Pest In China Research Articles

Comparative transcriptome analysis of Sogatella furcifera (Horv\xe1th) exposed to different insecticides

White-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), one of the main agricultural insect pests in China, is resistant to a wide variety of insecticides. We used transcriptome analysis to compare the expression patterns of resistance- and stress-response genes in S. furcifera subjected to imidacloprid, deltamethrin, and triazophos stress, to determine the molecular mechanisms of resistance to these insecticides. A comparative analysis of gene expression under imidacloprid, deltamethrin, and triazophos stress revealed 1,123, 841, and 316 upregulated unigenes, respectively, compared to the control. These upregulated genes included seven P450s (two CYP2 clade, three CYP3 clade, and two CYP4 clade), one GST, one ABC transporter (ABCF), and seven Hsps (one 90 and six Hsp70s) under imidacloprid stress; one P450 (CYP3 clade), two ABC transporters (one ABCF and one ABCD), and one Hsp (Hsp90) under deltamethrin stress; one P450 (CYP3 clade) and one ABC transporter (ABCF) under triazophos stress. In addition, 80 genes were commonly upregulated in response to the three insecticide treatments, including laminin, larval cuticle protein, and fasciclin, which are associated with epidermal formation. These results provide a valuable resource for the molecular characterisation of insecticide action in S. furcifera, especially the molecular characteristics of insecticide cross resistance.

A head transcriptome provides insights into odorant binding proteins of the bamboo grasshopper.

The bamboo grasshopper Ceracris kiangsu is a famous bamboo pest in China. The identification of genes involved in olfactory behavior of C. kiangsu is necessary for better understanding the molecular basis and expression profiles of behavior ecology. However, necessary genomic and transcriptomic data are lacking in the species, limiting control efficiency. The primary objective of this study was to find and describe odorant binding proteins in the head of the bamboo grasshopper. We performed the paired-end sequencing on an Illumina Hiseq2000 following the vendor's recommended protocol. Functional annotation was performed by comparison with public databases. OBP genes were first identified using BLASTN and BLASTX results from our C. kiangsu datebase, which was established from the date of transcriptome sequencing. The gene-specific primers were used to conduct RT-PCR to detect the tissue distribution of OBPs using a SYBR Premix ExTaq kit following the manufacturer's instructions with a real-time thermal cycler. We obtained more than 133million clean reads derived from the C. Kiangsu heads using the next-generation sequencing, which were assembled into 260,822 unique sequences (average 814bp). We have detected eight putative odorant binding protein genes (OBPs) of C. kiangsu for the first time, and analyzed the expression profiles of the OBPs in different tissues (head, antenna, mouthpart, body and leg). Our results reveal that the eight OBPs display a clear divergence, strongly indicating that they possessed diverse functions, and thus provides comprehensive sequence analysis for elucidating the molecular basis of OBPs in C. kiangsu. In addition, we find that the relative expression levels of OBP1, OBP2 and OBP8 are significantly higher in the antennae as compared to the other OBP genes, suggesting that these three OBP genes play crucial roles in the locust's odorant discrimination. In general, this is the first study to characterize the complete head transcriptome of C. kiangsu using high-throughput sequencing. The study opens a window for functional characterization of the OBPs of C. kiangsu, with potential for new or refined applications of semiochemicals for control of this notorious pest.

Control of Eucryptorrhynchus scrobiculatus (Coleoptera: Cuculionidae), a Major Pest of Ailanthus altissima (Sapindales: Simaroubaceae), Using a Modified Square Trap Net.

Eucryptorrhynchus scrobiculatus (Motschulsky) (Coleoptera: Cuculionidae) is a borer that mainly attacks the tree of heaven, Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae), and is one of the most damaging forestry pests in China. We developed a trap net for entangling and immobilizing soil-emerging weevils in order to reduce their impact. Recapture rates of weevils in the laboratory was significantly higher with nylon netting of 9, 10, or 11 mm mesh sizes than larger sizes, and these sizes were used to make trial nets for preventing weevil emergence from the soil around impacted trees in the field. Nets were 2 × 2 m with a reinforced border and Velcro-closable, radial slit which allowed the net to be arranged around the base of the tree while producing an unbroken barrier beneath the soil surface (i.e., a modified square trap net, MSTN). Recapture rates of weevils released in the soil did not differ among the MSTNs of 9, 10, or 11 mm mesh sizes. MSTN treatments significantly reduced emergence by naturally-occurring weevils from the soil surrounding trees and reduced numbers of weevils caught in population monitoring traps deployed in treated stands. The results demonstrated that MSTNs might be used to manage of E. scrobiculatus.

Screening potential reference genes for quantitative real-time PCR analysis in the oriental armyworm, Mythimna separata.

The oriental armyworm, Mythimna separata, is a major insect pest in China and other Asian countries. Unfortunately, suitable reference genes for quantitative real-time PCR (qRT-PCR) have not been previously identified in M. separata for normalizing target gene expression. In this study, we evaluated the expression stability of eight candidate genes (18S, ACT, EF1-α, GAPDH, RPS7, RPS13, RPL32 and TUB) in M. separata using the comparative ΔCt method, BestKeeper, Normfinder geNorm and ReFinder, a comprehensive software platform. The results indicated that the appropriate reference gene varied depending on the experimental conditions. We found that ACTIN, EF1-α and TUB were optimal for different developmental stages; TUB, RPS13 and EF1-α showed the most stable expresssion in different tissues; RPS13 and 18S were the best reference genes for monitoring expression under high temperature conditions; TUB, RPS13 and RPS7 exhibited the most stable expression under larval-crowding conditions; RPS7, EF1-α, RPL32 and GAPDH were the best for pesticide exposure experiments. This study provides tools for reliable normalization of qRT-PCR data and forms a foundation for functional studies of target gene expression in M. separata.

Effect of Oxygen on Verbenone Conversion From cis-Verbenol by Gut Facultative Anaerobes of Dendroctonus valens.

Since its introduction from North America, Dendroctonus valens LeConte has become a destructive forest pest in China. Although gut aerobic bacteria have been investigated and some are implicated in beetle pheromone production, little is known about the abundance and significance of facultative anaerobic bacteria in beetle gut, especially with regards to effects of oxygen on their role in pheromone production. In this study, we isolated and identified gut bacteria of D. valens adults in an anaerobic environment, and further compared their ability to convert cis-verbenol into verbenone (a multi-functional pheromone of D. valens) under different O2 concentrations. Pantoea conspicua, Enterobacter xiangfangensis, Staphylococcus warneri were the most frequently isolated species among the total of 10 species identified from beetle gut in anaerobic conditions. Among all isolated species, nine were capable of cis-verbenol to verbenone conversion, and the conversion efficiency increased with increased oxygen concentration. This O2-mediated conversion of cis-verbenol to verbenone suggests that gut facultative anaerobes of D. valens might play an important role in the frass, where there is higher exposure to oxygen, hence the higher verbenone production. This claim is further supported by distinctly differential oxygen concentrations between gut and frass of D. valens females.

An auto-contamination trap-strips system for biological control of Hyphantria cunea (Lepidoptera: Noctuidae), an invasive pest in China

ABSTRACTThe fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), is a major invasive pest in China, where it seriously threatens fruit and ornamental trees and windbreak systems. An auto-contamination trap-strips system was designed to disseminate Beauveria bassiana for biological control. The standard trap consisted of a yellow or green trap with a width no larger than 30 cm and with B. bassiana inside it. Therefore, the trap-strips provided an appropriate microenvironment for the fall webworm to pupate, and an acceptable humidity for B. bassiana to infect and reproduce. The average infection rates of the trap-strips systems were more than 90%. The present study demonstrated a practical application of how physical and biological control of this pest can be conducted efficiently and economically.

Gene Identification of Pheromone Gland Genes Involved in Type II Sex Pheromone Biosynthesis and Transportation in Female Tea Pest Ectropis grisescens.

Moths can biosynthesize sex pheromones in the female sex pheromone glands (PGs) and can distinguish species-specific sex pheromones using their antennae. However, the biosynthesis and transportation mechanism for Type II sex pheromone components has rarely been documented in moths. In this study, we constructed a massive PG transcriptome database (14.72 Gb) from a moth species, Ectropis grisescens, which uses type II sex pheromones and is a major tea pest in China. We further identified putative sex pheromone biosynthesis and transportation-related unigenes: 111 cytochrome P450 monooxygenases (CYPs), 25 odorant-binding proteins (OBPs), and 20 chemosensory proteins (CSPs). Tissue expression and phylogenetic tree analyses showed that one CYP (EgriCYP341-fragment3), one OBP (EgriOBP4), and one CSP (EgriCSP10) gene displayed an enriched expression in the PGs, and that EgriOBP2, 3, and 25 are clustered in the moth pheromone-binding protein clade. We considered these our candidate genes. Our results yielded large-scale PG sequence information for further functional studies.

Chlorantraniliprole resistance and its biochemical and new molecular target mechanisms in laboratory and field strains of Chilo suppressalis (Walker).

The rice striped stem borer (SSB), Chilo suppressalis (Walker), is one of the most economically important and destructive rice pests in China. To date, the efficiency of conventional insecticides has decreased greatly because of the development of high resistance. Since the introduction of chlorantraniliprole in 2008, SSB has presented resistance issues. In this study, laboratory resistant strains R1 and R2 [resistance ratio (RR) of 38.8 and 110.4, respectively] were established and a field population HR (RR of 249.6) was collected. Synergist assessment and enzyme activity data suggested the potential involvement of P450s and esterases in the resistance mechanism. No target (ryanodine receptor, RyR) mutation was found in R1, but a novel mutation Y4667D was found in R2. At the same position of RyR in HR strain, Y4667D and Y4667C were observed at low frequencies. In addition, the conserved mutation I4758M was found with a frequency of 94.4%. RyR mRNA expression was significantly lower in R1, R2 and HR than in S. When treated with chlorantraniliprole, RyR mRNA expression in all four strains was downregulated to ∼ 50%. A comprehensive analysis, including biochemical, target mutations and target mRNA expression, was conducted in an attempt to interpret the chlorantraniliprole resistance mechanism in both laboratory and field SSB strains. © 2017 Society of Chemical Industry.

Identification and Expression Patterns of Anoplophora chinensis (Forster) Chemosensory Receptor Genes from the Antennal Transcriptome.

The citrus long-horned beetle (CLB), Anoplophora chinensis (Forster) is a destructive native pest in China. Chemosensory receptors including odorant receptors (ORs), gustatory receptors (GRs), and ionotropic receptors (IRs) function to interface the insect with its chemical environment. In the current study, we assembled the antennal transcriptome of A. chinensis by next-generation sequencing. We assembled 44,938 unigenes from 64,787,784 clean reads and annotated their putative gene functions based on gene ontology (GO) and Clusters of Orthologous Groups of proteins (COG). Overall, 74 putative receptor genes from chemosensory receptor gene families, including 53 ORs, 17 GRs, and 4 IRs were identified. Expression patterns of these receptors on the antennae, maxillary and labial palps, and remaining body segments of both male and female A. chinensis were performed using quantitative real time-PCR (RT-qPCR). The results revealed that 23 ORs, 6 GRs, and 1 IR showed male-biased expression profiles, suggesting that they may play a significant role in sensing female-produced sex pheromones; whereas 8 ORs, 5 GRs, and 1 IR showed female-biased expression profiles, indicating that these receptors may be involved in some female-specific behaviors such as oviposition site seeking. These results lay a solid foundation for deeply understanding CLB olfactory processing mechanisms. Moreover, by comparing our results with those from chemosensory receptor studies in other cerambycid species, several highly probable pheromone receptor candidates were highlighted, which may facilitate the identification of additional pheromone and/or host attractants in CLB.

Advantages of diapause in Trichogramma dendrolimi mass production on eggs of the Chinese silkworm, Antheraea pernyi.

Trichogramma dendrolimi Matsumura is widely used as a biological control agent for control of lepidopteran agricultural pests in China and can be successfully reared using the large eggs of the Chinese silkworm, Antheraea pernyi. In this study, biological parameters of diapaused, non-diapaused, and cold-stored T. dendrolimi were investigated for two generations on host eggs of A. pernyi under laboratory conditions. The cold-stored T. dendrolimi performed more poorly than diapaused and non-diapaused T. dendrolimi based on biological parameters. In the F1 generation, the non-diapaused T. dendrolimi had a higher emergence rate, longer longevity, and a lower proportion of deformed individuals than diapaused T. dendrolimi. In the F2 generation, the diapaused T. dendrolimi had a lower proportion of unemerged parasitoids than non-diapaused T. dendrolimi. However, the diapaused T. dendrolimi had a higher number of parasitized hosts than non-diapaused T. dendrolimi in both generations. In the F1 generation, the index of population trend (I) was found to be similar for diapaused (140.792) and non-diapaused (141.542) T. dendrolimi and was approximately 3.4 times that of cold-stored T. dendrolimi (41.698). In the F2 generation, the diapaused T. dendrolimi showed the largest I (146.791), followed by non-diapaused (136.859) and cold-stored T. dendrolimi (59.607). In a 3-year augmentative field release from 2014 to 2016, diapaused T. dendrolimi showed effective parasitism on eggs of the Asian corn borer, Ostrinia furnacalis. These results indicated that diapaused T. dendrolimi can be an efficient alternative method for mass rearing of T. dendrolimi for long-term cold storage. © 2017 Society of Chemical Industry.

Species composition and distribution of thrips (Thysanoptera) in mango orchards of China

Abstract Mango is an important tropical fruit, and thrips are important pests that have threatened mango yield and quality in recent years. It is important to determine the dominant species and distribution of thrips in mango for effective thrips control. In the present study, the species of thrips in mango flowers in the five main mango-producing provinces of China, and the species of thrips in different phenological stages of mango in Hainan Province were investigated. Thrips species on weeds in mango agroecosystems were also determined. The results indicated that in total there are 41 species of thrips in mango orchards in the five main mango-producing provinces of China, belonging to 21 genera, five subfamilies and three families. These are 31 species in 13 genera of Thripidae, nine species in seven genera of Phlaeothripidae, and one species in one genus of Aeolothripidae. The major species of thrips differed across the main mango production areas. Thus, 26, 17, 23, 12 and 7 species of thrips were collected in mango orchards in Hainan, Guangxi, Yunnan, Sichuan and Fujian, respectively. Frankliniella occidentalis (Pergande), an important invasive pest in China, was only discovered in mango orchards in Yunnan and Sichuan. Thrips species and population dynamics are closely related to the phenological stage of mango. In Hainan, the dominant thrips species during the shoot period and young fruit stage was Scirtothrips dorsalis Hood. In the flowering period, the thrips population increased significantly and species composition became complicated in the field, with Thrips hawaiiensis and F. intonsa being the dominant species. Frankliniella intonsa and T. hawaiiensis were the dominant species on weeds in the mango ecosystem, which was consistent with them being dominant thrips species on mango. It is speculated that in mango ecosystems, weeds provide refuge to thrips and removing weeds benefits thrips control in mango orchards during the flowering period.

Control effect on cotton aphids of insecticides sprayed with unmanned aerial vehicles under different flight heights and spray volumes

Unmanned aerial vehicles (UAVs) are an emerging technology increasingly used to control plant diseases and pests in China. However, the efficacy of UAV spraying in cotton fields remains unclear. This paper assesses the droplet deposition of UAV spraying and analyzes how flight heights and spray volumes affect aphids control in cotton fields. Allura red was used as a tracer and Kromekote cards were used to collect the droplets. The research results demonstrated that droplet uniformity, droplet coverage, and droplet density were all higher at a flight height of 1.5 m and a spray volume of 22.5 L/ha. Control efficacy on the first day after spraying was correlated with the number of droplets deposited on the underside of leaves, and higher droplet coverage and density resulted in better pest control. Optimal control efficacy on the seventh day after spraying was achieved at the flight height of 1.0 m and 1.5 m, with control efficacy rates ranging from 57.93% to 80.53%. Field trials of five different insecticides verified the efficacy of UAV spraying controls against cotton aphids. These results provide a theoretical reference and technical support for subsequent UAV spraying to control for diseases and pests. Keywords: unmanned aerial vehicle, flight parameter, spray volume, droplet deposition, cotton aphids DOI: 10.33440/j.ijpaa.20210401.161 Citation: Hu H Y, Ren X L, Ma X Y, Li H H, Ma Y J, Wang D, et al. Control effect on cotton aphids of insecticides sprayed with unmanned aerial vehicles under different flight heights and spray volumes. Int J Precis Agric Aviat, 2021; 4(1): 44–51.

The first complete mitochondrial genome from the subfamily Phyllocephalinae (Heteroptera: Pentatomidae) and its phylogenetic analysis

The true bug, Gonopsis affinis, is an important pest in China. Here, we determined the complete mitogenome of G. affinis, which is the first for the subfamily Phyllocephalinae. This 16,011-basepair (bp) mitogenome comprises of 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes, and an A + T-rich region. The gene order and the orientation are similar to those of other sequenced Hemipteran species. All PCGs start with ATN codons, except COI, and end with TAA. The 22 tRNAs have a typical cloverleaf secondary structure except trnS-Ser (AGN), which lacks a dihydrouridine (DHU) arm. Phylogenetic analyses highly supported the monophyly of each family, and confirmed the reasonable placement of G. affinis.

Identification and Characterization of Hyphantria cunea Aminopeptidase N as a Binding Protein of Bacillus thuringiensis Cry1Ab35 Toxin.

The fall webworm, Hyphantria cunea (Drury) is a major invasive pest in China. Aminopeptidase N (APN) isoforms in lepidopteran larvae midguts are known for their involvement in the mode of action of insecticidal crystal (Cry) proteins from Bacillus thuringiensis. In the present work, we identified a putative Cry1Ab toxin-binding protein, an APN isoform designated HcAPN3, in the midgut of H. cunea by ligand blot and mass spectrometry. HcAPN3 was highly expressed throughout all larval developmental stages and was abundant in the midgut and hindgut tissues. HcAPN3 was down-regulated at 6 h, then was up-regulated significantly at 12 h and 24 h after Cry1Ab toxin treatment. We expressed HcAPN3 in insect cells and detected its interaction with Cry1Ab toxin by ligand blot assays. Furthermore, RNA interference (RNAi) against HcAPN3 using oral delivery and injection of double-stranded RNA (dsRNA) resulted in a 61–66% decrease in transcript level. Down-regulating of the expression of HcAPN3 was closely associated with reduced susceptibility of H. cunea to Cry1Ab. In addition, the HcAPN3E fragment peptide expressed in Escherichia coli enhanced Cry1Ab toxicity against H. cunea larvae. This work represents the first evidence to suggest that an APN in H. cunea is a putative binding protein involved in Cry1Ab susceptibility.

New microsatellites revealed strong gene flow among populations of a new outbreak pest, Athetis lepigone (Möschler).

Athetis lepigone (Möschler) (Lepidoptera: Noctuidae) is a new outbreak pest in China. Consequently, it is unclear whether the emergence and spread of the outbreak of this pest are triggered by rapid in situ population size increases in each outbreak area, or by immigrants from a potential source area in China. In order to explore the outbreak process of this pest through a population genetics approach, we developed ten novel polymorphic expressed sequence tags (EST)-derived microsatellites. These new microsatellites had moderately high levels of polymorphism in the tested population. The number of alleles per locus ranged from 3 to 19, with an average of 8.6, and the expected heterozygosity ranged from 0.269 to 0.783. A preliminary population genetic analysis using these new microsatellites revealed a lack of population genetic structure in natural populations of A. lepigone. The estimates of recent migration rate revealed strong gene flow among populations. In conclusion, our study developed the first set of EST-microsatellite markers and shed a new light on the population genetic structure of this pest in China.

Resistance Monitoring of Four Insecticides and a Description of an Artificial Diet Incorporation Method for Chilo suppressalis (Lepidoptera: Crambidae)

Chilo suppressalis (Walker; Lepidoptera: Crambidae) is one of the most damaging rice pests in China. Insecticides play a major role in its management. We describe how we monitored the resistance of C. suppressalis to four insecticides in seven field populations from Jiangxi, Hubei, and Hunan Provinces, China, in 2014-2016. The topical application method for resistance monitoring was suitable for triazophos, monosultap, and abamectin. The conventional rice seedling dipping method proved ineffective for testing chlorantraniliprole so the new artificial diet incorporation method was substituted. This new method provided more consistent results than the other methods, once baseline toxicity data had been established. All populations had moderate to high resistance to triazophos from 2014 to 2016. Monosultap resistance in two populations increased from low in 2014 to moderate in 2016 and the other five populations showed moderate to high-level resistance throughout. Abamectin resistance in three populations increased from sensitive or low in 2014 to moderate in 2015-2016, and the other populations had moderate to high levels of resistance. Resistance to chlorantraniliprole increased from sensitive or low in 2014 to moderate to high in 2016. These results suggested that resistance management strategies should be developed according to the needs of a specific location. It was suggested that, in these localities, organophosphate insecticides should be prohibited, the application of nereistoxin, macrolide antibiotic, and diamide insecticides should be limited, and other insecticides, including spinetoram and methoxyfenozide, that exhibited no resistance should be used rationally and in rotation to delay resistance development.

Monitoring insecticide resistance and diagnostics of resistance mechanisms in the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae) in China

Myzus persicae (Sulzer) is one of the most serious agricultural pests in China, and management strategies mainly rely on insecticidal treatment. To evaluate the resistance of field populations of M. persicae to seven insecticides, we assessed the susceptibility of 11 field populations collected from eight provinces in China using leaf-dip bioassays. Toxicity assays showed that M. persicae field populations have developed several levels of resistance to each tested insecticide. For pyrethroids, the field populations have developed a high level of resistance to β-cypermethrin and cypermethrin, while the resistance to bifenthrin is still low. The resistance ratios of field populations to imidacloprid ranged from 1.48 to 52.36, and eight populations have developed moderate to high resistance. Resistance to acetamiprid is low, and only two populations have a moderate level of resistance. Most of the field populations of M. persicae developed moderate to high resistance to methomyl and omethoate. To investigate potential resistance mechanisms, we analyzed the enzyme activity of carboxylesterases, the type of amplified esterase genes, as well as the kdr (L1014F) mutation. All of the field populations exhibited a higher esterase activity compared to the laboratory susceptible strain. An amplified FE4, as well as the L1014F mutation, were also found in all of our experimental field populations. These results provide valuable insight into the current status of insecticide resistance and will prove to be a valuable resource in designing appropriate resistance management strategies for M. persicae in China.

Proteomic analysis of Cry1Ac and Cry2Aa binding proteins in brush border membrane vesicles of the Chilo suppressalis midgut

Transgenic rice expressing Bacillus thuringiensis (Bt) Cry1Ac and Cry2Aa toxins have proven resistant to lepidopteran pests in China, including the striped stem borer, Chilo suppressalis. Identifying the molecular mechanisms through which Cry toxins affect insect pests is essential, both for understanding the nature of their toxicity, and for assessing the potential for the development of resistance to such toxins. In this study, both one-dimensional gel electrophoresis (1-DE), combined ligand blots and mass spectrometry, were used to identify proteins binding to the Cry1Ac and Cry2Aa toxins in brush border membrane vesicles (BBMVs) of the C. suppressalis larvae midgut. Aminopeptidase-N (APN), alkaline phosphatase (ALP), cadherin-like (CAD), ATP-binding cassette transporter subfamily C1 protein (ABCC1), actin, ATPase, alpha amylase, and heat shock protein cognate (HSPC), were detected in Cry1Ac binding bands, and APN, actin, ATPase and HSPC were identified as Cry2Aa potential binding proteins. The novel potential binding protein, delta-aminolevulinic acid dehydratase, was also detected in both Cry1Ac and Cry2Aa binding bands. This is the first study to comprehensively identify the proteins that bind to Cry1Ac and Cry2Aa toxins in C. suppressalis.

Morphological and phylogenetic analysis of a microsporidium (Nosema sp.) isolated from rice stem borer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae).

A new microsporidium was isolated from Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), one of the most important rice pests in China. The morphology and molecular systematics of this novel microsporidium were described in this study. The spores were long oval and measured 3.17×1.64μm on fresh smears. Ultrastructure of the spores was characteristic for the genus Nosema: a diplokaryon, 10-12 polar filament coils of the same type, and posterior vacuole. Small subunit rRNA gene sequence data and phylogenetic analysis further confirmed that the microsporidian species from C. suppressalis belong to the true Nosema sub-group of the genus Nosema. Besides, the microsporidium Nosema sp. CS could cause systemic infection of Bombyx mori and infect silkworms through vertical transmission. Therefore, mulberry field pest control should be carefully monitored, and sanitation of mulberry leaves is essential to control the pebrine disease in sericulture.

Bacterial volatile ammonia regulates the consumption sequence of d-pinitol and d-glucose in a fungus associated with an invasive bark beetle

Interactions among microbial symbionts have multiple roles in the maintenance of insect–microbe symbiosis. However, signals mediating microbial interactions have been scarcely studied. In the classical model system of bark beetles and fungal associates, fungi increase the fitness of insects. However, not all interactions are mutualistic, some of these fungal symbionts compete for sugars with beetle larvae. How this antagonistic effect is alleviated is unknown, and recent research suggests potential roles of bacterial symbionts. Red turpentine beetle (RTB), Dendroctonus valens LeConte, is an invasive pest in China, and it leads to wide spread, catastrophic mortality to Chinese pines. In the symbiotic system formed by RTB, fungi and bacteria, volatiles from predominant bacteria regulate the consumption sequence of carbon sources d-pinitol and d-glucose in the fungal symbiont Leptographium procerum, and appear to alleviate the antagonistic effect from the fungus against RTB larvae. However, active components of these volatiles are unknown. We detected 67 volatiles by Gas Chromatography-Mass Spectrometer (GC-MS). Seven of them were identified as candidate chemicals mediating bacteria-fungus interactions, among which ammonia made L. procerum consume its secondary carbon source D-pinitol instead of its preferred carbohydrate D-glucose. In conclusion, ammonia regulated the consumption sequence of these two carbon sources in the fungal symbiont.