Candidate pheromone receptors of codling moth Cydia pomonella respond to pheromones and kairomones

Olfaction plays a dominant role in the mate-finding and host selection behaviour of the codling moth (Cydia pomonella), a most important pest of apple, pear and walnut worldwide. Antennal transcriptome analysis revealed a number of abundantly expressed genes related to the moth olfactory system, including those encoding the olfactory receptors (ORs) CpomOR1, CpomOR3 and CpomOR6a, which belong to the pheromone receptor (PR) lineage, and the co-receptor (CpomOrco). Using heterologous expression in Drosophila olfactory sensory neurones, and in human embryonic kidney (HEK293T) cells, coupled with electrophysiological recordings, calcium imaging and patch-clamp recordings, we characterize the basic physiological and pharmacological properties of these receptors. We show that all three receptors form functional ionotropic receptor channels when co-expressed with CpomOrco. Both the homomeric CpomOrco and heteromeric CpomOrco+OR complexes can be activated by the common Orco agonists VUAA1 and VUAA3, as well as inhibited by the antagonistic amiloride derivatives. CpomOR3 responds to the plant volatile compound pear ester ethyl (E,Z)-2,4-decadienoate, while CpomOR6a responds to codlemone acetate (E,E)-8,10-dodecadien-1-yl acetate, a strong pheromone antagonist. These findings advance our understanding of OR function and ligand tuning. This knowledge contributes to research in insect ecology and evolution, and to the development of sustainable control strategies by manipulating chemosensory communication.