Expression profiles and functional prediction of ionotropic receptors in Asian corn borer, Ostrinia furnacalis(Lepidoptera:Crambidae)

Genes involved in chemosensation are essential for odorant-mediated insect behaviors. Odorant receptors(ORs) bind and respond to pheromones and plant volatiles, regulating insect behaviors such as mating and host-plant selection, while ionotropic receptors(IRs), which are present at lower levels in insects than ORs, influence ion channels, especially in agricultural pests. Asian corn borer, Ostrinia furnacalis, is the main pest of maize that causes huge economic losses in Asia. Twenty-one Ofur IRs have been identified, but none has been characterized. In this study, tissue-specific expression profiling, phylogenetic analysis, and electroantennography(EAG) analysis were applied to characterize the evolution, expression, and the potential function of Ofur IRs. It was found that 20 Ofur IRs were highly expressed in the antennae, except for Ofur IR75p3, whereas 10 and nine Ofur IRs were highly expressed in the proboscis and genitalia, respectively, indicating that these Ofur IRs were functionally associated with feeding and oviposition. EAG results showed that seven acids elicited responses in the antennae of O. furnacalis and that 2-oxopentanoic acid displayed a significant femalebiased response. Combined with the phylogenetic analysis, 10 Ofur IRs in clade 4 were roughly predicted to be candidate receptors for 2-oxopentanoic acid and other tested acids. These results provide basic information about Ofur IRs and may help advance the knolwedge on the olfactory system of O. furnacalis.