transporter, is involved in glucose and lipid metabolism. However, the specific molecular mechanism of Glut4 in insect reproduction, and its role in the response to insecticide-induced oxidative stress remain unclear. In this study, LmGlut4 was identified and analyzed in Locusta migratoria. Silencing of LmGlut4 significantly reduced vitellogenin (Vg) biosynthesis in the fat body and Vg absorption by oocytes, ultimately hindering ovarian development and oocyte maturation. Knockdown of LmGlut4 also inhibited the biosynthesis of key insect hormones, such as juvenile hormone (JH), 20-hydroxyecdysone (20E) and insulin. Furthermore, LmGlut4 knockdown led to reduced triglyceride (TG) and glycogen content in the fat body and ovary, as well as decreased capacity for trehalose biosynthesis in adipocytes. Additionally, ds LmGlut4 -treated locusts showed heightened sensitivity to deltamethrin, leading to increased triglyceride depletion during detoxification. This study sheds light on the biological function of LmGlut4 in the ovary and provides potential target genes for exploring biological pest management strategies. Schematic representation of how LmGlut4 affects female reproduction in Locusta migratoria. LmGlut4 directly or indirectly induces, at least in part via the JH, 20E and insulin pathways, Vg synthesis in the fat body and utilization in developing oocyte. ds LmGlut4 disrupts triglyceride and glycogen storage in fat bodies and oocytes, leading to severe energy depletion in deltamethrin-treated locusts. Figure concept references (Wang et al., 2021; Zheng et al., 2021). [Display omitted] • LmGlut4 regulates vitellogenin (Vg) biosynthesis and oocyte maturation in Locusta migratoria. • Knockdown of LmGlut4 disrupts hormone biosynthesis (JH / 20E and insulin). • Knockdown of LmGlut4 affects glycolipid metabolism. • LmGlut4 deficiency exacerbates energy depletion due to oxidative stress induced by deltamethrin. [ABSTRACT FROM AUTHOR]

The representation of odors in the locust antennal lobe with its >2,000 glomeruli has long remained a perplexing puzzle. We employed the CRISPR-Cas9 system to generate transgenic locusts expressing the genetically encoded calcium indicator GCaMP in olfactory sensory neurons. Using two-photon functional imaging, we mapped the spatial activation patterns representing a wide range of ecologically relevant odors across all six developmental stages. Our findings reveal a functionally ring-shaped organization of the antennal lobe composed of specific glomerular clusters. This configuration establishes an odor-specific chemotopic representation by encoding different chemical classes and ecologically distinct odors in the form of glomerular rings. The ring-shaped glomerular arrangement, which we confirm by selective targeting of OR70a-expressing sensory neurons, occurs throughout development, and the odor-coding pattern within the glomerular population is consistent across developmental stages. Mechanistically, this unconventional spatial olfactory code reflects the locust-specific and multiplexed glomerular innervation pattern of the antennal lobe. [Display omitted] • A transgenic line was established to express GCaMP6s in olfactory sensory neurons • Calcium imaging reveals a functionally ring-shaped odor code of glomerular clusters • Distinct ring regions encode chemical identity and ecological significance • The ring-shaped odor-coding pattern occurs consistently throughout development Migratory locusts, genetically expressing the calcium sensor GCaMP6s in olfactory sensory neurons, have an unconventional, ring-shaped olfactory code of glomerular clusters in the antennal lobe, a pattern that occurs consistently throughout development. [ABSTRACT FROM AUTHOR]

Syntaxin5 (Syx5) belongs to SNAREs family, which play important roles in fusion of vesicles to target membranes. Most of what we know about functions of Syx5 originates from studies in fungal or vertebrate cells, how Syx5 operates during the development of insects is poorly understood. In this study, we investigated the role of LmSyx5 in the gut development of the hemimetabolous insect Locusta migratoria. LmSyx5 was expressed in many tissues, with higher levels in the gut. Knockdown of LmSyx5 by RNA interference (RNAi) considerably suppressed feeding in both nymphs and adults. The ds LmSyx5- injected locusts lost body weight and finally died at a mortality of 100%. Furthermore, hematoxylin-eosin staining indicated that the midgut is deformed in ds LmSyx5 -treated nymphs and the brush border in midgut epithelial cells is severely damaged, suggesting that LmSyx5 is involved in morphogenesis of the midgut. TEM further showed that the endoplasmic reticulum of midgut cells have a bloated appearance. Taken together, these results suggest that LmSyx5 is essential for midgut epithelial homeostsis that affects growth and development of L. migratoria. Thus, Syx5 is a promising RNAi target for controlling L. migratoria , and even other pests. [Display omitted] • Knockdown of LmSyx5 caused 100% mortality by regulating feeding. • LmSyx5 plays important roles in the development of the midgut. • The endoplasmic reticulum morphology required LmSyx5 function. [ABSTRACT FROM AUTHOR]

Syntaxin 1A (Syx1A) has diverse and indispensable functions in animals. Previous studies have mainly focused on the roles of Syx1A in Drosophila, and so how Syx1A operates during the development of other insects remains poorly understood. This study investigated whether disrupting LmSyx1A using RNA interference (RNAi) affects the growth and development of Locusta migratoria. LmSyx1A was expressed in all tissues tested, with the highest expression observed in the fat body. After 5th-instar nymphs were injected with double-stranded LmSyx1A (dsLmSyx1A), none of the nymphs were able to molt normally and all eventually died. The silencing of LmSyx1A resulted in the cessation of feeding, body weight loss, and atrophy of the midgut and gastric cecum in locusts. Hematoxylin and eosin (H&E) staining showed that the columnar cells in the midgut were severely damaged, with microvilli defects visible in dsLmSyx1A-injected nymphs. Secretory vesicles were observed with transmission electron microscopy (TEM). In addition, reverse transcription quantitative polymerase chain reaction (RT-qPCR) further indicates that silencing LmSyx1A repressed the expression of genes involved in the insulin/mammalian target of rapamycin (mTOR)-associated nutritional pathway. Taken together, these results suggest that LmSyx1A significantly affects the midgut cell layer of locust nymphs, which was partially associated with the downregulation of the insulin/mTOR-associated nutritional pathway. Thus, we argue that LmSyx1A is a suitable target for developing dsRNA-based biological pesticides for managing L. migratoria., (© 2024 Institute of Zoology, Chinese Academy of Sciences.)

Locusta migratoria is an important phytophagous pest, and its gut microbial communities play an important role in cellulose degradation. In this study, the gut microbial and cellulose digestibility dynamics of Locusta migratoria were jointly analyzed using high-throughput sequencing and anthrone colorimetry. The results showed that the gut microbial diversity and cellulose digestibility across life stages were dynamically changing. The species richness of gut bacteria was significantly higher in eggs than in larvae and imago, the species richness and cellulose digestibility of gut bacteria were significantly higher in early larvae (first and second instars) than in late larvae (third to fifth instars), and the diversity of gut bacteria and cellulose digestibility were significantly higher in imago than in late larvae. There is a correlation between the dynamics of gut bacterial communities and cellulose digestibility. Enterobacter , Lactococcus, and Pseudomonas are the most abundant genera throughout all life stages. Six strains of highly efficient cellulolytic bacteria were screened, which were dominant gut bacteria. Carboxymethyl cellulase activity (CMCA) and filter paper activity (FPA) experiments revealed that Pseudomonas had the highest cellulase enzyme activity. This study provides a new way for the screening of cellulolytic bacteria and lays the foundation for developing insects with significant biomass into cellulose-degrading bioreactors., Importance: Cellulose is the most abundant and cheapest renewable resource in nature, but its degradation is difficult, so finding efficient cellulose degradation methods is an urgent challenge. Locusta migratoria is a large group of agricultural pests, and the large number of microorganisms that inhabit their intestinal tracts play an important role in cellulose degradation. We analyzed the dynamics of Locusta migratoria gut microbial communities and cellulose digestibility using a combination of high-throughput sequencing technology and anthrone colorimetry. The results revealed that the gut microbial diversity and cellulose digestibility were dynamically changed at different life stages. In addition, we explored the intestinal bacterial community of Locusta migratoria across life stages and its correlation with cellulose digestibility. The dominant bacterial genera at different life stages of Locusta migratoria were uncovered and their carboxymethyl cellulase activity (CMCA) and filter paper activity (FPA) were determined. This study provides a new avenue for screening cellulolytic bacteria and lays the foundation for developing insects with significant biomass into cellulose-degrading bioreactors., Competing Interests: The authors declare no conflict of interest.

The coat protein II (COPII) complex consists of five primary soluble proteins, namely the small GTP-binding protein Sar1, the inner coat Sec23/Sec24 heterodimers, and the outer coat Sec13/Sec31 heterotetramers. COPII is essential for cellular protein and lipid trafficking through cargo sorting and vesicle formation at the endoplasmic reticulum. However, the roles of COPII assembly genes remain unknown in insects. In present study, we identified five COPII assembly genes (LmSar1 , LmSec23 , LmSec24 , LmSec13 and LmSec31) in Locusta migratoria. RT-qPCR results revealed that these genes showed different expression patterns in multiple tissues and developmental days of fifth-instar nymphs. Injection of double-stranded RNA against each LmCOPII gene induced a high RNAi efficiency, and considerably suppressed feeding, and increased mortality to 100 %. Results from the micro-sectioning and hematoxylin–eosin staining of midguts showed that the brush border was severely damaged and the number of columnar cells was significantly reduced in ds LmCOPII -injected nymphs, as compared with the control. The dilated endoplasmic reticulum phenotype of columnar cells was observed by transmission electron microscopy. RT-qPCR results further indicated that silencing any of the five genes responsible for COPII complex assembly repressed the expression of genes involved in insulin/mTOR-associated nutritional pathway. Therefore, COPII assembly genes could be promising RNAi targets for insect pest management by disrupting gut and cuticle development. [ABSTRACT FROM AUTHOR]

The Osiris gene family is believed to play important roles in insect biology. Previous studies mainly focused on the roles of Osiris in Drorophila , how Osiris operates during the development of other species remains largely unknown. Here, we investigated the role of LmOsi17 in development of the hemimetabolous insect Locusta migratoria. LmOsi17 was highly expressed in the intestinal tract of nymphs. Knockdown of LmOsi17 by RNA interference (RNAi) in nymphs resulted in growth defects. The ds LmOsi17 -injected nymphs did not increase in body weight or size and eventually died. Immunohistochemical analysis showed that LmOsi17 was localized to the epithelial cells of the foregut and the gastric caecum. Histological observation and hematoxylin-eosin staining indicate that the foregut and gastric caecum are deformed in ds LmOsi17 treated nymphs, suggesting that LmOsi17 is involved in morphogenesis of foregut and gastric caecum. In addition, we observed a significant reduction in the thickness of the new cuticle in ds LmOsi17 -injected nymphs compared to control nymphs. Taken together, these results suggest that LmOsi17 contributes to morphogenesis of intestinal tract that affects growth and development of nymphs in locusts. [Display omitted] • LmOsi17 is highly expressed in the intestinal tract of locusts. • Knockdown of LmOsi17 disrupts nymphal growth and development. • LmOsi17 is required for morphogenesis of gastric caecum and foregut. • New cuticle thickening is affected in LmOsi17 silenced nymphs. [ABSTRACT FROM AUTHOR]

7-dehydrocholesterol (7-DHC) is a key intermediate product used for biosynthesis of molting hormone. This is achieved through a series of hydroxylation reactions catalyzed by the Halloween family of cytochrome P450s. Neverland is an enzyme catalyzes the first reaction of the ecdysteroidogenic pathway, which converts dietary cholesterol into 7-DHC. However, research on the physiological function of neverland in orthopteran insects is lacking. In this study, neverland from Locusta migratoria (LmNvd) was cloned and analyzed. LmNvd was mainly expressed in the prothoracic gland and highly expressed on days 6 and 7 of fifth instar nymphs. RNAi-mediated silencing of LmNvd resulted in serious molting delays and abnormal phenotypes, which could be rescued by 7-DHC and 20-hydroxyecdysone supplementation. Hematoxylin and eosin staining results showed that RNAi-mediated silencing of LmNvd disturbed the molting process by both promoting the synthesis of new cuticle and suppressing the degradation of the old cuticle. Quantitative real-time PCR results suggested that the mRNA expression of E75 early gene and chitinase 5 gene decreased and that of chitin synthase 1 gene was markedly upregulated after knockdown of LmNvd. Our results suggest that LmNvd participates in the biosynthesis process of molting hormone, which is involved in regulating chitin synthesis and degradation in molting cycles. [Display omitted] • LmNvd was and highly expressed in the sixth to seventh days in prothoracic gland of fifth-instar nymphs. • RNA silencing of LmNvd resulted in serious molting delay and abnormal phenotypes. • Molting delay and abnormal phenotypes can be rescued by supplementary 7-DC and 20E. [ABSTRACT FROM AUTHOR]

Background and Objective: With the global population on the rise, edible insects are considered a potential solution to food security, although concerns about risks such as anaphylaxis exist., Methods: 2,014 participants underwent testing with the Allergy Explorer-ALEX-2 including extracts of three novel foods: Acheta Domesticus (Ad), Locusta migratoria (Lm), and Tenebrio molitor (Tm). The IgE-mediated sensitization status was investigated in participants who had never knowingly consumed these insects. Data was recorded using an electronic database., Results: 195 individuals (9.7% of all participants) were sensitized to insects. Tropomyosin was co-recognized by 34%, and 18.5% were positive for arginine kinases. Reactivity to Sarcoplasmic-CB, Troponin-C, Paramyosin, or Myosin-light-chain was found in less than 5% of the population, whereas 108 individuals (55.4%) did not show any reactivity to invertebrate panallergens. Additionally, 33 individuals (16.9%) exhibited monosensitization exclusively to insects. Multivariate analysis revealed an inverse association between arachnid reactivity and sensitization to insect allergens, while Mollusca, Blattoidea, and tropomyosin reactivity displayed a direct relationship. Furthermore, Myosin-light-chain reactivity correlated with Ad and Lm, and Troponin-C with Ad and Tm sensitization., Conclusion: Edible insect extract IgE sensitization was observed in individuals without prior exposure to such foods. Mites showed a low likelihood of being primary sensitizers due to their inverse association with insect reactivity. Conversely, the direct association of insect sensitization with mollusk and cockroach extract reactivity suggests their potential as primary sensitizers in these participants. Tropomyosin consistently exhibited a positive association with reactivity to all studied insects, supporting its role as a primary sensitizer.

Background: The oriental migratory locust is a major crop pest across eastern and south-eastern Asia. Metarhizium anisopliae is an effective biopesticide agent used for locust control, but its performance is temperature dependent, and thus can be more variable than chemical pesticide performance. To predict biopesticide performance for the control of the oriental migratory locust, we adapted a previous temperature-dependent model and validated it using field trial data. To increase the applicability of this model, we explored the use of readily available temperature variables, as well as our own satellite-derived canopy temperature variable, to run the model., Results: Compared to collected in situ temperature data, our canopy temperature variable most accurately represented the ambient temperature experienced by the locust. When the biopesticide performance model was run using this canopy temperature and compared to field trials results, the model predictions were more accurate than when the model was run with the other temperature variables. The accuracy of the biopesticide performance model was impacted by vegetation cover, but across the areas most associated with locust oviposition, growth and migration, the model predictions were satisfactorily accurate to guide biopesticide operational use., Conclusion: We validated the model in six provinces in China, representing the three agro-ecological zones largely representative of the oriental migratory locust problem areas in China, Thailand, Cambodia and Vietnam. Whilst further validation work is needed, this model could be used in these countries to assess, at a fine spatial scale, the appropriateness of M. anisopliae for controlling the oriental migratory locust. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Swarming locusts cause huge plagues across the world threatening food production. Before swarms form, locust populations exhibit a dramatic phase change from a solitary to a gregarious phase. The cause of this phase change is a complicated interplay of conspecific and environmental cues and is, especially for one of the major pests, the migratory locust Locusta migratoria, still not well understood. Here we study the behavior of both solitary and gregarious L. migratoria towards the headspace odors of conspecifics. As we do not find a general attraction of gregarious animals to the headspace of gregarious conspecifics, swarm formation does not seem to be mainly governed by olfactory aggregation cues. When testing for potential mating signals, we observe that the headspace of virgin gregarious females is highly attractive only towards virgin males of the same phase, while mated gregarious males and solitary males, regardless of their mating state, do not become attracted. Interestingly, this phase-specific attraction goes along with the finding, that mating behavior in experiments with inter-phasic pairings is extremely rare. Our data suggest that odor emissions in L. migratoria play a significant role in a mating context., (© 2023. The Author(s).)