Mycophagous Mite, Tyrophagus putrescentiae, Prefers to Feed on Entomopathogenic Fungi, except Metarhizium Generalists.

(1) Background: The mycophagous mite, Tyrophagus putrescentiae, was found to feed on entomopathogenic fungi (EPF) in our previous experiments, which seriously impacted the culture and preservation of fungal strains. Therefore, it is necessary to investigate the biological characteristics of the occurrence and damage to EPF. (2) Methods: The mite's growth and development and feeding preference were surveyed by comparative culture and observation; also, optical and electronic microscopies were employed. (3) Results: T. putrescentiae could survive normally after being fed on seven EPF species, including Purpureocillium lilacinum, Marquandii marquandii, Cordyceps fumosorosea, Beauveria bassiana, Metarhizium flavoviride, Lecanicillium dimorphum, and Metacordyceps chlamydosporia. The first four fungi were the mite's favorites with their greater feeding amount and shorter developmental duration. Interestingly, the mite could also feed on Metarhizium anisopliae and Metarhizium robertsii, but this led to the mite's death. After feeding on M. anisopliae and M. robertsii, the mites began to die after 24 h, and the mortality rate reached 100% by 72 h. Observation under optical microscopy and scanning electron microscopy revealed that the conidia of M. anisopliae and M. robertsii adhered to the mite's surface, but there was no evidence of penetration or invasion. However, dissection observation indicated that the two Metarhizium species germinate and grow within the mite's digestive tract, which implies that Metarhizium generalists with broad-spectrum hosts and the production of destruxins have acaricidal activity toward the mycophagous mites.

Purpureocillium jiangxiense sp. nov.: Entomopathogenic Effects on Ostrinia furnacalis and Galleria mellonella.

The genus Purpureocillium is renowned for its role in biocontrol and biotechnological applications. The identification of new species within this genus is crucial for broadening our understanding of its ecological roles and potential utility in sustainable agriculture. This study aimed to characterize a new species of Purpureocillium, isolated from soil in eastern China, and to evaluate its bioactivity against Ostrinia furnacalis (corn moth) and Galleria mellonella (greater wax moth). We utilized morphological characterization; molecular phylogenetic analysis employing ITS, nrLSU, and tef1 genes; and bioactivity assays to identify and characterize the new species. The newly identified species, Purpureocillium jiangxiense sp. nov., displays unique morphological and genetic profiles compared to known species. Bioactivity tests showed that this species exhibits inhibitory effects against O. furnacalis and G. mellonella, highlighting its potential in biocontrol applications. By the ninth day at a spore concentration of 1 × 108 spores/mL, the mortality rate of the corn moth and greater wax moth reached 30% to 50% respectively. The discovery of P. jiangxiense sp. nov. adds to the genetic diversity known within this genus and offers a promising candidate for the development of natural biocontrol agents. It underscores the importance of continued biodiversity exploration and the potential for natural solutions in pest and disease management.

Destruxin A inhibits the hemocytin-mediated hemolymph immunity of host insects to facilitate Metarhizium infection.

Insects have an effective innate immune system to protect themselves against fungal invasion. Metarhizium employs a toxin-based strategy using a nonribosomal peptide called destruxin A (DA) to counteract the host immune response. However, the mechanism by which DA inhibits insect immunity is still unclear. Here, we identified 48 DA-binding proteins in silkworm hemolymph, with the binding affinity (KD) ranging from 2 to 420 µM. Among these proteins, hemocytin, an important immune factor, was determined to be the strongest DA-binding protein. DA binds to hemocytin and regulates its conformation in a multisite manner. Furthermore, DA exerts a significant inhibitory effect on hemocytin-mediated hemocyte aggregation. By disrupting the interaction between hemocytin, actin A3, and gelsolin, DA prevents the transformation of granules into vesicles in hemocytes. These vesicles are responsible for storing, maturing, and exocytosing hemocytin. Therefore, hemocytin secretion is reduced, and the formation of structures that promote aggregation in outer hemocytes is inhibited.

Hemocytin, the special aggregation factor connecting insect hemolymph immunity, a potential target of insecticidal immunosuppresant.

Insects possess an effective innate immunity that enables them to adapt to their intricate living environment and fend off various pathogens (or parasites). This innate immunity comprises both humoral and cellular immunity, which synergistically orchestrate immune responses. Hemocytin, a lectin with a distinctive structure, plays a crucial role in insect hemolymph immunity. Hemocytin is involved in the early immune response, facilitating processes such as coagulation, nodulation, and encapsulation in the hemolymph. It prevents hemolymph overflow and microbial pathogens invasion resulting from epidermal damage, and also aids in the recognition and elimination of invaders. However, the research on hemocytin is still limited. Our previous findings demonstrated that destruxin A effectively inhibits insect hemolymph immunity by interacting with hemocytin, suggesting that hemocytin could be a potential target for insecticides development. Therefore, it is crucial to gain a deeper understanding of hemocytin. This review integrates recent advancements in the study of the structure and function of insect hemocytin and also explores the potential of hemocytin as a target for insecticides. This review aims to enhance our comprehension of insect innate immunity and provide innovative ideas for the development of environmentally friendly pesticides.

Comparative transcriptome analysis reveals the molecular mechanism of sterility induced by irradiation of Plutella xylostella (Linnaeus).

Plutella xylostella (Linnaeus) is an important pest of cruciferous plants, which is harmful all over the world, causing serious economic losses, and its drug resistance is increasing rapidly. The sterile insect technique (SIT) is a green control method and does not cause resistance. In this study, transcriptomics and bioinformatics were used to explore the effects of irradiation on the reproductive function of Plutella xylostella, and the response mechanism of sterility under irradiation was initially revealed. We identified 3342 (1682 up-regulated, 1660 down-regulated), 1963 (1042 up-regulated, 921 down-regulated) and 1531 (721 up-regulated, 810 down-regulated) differentially expressed genes (DEGs) in the 200 Gy vs CK (Control Check), 400 Gy vs CK and 400 Gy vs 200 Gy groups, respectively. GO and KEGG analyses were performed for DEGs in each group. The results showed that 200 Gy activated the downstream phosphorylation pathway and inhibited the cytochrome p450 immune response mechanism. 400 Gy promoted protein decomposition and absorption pathways, autophagy pathways, etc. Down-regulated genes were concentrated in the transformation process of energy metabolizing substances such as ATP, phosphorylation signaling pathway, and insulin, while up-regulated genes were concentrated in biological regulation and metabolic processes. Eight genes in the phosphorylation pathway were selected for qRT-PCR verification, and the results showed that the phosphorylation of different dose groups was regulated in different ways. 400 Gy used positive feedback regulation, while the phosphorylation of F1 used negative feedback regulation.

Mechanism of destruxin a inhibits juvenile hormone binding protein transporting juvenile hormone to affect insect growth.

Destruxin A, a non-ribosomal peptide toxin produced by Metarhizium, exhibits potent insecticidal activity by targeting various tissues, organs, and cells of insects. Our previous research has revealed that DA possesses the ability to bind to multiple proteins. In this study, we aimed to identify the most sensitive binding proteins of DA and investigate the physiological processes in which DA regulated. Through RNAi technology, we screened 22 binding proteins of DA in silkworm hemolymph. Among them, the juvenile hormone binding protein (JHBP), a hormone transport protein crucial for growth and development regulation, exhibited the highest sensitivity to DA. Subsequent experiments demonstrated that DA could inhibit the body weight gain of silkworm larvae, accelerate the pupation occurrence, and modulate the content of free juvenile hormone (JH) in the hemolymph. We also observed that DA could induce conformational changes in both the JHBP and the JHBP-JH binding complex. Notably, at low dosage, DA influenced the binding of JHBP to JH, while at high dosage, it irreversibly affected the binding of JHBP to JH. Molecular docking and point-mutant experiments suggested that DA might affect the N-arm of JHBP, which is responsible for JH binding. Additionally, we discovered that JHBP is widely distributed in various tissues of the silkworm, including the epidermis, gut, fat body, Malpighian tubule, gonad, muscle, trachea, and hemocyte. This study provides novel insights into the insecticidal mechanism of DA and enhances our understanding of the pathogenic process of Metarhizium.

Molecular Mechanism of Male Sterility Induced by 60Co γ-Rays on Plutella xylostella (Linnaeus).

Plutella xylostella (Linnaeus) is one of the notorious pests causing substantial loses to numerous cruciferous vegetables across many nations. The sterile insect technique (SIT) is a safe and effective pest control method, which does not pollute the environment and does not produce drug resistance. We used proteomics technology and bioinformatics analysis to investigate the molecular mechanisms responsible for the effects of different doses of radiation treatment on the reproductive ability of male P. xylostella. A total of 606 differentially expressed proteins (DEPs) were identified in the 200 Gy/CK group, 1843 DEPs were identified in the 400 Gy/CK group, and 2057 DEPs were identified in the 400 Gy/200 Gy group. The results showed that after 200 Gy irradiation, the testes resisted radiation damage by increasing energy supply, amino acid metabolism and transport, and protein synthesis, while transcription-related pathways were inhibited. After 400 Gy irradiation, the mitochondria and DNA in the testis tissue of P. xylostella were damaged, which caused cell autophagy and apoptosis, affected the normal life activities of sperm cells, and greatly weakened sperm motility and insemination ability. Meanwhile, Western blotting showed that irradiation affects tyrosine phosphorylation levels, which gradually decrease with increasing irradiation dose.

Effects of destruxin A on hemocytes of the domestic silkworm, Bombyx mori.

Introduction: Destruxin A (DA) is a mycotoxin isolated from the entomopathogenic fungus Metarhizium anisopliae which has demonstrated inhibitory activity against various insect species. However, the mechanism of inhibition on target sites in insects remains unknown. Methods: In this research, the dose-response relationship between DA and morphological changes in body tissues and organs of domestic silkworm, Bombyx mori, were investigated by histopathological methods to identify the target sites that responded to DA. Results and Discussion: The results showed that responses of individual tissues and organs varied with DA dosage and treatment time. At low doses (i.e., 0.01µg/g), the hemocytes were the most sensitive to DA with morphological changes apparent at 6 h after treatment. However, the muscle cells, fat body, and Malpighian tubules were unaltered. At higher doses (i.e., > 0.1µg/g), morphological changes were observed in muscle cells, fat body, and Malpighian tubules at 24 h after treatment. The results indicated that DA can be an immunosuppressant by damaging host cells like hemocytes, and at higher doses may potentially impact other physiological processes, including muscle function, metabolism, and excretion. The information presented in the current study will facilitate development of mycopesticides and novel immunosuppressants.

Screening of Fungal Strains and Formulations of Metarhizium anisopliae to Control Phyllotreta striolata in Chinese Flowering Cabbage.

(1) Background: The cabbage flea beetle (CFB; Phyllotreta striolata) seriously damages the production of Chinese flowering cabbage (CFC; Brassica campestris L. ssp. chinensis var. utilis), which is a key leafy vegetable in South China. A large number of chemical insecticides have been sprayed to control this pest; as a result, residues and resistances are becoming an issue. It is necessary to develop biocontrol technologies to address this issue. (2) Methods: Fungal strains were selected based on bioactivity against CFB, and CFC seed pelletization with fungal conidia was subject to evaluation of control efficacy against CFB. The effective mixture of fungus and chemical insecticide was determined based on safety and joint toxicology tests. (3) Results: The screening of 103 strains from 14 genera identified the Metarhizium anisopliae strain MaGX19S02 (Ma) as the one with the highest virulence. The LC50s of Ma to CFB adult and second instar larvae on day 9 post-treatment were 3.04 × 106 and 27.2 × 106 spores/mL, respectively. In the pot test, the pelletization of CFC seeds with Ma conidia (50/25/12.5 mg in 1 g seed with 4 g fillers) demonstrated significant CFB mortalities (45-82%) 20 days after the larvae were introduced. In the field test, the seed pelletization achieved 57-81% control efficacy 14 days after sowing. Furthermore, the combination of Ma with chlorfenapyr (Chl) demonstrated a synergistic effect against CFB; based on this result, we prepared the mixture formulation of 20% Ma-Chl wettable powder (WP). The assessment of the effects of 20% Ma-Chl WP (500× diluent) against CFB revealed 93.33% mortality in the pot test and 61.3% control efficacy in the field test on day 7 post-treatment. (4) Conclusions: The findings demonstrate the potential of Ma to control CFB in the field. Seed pelletization with Ma conidia effectively controlled CFB larvae and protected CFC seedlings, wherein a mixture formulation of 20% Ma-Chl WP had substantial efficacy in controlling CFB adults. Our research provides new methods for CFB biocontrol.

Binding proteins of destruxin A from Metarhizium against insect cell.

Destruxin A (DA) is a cyclo-hexadepsipeptidic insecticidal mycotoxin isolated from the entomopathogenic fungi, Metarhizium spp. However, its mode of action is unknown. In this study, we isolated 149 candidate DA-binding proteins by drug affinity response target stability, and determined the interactions of 80 canditates with DA in vitro by surface plasmon resonance. The affinity coefficients (KD) ranged from 24 to 469 µM. Binding proteins were functionally diverse and included cytoskeletal components and cell motility, protein transcription and translation pathways, ubiquitin dependent protein metabolic processes, nucleus pore entry and exit, and endoplasmic reticulum vesicle transport and etc. Electron microscopy revealed that DA damaged the cytoskeleton and multiple organelles, disrupted cell adhesion and motility, and led to cell death. DA appeared to have a multi-targeted approach to cellular structures and multiple life processes, leading to cell death. The results of this study could provide molecular evidence for the analysis of the insecticidal toxicology of DA and further improve the study of the pathogenic insect mechanism of Metarhizium.

Interaction of Destruxin A with Three Silkworm Proteins: BmCRT, BmDPP3, and BmPDIA5.

Destruxin A (DA), a hexa-cyclodepsipeptidic mycotoxin produced by the entomopathogenic fungus Metarhizium anisopliae, has insecticidal activity, but its molecular mechanism of action is still not clear. Three proteins with modification-related functions, calreticulin (BmCRT), dipeptidyl peptidase Ⅲ (BmDPP3), and protein disulfide isomerase A5 (BmPDIA5), were selected to verify the interactions with DA in this study. The kinetic data of the interactions were measured by surface plasmon resonance (SPR) and bio-layer interferometry (BLI) in vitro. The KD values of DA with BmCRT, BmDPP3, and BmPDIA5 ranged from 10-4 to 10-5 mol/L, which suggested that the three proteins all had fairly strong interactions with DA. Then, it was found that DA in a dose-dependent manner affected the interactions of the three proteins with their partners in insect two-hybrid tests in SF-9 cells. Furthermore, the results of enzyme activities by ELISA indicated that DA could inhibit the activity of BmDPP3 but had no significant effect on BmPDIA5. In addition, DA induced the upregulation of BmDPP3 and the downregulation of BmCRT. The results prove that BmCRT, BmDPP3, and BmPDIA5 are all binding proteins of DA. This study might provide new insights to elucidate the molecular mechanism of DA.

Entomopathogenic Fungi Biodiversity in the Soil of Three Provinces Located in Southwest China and First Approach to Evaluate Their Biocontrol Potential.

Entomopathogenic fungi (EF), who represent active agents to control insect natural populations, usually persist in terrestrial habitats. Southwest area in China has various climate conditions and abundant plant biodiversity (crop, forest, grassy, orchard and arable areas). Nevertheless, the potential of soil-inhabitant EF as insect pest biocontrol agents, is unknown. In this study, first the EF biodiversity from soil of three provinces (Guizhou, Sichuan, and Yunnan) was surveyed. Then, the virulence of 29 isolated strains against Bemesia tabaci and Spodoptera litura was assessed. After analyzing 212 soil samples, 497 isolated fungi were identified. Out of them, 490 isolates were classified in 45 species of 24 genera, whereas the other seven isolates, belonging to Paecilomyces and Purpureocillium genera, were not identified under species level. Furthermore, the EF biodiversity from soil of Sichuan, Yunan, and Guizhou areas, analyzed by Shannon Wiener Index (SWI) was rated at 2.98, 1.89, and 2.14, while SWIs-biodiversity in crop, forest, grassy, orchard and arable areas was rated at 2.88, 2.74, 3.05, 2.39, and 2.47. SWI data suggested that soil from Sichuan area and grassy had higher EF biodiversity compared with other analyzed provinces and areas. Virulence bioassay results indicated that, out of the 29 isolates tested, 24 were pathogenic against B. tabaci and S. litura, resulting in mortality rates >10%. In conclusion, this study reports the EF distribution and biodiversity in soil from three provinces located at Southwest China, whereas their potential use as a tool for the B. tabaci and S. litura biocontrol must be further investigated.

Entomotoxic Activity of the Extracts from the Fungus, Alternaria tenuissima and Its Major Metabolite, Tenuazonic Acid.

The study of fungal antibiotics in their competitive interactions with arthropods may lead to the development of novel biorational insecticides. Extracts of Alternaria tenuissima MFP253011 obtained using various methods showed a wide range of biological activities, including entomotoxic properties. Analysis of their composition and bioactivity allowed us to reveal several known mycotoxins and unidentified compounds that may be involved in the entomotoxic activity of the extracts. Among them, tenuazonic acid (TeA), which was the major component of the A. tenuissima extracts, was found the most likely to have larvicidal activity against Galleria mellonella. In the intrahaemocoel injection bioassay, TeA was toxic to G. mellonella and of Zophobas morio with an LT50 of 6 and 2 days, respectively, at the level of 50 µg/larva. Administered orally, TeA inhibited the growth of G. mellonella larvae and caused mortality of Acheta domesticus adults (LT50 7 days) at a concentration of 250 µg/g of feed. TeA showed weak contact intestinal activity against the two phytophages, Tetranychus urticae and Schizaphis graminum, causing 15% and 27% mortality at a concentration of 1 mg/mL, respectively. TeA was cytotoxic to the Sf9 cell line (IC50 25 µg/mL). Thus, model insects such as G. mellonella could be used for further toxicological characterization of TeA.

Destruxin A Interacts with Aminoacyl tRNA Synthases in Bombyx mori.

Destruxin A (DA), a hexa-cyclodepsipeptidic mycotoxin produced by the entomopathogenic fungus Metarhizium anisopliae, exhibits insecticidal activities in a wide range of pests and is known as an innate immunity inhibitor. However, its mechanism of action requires further investigation. In this research, the interactions of DA with the six aminoacyl tRNA synthetases (ARSs) of Bombyx mori, BmAlaRS, BmCysRS, BmMetRS, BmValRS, BmIleRS, and BmGluProRS, were analyzed. The six ARSs were expressed and purified. The BLI (biolayer interferometry) results indicated that DA binds these ARSs with the affinity indices (KD) of 10-4 to 10-5 M. The molecular docking suggested a similar interaction mode of DA with ARSs, whereby DA settled into a pocket through hydrogen bonds with Asn, Arg, His, Lys, and Tyr of ARSs. Furthermore, DA treatments decreased the contents of soluble protein and free amino acids in Bm12 cells, which suggested that DA impedes protein synthesis. Lastly, the ARSs in Bm12 cells were all downregulated by DA stress. This study sheds light on exploring and answering the molecular target of DA against target insects.

The Chemical Ecology Approach to Reveal Fungal Metabolites for Arthropod Pest Management.

Biorational insecticides (for instance, avermectins, spinosins, azadirachtin, and afidopyropen) of natural origin are increasingly being used in agriculture. The review considers the chemical ecology approach for the search for new compounds with insecticidal properties (entomotoxic, antifeedant, and hormonal) produced by fungi of various ecological groups (entomopathogens, soil saprotrophs, endophytes, phytopathogens, and mushrooms). The literature survey revealed that insecticidal metabolites of entomopathogenic fungi have not been sufficiently studied, and most of the well-characterized compounds show moderate insecticidal activity. The greatest number of substances with insecticidal properties was found to be produced by soil fungi, mainly from the genera Aspergillus and Penicillium. Metabolites with insecticidal and antifeedant properties were also found in endophytic and phytopathogenic fungi. It was noted that insect pests of stored products are mostly low sensitive to mycotoxins. Mushrooms were found to be promising producers of antifeedant compounds as well as insecticidal proteins. The expansion of the number of substances with insecticidal properties detected in prospective fungal species is possible by mining fungal genomes for secondary metabolite gene clusters and secreted proteins with their subsequent activation by various methods. The efficacy of these studies can be increased with high-throughput techniques of extraction of fungal metabolites and their analysis by various methods of chromatography and mass spectrometry.

The Metarhizium anisopliae Toxin, Destruxin A, Interacts with the SEC23A and TEME214 Proteins of Bombyx mori.

Destruxin A (DA), a mycotoxin isolated from the entomopathogenic fungus Metarhizium anisopliae, has good insecticidal and immune-inhibitory activity, but the action mechanism has not yet been elucidated. In order to identify the DA-binding proteins, we conducted drug affinity responsive target stability (DARTS) experiments, which indicated that the silkworm's (Bombyx mori) transmembrane protein 214 (BmTEME214) and protein transport protein SEC23A isoform X2 (BmSEC23) are the potential DA-binding proteins. The current research was focused on validation of the interaction between DA and these two proteins via bio-layer interferometry (BLI) in vitro, insect two-hybrid (I2H) in Sf9 cells, and RNAi in the insect. The results of the BLI tests showed that DA has strong affinity to bind BmTEME214 and BmSEC23 proteins with a KD value of 0.286 and 0.291 µM, respectively. In the I2H experiments, DA inhibited (at 0.02 µg/mL) and activated (at 0.002-0.0002 µg/mL) the protein interactions of BmSEC23-BmSEC13, but it only inhibited the BmTMEM214-BmSEC13L interaction. Furthermore, in the RNAi tests, an apparent increase in the silkworm's mortality was recorded in the joint treatment of DA with dsBmSEC23 or dsBmTMEM214 when compared with the single treatment of DA (1.5 µg/g body), 40 µg/g body dsBmSEC23, or dsBmTMEM214. This research confirmed that BmSEC23 and BmTMEM214 are the DA-binding proteins and provided new insights to understand the action mechanism of DA.

Secondary Metabolites of Purpureocilliumlilacinum.

Fungi can synthesize a wealth of secondary metabolites, which are widely used in the exploration of lead compounds of pharmaceutical or agricultural importance. Beauveria, Metarhizium, and Cordyceps are the most extensively studied fungi in which a large number of biologically active metabolites have been identified. However, relatively little attention has been paid to Purpureocillium lilacinum. P. lilacinum are soil-habituated fungi that are widely distributed in nature and are very important biocontrol fungi in agriculture, providing good biological control of plant parasitic nematodes and having a significant effect on Aphidoidea, Tetranychus cinnbarinus, and Aleyrodidae. At the same time, it produces secondary metabolites with various biological activities such as anticancer, antimicrobial, and insecticidal. This review attempts to provide a comprehensive overview of the secondary metabolites of P. lilacinum, with emphasis on the chemical diversity and biological activity of these secondary metabolites and the biosynthetic pathways, and gives new insight into the secondary metabolites of medical and entomogenous fungi, which is expected to provide a reference for the development of medicine and agrochemicals in the future.

Diversity of Linear Non-Ribosomal Peptide in Biocontrol Fungi.

Biocontrol fungi (BFs) play a key role in regulation of pest populations. BFs produce multiple non-ribosomal peptides (NRPs) and other secondary metabolites that interact with pests, plants and microorganisms. NRPs-including linear and cyclic peptides (L-NRPs and C-NRPs)-are small peptides frequently containing special amino acids and other organic acids. They are biosynthesized in fungi through non-ribosomal peptide synthases (NRPSs). Compared with C-NRPs, L-NRPs have simpler structures, with only a linear chain and biosynthesis without cyclization. BFs mainly include entomopathogenic and mycoparasitic fungi, that are used to control insect pests and phytopathogens in fields, respectively. NRPs play an important role of in the interactions of BFs with insects or phytopathogens. On the other hand, the residues of NRPs may contaminate food through BFs activities in the environment. In recent decades, C-NRPs in BFs have been thoroughly reviewed. However, L-NRPs are rarely investigated. In order to better understand the species and potential problems of L-NRPs in BFs, this review lists the L-NRPs from entomopathogenic and mycoparasitic fungi, summarizes their sources, structures, activities and biosynthesis, and details risks and utilization prospects.

Interactions of Destruxin A with Silkworms' Arginine tRNA Synthetase and Lamin-C Proteins.

Destruxin A (DA), a cyclodepsipeptidic mycotoxin produced by entomopathogenic fungus Metarhizium anisopliae, has good insecticidal activity and potential to be a new pesticide. However, the mechanism of action is still obscure. Our previous experiments showed that DA was involved in regulation of transcription and protein synthesis and suggested that silkworms' arginine tRNA synthetase (BmArgRS), Lamin-C Proteins (BmLamin-C) and ATP-dependent RNA helicase PRP1 (BmPRP1) were candidates of DA-binding proteins. In this study, we employed bio-layer interferometry (BLI), circular dichroism (CD), cellular thermal shift assay (CETSA), and other technologies to verify the interaction of DA with above three proteins in vitro and in vivo. The results of BLI indicated that BmArgRS and BmLamin-C were binding-protein of DA with KD value 5.53 × 10-5 and 8.64 × 10-5 M, but not BmPRP1. These interactions were also verified by CD and CETSA tests. In addition, docking model and mutants assay in vitro showed that BmArgRS interacts with DA at the pocket including Lys228, His231, Asp434 and Gln437 in its enzyme active catalysis region, while BmLamin-C binds to DA at His524 and Lys528 in the tail domain. This study might provide new insight and evidence in illustrating molecular mechanism of DA in breaking insect.

Biodiversity of Entomopathogenic Fungi in the Soils of South China.

The southern part of China, located in tropical and south subtropical areas has unique natural environments, but the distributions of entomopathogenic fungi (EFs) in the soil are not clear. In this research, 198 soil samples were collected from the four Provinces (Autonomous Region) of South China. The results indicated that a total of 292 fungal isolates were obtained from 176 soil samples. Then, based on the morphological and rDNA-ITS sequences analysis, 213 EFs isolates of 19 species in 12 genera were identified. Furthermore, Purpureocillium lilacinum with 75 isolates was recognized as the absolutely dominant EF species, while Isaria javanica, Metarhizium anisopliae, and Beauveria bassiana (respectively with 29, 26, and 26 isolates) were the richer species. The data also indicated that Guangxi Province has the best EFs diversity with the Shannon-Wiener index (SWI) of 2.29, the soils covered with grass had the best EFs diversity with the 2.14 SWI, while the orchard and fallow land had the lowest SWI of 1.52, which suggested that the diversity of plants and insects on ground, as well as the massive application of broad-spectrum fungicides, affect the EFs diversity in the soil. Finally, the rare species, Nectria mauritiicola and Scopulariopsis brumptii were first reported about their entomopathogenic activities against Bemisia tabaci. Our experiment will give new insights to the understanding of EFs distribution characteristics and their biodiversity conservation.