Larix olgensis, a keystone timber species in Northeast China, is increasingly threatened by Neofusicoccum laricinum-induced shoot blight, a devastating disease that compromises forest health and necessitates sustainable management strategies. Here, we demonstrate that the endophytic bacterium Bacillus amyloliquefaciens JL54 elicits multifaceted defense responses in L. olgensis, enhancing resistance to pathogen infection. Greenhouse assays revealed that JL54 pretreatment reduced disease incidence by 12.5% and achieved 43.75% control efficacy while maintaining host vigor. Histochemical analyses identified JL54-induced rapid hydrogen peroxide (H2O2) accumulation, extensive lignin deposition, and localized programmed cell death (PCD), indicative of a primed immune response. Transcriptomic analyses uncovered distinct temporal defense patterns: early-stage responses (0 h post-inoculation) were characterized by upregulation of cutin, suberin, and wax biosynthesis pathways, reinforcing physical barriers, whereas late-stage responses (12 h post-inoculation) were dominated by ribosome- and proteostasis-related pathways (e.g., heat shock proteins [HSPs], glutathione S-transferases [GSTs]) to mitigate cellular damage. Biochemical assays corroborated these findings, with JL54 colonization reducing membrane lipid peroxidation (27.2% decrease in malondialdehyde content) and significantly elevating the activity of key defense enzymes, including peroxidase (POD), phenylalanine ammonia-lyase (PAL), and GST. Phytohormone profiling implicated jasmonic acid (JA) as the central mediator of induced systemic resistance (ISR), with JL54-potentiated JA signaling preceding pathogen containment. Collectively, these results demonstrate that JL54 contributes to a coordinated defense strategy in L. olgensis, integrating structural reinforcement (cuticle/lignin), oxidative stress management, and JA-mediated immune priming. These insights advance the understanding of endophyte-conferred resistance in conifers and highlight JL54’s potential as a biocontrol agent for sustainable forestry.

The sulfonylurea receptor (SUR) is a well-established therapeutic target in human type 2 diabetes due to its central in insulin secretion. However, its functional significance in insect carbohydrate metabolism remains poorly understood. In this study, we investigated the role of SUR in the fall webworm, Hyphantria cunea, a destructive defoliator responsible for substantial agriculture and forestry losses. The H. cunea SUR gene (HcSUR) was cloned and characterized, and its biological functions were examined using RNA interference (RNAi). Expression analysis revealed that HcSUR is predominantly expressed in the larval fat body. Silencing of HcSUR significantly delayed larval growth and molting, increased mortality, and reduced nutrient utilization efficiency. Metabolomic profiling demonstrated that HcSUR knockdown disrupted multiple carbohydrate metabolic pathways, including glycolysis, the tricarboxylic acid (TCA) cycle, and glycogen/trehalose metabolism. These alterations resulted in abnormal accumulation of trehalose and glycogen in the fat body, accompanied by a marked reduction in ATP levels. In addition, HcSUR silencing caused intracellular Ca2+ overload in fat body cells and significantly upregulated the expression of several insulin-like peptide (HcILP) genes. Collectively, these findings indicate that HcSUR acts as a key regulatory node linking calcium homeostasis, ILP signaling, and carbohydrate metabolism to control larval development. We propose an HcSUR-Ca2+-ILPs-metabolic homeostasis regulatory model in H. cunea, which expand current understanding of SUR function in insects and provides a theoretical basis for developing environmentally friendly pest management strategies targeting energy homeostasis.

The pea aphid (Acyrthosiphon pisum) is a destructive phloem-feeding pest of alfalfa. Its overreliance on chemical insecticides necessitates the development of sustainable, plant-based resistance strategies. Plant flavonoids are important in induced defense, but their dynamic responses to aphid feeding and subsequent insecticidal effects remain unclear. Using the highly resistant alfalfa variety ‘Gannong No. 5’ (GN5), this study integrated behavioral assays, performance bioassays, untargeted and targeted metabolomics, and exogenous flavonoid feeding assays to investigate how pea aphid infestation alters flavonoid metabolism and thereby affects aphid performance. Bioassays confirmed strong antibiosis of GN5 against A. pisum. Behavioral choice assays showed that, at 2 h post-release, aphids significantly avoided plants pre-infested for 12 h and 48 h, but not those pre-infested for 24 h; by 8 h post-release, they significantly avoided all pre-infested plants regardless of infestation duration. Prolonged pre-infestation (48 h) also reduced average fecundity per female. Non-targeted metabolomics revealed substantial metabolic reprogramming after 48 h of aphid feeding, with most flavonoids and isoflavonoids significantly upregulated. Targeted metabolomics identified 28 flavonoids, among which only sakuranetin and chrysin were significantly upregulated after 48 h, indicating their specific induction. Finally, performance bioassays confirmed insecticidal effects in a concentration-dependent manner: sakuranetin at 0.1 μg/μL reduced reproduction, and at 10.0 μg/μL reduced survival; chrysin at 0.1 μg/μL reduced both survival and reproduction. Collectively, these results demonstrate that pea aphid feeding triggers the induction of specific defensive flavonoids in GN5, which may contribute to antibiosis. This study provides a theoretical basis for exploring flavonoid-based approaches in sustainable aphid management.

Acyrthosiphon pisum (pea aphid) is a major pest of leguminous crops, resulting in substantial economic losses worldwide. In recent years, entomopathogenic fungi (EPF) and RNA interference (RNAi) have emerged as effective biological control strategies for managing A. pisum. This study evaluated five entomopathogenic fungal strains and combined with transcriptomic analysis, to investigate the pathogenic mechanism of Akanthomyces dipterigenus against A. pisum, and explored the potential roles of two genes ApSlc19a3 and ApEXT2 in the defense against fungal infection. A. dipterigenus demonstrated the highest pathogenicity against adult A. pisum (LC50: 1.22 × 104 conidia mL-1; LT50: 3.909 d at 1.0 × 108 conidia mL-1). Sublethal and transgenerational effects showed that LC50 treatments of A. dipterigenus significantly reduced the longevity and fecundity of F0, LC50 treatment significantly reduced the mean generation time (T) and adult longevity in F1, LC30 treatment decreased the intrinsic rate of increase (r) and finite rate of increase (λ) in F1, along with a reduction in fecundity. Transcriptomic analysis of A. pisum infected with A. dipterigenus identified ApSlc19a3 and ApEXT2 as genes responsive to fungal infection, differentially expressed across developmental stages, and highly transcribed in the midgut and cuticle. RNAi silencing of these genes significantly enhanced the susceptibility of adult A. pisum to fungal infection. Therefore, the combined application of this RNAi approach with A. dipterigenus exhibits notable potential for controlling A. pisum. These findings provide important insights and a promising framework for future mechanistic studies and the implementation of biological control within sustainable pest management strategies.

Tetranychus urticae Koch (Acari: Tetranychidae) is a globally distributed agricultural pest with a broad host range and a high propensity for developing pesticide resistance, urgently requiring novel control strategies based on molecular targets. In this study, comparative transcriptomic analysis identified a previously uncharacterized gene, TuPSEG, which is specifically highly expressed in mite proterosomas and is induced by host plants. Sequence analysis revealed that TuPSEG encodes a hydrophilic secreted protein containing a signal peptide, with no known conserved domains, and exhibits high conservation only among closely related Tetranychus species. Developmental expression profiling showed that TuPSEG expression peaks in adult females, and its transcript levels significantly increase with prolonged feeding, with stronger induction observed after transfer to non-adapted hosts such as Citrus sinensis (L.) Osbeck and Solanum lycopersicum (L.). RNAi-mediated silencing of TuPSEG reduced feeding damage area on Glycine max leaves by 53.58% and resulted in a corrected mortality rate of 30.82% over 10 d, whereas survival was unaffected under artificial diet feeding, indicating that this gene specifically participates in plant feeding. Off-target assessment demonstrated that dsRNA targeting TuPSEG poses a minimal predicted risk to non-target organisms (natural enemies and crops) while exhibiting high specificity toward closely related spider mite species. In conclusion, TuPSEG plays a key role in host adaptation of spider mites, and its species-specificity offers a potential target for developing RNAi-based precision control technologies.

The widespread use of insecticides in forest ecosystems has raised significant concerns about their nontarget effects on biological control agents (BCAs), such as predators and parasitoid wasps, which play a pivotal role in natural pest suppression. This review evaluates the lethal and sublethal impacts of various insecticide classes on BCAs. Systemic insecticides, while effective in controlling pests, have been shown to impair the reproduction, foraging behavior, and host-seeking abilities of BCAs, leading to disruptions in pest regulation and biodiversity loss. In Pinus koraiensis (Siebold & Zucc) forests, parasitoid wasps such as Baryscapus dioryctriae (Yang & Song) are critical for managing pests such as Dioryctria pryeri. However, insecticide exposure threatens their efficacy, exacerbating pest outbreaks and ecosystem instability. The deployment of B. dioryctriae as a BCA provides a sustainable alternative to chemical control, with demonstrated success in reducing pest populations and minimizing environmental impacts. Integrated pest management (IPM) frameworks that combine biological control with targeted insecticide use offer promising solutions to mitigate nontarget effects. Future research should focus on optimizing mass-rearing and release strategies for BCAs, exploring semiochemical-based pest disruption and assessing the long-term ecological consequences of low-dose insecticide exposure. By advancing IPM approaches, forest managers can achieve effective pest control while preserving the ecological integrity and biodiversity of forest ecosystems.

Beta-cypermethrin is widely applied in Korean pine (Pinus koraiensis Siebold & Zucc.) seed orchards to control cone- and seed-infesting moths (e.g., Dioryctria spp.), yet its Wsublethal risks to non-target beneficial arthropods remain insufficiently characterized. Here, we systematically evaluated the ecological and physiological consequences of beta-cypermethrin exposure on the key parasitoid wasp Baryscapus dioryctriae Yang & Song, an important biological control agent in P. koraiensis forests. Adult wasps were exposed to LC30 and LC50 residue concentrations, and sublethal effects were quantified across reproductive, developmental, and biochemical endpoints over two generations. Sublethal exposure resulted in significant reductions in parasitism rates and offspring emergence, as well as altered developmental durations and adult longevity in both F0 and F1 generations. Enzymatic assays revealed time-dependent activation of detoxification enzymes (GST, CarE, AChE) alongside suppression of antioxidant defenses (CAT strongly; SOD early with partial recovery; POD biphasic), consistent with a sustained oxidative-stress burden. LC-MS/MS residue analysis further confirmed the accumulation and slow clearance of both beta-cypermethrin and its metabolite 3-phenoxybenzoic acid (PBA) within parasitoid tissues. These findings collectively demonstrate that even non-lethal concentrations of beta-cypermethrin can undermine the ecological fitness and persistence of B. dioryctriae, posing a tangible threat to the sustainability of biological control services. To safeguard beneficial parasitoids, integrated pest management strategies must incorporate selective insecticide use and exposure mitigation, especially in forest habitats where biological control is indispensable.

Heat shock proteins (HSPs) play a fundamental role in mediating thermotolerance in insects; however, their stage-specific contributions to thermal adaptation in the corn aphid, Rhopalosiphum maidis, remain poorly characterized. Here, we systematically characterized Hsp70-mediated thermotolerance mechanisms across the developmental stages of this devastating maize pest. A total of 15 Hsp70 genes were identified, each containing conserved functional domains such as EEVD and GIDLGTTYS motifs, ATP-binding sites, and nuclear localization signals. Subcellular localization predictions revealed a typical eukaryotic distribution pattern, with 12 localized to the cytosol, two to the endoplasmic reticulum, and one to the mitochondria. Following sequence alignment, nine non-redundant Hsp70 genes were selected for further functional analysis. Thermotolerance assays supported that third-instar nymphs were the most susceptible to heat stress, showing only 53.0 % survival at 40 °C, whereas adults exhibited the highest tolerance, with an LT50 of 43.11 °C. Expression profiling revealed significant upregulation of five Hsp70 genes-R. maidis Hsp70-8, -11, -12, -13 and -14-specifically in third-instar nymphs at 36 °C. RNAi-mediated silencing of these genes resulted in a 56.0-68.0 % increase in mortality among third-instar nymphs. Additionally, the recombinant R. maidis HSP70-7 (55 kDa) was successfully expressed. These findings underscore the existence of developmental trade-offs in thermotolerance in R. maidis and emphasize the functional diversification of Hsp70 genes, supporting their potential as RNAi targets for pest management under increasing climatic temperatures.

The polyphagous pest mite Tetranychus truncatus represents a major and expanding agricultural threat worldwide due to its exceptional ability to rapidly develop acaricide resistance and endure various abiotic stresses, a challenge exacerbated by global climate change. Although heat shock protein 70 (Hsp70) molecular chaperones are known to play essential roles in cellular stress responses, their specific function in mediating cross-tolerance in mites remains insufficiently explored. In this study, we identified and systematically characterized five Hsp70 genes in T. truncatus through comprehensive transcriptomic analysis. Under controlled thermal stress conditions (38-42 °C), TtHsp70-1, TtHsp70-2, and TtHsp70-3 were significantly and consistently upregulated, suggesting their involvement in heat adaptation. Notably, exposure to sublethal doses (LC30) of widely used acaricides, propargite, abamectin, and fenpropathrin, specifically induced the expression of TtHsp70-1 and TtHsp70-2, indicating a unique and critical role in chemical adaptation. RNA interference (RNAi)-mediated silencing of these two genes using specific double-stranded RNA drastically impaired thermotolerance, increasing heat-induced mortality by 12.5-35.0 %. Moreover, knockdown significantly enhanced chemical susceptibility, elevating pesticide-induced mortality by 7.5-38.8 % across all tested acaricides. Collectively, these results demonstrate that TtHsp70-1 and TtHsp70-2 are crucial for T. truncatus to cope with heat and chemical stressors at the molecular level, providing important insights into how pests adapt to increasingly extreme climatic conditions.

With a generally warming global climate, the number of Tetranychus truncatus specimens in the Hexi region in China has been increasing. As ectotherms, the growth and development of T. truncatus are greatly affected by changes in environmental temperature. The effect of heatwaves on organisms depends on a delicate balance between damage and repair periods. Therefore, we simulated nine patterns of periodically recurring changes in the frequency of high-temperature days using an intraday gradual temperature change model to study and compare the effects on the development and reproduction of pyridaben-sensitive and -resistant strains of T. truncatus . The results showed that the influence of the frequency of high-temperature days on developmental stages, longevity and fecundity was different between the two strains. The egg and immature stages of the sensitive strain were all affected by hot days, whereas the adult stage was less affected by the frequency. The egg stage of the resistant strain was less affected; it was mainly affected in the immature and adult stages. Under the moderate condition of increasing the proportion of days at normal temperature, the longevity of the resistant strain gradually increased and reached a maximum at a 1:3 frequency, and then it decreased with the increase in high-temperature days. The longevity of the sensitive strain was less affected by frequency, and there was no significant difference between most treatment and control groups. In addition, both sensitive and resistant strains were able to complete growth and development under all nine frequencies of high-temperature days, but the reproductive rate was lower than it was at normal temperatures, indicating that both strains of T. truncatus adapted to high temperatures at the expense of reduced reproduction rates. This lays a key theoretical foundation for predicting the occurrence of agricultural pest populations under the background of climate warming and developing appropriate control strategies.

Cuticular proteins, in conjunction with chitin, compose the insect exoskeleton, and play a key role in the growth, development, and molting of insects. However, the specific functions of most cuticular protein genes in the growth, development, and reproductive processes of the pea aphid (Acyrthosiphon pisum) remain unclear. In this study, we have identified six cuticular protein genes in the pea aphid, namely ApCP7, ApCP10, ApCP19, ApCP19.8-like, ApCP35 and ApCP62. We found that the expression levels of six genes were highly expressed during the adult stage, and except for ApCP10, which is highly expressed in the pea aphid cuticle, other genes were highly expressed in the ovaries. Subsequently, we observed that the survival rate and fecundity of pea aphid were significantly lower than those of the control group after silencing ApCP7 and ApCP62 through RNA interference. Furthermore, when ApCP7 transcript levels were reduced, aphid encountered difficulties in molting, were smaller in body size, and exhibited a darker body color. These results indicate that ApCP7 and ApCP62 are involved in the development and reproduction of pea aphid, and could be used as RNAi targets for controlling pea aphid.

Baryscapus dioryctriae (Chalcidodea: Eulophidae) is a parasitic wasp that parasitizes the pupae of many Pyralidae members and has been used as a biological control agent against Dioryctria pests of pinecones. This B. dioryctriae assembly has a genome size of 485.5 Mb with a contig N50 of 2.17 Mb, and scaffolds were assembled onto six chromosomes using Hi-C analysis, significantly increasing the scaffold N50 to 91.17 Mb, with more than 96.13

Tetranychus truncatus (Acari: Tetranychidae) has caused serious economic losses on some crops (soybean, corn, and cotton) in China, and has developed resistance to most acaricides. Our laboratory study found that T. truncatus was resistant to pyridaben and also adapted to high temperature (34–40 °C). High temperature stress may cause arthropods to produce a large amount of reactive oxygen species (ROS), causing oxidative damage. Antioxidant enzymes, as the main antioxidants, can reduce the damage caused by excessive ROS in arthropods. In order to study the adaptation mechanism of the pyridaben-resistant strain of T. truncatus to high temperature and the role of antioxidant enzyme genes under high temperature stress, four antioxidant enzyme genes, TtSOD, TtPOD3, TtPOD4, and TtGSTs2, were screened according to the transcriptome sequencing data of pyridaben-susceptible and -resistant strains in T. truncatus. Firstly, the phylogeny and structure analyses of these four genes were carried out. Then, real-time quantitative PCR (RT-qPCR) technology was used to analyze the gene expression patterns of antioxidant enzymes in two strains of T. truncatus at three different high temperature ranges (34 °C, 38 °C, and 42 °C). The results showed that the expression levels of four antioxidant enzyme genes of two strains of T. truncatus were induced by high temperature stress, and the expression levels of antioxidant enzyme genes were significantly different in each development state. The gene expression of antioxidant enzyme genes in resistant strains at the adult stage was significantly higher than that in susceptible strains. After the TtSOD and TtPOD4 genes of adult mites of the resistant strain were silenced by RNA interference (RNAi) technology, the mortality rate of mites with TtPOD4 gene silencing reached 41.11% after 96 h at 34 °C, which was significantly higher than that of the control and TtSOD gene silencing. It has been confirmed that the TtPOD4 gene plays a key role in the adaptation of pyridaben-resistant strain of T. truncatus to high temperature. It lays a theoretical foundation for revealing the thermal adaptation mechanism of T. truncatus.

Reverse chemical ecology has been widely applied for the functional characterization of olfactory proteins in various arthropods, but few related studies have focused on parasitic wasps. Here, the odorant carrier Niemann-Pick C2 protein of Baryscapus dioryctriae (BdioNPC2b) was studied in vitro and in vivo. Ligand binding analysis revealed that BdioNPC2b most strongly bound to 2-butyl-2-octenal and which compound could elicit an EAG response and attracted B. dioryctriae adults. Moreover, this odorant attractant significantly improved the reproductive efficiency of B. dioryctriae compared to that of the control. Then, the relationship between BdioNPC2b and 2-butyl-2-octenal was validated by RNAi, and site-directed mutagenesis revealed the involvement of three key residues of BdioNPC2b in binding to 2-butyl-2-octenal through hydrogen bonding. Our findings provide not only a deeper understanding of the olfactory function of NPC2 in wasps but also useful information for improving the performance of the parasitoid B. dioryctriae as a biological control agent.

BACKGROUND: Cuticular proteins (CPs) play essential roles in forming cuticular structures in insects. However, the specific functions and regulatory mechanisms of CPs remain largely unexplored. In this study, the Larval cuticular protein 17 (HcLCP-17) gene was identified from Hyphantria cunea, a highly destructive and polyphagous forest pest. To investigate the role of HcLCP-17 in cuticular function and transcriptional regulation mediated by 20E-responsive transcription factors (ERTFs), we employed RNA interference (RNAi) and yeast one-hybrid assay techniques. Additionally, we examined the molecular mechanism by which chlorbenzuron, a type of benzoylphenylurea (BPU) that functions as a chitin synthesis inhibitor (CSI), affects the 20E signaling pathway and ultimately regulates HcLCP-17 expression. RESULTS: HcLCP-17 encodes a polypeptide consisting of 393 amino acids, which includes a chitin-binding domain. Silencing HcLCP-17 resulted in a disturbance in the structural organization of the larval cuticle and a notable reduction in chitin levels. HcLCP-17 expression was controlled by the interaction between Broad-Complex (Br-C) and beta Fushi Tarazu Factor-1 (beta FTZ-F1) with its promoter fragment. Furthermore, the inhibitory effect of chlorbenzuron on HcLCP-17 expression was found to be potentially mediated by Br-C and beta FTZ-F1. CONCLUSION: The study presents a novel mode of action for the 20E signaling pathway in regulating the expression of CPs and reveals the potential mode-of-action of BPUs in insect cuticles. These findings provide a theoretical basis for future utilization of LCP-17 as a pesticide target making a significant contribution to the development of effective pest management strategies. (c) 2024 Society of Chemical Industry.

The adaptability of insects to hosts has long been a focal point in the study of insect-plant interactions. The pea aphid (Acythosiphon pisum), a significant pest of numerous leguminous crops, not only inflicts direct economic losses but also disseminates various plant viruses. To understand how pea aphids adapt to diverse alfalfa varieties. We analyzed the differentially expressed genes (DEGs) of pea aphids in distinct alfalfa varieties using transcriptome sequencing, and subsequently conducted functional validation of these genes. Comparative analysis between pea aphids feeding on susceptible and resistant strains revealed that DEGs in aphids feeding on resistant strains were primarily associated with transcriptional enrichment in the sugar, amino acid, protein, and lipid metabolism pathways. Fourteen DEGs related to adaptation of the pea aphid to alfalfa were chosen, including five carboxylesterases (CarE), four cytochrome P450s, three glutathione S-transferases, and two peroxidases (POD). RT-qPCR results indicated significant up-regulation of two carboxylesterase genes and two peroxidase genes after 24 h of feeding resistant alfalfa (Gannong 5, GN5) compared to the susceptible varieties (Hunter River, LRH), particularly highlighting the high expression levels of ApCarE4 and ApPOD3. Simultaneously, RNAi-induced knockdown of ApCarE4 and ApPOD3 led to a higher mortality of pea aphids in the alfalfa Hunter River. These results indicate that ApPOD3 and ApCarE4 are involved in the detoxification of metabolic functions in the adaptation of pea aphids to host switching. These findings contribute to the understanding of pea aphid adaptation to host plants and lay a foundation for further exploration of the physiological roles of carboxylesterase and peroxidase genes in pea aphids.

Migratory birds play an important role in the cross-regional transmission of zoonotic pathogens. Assessing the presence of zoonotic pathogens carried by migratory birds is critical for disease control. However, information about Blastocystis infection in the migratory birds is very limited. Thus, we conducted this study with the aim to explore the occurrence, prevalence and subtyping of Blastocystis in four breeds of migratory birds in northeastern China. From October 2022 to April 2023, a total of 427 fresh fecal samples were obtained from four breeds of migratory birds in five nature reserves in northeastern China, and screened for Blastocystis by PCR amplification. Twenty-one (4.92 %) of the studied samples were confirmed Blastocystis-positive, and two known zoonotic subtypes ST6 and ST7 were founded, with ST7 being the major subtype. Until now, we firstly reported the infection status and subtyping of Blastocystis in the migratory Greater White-Fronted Goose, White Stork, Oriental White Stork and Bean Goose in China. More importantly, these findings present further data on the genetic diversity and transmission routes of Blastocystis and further arouse public health concerns about this organism.

ABSTRACT In order to provide a highly feasible research pathway for the control of larch shoot blight, healthy larch branches and leaves were collected from 13 sampling sites in 8 provinces in China. The antagonistic endophytic bacteria obtained from the screening were used to carry out disease control experiments in potted seedlings. The safety evaluation test was conducted on the antagonistic bacteria. Subsequently, the strains with better preventive effect and high safety were identified by morphological and molecular methods. A total of 391 strains of endophytic bacteria were isolated from healthy larch branches and leaves. Seventy-eight strains of larch endophytic bacteria with antagonistic effect were obtained by primary sieving. Ten strains of endophytic bacteria with obvious antagonism were further obtained by secondary sieving, and all of them had an inhibition rate of more than 57%. Among them, strains YN 2, JL 6, NMG 23, and JL 54 showed the highest inhibition rate of 63.16%–65.08%, which was significantly different from the other treatments. The results of the pot test showed that 14 days after inoculation with the pathogen, strains YN 2 and JL 54 were more effective in the control of larch shoot blight, with the preventive effects reaching 57.7% and 50.0%, respectively. Strains JL 6 and JL 54 were biologically safe in the safety evaluation test. Therefore, strain JL 54 was selected for identification. It was identified as Bacillus amyloliquefaciens through morphological observation, 16S rDNA sequence, gyrB gene sequence and 16S rDNA- gyrB tandem feature sequence analysis. IMPORTANCE Larch shoot blight is a widely distributed, damaging, and rapidly spreading fungal disease of forest trees that poses a serious threat to larch plantations. Endophytic bacteria have biological effects on host plants against pests and diseases, and they have a growth-promoting effect on plants. In this paper, we investigated for the first time the biocontrol effect of endophytic bacteria on larch shoot blight by screening endophytic bacteria with the function of antagonizing dieback fungi. Bacillus amyloliquefaciens JL 54 has a better prospect of biocontrol against larch shoot blight, which lays the foundation for the application of this bacterium in the future.

BACKGROUND:Healthy cultures of arthropods are important for pest management programs (e.g. biocontrol). Little is known about how rearing conditions may affect pheromonal interactions. We investigated how rearing histories and densities affect pheromone emission/production in two stink bug species (Hemiptera: Heteroptera), the predatory bug Arma custos, a biocontrol agent, and the bean bug Riptortus pedestris, a pest on legume crops. RESULTS:Nymphs from newly established laboratory colonies of both species produced higher amounts of the defense (dispersal) compound, 4-oxo-(E)-hexenal (OHE), in the presence of conspecific nymphs. Also, when two or more A. custos males were placed together, the dorsal abdominal glands (DAGs) ceased to release aggregation pheromone, whereas the metathoracic glands (MTGs) increased the emission of defensive odors. These changes resulted from exposure to conspecific pheromone odors, as confirmed by exposing bugs to pheromone standards. Hence, pheromone emissions in these stink bugs are readily changed in response to the odors of conspecifics, which may become a problem after long-term rearing. Indeed, an old laboratory colony of A. custos (~30 generations) exhibited less-developed DAGs and reduced pheromone production. Instead, males released significantly more defensive odors from the enlarged MTGs. Furthermore, long-term rearing conditions appeared to favor nymphs that were able to share space with conspecifics by releasing less OHE, which has not yet occurred in the new laboratory colonies. CONCLUSION:Rearing density affects pheromone release in newly established laboratory colonies of stink bug species, whereas long-term rearing results in new pheromonal compositions coinciding with adaptive changes in gland development. © 2023 Society of Chemical Industry.