noneEnter Chemosensory proteins (CSPs), which are assumed to be related with the process of storing and releasing the chemical odors for insects, belong to a class of small soluble polypeptides in insect chemical receptors. In this study, chemosensory protein of Microplitis mediator MmedCSP1 was expressed using pGEX-4T-1/BL21 (DE3) prokaryotic expression system, and then purified using GSTrap FF, and the binding characteristics of MmedCSP1 to 50 kinds of chemical molecules were further studied using bis-ANS (4, 4'-dianilino-1, 1'-binaphthyl-5, 5'-sulfonate) as fluorescent probes. The results showed that MmedCSP1 could bind to methyl salicylate, pentane, ocimene, [beta]-ionone, 3, 4-dimethylbenzaldehyde, 2-hexanone and cis-3-hexen-l-ol. However, only P-Ionone replaced the bis-ANS of MmedCSP1 by 50%, and the binding constant was 16.89 [mu]mol/L. These results suggest that MmedCSP1 is involved in the process of storing and releasing methyl salicylate, pentane, ocimene, P-ionone, 3, 4-dimethylbenzaldehyde, 2-hexanone and cis-3-hexen-l-ol for M. mediator, and has different transport capability in storing and releasing those odorants. BR Biochemistry. Sensory reception. Genetics. Molecular genetics. Microplitis mediator (Braconidae). Microplitis mediator: Proteins, Chemosensory protein MmedCSP1, Binding characterization, Chemoreception, Gene expression. ST Animalia, Arthropoda, Insecta, Hymenoptera, Apocrita, Terebrantia, Ichneumonoidea, Braconidae. Arthropods; Hymenopterans; Insects; Invertebrates.