Identification And Functional Analysis Of The Pheromone Biosynthesis Activating Neuropeptide (PBAN) In The Common Cutworm Moth Spodoptera Litura(Lepidoptera: Noctuidae)

Spodoptera litura is one of the most destructive insect pests of many agricultural crops and notorious for developing insecticide resistance. Developing environmental friendly control methods such as novel pheromone and RNAi related control strategies is imperative to control this pest.Sex pheromone based mass trapping and mating disruption have been widely used in forecasting and control of many pest insects. Accordingly, the internal mechanisms of sex pheromone biosynthesis and release in insects have also become one of the key topics of this research field. Sex-pheromone production in moths is regulated by the pheromone biosynthesis activating neuropeptide (PBAN). Pban is synthesised in the suboesophageal ganglion and is released into the hemolymph to reach the pheromone gland (PG) and then stimulates pheromone biosynthesis. Four possible sex pheromone components have been identified in S. litura:Z-9,E11-14:Ac, Z-9,E12-14:Ac, Z9-14:Ac and E11-14:Ac, with a strict100:27:20:27ratio in PG.In the present study, the full-length cDNA encoding the Diapause Hormone and Pheromone Biosynthesis Activating Neuropeptide (DH-PBAN) was identified and characterized in S. litura. This809bp transcript contains a573nucleotides ORF encoding a191-amino acid protein, from which five putative neuropeptides, including PBAN, DH, and α-,β-and y-Subesophageal Ganglion Neuropeptides, were derived. Phylogenetic analysis showed that both the whole protein and each of the five neuropeptides have high similarities to those of DH-PBANs from other insect orders particularly Lepidoptera. Females treated with TKYFSPRLamide (the active core fragment of PBAN) produced significant more four types of pheromone compounds (A;B;C;D) than controls. RNA interference by injection of PBAN dsRNA significantly reduced the relative expression levels of this gene in adult females (approximately reduced by60%). As a consequence, females treated with PBAN dsRNA produced significant less four types of pheromone compounds (A;B;C;D) than controls. These results suggest that PBAN function in activating sex-pheromone biosynthesis and the RNAi of DH-PBAN gene can be induced by the injection of dsRNA into the body cavity in S. litura. This study suggests the possibility of novel pheromone related pest control strategies based on RNAi techniques.