Host plant odour and sex pheromone are integral to mate finding in codling moth

The great diversity of specialist plant-feeding insects suggests that host plant shifts may initiate speciation, even without geographic barriers. Pheromones and kairomones mediate sexual communication and host choice, and the response to these behaviour-modifying chemicals is under sexual and natural selection, respectively. The idea that the interaction of mate signals and habitat cues facilitates reproductive isolation and ecological speciation is well-established, while the traits and the underlying sensory mechanisms remain unknown. The larva of codling moth feeds in the apple. We show for the first time that the response of male moths to female sex pheromone relies upon presence of a kairomone released from apple. In a non-host tree, attraction to pheromone alone is very strongly reduced, but is fully rescued by blending pheromone with the apple kairomone. This affords a mechanism how host plant shifts shape new mate-finding signals that can give rise to assortative mating and rep..., Plant headspace analysis: Volatiles released from green, fruiting branches of apple and birch trees at the trapping site have been collected for chemical analysis by gas chromatography-mass spectrometry., , # Host plant odour and sex pheromone are integral to mate finding in codling moth

[https://doi.org/10.5061/dryad.9ghx3ffrj](https://doi.org/10.5061/dryad.9ghx3ffrj)

## Description of the data and file structure

Plant headspace analysis. Compounds identified by GC-MS (gas chromatography - mass spectrometry) from headspace collections from green fruiting branches of birch Betula pubescens and apple Malus domestica. Columns show (A) chemical names, (B) CAS number, (C to F) retention times indices (RI) on two columns, HP-5 and DB-Wax, experimental (calculated) and according to a MS library (NIST), (G and H) occurrence of compounds in birch (n=7 replicates), mean relative amount and standard deviation, and (I and J) occurrence of compounds in apple (n=8 replicates), mean relative amount and standard deviation. (\"n/a\" refers to CAS numbers and library retention times indices that are not available, as well as as to retention time indices that could not be calculated, for example due to sma...