Three chemosensory proteins from the rice leaf folder Cnaphalocrocis medinalis involved in host volatile and sex pheromone reception.

Chemosensory proteins (CSPs) have been considered to play a key role in chemoreception in insects. As stated in our earlier study, three CSP genes from rice leaf folder Cnaphalocrocis medinalis have been identified and showed potential physiological functions in olfaction. Here, we conducted western blot, immunolocalization, competitive binding assay and knockdown assay by RNA interference both in vitro and in vivo to reveal the functions of these three CSPs in C. medinalis. Results showed that both CmedCSP1 and CmedCSP2 are housed in sensilla basiconica and showed high binding affinities to a wide range of host-related semiochemicals. On the other hand, CmedCSP3 is highly expressed in sensilla trichodea of males and sensilla basiconica of females. It showed binding affinities to plant volatiles, especially terpenoids, as well as two of the C. medinalis sex pheromone components, Z11-16:Ac and Z11-16:Al. The transcript expression level of the three CSP genes significantly decreased after injecting target double-stranded RNAs and resulted in remarkably down-regulation on electroantennogram responses evoked by host-related semiochemicals and one sex pheromone compound, which have high binding affinities with CmedCSPs. In conclusion, the three CmedCSPs tested are involved in C. medinalis reception of semiochemicals, including host attractants and sex pheromones.