Insect Chemosensory Proteins Research Articles

Insect Chemosensory Proteins against COVID-19

This article describes a novel strategy to fight SARS-CoV-2 infection by employing tiny soluble binding proteins called “Odorant Binding Proteins” (OBPs), “Niemann-Pick Type C2 (NPC2s)”, and “Chemosensory Proteins” (CSPs). The possible interactions between these proteins and sensory receptors are not relevant to COVID-19. We concentrate on the interaction between the protein-binding site and C18 lipids in COVID. Extended lipid chains, like palmitic acid (C18), oleic acid (C18:1), and linoleic acid (C18:2) resemble the primary components of membrane viral particles. The virus’s surface is covered in C18 lipids. In light of this, OBPs’, NPC2s’ and CSPs’ capacity to interact with C18-lipids and transfer them to Degradative Enzymes (ODEs) may provide a novel molecular strategy for combating coronavirus infection, regardless of the course of viral mutation. In order to confine COVID virus variations in a hydrophobic pocket and/or produce viral particles devoid of an outer protective envelope, proteins with the ability to bind long lipid chains on viral surfaces or peplos may show great promise.

Two cuticle-enriched chemosensory proteins confer multi-insecticide resistance in Spodoptera frugiperda

Recent studies revealed that insect chemosensory proteins (CSPs) both play essential roles in insect olfaction and insect resistance. However, functional evidence supporting the crosslink between CSP and insecticide resistance remains unexplored. In the present study, 22 SfruCSP transcripts were identified from the fall armyworm (FAW) and SfruCSP1 and SfruCSP2 are enriched in the larval cuticle and could be induced by multiple insecticides. Both SfruCSP1 and SfruCSP2 are highly expressed in the larval inner endocuticle and outer epicuticle, and these two proteins exhibited high binding affinities with three insecticides (chlorfenapyr, chlorpyrifos and indoxacarb). The knockdown of SfruCSP1 and SfruCSP2 increased the susceptibility of FAW larvae to the above three insecticides, and significantly increased the penetration ratios of these insecticides. Our in vitro and in vivo evidence suggests that SfruCSP1 and SfruCSP2 are insecticide binding proteins and confer FAW larval resistance to chlorfenapyr, chlorpyrifos and indoxacarb by an insecticide sequestration mechanism. The study should aid in the exploration of larval cuticle-enriched CSPs for insect resistance management.

Evidence for the Involvement of the Chemosensory Protein AgosCSP5 in Resistance to Insecticides in the Cotton Aphid, Aphis gossypii.

Simple SummaryInsect chemosensory proteins (CSPs) are potential targets for insect pest control strategies and are proposed to function in insect chemoreception, because they play a role in crop host location by binding and transporting odorant molecules. They are also thought to have other functions, for example, in tissue regeneration and in insecticide resistance, because they also express in nonolfactory tissues and are capable of binding insecticides. However, there are few reports that provide direct evidence for this proposal. In this study, we discovered gene gain-and-loss among aphid populations, possibly associated with different insecticide resistance, and then identified and cloned a CSP gene responsive to insecticide treatments. The introduction of such gene in Drosophila fruit flies made the transgenic flies less sensitive to the treatment of different insecticides. Our study advances the research of insect CSP functions and offers valuable new information to target CSPs for pest management.It has been speculated that insect chemosensory proteins (CSPs) may have additional roles beyond olfaction. In this study, the phylogenetic and genomic analyses of the CSPs of the cotton aphid, Aphis gossypii, revealed the presence of gene gain-and-loss among different aphid field populations. Differential expressions of eight CSP genes were demonstrated after treatments with insecticides of different modes of action. The expression of AgosCSP5 was significantly upregulated by the insecticide treatments in a dose-dependent manner. The Drosophila flies overexpressing AgosCSP5 were significantly less susceptible to the insecticides, omethoate, imidacloprid and cypermethrin but not to deltamethrin and tau-fluvalinate, compared with control flies. The transgenic Drosophila flies exhibited an LC50 resistance ratio of 2.6 to omethoate, compared with control flies. Likewise, the mortality of the transgenic flies to imidacloprid and cypermethrin was significantly lower than that of the control flies (p < 0.01). Homology modelling, molecular docking and dynamic simulation supported the interactions and revealed a higher stability of AgosCSP5/insecticide complexes than AgosCSP5/semiochemical complexes. Our study demonstrates for first time the in vivo evidence for the involvement of CSP genes in insecticide resistance of crop insect pests and provides new insights of the newly discovered CSP-mediated insect resistance mechanism to insecticides.

Odorant binding proteins promote flight activity in the migratory insect, Helicoverpa armigera.

Migratory insects are capable of actively sustaining powered flight for several hours. This extraordinary phenomenon requires a highly efficient transport system to cope with the energetic demands placed on the flight muscles. Here, we provide evidence that the role of the hydrophobic ligand binding of odorant binding proteins (OBPs) extends beyond their typical function in the olfactory system to support insect flight activity via lipid interactions. Transcriptomic and candidate gene analyses show that two phylogenetically clustered OBPs (OBP3/OBP6) are consistently over-expressed in adult moths of the migrant Old-World bollworm, Helicoverpa armigera, displaying sustained flight performance in flight activity bioassays. Tissue-specific over-expression of OBP6 was observed in the antennae, wings and thorax in long-fliers of H.armigera. Transgenic Drosophila flies over-expressing an H.armigera transcript of OBP6 (HarmOBP6) in the flight muscle attained higher flight speeds on a modified tethered flight system. Quantification of lipid molecules using mass spectrometry showed a depletion of triacylglyerol and phospholipids in flown moths. Protein homology models built from the crystal structure of a fatty acid carrier protein identified the binding site of OBP3 and OBP6 for hydrophobic ligand binding with both proteins exhibiting a stronger average binding affinity with triacylglycerols and phospholipids compared with other groups of ligands. We propose that HarmOBP3 and HarmOBP6 contribute to the flight capacity of a globally invasive and highly migratory noctuid moth, and in doing so, extend the function of this group of proteins beyond their typical role as chemosensory proteins in insects.

Comprehensive History of CSP Genes: Evolution, Phylogenetic Distribution and Functions.

In this review we present the developmental, histological, evolutionary and functional properties of insect chemosensory proteins (CSPs) in insect species. CSPs are small globular proteins folded like a prism and notoriously known for their complex and arguably obscure function(s), particularly in pheromone olfaction. Here, we focus on direct functional consequences on protein function depending on duplication, expression and RNA editing. The result of our analysis is important for understanding the significance of RNA-editing on functionality of CSP genes, particularly in the brain tissue.

Solution structure of insect CSP and OBPs by NMR.

Insect odorant binding proteins (OBPs) and chemosensory proteins (CSPs) are proteins deputed to the solubilization, transport and stabilization of lipophilic and odorant compounds. These proteins have a conserved fold, which undergoes massive structural rearrangements in order to accommodate medium to large-sized lipophilic ligands. Solution NMR spectroscopy, due to its intrinsically dynamic nature, is the perfect technique to extrapolate structural information and dynamic parameters and to elucidate the conformational changes that occur upon ligand binding. This chapter will describe in detail the experimental protocols for the production and purification of isotope-labeled recombinant CSPs and OBPs for NMR studies. Detailed procedures for spectra acquisition, processing and analysis will be presented, focusing on the protein CSP-sg4 from Schistocerca gregaria as a model. Finally, experiments aimed at providing information on protein flexibility and ligand binding modes will also be described.

Bioinformatic, genomic and evolutionary analysis of genes: A case study in dipteran CSPs.

Understanding physiological tasks may start by a good understanding of evolutionary traits in a given protein gene family. The successful completion of various genome projects is a key step forward for comparative analysis of similar and/or orthologous genes between species, measuring genetic relatednesses, studying evolutionary changes among different behaviors, helping to identify specifically conserved genes or genes that are variable enough to determine a new strain or organism. How evolutionary data can improve the understanding of a protein gene family is exploited here in the case of the insect Chemosensory Proteins (CSPs) as a guidance model. In this chapter, Diptera are presented not only as a huge diversity of appearances (phenotypes), behaviors and lifestyles, but also as major differences that are gene copy numbers, gene family members, polymorphisms and evolutionary rate variations, without any a priori assumption about the origin and function of the sampled gene family.

OcomCSP12, a Chemosensory Protein Expressed Specifically by Ovary, Mediates Reproduction in Ophraella communa (Coleoptera: Chrysomelidae).

Chemosensory proteins (CSPs) are considered to be the transporter linking odorant chemicals and receptors on sensory neurons. However, the extensive expression patterns of CSPs in insects suggest that CSPs are also involved in other physiological processes; the range of their functions, however, remains uncertain. In this study, we successfully characterized and cloned the CSP12 of Ophraella communa (OcomCSP12). The open reading frame of OcomCSP12 encodes 131 amino acids, with four conserved cysteine residues. The expression patterns of OcomCSP12 validated by quantitative real-time PCR (qRT-PCR) showed that OcomCSP12 is specifically expressed in female ovary. Furthermore, compared with the control treatment, silencing OcomCSP12 resulted in significantly reduced oviposition in females. Surprisingly, the knock-down rate of OcomCSP12 exceeded 95% and remained depressed for more than 15 days, indicating that RNA interference (RNAi) was a suitable method for exploring the function of CSP12 in O. communa. These findings increase our understanding of the expression profile and function of the CSP gene family in insects.

Biosensors to Monitor Water Quality Utilizing Insect Odorant-Binding Proteins as Detector Elements.

In the developing world, the identification of clean, potable water continues to pose a pervasive challenge, and waterborne diseases due to fecal contamination of water supplies significantly threaten public health. The ability to efficiently monitor local water supplies is key to water safety, yet no low-cost, reliable method exists to detect contamination quickly. We developed an in vitro assay utilizing an odorant-binding protein (OBP), AgamOBP1, from the mosquito, Anopheles gambiae, to test for the presence of a characteristic metabolite, indole, from harmful coliform bacteria. We demonstrated that recombinantly expressed AgamOBP1 binds indole with high sensitivity. Our proof-of-concept assay is fluorescence-based and demonstrates the usefulness of insect OBPs as detector elements in novel biosensors that rapidly detect the presence of bacterial metabolic markers, and thus of coliform bacteria. We further demonstrated that rAgamOBP1 is suitable for use in portable, inexpensive “dipstick” biosensors that improve upon lateral flow technology since insect OBPs are robust, easily obtainable via recombinant expression, and resist detector “fouling.” Moreover, due to their wide diversity and ligand selectivity, insect chemosensory proteins have other biosensor applications for various analytes. The techniques presented here therefore represent platform technologies applicable to various future devices.

Combinatorial multispectral, thermodynamics, docking and site-directed mutagenesis reveal the cognitive characteristics of honey bee chemosensory protein to plant semiochemical

In the chemoreceptive system of insects, there are always some soluble binding proteins, such as some antennal-specific chemosensory proteins (CSPs), which are abundantly distributed in the chemosensory sensillar lymph. The antennal-specific CSPs usually have strong capability to bind diverse semiochemicals, while the detailed interaction between CSPs and the semiochemicals remain unclear. Here, by means of the combinatorial multispectral, thermodynamics, docking and site-directed mutagenesis, we detailedly interpreted a binding interaction between a plant semiochemical β-ionone and antennal-specific CSP1 from the worker honey bee. Thermodynamic parameters (ΔH < 0, ΔS > 0) indicate that the interaction is mainly driven by hydrophobic forces and electrostatic interactions. Docking prediction results showed that there are two key amino acids, Phe44 and Gln63, may be involved in the interacting process of CSP1 to β-ionone. In order to confirm the two key amino acids, site-directed mutagenesis were performed and the binding constant (KA) for two CSP1 mutant proteins was reduced by 60.82% and 46.80% compared to wild-type CSP1. The thermodynamic analysis of mutant proteins furtherly verified that Phe44 maintained an electrostatic interaction and Gln63 contributes hydrophobic and electrostatic forces. Our investigation initially elucidates the physicochemical mechanism of the interaction between antennal-special CSPs in insects including bees to plant semiochemicals, as well as the development of twice thermodynamic analysis (wild type and mutant proteins) combined with multispectral and site-directed mutagenesis methods.

Genotyping and Bio-Sensing Chemosensory Proteins in Insects.

Genotyping is the process of determining differences in the genetic make-up of an individual and comparing it to that of another individual. Focus on the family of chemosensory proteins (CSPs) in insects reveals differences at the genomic level across various strains and biotypes, but none at the level of individuals, which could be extremely useful in the biotyping of insect pest species necessary for the agricultural, medical and veterinary industries. Proposed methods of genotyping CSPs include not only restriction enzymatic cleavage and amplification of cleaved polymorphic sequences, but also detection of retroposons in some specific regions of the insect chromosome. Design of biosensors using CSPs addresses tissue-specific RNA mutations in a particular subtype of the protein, which could be used as a marker of specific physiological conditions. Additionally, we refer to the binding properties of CSP proteins tuned to lipids and xenobiotic insecticides for the development of a new generation of biosensor chips, monitoring lipid blood concentration and chemical environmental pollution.

Differential expression of chemosensory-protein genes in midguts in response to diet of Spodoptera litura

While it has been well characterized that chemosensory receptors in guts of mammals have great influence on food preference, much remains elusive in insects. Insect chemosensory proteins (CSPs) are soluble proteins that could deliver chemicals to olfactory and gustatory receptors. Recent studies have identified a number of CSPs expressed in midgut in Lepidoptera insects, which started to reveal their roles in chemical recognition and stimulating appetite in midgut. In this study, we examined expression patterns in midgut of 21 Spodoptera litura CSPs (SlitCSPs) characterized from a previously reported transcriptome, and three CSPs were identified to be expressed highly in midgut. The orthologous relationships between midgut expressed CSPs in S. litura and those in Bombyx mori and Plutella xylostella also suggest a conserved pattern of CSP expression in midgut. We further demonstrated that the expression of midgut-CSPs may change in response to different host plants, and SlitCSPs could bind typical chemicals from host plant in vitro. Overall, our results suggested midgut expressed SlitCSPs may have functional roles, likely contributing to specialization and adaption to different ecosystems. Better knowledge of this critical component of the chemsensation signaling pathways in midguts may improve our understanding of food preference processes in a new perspective.

Identification and expression profiling of five chemosensory protein genes in the whitefly MED, Bemisia tabaci

Insect chemosensory proteins (CSPs) are small, water-soluble proteins involved in detection and recognition of chemical cues and semiochemicals. A better understanding of CSPs and their function could aid in the development of pest control strategies that are based on chemosensory regulation. We screened our unpublished transcriptome data of Bemisia tabaci and identified five CSP genes (BtabCSPs) including two novel BtabCSPs viz. BtabCSP4 and BtabCSP5. Phylogenetic analysis of amino acid sequences of the proteins encoded by these genes revealed that BtabCSPs are distinct from CSPs of other hemipterans. Quantitative PCR analysis showed differential expression of these genes in different stages. In the adult stage, BtabCSP1, 2 and 4 had significantly higher expression than BtabCSP3 and 5 respectively. On the other hand, BtabCSP2 and 5 were relatively highly expressed in stage of pseudopupae compared to BtabCSP1, 3 and 4. In the third instar BtabCSP3, 4 and 5 exhibited higher expression compared to other CSP genes. Expression of all CSP genes was relatively low in the first and second instars compared to later developmental stages. The identification of novel BtabCSPs and the expression profiling of CSP genes in general may help facilitate development of pest management strategies based on disruption of CSP-driven behaviors.

Chemosensillum immunolocalization and ligand specificity of chemosensory proteins in the alfalfa plant bug Adelphocoris lineolatus (Goeze).

Insect chemosensory proteins (CSPs) are a family of small soluble proteins. To date, their physiological functions in insect olfaction remain largely controversial in comparison to odorant binding proteins (OBPs). In present study, we reported the antenna specific expression of three CSPs (AlinCSP4-6) from Adelphocoris lineolatus, their distinct chemosensillum distribution as well as ligand binding capability thus providing the evidence for the possible roles that they could play in semiochemical detection of the plant bug A. lineolatus. The results of qRT-PCR and western blot assay clearly showed that all of these three CSPs are highly expressed in the adult antennae, the olfactory organ of insects. Further cellular investigation of their immunolocalization revealed their dynamic protein expression profiles among different types of antennal sensilla. In a fluorescence competitive binding assay, the selective ligand binding was observed for AlinCSP4-6. In ad`dition, a cooperative interaction was observed between two co-expressed CSPs resulting in an increase of the binding affinities by a mixture of AlinCSP5 and AlinCSP6 to terpenoids which do not bind to individual CSPs. These findings in combination with our previous data for AlinCSP1-3 indicate a possible functional differentiation of CSPs in the A. lineolatus olfactory system.

Identification and expression profiles of putative chemosensory protein genes in Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)

Insect chemosensory proteins (CSPs) are small, water-soluble proteins which can bind and transport hydrophobic odorants through sensillum lymph to activate odorant receptors, thus play important roles in the olfactory recognition. In the present study, by searching the transcriptome data sets, a total of 22 candidate CSP genes were identified from Cnaphalocrocis medinalis, a serious lepidopteran rice pest in Asia. CSP proteins encoded by these genes showed typical characteristics: an N-terminal signal peptide, four conserved cysteine residues and the pattern of cysteine spacing. The expression profiles of these putative CSP genes were investigated using real-time quantitative PCR. The results showed that five genes (CmedCSP4, CmedCSP8, CmedCSP11, CmedCSP18 and CmedCSP21) were expressed primarily in antennae, suggesting their involvement in olfactory processes; whilst other genes are mainly expressed in non-olfactory tissues, such as abdomen and legs, indicating a broader physiological function for these CSPs. The findings will lead to a better understanding of the molecular mechanisms of chemoreception in C. medinalis.

Synthetic blends of volatile, phytopathogen-induced odorants can be used to manipulate vector behavior

Volatile organic compounds (VOCs) are emitted from all plants and these VOCs are important means of communication between plants and insects. It has been documented that pathogen infections alter VOC profiles rendering infected plants more attractive to specific vectors transmitting these pathogens than uninfected plants, thus potentially aiding in pathogen propagation. Mimicking these chemical cues might enable insect attraction away from the plant or disruption of host finding behavior of the vector. However, the practical implications have not been fully explored. We used citrus, Diaphorina citri and huanglongbing (HLB) as a model host-vector-disease system because HLB threatens citrus production worldwide and is similar to other critical diseases of food crops, such as Zebra Chip affecting potato. We formulated a synthetic chemical blend using selected HLB-specific biomarker compounds, and tested the blend with the Attenu assay system for chemosensory proteins. The Attenu assay system is a procedure that identifies interactions between insect chemosensory proteins and their ligands. We found that an equimolar mixture of compounds mimicking the volatile profile of HLB-infected citrus bound chemosensory proteins. Further investigation of this blend in laboratory behavioral assays resulted in development of a synthetic lure that was more attractive to D. citri than natural citrus tree volatiles. This strategy could provide a new route to produce chemical lures for vector population control for a variety of plant and/or animal systems and it may result in the development of a practical lure for monitoring vectors of disease, such as D. citri.

Soluble proteins of chemical communication: an overview across arthropods.

Detection of chemical signals both in insects and in vertebrates is mediated by soluble proteins, highly concentrated in olfactory organs, which bind semiochemicals and activate, with still largely unknown mechanisms, specific chemoreceptors. The same proteins are often found in structures where pheromones are synthesized and released, where they likely perform a second role in solubilizing and delivering chemical messengers in the environment. A single class of soluble polypeptides, called Odorant-Binding Proteins (OBPs) is known in vertebrates, while two have been identified in insects, OBPs and CSPs (Chemosensory Proteins). Despite their common name, OBPs of vertebrates bear no structural similarity with those of insects. We observed that in arthropods OBPs are strictly limited to insects, while a few members of the CSP family have been found in crustacean and other arthropods, where however, based on their very limited numbers, a function in chemical communication seems unlikely. The question we address in this review is whether another class of soluble proteins may have been adopted by other arthropods to perform the role of OBPs and CSPs in insects. We propose that lipid-transporter proteins of the Niemann-Pick type C2 family could represent likely candidates and report the results of an analysis of their sequences in representative species of different arthropods.

Antenna-predominant and male-biased CSP19 of Sesamia inferens is able to bind the female sex pheromones and host plant volatiles

Insect chemosensory proteins (CSPs) are proposed to capture and transport hydrophobic chemicals across the sensillum lymph to olfactory receptors (ORs), but this has not been clarified in moths. In this study, we built on our previously reported segment sequence work and cloned the full length CSP19 gene (SinfCSP19) from the antennae of Sesamia inferens by using rapid amplification of cDNA ends. Quantitative real time-PCR (qPCR) assays indicated that the gene was expressed in a unique profile, i.e. predominant in antennae and significantly higher in male than in female. To explore the function, recombinant SinfCSP19 was expressed in Escherichia coli cells and purified by Ni–ion affinity chromatography. Binding affinities of the recombinant SinfCSP19 with 39 plant volatiles, 3 sex pheromone components and 10 pheromone analogs were measured using fluorescent competitive binding assays. The results showed that 6 plant volatiles displayed high binding affinities to SinfCSP19 (Ki=2.12–8.75μM), and more interesting, the 3 sex pheromone components and analogs showed even higher binding to SinfCSP19 (Ki=0.49–1.78μM). Those results suggest that SinfCSP19 plays a role in reception of female sex pheromones of S. inferens and host plant volatiles.

Functional Characterizations of Chemosensory Proteins of the Alfalfa Plant Bug Adelphocoris lineolatus Indicate Their Involvement in Host Recognition

Insect chemosensory proteins (CSPs) have been proposed to capture and transport hydrophobic chemicals from air to olfactory receptors in the lymph of antennal chemosensilla. They may represent a new class of soluble carrier protein involved in insect chemoreception. However, their specific functional roles in insect chemoreception have not been fully elucidated. In this study, we report for the first time three novel CSP genes (AlinCSP1-3) of the alfalfa plant bug Adelphocoris lineolatus (Goeze) by screening the antennal cDNA library. The qRT-PCR examinations of the transcript levels revealed that all three genes (AlinCSP1-3) are mainly expressed in the antennae. Interestingly, these CSP genes AlinCSP1-3 are also highly expressed in the 5th instar nymphs, suggesting a proposed function of these CSP proteins (AlinCSP1-3) in the olfactory reception and in maintaining particular life activities into the adult stage. Using bacterial expression system, the three CSP proteins were expressed and purified. For the first time we characterized the types of sensilla in the antennae of the plant bug using scanning electron microscopy (SEM). Immunocytochemistry analysis indicated that the CSP proteins were expressed in the pheromone-sensitive sensilla trichodea and general odorant-sensitive sensilla basiconica, providing further evidence of their involvement in chemoreception. The antennal activity of 55 host-related semiochemicals and sex pheromone compounds in the host location and mate selection behavior of A. lineolatus was investigated using electroantennogram (EAG), and the binding affinities of these chemicals to the three CSPs (AlinCSP1-3) were measured using fluorescent binding assays. The results showed several host-related semiochemicals, (Z)-3-hexen-1-ol, (E)-2-hexen-1-al and valeraldehyde, have a high binding affinity with AlinCSP1-3 and can elicit significant high EAG responses of A. lineolatus antennae. Our studies indicate the three antennae-biased CSPs may mediate host recognition in the alfalfa plant bug A. lineolatus.

Cloning and characterization of three chemosensory proteins from Spodoptera exigua and effects of gene silencing on female survival and reproduction

Insect chemosensory proteins (CSPs) are supposed to transport hydrophobic chemicals to receptors on sensory neurons. However, CSPs are broadly expressed in various insect tissues, suggesting their involvement in the physiological processes beyond chemoreception. So, the exact physiological roles of CSPs in insects still need to be unraveled. In this study, three full-length of CSP genes from Spodoptera exigua have been cloned and characterized. The deduced amino acid sequences of SexiCSP1, SexiCSP2 and SexiCSP3 revealed open reading frames of 128, 128 and 126 amino acids, respectively, with four conserved cysteine residues. The expression patterns of the three SexiCSPs were further investigated by real-time PCR. Three SexiCSPs were expressed in antennae, heads, legs, wings, thoraxes, abdomens, testes and ovaries, with the highest expression level in female and male antennae. Furthermore, all three SexiCSPs mRNA were distributed extensively in the tested development stages with the highest expression level in pupae. RNAi-based gene silencing study resulted in a dramatic reduction of corresponding mRNA in female S. exigua after injection with dsRNA of all three SexiCSPs. Consequentially, 42.5% of mortalities, 68.3% (compare to DEPC water injected control) and 71.4% (compare to uninjected control) oviposition inhibition, and significantly effected egg hatching were observed in the female S. exigua injected with dsSexiCSP3 as compared to control treatments. On the other hand, dsSexiCSP1 and dsSexiCSP2 injected female adults did not show effects on survival and reproduction. Our study confirms the utility of RNAi approach to functional characterization of CSP genes in S. exigua and provides a starting point for further studies on female survival and reproduction in this insect. It also reveals the potential pest controlling method, as insect behavior regulation agent that disrupts the expression of chemosensory proteins.