Nicotinic Acetylcholine Receptor Alpha6 Contributes to Antiviral Immunity via IMD Pathway in Drosophila melanogaster.

Currently, insecticides that target nicotinic acetylcholine receptors (nAChR) are widely used. Studies on the sublethal effects of insecticides have found that they can affect the amount of virus in insects. The mechanism by which insecticides affect insect virus load remain unclear. Here, we show that nAChR targeting insecticide can affect viral replication through the immune deficiency (IMD) pathway. We demonstrate that a low dose of spinosad (6.8 ng/mL), acting as an antagonist to Drosophila melanogaster nicotinic acetylcholine receptor α6 (Dα6), significantly elevates Drosophila melanogaster sigmavirus (DMelSV) virus titers in adults of Drosophila melanogaster. Conversely, a high dose of spinosad (50 ng/mL), acting as an agonist to Dα6, substantially decreases viral load. This bidirectional regulation of virus levels is absent in Dα6-knockout flies, signifying the specificity of spinosad's action through Dα6. Furthermore, the knockdown of Dα6 results in decreased expression of genes in the IMD pathway, including dredd, imd, relish, and downstream antimicrobial peptide genes AttA and AttB, indicating a reduced innate immune response. Subsequent investigations reveal no significant difference in viral titers between relish mutant flies and Dα6-relish double mutants, suggesting that the IMD pathway's role in antiviral defense is dependent on Dα6. Collectively, our findings shed light on the intricate interplay between nAChR signaling and the IMD pathway in mediating antiviral immunity, highlighting the potential for nAChR-targeting compounds to inadvertently influence viral dynamics in insect hosts. This knowledge may inform the development of integrated pest management strategies that consider the broader ecological impact of insecticide use.

Metarhizium rileyi with broad-spectrum insecticidal ability confers resistance against phytopathogens and insect pests as a phytoendophyte.

BACKGROUND: Entomophagous fungi (EPF) not only directly kill insect pests, but also colonize plants and improve their resistance against pests. However, most previous research has focused on Beauveria bassiana and Metarhizium anisopliae, and there are few reports on whether other EPF can enhance resistance against pests via endogenous colonization. Herein, an EPF strain was isolated from diseased larvae of Spodoptera litura in a soybean field, and subjected to genome-wide sequencing at the chromosomal level. The pathogenicity of the isolate toward various pest insects was evaluated, and the ability to colonize plants and induce resistance against phytopathogens and insect pests was tested. RESULTS: The purified isolate was identified as M. rileyi and designated MrS1Gz1-1. Biological assays revealed its strong pathogenicity toward five insect pests belonging to Lepidoptera and Hemiptera. Furthermore, the strain inhibited the growth of soil-borne plant disease caused by Sclerotinia sclerotiorum in vitro. It colonized plants as an endophyte via soil application, thereby inducing plant resistance-related genes against phytopathogen infection, and it disrupted the feeding selectivity of S. litura larvae. CONCLUSION: M. rileyi MrS1Gz1-1 has potential as a broad-spectrum microbial control agent that can induce resistance against phytopathogens and insect pests feeding as an endotype. The complete genome provides a valuable resource for exploring host interactions. © 2024 Society of Chemical Industry.

Molecular and biochemical changes in Locusta migratoria (Orthoptera: Acrididae) infected with Paranosema locustae.

Microsporidia are a group of eukaryotic intracellular parasitic organisms that infect almost all vertebrates and invertebrates. Paranosema locustae are specialized parasites of Orthoptera that are often used as biological controls of locusts, with slow effects of action. In this study, we found that after infection with P. locustae, changes in energy metabolism in male and female Locusta migratoria as were consistent, with no gender differences. During the first 8 days of infection, L. migratoria used sugar as a source of energy. After 8 days, lipids and proteins were consumed to provide energy when the spore load was considerably heavy, and energy supply was insufficient. With increasing infection concentration and time, energy conversion from sugar, fats, and proteins was improved, which may explain why high mortality did not occur until about 15 days after P. locustae infection. The tandem mass tag-based quantitative proteomics analysis revealed that most altered metabolism-related proteins were upregulated (27 of 29 in the metabolic pathway). This result suggests that P. locustae infection accelerated metabolism in L. migratoria, which facilitated the pathogen's life cycle, inhibiting the growth and development of the locusts and eventually killing them. Our findings will be useful to better understand of the chronic pathogenic mechanisms of P. locustae and inform on applications of P. locustae to control locusts.

Effect of ultraviolet radiation on Beauveria bassiana virulence and development of protective formulations.

Locusta migratoria is a serious agricultural pest in China. Beauveria bassiana is one of the most important pathogens of grasshoppers and locusts. The effects of ultraviolet light were evaluated on the B. bassiana strain BbZJ1. The results showed that 253.7 and 360 nm wavelength UV (Ultra Violet) did not affect the germination of B. bassiana after its recovery from UV treatments. Nevertheless, the virulence of B. bassiana BbZJ1 after its recovery from radiation of UV (253.7 nm) increased. The mortality rates were 85.00% for the BbZJ1 control, was 96.67% for BbZJ1 recovered from radiation of UV (253.7 nm) for 60 min. After treatment with 253.7 nm UV radiation for 60 min, the expression levels of stress-resistant genes BbAlg9 and Bbadh2 in BbZJ1 strain were 2.68 and 2.29 times higher than those in the control group, respectively. Meanwhile, the B. bassiana prepared in 5% groundnut oil showed highest tolerance levels to the ultraviolet radiation. The 5% groundnut oil was the most suitable potential UV-protectant for B. bassiana in terms of cost and availability.

Transcriptomic analysis of entomopathogenic fungus Beauveria bassiana infected by a hypervirulent polymycovirus BbPmV-4.

Polymycoviridae is a recently established family of mycoviruses. Beauveria bassiana polymycovirus 4 (BbPmV-4) was previously reported. However, the effect of the virus on host fungus B. bassiana was not clarified. Here, a comparison between virus-free and virus-infected isogenic lines of B. bassiana revealed that BbPmV-4 infection of B. bassiana changes morphology and could lead to decreases in conidiation and increases in virulence against Ostrinia furnacalis larvae. The differential expression of genes between virus-free and virus-infected strains was compared by RNA-Seq and was consistent with the phenotype of B. bassiana. The enhanced pathogenicity may be related to the significant up-regulation of genes encoding mitogen activated protein kinase, cytochrome P450, and polyketide synthase. The results enable studies of the mechanism of interaction between BbPmV-4 and B. bassiana.

Defensive Resistance of Cowpea Vigna unguiculata Control Megalurothrips usitatus Mediated by Jasmonic Acid or Insect Damage.

Vigna unguiculata is a vital vegetable crop in Southeast Asia, and Megalurothrips usitatus can cause huge damage to this crop. Enhancing the resistance of V. unguiculata against M. usitatus is a promising way to protect this crop; however, there is limited information regarding the mechanism underlying the resistance of V. unguiculata against M. usitatus. Here, a behavior assay was performed to explore the resistance of V. unguiculata against M. usitatus after insect damage or treatment by jasmonic acid (JA). Furthermore, transcriptome and metabonomics analysis was used to detect the putative mechanism underlying the resistance of V. unguiculata against M. usitatus. The pre-treatment of Vigna unguiculata with JA or infestation with Megalurothrips usitatus alleviated the damage resulting from the pest insect. We further identified differentially expressed genes and different metabolites involved in flavonoid biosynthesis and alpha-linolenic acid metabolism. Genes of chalcone reductase and shikimate O-hydroxycinnamoyltransferase involved in flavonoid biosynthesis, as well as lipoxygenase and acyl-CoA oxidase involved in alpha-linolenic acid metabolism, were upregulated in plants after herbivory or JA supplementation. The upregulation of these genes contributed to the high accumulation of metabolites involved in flavonoid biosynthesis and the alpha-linolenic acid metabolism pathway. These transcriptional and metabolite changes are potentially responsible for plant defense and a putative regulatory model is thus proposed to illustrate the cowpea defense mechanism against insect attack. Our study provides candidate targets for the breeding of varieties with resistance to insect herbivory by molecular technology.

Symbiotic Bacteria System of Locusta migratoria Showed Antifungal Capabilities against Beauveria bassiana.

The stability of symbiotic flora is an important indicator of the health of an organism. Symbiotic bacteria have been proven to be closely involved in the immune process of organisms. The pathogenicity of Beauveria bassiana was studied in relation to symbiotic bacteria on the surface and inside of the migratory locust (Locusta migratoria). The results showed that the surface disinfection of test locusts contributed to the pathogenicity of B. bassiana to locusts. Most of the surface bacteria of L. migratoria caused some inhibition of B. bassiana growth, and LM5-4 (Raoultella ornithinolytica), LM5-2 (Enterobacter aerogenes), and LM5-13 (Citrobacter freundii) showed the highest inhibitory effect on the growth of B. bassiana. The inoculation of locusts with additional surface symbiotic bacteria reduced the virulence of B. bassiana to L. migratoria. Infection by different strains of B. bassiana caused similar changes in the symbiotic flora of migratory locusts. The inoculation of locusts with additional intestinal symbiotic bacteria (Enterobacter sp.) reduced the virulence of B. bassiana to L. migratoria. These findings illustrate the effect of bacterial communities on fungal infections in L. migratoria when seen from the perspective of ecology in a microenvironment. The active antifungal substances of such bacteria and their mechanisms of action need further study.

First record of Aspergillus nomiae as a broad-spectrum entomopathogenic fungus that provides resistance against phytopathogens and insect pests by colonization of plants.

Introduction: Aspergillus nomiae is known as a pathogenic fungus that infects humans and plants but has never been reported as an entomophagous fungus (EPF) that can provide other functions as an endotype. Methods: A strain of EPF was isolated and identified from diseased larvae of Spodoptera litura in a soybean field and designated AnS1Gzl-1. Pathogenicity of the strain toward various insect pests was evaluated, especially the ability to colonize plants and induce resistance against phytopathogens and insect pests. Results: The isolated EPF strain AnS1Gzl-1 was identified as A. nomiae; it showed strong pathogenicity toward five insect pests belonging to Lepidoptera and Hemiptera. Furthermore, the strain inhibited the growth of Sclerotinia sclerotiorum in vitro, a causal agent of soil-borne plant disease. It colonized plants as an endophyte via root irrigation with a high colonization rate of 90%, thereby inducing plant resistance against phytopathogen infection, and disrupting the feeding selectivity of S. litura larvae. Discussion: This is the first record of a natural infection of A. nomiae on insects. A. nomiae has the potential to be used as a dual biocontrol EPF because of its ability to not only kill a broad spectrum of insect pests directly but also induce resistance against phytopathogens via plant colonization.

Characterization of a Novel Pathogenic Reovirus in Grasshoppers.

Grasshoppers can swarm in the millions and destroy crops over wide areas, posing a major economic threat to agriculture. A wide range of insect-related viruses has recently been reported in the metagenomics of grasshoppers. Here, we identified and isolated a novel reovirus from grasshoppers, named Acrididae reovirus (ARV). The complete genome of ARV was composed of nine dsRNA segments. Phylogenetic analysis revealed that ARV formed a monophyletic lineage with unclassified insect-associated reoviruses and was sufficiently distinct from known genera of Reoviridae. ARV could replicate in its host Locusta migratoria and result in host death. Lower-dose ARV infection affected ovary development and resulted in a significant reduction in fecundity. The identification and characterization of a novel pathogenic reovirus could potentially promote the development of new biological control agents.

Functional characterization of a terpene synthase responsible for (E)-ß-ocimene biosynthesis identified in Pyrus betuleafolia transcriptome after herbivory.

(E)-ß-ocimene, a ubiquitous monoterpene volatile in plants, is emitted from flowers to attract pollinators and/or from vegetative tissues as part of inducible defenses mediated by complex signaling networks when plants are attacked by insect herbivores. Wild pear species Pyrus betuleafolia used worldwide as rootstock generally displays valuable pest-resistant traits and is a promising genetic resource for pear breeding. In the current study, transcriptional changes in this wild pear species infested with a polyphagous herbivore Spodoptera litura and the underlying molecular mechanisms were fully investigated. A total of 3,118 differentially expressed genes (DEGs) were identified in damaged pear leaf samples. Spodoptera litura larvae infestation activated complex phytohormonal signaling networks in which jasmonic acid, ethylene, brassinosteroids, cytokinin, gibberellic acid and auxin pathways were induced, whereas salicylic acid and abscisic acid pathways were suppressed. All DEGs associated with growth-related photosynthesis were significantly downregulated, whereas most DEGs involved in defense-related early signaling events, transcription factors, green leaf volatiles and volatile terpenes were significantly upregulated. The PbeOCS (GWHGAAYT028729), a putative (E)-ß-ocimene synthase gene, was newly identified in P. betuleafolia transcriptome. The upregulation of PbeOCS in S. litura-infested pear leaves supports a potential role for PbeOCS in herbivore-induced plant defenses. In enzyme-catalyzed reaction, recombinant PbeOCS utilized only geranyl pyrophosphate but not neryl diphosphate, farnesyl pyrophosphate or geranylgeranyl diphosphate as a substrate, producing (E)-ß-ocimene as the major product and a trace amount of (Z)-ß-ocimene. Moreover, as a catalytic product of PbeOCS, (E)-ß-ocimene showed repellent effects on larvae of S. litura in dual-choice bioassays. What is more, (E)-ß-ocimene increased mortalities of larvae in no-choice bioassays. These findings provide an overview of transcriptomic changes in wild pears in response to chewing herbivores and insights into (E)-ß-ocimene biosynthesis in pear plants, which will help elucidate the molecular mechanisms underlying pear-insect interactions.

Effects of Nutritional Composition of Different Prey Eggs on Development and Reproduction of the Predatory Bug, Orius sauteri (Hemiptera: Anthocoridae).

Orius sauteri (Poppius) is an important predator of many economically important insect pests. The mass rearing of O. sauteri is difficult, limiting its application in pest control. Here we assessed the nutritional quality of eggs of Sitotroga cerealella (Olivier), Agrotis ypsilon (Rottemberg), or Spodoptera litura (Fabricius), and their potential for rearing O. sauteri in the laboratory for two generations. Of species tested, S. cerealella eggs resulted in the highest survival and reproduction of O. sauteri compared to the other two lepidopteran species. Eggs of A. ypsilon were a suitable diet for the nymphal stage, which developed faster on A. ysilon eggs than those of S. cerealella eggs. Conversely, eggs of S. litura were not a suitable diet for O. sauteri, and they disrupted the development and reproduction of O. sauteri. Sitotroga cerealella eggs showed advantages in all the nutritional components evaluated. Orius sauteri fed S. litura eggs contained significantly lower protein levels than those fed on the other eggs tested. Spodoptera litura eggs significantly enhanced the CAT activity in O. sauteri, which suggests that some components from S. litura eggs harmed the development and reproduction of O. sauteri. Based on these results, we suggest using a combined diet for mass rearing of the pirate bug, feeding the nymphs and adults with A. ypsilon eggs and S. cerealella eggs, respectively. This study contributes to the discovery of artificial diets for mass rearing O. sauteri and other Orius species in the future.

Interspecific spread of dsRNA mycoviruses in entomogenous fungi Beauveria spp.

Mycoviruses can spread interspecifically and intraspecifically in plant pathogenic fungi, as well as spreading intraspecifically in entomogenous fungi, especially Beauveria bassiana. However, whether mycoviruses are common in Beauveria spp. and can spread interspecifically between Beauveria species are unclear. Herein, four Beauveria species, but not B. bassiana, were randomly selected for double stranded RNA (dsRNA) detection. Furthermore, two previously reported dsRNA mycoviruses from B. bassiana, BbCV-2 and BbPmV-4, were used to study the interspecific transmission among B. bassiana, B. amorpha, and B. aranearum, using hyphal anastomosis and a novel insect coinfection transmission method. The results showed that dsRNA mycoviruses exist universally in Beauveria spp. and could spread interspecifically between different Beauveria species. The transmission efficiency from B. bassiana to the other two Beauveria species was significantly higher than that of the reverse transmission. Both viruses could stably and vertically spread in B. amorpha and B. aranearum, which affected their growth rate and colony morphology.

Identification of diverse viruses associated with grasshoppers unveils the parallel relationship between host phylogeny and virome composition.

Grasshoppers (Orthoptera: Acridoidea) are one of the most dangerous agricultural pests. Environmentally benign microbial pesticides are increasingly desirable for controlling grasshopper outbreaks in fragile ecosystems. However, little is known about natural pathogens infecting this pest. Here we profile the rich viral communities in forty-five grasshopper species and report 302 viruses, including 231 novel species. Most of the identified viruses are related to other insect viruses, and small RNA sequencing indicates that some are targeted by host antiviral RNA interference (RNAi) pathway. Our analysis of relationships between host phylogeny and virus diversity suggests that the composition of viromes is closely allied with host evolution. Overall, this study is a first extensive exploration of viruses in grasshoppers and provides a valuable comparative dataset of both academic and applied interest.

Bt Cry1Ab/2Ab toxins disrupt the structure of the gut bacterial community of Locusta migratoria through host immune responses.

The gut microbiota of insects plays a vital role in digestion, nutrient acquisition, metabolism of dietary toxins, pathogen immunity and maintenance of gut homeostasis. Bacillus thuringinensis (Bt) poisons target insects through its toxins that are activated in the insect gut. The effects of Bt toxins on gut microbiota of insects and their underlying mechanisms are not well understood. In this study, we found that Cry1Ab/2Ab toxins significantly changed the gut bacterial community's structure and reduced the total load of gut bacteria in the Locusta migratoria. In addition, Cry toxins significantly increased the level of reactive oxygen species (ROS) in the gut of locusts. Our results also showed that Cry1Ab/2Ab toxins induced the host gut's immune response by up-regulating of key genes in the Immune deficiency (IMD) and Toll pathway. RNA interference showed that knocking down Relish could narrow the difference in the load, diversity, and composition in gut bacteria caused by Cry toxins. Our findings suggest that Bt potentially influences the gut bacterial community of L. migratoria through host immune response.

Effect of genetically modified maize expressing the Cry1Ab and EPSPS proteins on growth, development, and gut bacterial diversity of the non-target arthropod Locusta migratoria.

The widespread cultivation of genetically modified (GM) crops has raised concerns for their safety. Here, we evaluated the effects of a GM maize variety expressing the Cry1Ab (14.76 ± 0.87 µg/g FW) and EPSPS proteins (191.55 ± 15.69 µg/g FW) on the life-history traits and gut bacterial community of a non-target arthropod, Locusta migratoria, in the laboratory. We found that GM maize had no significant effect on the survival or body weight of different development stages of L. migratoria. The midgut and hindgut bacterial diversities and compositions were determined using high-throughput sequencing targeting the V3-V4 regions of the 16S rRNA. No significant changes were found in the species diversity or abundance between insects in the GM-fed treatment and the non-GM control. Furthermore, the concentration of Cry1Ab and EPSPS in the gut was determined after digestion of GM maize. Results showed that the contents of Cry1Ab/EPSPS rapidly decreased and were hard to detect after 72 h. Based on the parameters assessed, we can conclude that the GM maize variety examined has no significant adverse effect on L. migratoria.

Effects of aphid-induced semiochemicals from cover plants on Harmonia axyridis (Coleoptera: Coccinellidae).

BACKGROUND: Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is an important natural enemy of aphids. Plant species and plant health conditions can affect the behavior of H. axyridis. To determine plant effects on this lady beetle, we examined beetle responses to four cover crops: coriander (Coriadrum sativum L., Apiales: Apiaceae), marigold (Tagetes erecta L., Asterales: Asteraceae), sweet alyssum (Lobularia maritima L., Brassicales: Brassicaceae), and alfalfa (Medicago sativa L., Fabales: Fabaceae). Our goal was to better understand this predator's ovipositional behavior in response to different plants and its olfactory response to the aphid-induced volatiles from these plants. RESULTS: We found that this lady beetle did not have any significant oviposition preference among the four plant species, but H. axyridis preferred to lay eggs on the lower surface of leaves, regardless of the plant species. H. axyridis females had a significant preference for aphid-infested marigolds, but were not attracted by any of the other three cover plants or marigolds without aphid damage. Compared to the uninfested marigold plants, the emission of 12 compounds significantly increased on the aphid-infested marigolds, and two of them were attractive to H. axyridis under suitable concentrations. CONCLUSION: H. axyridis did not show any significant oviposition preference among the four cover crops. Aphid-infested marigolds can attract H. axyridis. Indole and terpinen-4-ol mediated lady beetle attraction. These synomones have potential for manipulating populations of H. axyridis as a component of conservation biological control. © 2022 Society of Chemical Industry.

Antenna-Biased Odorant Receptor HvarOR25 in Hippodamia variegata Tuned to Allelochemicals from Hosts and Habitat Involved in Perceiving Preys.

Odorant receptors (ORs) of ladybird Hippodamia variegata play vital chemosensory roles in searching and locating preys. In the current study, 37 ORs were initially identified from the antennal transcriptome of H. variegata. The quantitative polymerase chain reaction demonstrated that several HvarORs including HvarOR25 were specific or enriched in ladybird antennae. In two-electrode voltage clamp recordings, recombinant HvarOR25 was narrowly tuned to six chemical ligands including aphid-induced, aphid-derived, and plant-derived volatiles. In electroantennogram assays, all six volatiles elicited electrophysiological responses. Among the six volatiles, cis-3-hexenyl acetate, hexyl butyrate, hexyl hexanoate, and 3-methyl-3-buten-1-ol were attractive for both sexes of H. variegata. Additionally, molecular docking indicated that HvarOR25 was bound to all ligands with high binding affinities. Taken together, HvarOR25 facilitates perception of preys by recognizing relevant allelochemicals from hosts and habitat. Our findings provide valuable insights into understanding biological functions of HvarORs and help to develop a novel biocontrol strategy based on olfactory-active compounds.

Transcriptomic and Metabolomic Analysis of Wheat Kernels in Response to the Feeding of Orange Wheat Blossom Midges (Sitodiplosis mosellana) in the Field.

The orange wheat blossom midge (Sitodiplosis mosellana Géhin) is an insect pest that feeds on wheat (Triticum aestivum L.). The resistance mechanisms of wheat to S. mosellana infestation are largely unknown. In this study, the wheat varieties LX99 and 6218 were identified as highly resistant and susceptible, respectively, via field investigations conducted over two consecutive years. Morphological and microstructural observations of mature wheat kernels following S. mosellana infestation revealed that the degree of cell structure damage in resistant LX99 grains was less than that in susceptible 6218 grains. Transcriptomic and metabolomic analyses of seeds following S. mosellana feeding showed that the differentially expressed genes and differentially accumulated metabolites from LX99 were mostly enriched in several primary and secondary metabolic pathways, including phenylpropanoid biosynthesis, flavonoid biosynthesis, and phenylalanine biosynthesis. Additionally, phenylpropanoid- and flavonoid-related gene expression was significantly upregulated following S. mosellana infestation in LX99 relative to that in 6218. Some metabolites involved in phenylpropanoid/flavonoid pathways, such as cinnamic acid, coumarin, epigallocatechin, and naringenin, were only induced in infested LX99 kernels. These results suggest that phenylpropanoid/flavonoid pathways play important roles in wheat kernel resistance to S. mosellana attack and provide useful insights for the breeding and utilization of resistant varieties.

Interference with orco gene expression affects host recognition in Diorhabda tarsalis.

Introduction: Diorhabda tarsalis Weise is an important insect pest of the Chinese licorice Glycyrrhiza uralensis Fisch. Behavior of the beetle, including host location, oviposition site selection, self-defense, and aggregation, were regulated by plant volatiles or insect pheromones. Aim: In this study, Identification of ORs and function research on orco were carried out, these could lead to the development of understand for olfaction mechanism in D. tarsalis. Methods: ORs were identified by PacBio RS II platform to sequence the antennas of adult D. tarsalis, the function of orco was explored by dsRNA interference. Results: 29 odorant receptor candidate genes of D. tarsalis were obtained, which code for 130-479 amino acids. Phylogenetic trees of olfactory receptors were constructed with 243 ORs from eight Coleoptera species. DtarORco, DtarOR7 and DtarOR26 are specifically expressed in the antenna, and the expression levels were significantly higher than other DtarORs in antenna, there were no differential expression between male and female beetles. An odorant coreceptor gene (DtarORco) has characteristics of an odorant receptor family member, the encoded mature protein has a predicted molecular weight of 53.898 kDa, dsRNA L4440 expression vectors were constructed and successfully transformed into ribonuclease III-deficient Escherichia coli strain HT115 DE3. After interference treatment, the relative expression level of DtarORco in D. tarsalis antennae significantly decreased and electrophysiological responses to host localization odor signals significantly decreased. At the same time, beetles lost the ability to locate hosts. Discussion: The research on its mechanism of olfaction may lead to the development of new control measures that are environmentally friendly.

Influence of Plant Physical and Anatomical Characteristics on the Ovipositional Preference of Orius sauteri (Hemiptera: Anthocoridae).

Natural enemies play an important role in managing insect pests. Orius sauteri (Poppius) (Hemiptera: Anthocoridae), a predator of many soft-body insects, is an important biological control agent in Asia. Understanding this predator's egg-laying preferences and a habitat needs is important for its success in pest control. We investigated the plant acceptability and ovipositional preference of O. sauteri for coriander (Coriadrum sativum L., Apiales: Apiaceae), marigold (Tagetes erecta L., Asterales: Asteraceae), sweet alyssum (Lobularia maritima L., Brassicales: Brassicaceae), and alfalfa (Medicago sativa L., Fabales: Fabaceae), and focused on the effects of plant physical and anatomical characteristics on the ovipositional preference of O. sauteri. The results showed that O. sauteri can lay eggs on uninfested plants in the vegetative stage and their eggs hatched normally. Orius sauteri females prefer plants with high stomatal density, a large stomatal area, and fewer trichomes as oviposition hosts, and the depth of egg placement was determined by leaf thickness. Our studies suggested that O. sauteri females can select oviposition hosts and specific oviposition sites by assessing the structural qualities of plant surface. Coriander and marigold are potentially suitable host plants for O.sauteri. The results aid the selection of cover crops to enhance natural enemies in the fields.