AUTHOR=Ning Xiaoyu , Huang Cong , Dong Changhong , Jin Jisu , Qiao Xi , Guo Jianying , Qian Wanqiang , Cao Fengqin , Wan Fanghao 

TITLE=RNAi verifications on olfactory defects of an essential biocontrol agent Agasicles hygrophila (Coleoptera: Chrysomelidae) regarding mating and host allocation

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2023.1104962

DOI=10.3389/fevo.2023.1104962

ISSN=2296-701X

ABSTRACT=<p>Alligator weed <italic>Alternanthera philoxeroides</italic> is a perennial, worldwide pernicious weed. The beetle <italic>Agasicles hygrophila</italic> is considered to be a classical biological agent used to control <italic>A. philoxeroides</italic>. In the insect peripheral olfactory system, the odorant receptor co-receptor (ORco) plays an important function in the perception of odors in insects. However, the function of ORco in the mating and host-finding behaviors of <italic>A. hygrophila</italic> remains unclear. In this study, we characterized the odorant receptor co-receptor of <italic>A. hygrophila</italic> (<italic>AhygOrco</italic>). Real-time quantitative PCR (qRT–PCR) showed that <italic>AhygOrco</italic> was predominantly expressed in the antennae of both male and female adults, and the difference between male and female antennae was not significant. The RNA interference (RNAi) results showed that compared to the control, the injection of <italic>AhygOrco</italic> dsRNA strongly reduced the expression of <italic>AhygOrco</italic> by 90% in male beetles and 89% in female beetles. The mate-seeking and feeding behavior of <italic>AhygOrco</italic>-silenced beetles were significantly inhibited. Male adults were significantly less successful in finding a mate compared to the control group. Furthermore, host allocation abilities toward <italic>A. philoxeroides</italic> of both adults were significantly repressed. These results indicated that <italic>AhygOrco</italic> is associated with <italic>A. hygrophila</italic> feeding and mate-seeking and that inhibition of <italic>AhygOrco</italic> expression is one of the causes of reduced host and mate recognition in <italic>A. hygrophila</italic>. Meanwhile, the study provides support for exploring gene functions based on RNAi.</p>