Abstract

Aulacocentrum confusum is the dominant parasitoid wasp of Glyphodes pyloalis , an outbreak pest of mulberry trees recent years, and demonstrates great promise for biological control. However, the molecular mechanism of the olfactory system, especially the function of olfactory protein in A. confusum is limited. In the present study, we expressed the odorant-binding protein 7 of A. confusum (AconOBP7) and found that it exhibits strong binding affinity to benzyl benzoate. The molecular dynamics simulation results indicated that three amino acid residues (Leu75, Met107 and Pro72) contribute predominantly to the binding between AconOBP7 and benzyl benzoate. Subsequently, we constructed three mutants including AconOBP7-L75A, AconOBP7-M107A and AconOBP7-P72A. The IC 50 values of AconOBP7 and three mutants to benzyl benzoate were 7.88 ± 0.67 μM, 31.19 ± 1.53 μM, 47.23 ± 1.64 μM and 48.18 ± 1.30 μM, respectively, suggesting the binding affinity of these mutants to benzyl benzoate were all significantly decreased . These results indicated that three residues play major roles in the binding process between AconOBP7 and benzyl benzoate. This study lays the foundation of the molecular mechanism of the olfactory system in parasitic wasp and provides references in biological control.