Essential role for SNMP1 in detection of sex pheromones in Helicoverpa armigera.

The sensory neuron membrane protein, SNMP1, was initially discovered in moths and is associated with sex pheromone sensitive neurons, suggesting a role in the detection of these semiochemicals. Although DrosophilaSNMP1 has been reported to be involved in detecting of the sex pheromone cis-vaccenyl acetate (cVA), the role of this protein in moths in vivo is still largely unexplored. In this study we developed a SNMP1-/- homozygous mutant line of Helicoverpa armigera using CRISPR/Cas9. Wind-tunnel behavioral experiments showed that HarmSNMP1-/- males could not be attracted by sex pheromones (Z11-16:Ald/Z9-16:Ald = 97/3), while mating behavior obvervations revealed that the SNMP1 mutant males didn't react much to calling females and the rate of copulation was significantly decreased. The electrophysiological results indicated that HarmSNMP1 contributes to the detection of 16-carbon liner sex pheromones, (Z)-11-hexadecenal (Z11-16:Ald), (Z)-9-hexadecenal (Z9-16:Ald), (Z)-11-hexadecanol (Z11-16:OH) and 16-carbon acetate (Z)-11-hexadecenyl acetate (Z11-16:OAc), but is not required for detecting the 14-carbon sex pheromone component (Z)-9-tetradecenal (Z9-14:Ald) an analogue of Z11-16:Ald, (Z)-9-tetradecen-1-yl formate (Z9-14:OFor), which can activate the Z11-16:Ald-responsive neuron. Taken together, our studies indicated that HarmSNMP1 has an important role in the detection of long-chain sex pheromones, but is not essential for detecting shorter chain sex pheromone in vivo.