Shujing Gao’s research while affiliated with Chinese Academy of Agricultural Sciences and other places

Oedaleus decorus asiaticus (O. decorus) is a significant pest in the grasslands of Inner Mongolia, posing considerable challenges to the development of animal husbandry. To understand the key factors influencing the population distribution of O. decorus, field surveys were conducted from 2018 to 2020, during which the population count, growth stage, and location information of O. decorus were recorded. Daily soil moisture (SM) data and daily land surface temperature (LST) data were obtained from the National Tibetan Plateau Data Center, and a Generalized Additive Model (GAM) was constructed. Our findings indicate that the SM (S8) in August of the previous year is the most critical factor, with an F-value of 27.422, followed by the LST (L10) in October of the previous year, the LST (L6) in June of the survey year, the SM (S9) in September of the previous year, the LST (L3) in March of the survey year, and the LST (L5) in May of the survey year, with F-values of 7.848, 7.223, 5.823, 4.919, and 3.547, respectively. S8 and S9 can be regarded as vital indicators for predicting and monitoring the occurrence of O. decorus. However, the contributions of S8 and S9 to O. decorus density differ considerably. S8 is negatively correlated with O. decorus density, while S9 values below 0.29 m³/m³ can promote the growth of O. decorus. A higher LST during early overwintering correlates with increased O. decorus density. During the survey year, LST emerged as the primary factor affecting grasshopper density. Additionally, it plays a more complex role during incubation periods. This study clearly identifies SM and LST as the major factors influencing the occurrence of O. decorus, which will aid in predicting and monitoring its density.

Gynaephora qinghaiensis is a major pest in the alpine meadow regions of China. While the females are unable to fly, the males can fly and cause widespread damage. The aim of this study was to use transcriptome analysis to identify and verify genes expressed at different developmental stages of Gynaephora qinghaiensis, with particular emphasis on genes associated with wing development. High-throughput sequencing was performed on an Illumina HiSeqTM2000 platform to assess transcriptomic differences in the wings of male and female pupa and male and female adults of Gynaephora qinghaiensis, and the expression levels of the differentially expressed genes (DEGs) were verified by real-time fluorescence quantitative PCR (RT-qPCR). A total of 60,536 unigenes were identified from the transcriptome data, and 25,162 unigenes were obtained from a comparison with four major databases. Further analysis identified 18 DEGs associated with wing development in Gynaephora qinghaiensis. RT-qPCR verification of the expression levels showed consistency with the RNA sequencing results. Spatio-temporal expression profiling of the 18 genes indicated different levels of expression in the thoraces of male and female pupa, as well as between the wing buds of adult females and the wings of adult males. GO annotation analysis showed that the DEGs were associated with similar categories with no significant enrichment and were involved in cellular processes, cellular anatomical entities, and binding. KEGG analysis indicated that the DEGs were associated with endocytosis and metabolic pathways. The results of this study expand the information on genes associated with Gynaephora qinghaiensis wing development and provide support for further investigations of wing development at the molecular level.

The beet webworm, Loxostege sticticalis, is a typical migratory pest. Although miRNAs participate in many physiological functions, little is known about the functions of miRNAs in olfactory regulation. In this study, 1120 (869 known and 251 novel) miRNAs were identified in the antennae of L. sticticalis by using high-throughput sequencing technology. Among the known miRNAs, 189 from 49 families were insect-specific, indicating that these miRNAs might play unique roles in insects. Furthermore, based on the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, we found that 3647 and 1393 miRNAs were associated with localization and the regulation of localization, respectively, and 80 miRNAs were enriched in the neuroactive ligand–receptor interaction pathway. These miRNAs might be involved in the olfactory system of L. sticticalis. Notably, qRT-PCR showed that most of the tested miRNAs presented similar expression patterns compared with the RNA-seq data and that miR-87-3, novel-miR-78, and novel-miR-142 were significantly differentially expressed in the antennae of males and females. In addition, 21 miRNAs were predicted to target 23 olfactory genes, including 10 odorant-binding proteins (OBPs), 3 chemosensory proteins (CSPs), 4 odorant receptors (ORs), 1 ionotropic receptor (IR), and 5 gustatory receptors (GRs). The olfactory-related miRNAs exhibited low-abundance transcripts, except undef-miR-55 and undef-miR-523, and gender-biased expression was not observed for olfactory-related miRNAs. Our findings provide an overview of the potential miRNAs involved in olfactory regulation, which may provide important information on the function of miRNAs in the insect olfactory system.

Simple Summary Diapause is a state in which insects respond to environmental changes, leading to developmental stagnation, which is crucial in the life history of insects. miRNA regulates the expression of genes after transcription and participates in the regulation of important biological processes of insect growth and development. In this study, we screened differentially expressed miRNAs (DEMs) in non-diapause/diapause and diapause/non-diapause comparison groups of Ostrinia furnacalis and predicted their target genes. The expression patterns of key target genes Kr-h, JHE, JHEH, FOXO, Cry, and Per in diapause-related metabolic pathways at different stages of diapause were opposite to those of miRNAs, suggesting their regulatory roles in the diapause process. This study improves the scientific understanding of diapause in O. furnacalis; the learning can be applied to other insects. Abstract microRNAs (miRNAs) function as vital regulators of diapause in insects through their ability to post-transcriptionally suppress target gene expression. In this study, the miRNA of Ostrinia furnacalis, an economically important global crop pest species, was characterized. For the included analyses, 9 small RNA libraries were constructed using O. furnacalis larvae in different diapause states (non-diapause, ND; diapause, D; diapause-termination, DT). The results identified 583 total miRNAs, of which 256 had previously been identified, whereas 327 were novel. Furthermore, comparison analysis revealed that 119 and 27 miRNAs were differentially expressed in the D vs. ND and DT vs. D, respectively. Moreover, the expression patterns of their miRNAs were also analyzed. GO and KEGG analysis of the target genes of differentially expressed miRNAs highlighted the importance of these miRNAs as diapause regulators in O. furnacalis, especially through metabolic processes, endocrine processes, 20-hydroxyecdysone, and circadian clock signaling pathways. In summary, this study highlighted the involvement of specific miRNAs in the control of diapause in O. furnacalis. To the best of our knowledge, this is the first study to identify miRNA expression patterns in O. furnacalis, thereby providing reference and novel evidence enhancing our current understanding of how small RNAs influence insect diapause.

In order to determine the specific genes and proteins that are affected by matrine and play a role in regulating metabolism in the locust species Oedaleus asiaticus, we conducted RNA-seq, proteomic sequencing, and bioinformatics analyses on third-instar nymphs. These nymphs were divided into two groups: one group was grown under normal conditions, while the other group was treated with matrine. The purpose of this investigation was to gain insight into the molecular mechanisms underlying matrine resistance. Genes and proteins that exhibited differential expression were identified and subjected to analysis using bioinformatics software. The DESeq analysis revealed a total of 743 transcripts that were differentially expressed (DETs). Among these, 208 transcripts were up-regulated, and 535 were downregulated in ZO/ZCK. The iTRAQ discovered that 34 and 65 proteins were, respectively, up- and down-regulated in ZO/ZCK. Additionally, enrichment studies based on Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed. The KEGG and GO analysis of the DEGs suggested the essential roles of matrine treatment in the regulation of O. asiaticus, especially via the biosynthesis of amino acids, glycolysis/gluconeogenesis, iInsulin signaling pathway and MAPK signaling pathway. The findings demonstrated that matrine exerted control of the growth of O. asiaticus via modulating the synthesis of metabolism and biosynthesis. Increased expression of detoxifying enzymes was observed, which may be related to matrine detoxification. These findings provide a basis for better comprehension of the molecular mechanism behind the regulation of development mediated by matrine in Asian locust hoppers.

Smooth bromegrass (Bromus inermis Leyss.) is an excellent forage species widely distributed in Gansu, Qinghai, Inner Mongolia, and other provinces of China (Gong et al. 2019). In July 2021, typical leaf spot symptoms were observed on the leaves of smooth bromegrass plants in Ewenki Banner of Hulun Buir, China (49°5'8″N, 119°44'28″E, alt. 622.5 m). Approximately 90% of plants were affected, with symptoms apparent throughout the plant but mainly concentrated on the lower middle leaves. We collected 11 plants to identify the causal pathogen of leaf spot on smooth bromegrass. Samples (5×5 mm) of symptomatic leaves were excised and surface-sanitized with 75% ethanol for 3 min, rinsed three times with sterile distilled water, and incubated on water agar (WA) at 25℃ for three days. The lumps were cut along the edges and transplanted to potato dextrose agar (PDA) for subculture. After two purification cultures, ten strains, termed HE2 to HE11, were collected. The front side of the colony morphology was cottony or woolly, the center was greyish-green, circled with greyish-white color, with reddish pigmentation on the reverse. The conidia were globose or subglobose, yellow-brown or dark brown, with surface verrucae, and 23.89±3.76×20.28±3.23 μm (n = 50) in size. The morphological characteristics of the mycelia and conidia of the strains mtched those of Epicoccum nigrum (El-Sayed et al. 2020). The primers ITS1/ITS4 (White et al. 1991), LROR/LR7 (Rehner and Samuels 1994), 5F2/7cR (Sung et al. 2007), and TUB2Fd/TUB4Rd (Woudenberg et al. 2009) were used to amplify and sequence four phylogenic loci (ITS, LSU, RPB2 and β-tubulin), respectively. The sequences of ten strains have been deposited in GenBank, and the detailed accession numbers were shown in Table S1. BLAST analysis of these sequences showed 99-100%, 96-98%, 97-99% and 99-100% homology with the E. nigrum strain in the ITS, LSU, RPB2 and TUB sequenced regions, respectively. The sequences of ten test strains and other Epicoccum spp. strains obtained from GenBank were aligned by ClustalW by MEGA (version 11.0) software. After a series of alignment, cutting and splicing, the phylogenetic tree was constructed by the neighbor-joining method with 1000 bootstrap replicates based on the ITS, LSU, RPB2, and TUB sequences. The test strains were clustered together with E. nigrum, with branch support rate of 100%. Combined with morphological and molecular biological characteristics, ten strains were identified as E. nigrum. For the pathogenicity test, the seeds of smooth bromegrass were soaked for four days and then sown into six pots (10 cm diameter × 15 cm height) and kept in a greenhouse under a 16-h photoperiod with temperatures of 20-25°C and 60% relative humidity. Microconidia of the strain produced on wheat bran medium after 10 days were washed with sterile deionized water, filtered through three layers of sterile cheese cloth, quantified, and the concentration adjusted to 1 × 106 microconidia/ml with a hemocytometer. When the plants had grown to a height of about 20 cm, the leaves of plants in three pots were sprayed with the spore suspension, 10 mL per pot, while the remaining three pots were inoculated with sterile water and served as controls (LeBoldus and Jared 2010). The inoculated plants were cultured in an artificial climate box under a 16-h photoperiod with temperatures of 24°C and 60% relative humidity. Brown spots were apparent on the leaves of the treated plants after five days, whereas the leaves of the controls remained healthy. The same E. nigum strain were re-isolated from the inoculated plants and identified by the morphological and molecular techniques described above. To our knowledge, this is the first report of leaf spot disease caused by E. nigrum on smooth bromegrass in China, as well as in the world. Infection with this pathogen could reduce the yield and quality of smooth bromegrass production. For this reason, strategies for the management and control of this disease should be developed and implemented.

Simple Summary Oedaleus asiaticus (Bey-Bienko) is one of the most dominant locust species in grassland and pastoral areas in Inner Mongolia of northern China. It is highly abundant and usually makes up more than half (sometimes even up to 90%) of the local locust community in locust outbreaks. Locust aggregation is a prerequisite for a locust outbreak, requiring phase change from solitary to gregarious individuals. In this study, we used Illumina sequencing technology to screen 3911, 7478, 3142, and 1852 differentially expression genes (DEGs) in Oedaleus asiaticus during phase transition after 1, 3, 5, and 7 days of high-density treatment, respectively, and recorded the transition from green to brown individuals in different stages. The change in expression patterns of JHAMT, JHEH, DIB, HPD, TAT, PAH, DDC, CSP, and TO, which are the key genes of phase transition relevant metabolic pathways, at different stages of the phenotypic transformation suggests their regulatory role in the phenotypic process. This study improves the scientific understanding of phase variation in locusts; the learning can be applied to other insects. Abstract The high-density-dependent phase change from solitary to gregarious individuals in locusts is a typical example of phenotypic plasticity. However, the underlying molecular mechanism is not clear. In this study, first, Oedaleus asiaticus were treated with high-density population stress and then analyzed by Illumina sequencing on days 1, 3, 5, and 7 of the body color change to identify the stage-specific differentially expressed genes (DEGs). The KEGG pathway enrichment analysis of the identified DEGs revealed their role in metabolic pathways. Furthermore, the expression patterns of the nine key DEGs were studied in detail; this showed that the material change in locusts began on the third day of the high-density treatment, with the number of DEGs being the largest, indicating the importance of this period in the phase transition. In addition, the phenotypic change involved several key genes of important regulatory pathways, possibly working in a complex network. Phenotypic plasticity in locusts is multifactorial, involving multilevel material network interactions. This study improves the mechanistic understanding of phenotypic variation in insects at the genetic level.

Oedaleus asiaticus (Bey-Bienko) is an economically devastating locust species found in grassland and pastoral areas of the Inner Mongolia region of northern China. In this study, resistance to three frequently used insecticides (beta-cypermethrin, matrine, and azadirachtin) was investigated in six field populations of O. asiaticus using the leaf-dip bioassay method. The inhibitory effects of synergists and the activities of detoxification enzyme activities in the different populations were determined to explore potential biochemical resistance mechanisms. The results showed that the field populations SB (resistance ratio [RR] = 7.85), ZB (RR = 5.64), and DB (RR = 6.75) had developed low levels of resistance to beta-cypermethrin compared with a susceptible control strain. Both the SB (RR = 5.92) and XC (RR = 6.38) populations had also developed low levels of resistance against matrine, with the other populations remaining susceptible to both beta-cypermethrin and matrine. All field populations were susceptible to azadirachtin. Synergism analysis showed that triphenyl phosphate (TPP) and diethyl-maleate (DEM) increased the toxicity of beta-cypermethrin significantly in the SB population, while the synergistic effects of TPP, piperonyl butoxide (PBO), and DEM on the toxicity of matrine were higher in SB (SR 3.86, 4.18, and 3.07, respectively) than in SS (SR 2.24, 2.86, and 2.29, respectively), but no synergistic effects of TPP, PBO, and DEM on azadirachtin were found. Biochemical assays showed that the activities of carboxylesterases (CarEs) and glutathione-S-transferases (GSTs) were significantly raised in all field populations of O. asiaticus, with a significant positive correlation observed between beta-cypermethrin resistance and CarE activity. The activities of cytochrome P450 monooxygenases (P450) and multi-function oxidases (MFO) were elevated in all six field populations, and P450 activity displayed strong positive correlations with the three insecticides. Our findings suggest that resistance to beta-cypermethrin in O. asiaticus may be mainly attributed to elevated CarE and GST activities, while P450 plays an important role in metabolizing matrine and azadirachtin. Our study provides insights that will help improve insecticide resistance management strategies.

Diapause is a physiological process in which insects can survive in a natural environment that is not conducive to their survival, which is the result of long-term adaptation to environmental conditions. It provides a great adaptive advantage for insects, allowing insects to survive in unsuitable seasonal environments to synchronize their life cycles with those suitable for growth, development, and reproduction. The process of regulating insect diapause is a complex process interacting with multiple mechanisms. In this chapter, a review is given of the current knowledge of diapause types, environmental inducing factors, sensitive states, and the endogenous molecular mechanism associated with diapause in flies (Diptera). Research regarding both the diapause process and intrinsic mechanism is reviewed.