Transcriptome analysis of Helicoverpa armigera male hairpencils: Alcohol biosynthesis and requirement for mating success

Abstract

Many female animals use different strategies to assess male quality to increase their own reproductive fitness. In moths, females usually use chemical signals (sex pheromones) to attract males from a distance. Once males approach a female, they release close range pheromones from hairpencils to facilitate female acceptance. However, detailed mechanisms involved in male sex pheromone biosynthesis and its action in promoting female acceptance have not yet been fully characterized. This study screened a series of candidate genes via a transcriptome analysis of the male hairpencil of Helicoverpa armigera. Using pharmacological inhibitor and RNAi-mediated knockdown assays, we demonstrated that Ca²⁺ and cyclic-AMP were involved in pheromone biosynthesis activating neuropeptide (PBAN)-induced male sex pheromone biosynthesis. The functional analysis of candidate enzymes involved in the male sex pheromone biosynthesis pathway demonstrated that a decreased mRNA levels of acetyl-CoA carboxylase, Δ11-desaturase, and fatty-acyl reductase 2 by RNAi-mediated knockdown led to a significant decrease in the production of fatty acyl alcohols and the efficacy of female acceptance. Our results demonstrated the important role of the fatty acyl alcohol biosynthetic pathway in a PBAN-induced male sex pheromone biosynthesis and the importance of hairpencil compounds in female mating acceptance.

Keywords: Female acceptance; Hairpencil; RNAi; Sex pheromone; Transcriptome.