Helicoverpa armigera is a typical polyphagous species whose larvae primarily bore in flower buds and fruits of host plants, causing serious damage to many crops. Olfaction plays a key role in host selection, but the molecular basis of olfactory perception in larvae is poorly understood. Herein, we identified a highly expressed odorant receptor, HarmOr54, in larval antennae through qRT-PCR and in situ hybridization experiments. Drosophila T1 neurons expressing HarmOr54 ectopically showed specific responses to (-)-bornyl acetate and 2-ethylhexyl acetate. CRISPR/Cas9-generated homozygous mutant larvae lost avoidance to (-)-bornyl acetate, unlike wild-type larvae, while 2-ethylhexyl acetate showed no behavioral effect. Structural modeling and docking revealed that both ligands bound to the same HarmOr54 pocket, but (-)-bornyl acetate displayed stronger binding affinity. These findings enhance our understanding of the olfactory mechanisms in lepidopteran larvae and provide new insights into pest control strategies targeting the larval stage.
Fan et al. (Tue,) studied this question.