Identification of the Differences in Olfactory System Between Male and Female Oriental Tobacco Budworm Helicoverpa assulta 

Abstract

Background: The olfactory system of insects facilitates their search for host and mates, hence it plays an essential role for insect survival and reproduction. Insects recognize odor substances through olfactory neurons and olfactory genes. Previous studies showed that there are significant sex-specific differences in how insects identify odorant substances, especially sex pheromones. However, whether the sex-specific recognition of odorant substances is caused by differences in the expression of olfaction-related genes between males and females remains unclear. Results: In order to clarify this problem, the whole transcriptome sequence of the adult Helicoverpa assulta, an important agricultural pest of tobacco and other Solanaceae plants, was obtained using PacBio sequencing. RNA-seq analysis showed that there were 27 odorant binding proteins (OBPs), 24 chemosensory proteins (CSPs), 4 pheromone-binding proteins (PBPs), 68 odorant receptors (OR) and 2 sensory neuron membrane proteins (SNMPs) genes that were expressed in the antennae of male and female H. assulta. Females had significantly higher expression of GOBP1-like, OBP, OBP3, PBP3 and SNMP1 than males, while males had significantly higher expression of GOBP1, OBP7, OBP13, PBP2 and SNMP2. Conclusions: Our findings improve our understanding of olfactory genes in H. assulta, and can be used to further study pheromone identification, mate search, and sex differences in an insect’s ability to search for hosts. These results improve our understanding of mate search and host differentiation in H. assulta.