Characterization of CrufCSP1 and Its Potential Involvement in Host Location by Cotesia ruficrus (Hymenoptera: Braconidae), an Indigenous Parasitoid of Spodoptera frugiperda (Lepidoptera: Noctuidae) in China

Simple SummaryA previous study found that an indigenous endoparasitic waspCotesia ruficrus, has a good control effect on the invasive pestSpodoptera frugiperda. Understanding the molecular mechanism of host recognition ofC. ruficruswould help improve its biological control effect. Chemoreceptor proteins (CSPs) play a crucial role in insect olfactory perception. The CrufCSP1 protein was obtained via prokaryotic expression, and its binding properties were evaluated using fluorescence binding assays. Molecular docking was used to verify the function of CrufCSP1. The findings revealed that CrufCSP1 has the ability to bind with seven host-related compounds. This information serves as a crucial reference for developing natural enemy attractants for pest control.AbstractChemosensory proteins (CSPs) are a class of soluble proteins that facilitate the recognition of chemical signals in insects. While CSP genes have been identified in many insect species, studies investigating their function remain limited.Cotesia ruficrus(Hymenoptera: Braconidae) holds promise as an indigenous biological control agent for managing the invasive pestSpodoptera frugiperda(Lepidoptera: Noctuidae) in China. This study aimed to shed light on the gene expression, ligand binding, and molecular docking of CrufCSP1 inC. ruficrus. A RT-qPCR analysis revealed that the expression of CrufCSP1 was higher in the wings, with male adults exhibiting significantly higher relative expression levels than other developmental stages. A fluorescence competitive binding analysis further demonstrated that CrufCSP1 has a high binding ability with several host-related volatiles, withtrans-2-hexenal, octanal, and benzaldehyde showing the strongest affinity to CrufCSP1. A molecular docking analysis indicated that specific amino acid residues (Phe24, Asp25, Thr53, and Lys81) of CrufCSP1 can bind to these specific ligands. Together, these findings suggest that CrufCSP1 may play a crucial role in the process ofC. ruficruslocating hosts. This knowledge can contribute to the development of more efficient and eco-friendly strategies for protecting crops and managing pests.Keywords:chemosensory protein;Cotesia ruficrus;expression profiles;fluorescence binding assay;molecular docking;Spodoptera frugiperda;biological control