Response of female oriental fruit moth to volatiles from apple and peach trees at three phenological stages

The attractiveness of peach ( Prunus persica L. Batsch) and apple ( Malus domestica L. Borkh.) (both Rosaceae) tissue to gravid female oriental fruit moth, Grapholita (=  Cydia ) molesta (Busck) (Lepidoptera: Tortricidae), was assessed at three distinct stages throughout the growing season using a dual-choice bioassay. Plant material offered to the female moths consisted of a plant shoot in early spring, before fruit became available. Later, it consisted of a leaf-bearing twig and a fruit, either alone or in combination. The level of attraction of the female moths to the various plant tissues varied substantially over time and according to the plant species. Before fruit became available, female moths were significantly attracted to peach as well as to apple shoots. During the early fruit growth stage, moths were attracted to a leaf-bearing twig originating from a peach tree, but not to that from an apple tree. In peach, it was the vegetative tissue that accounted for the attraction, whereas in apple, it was the reproductive tissue (a developing fruit). During the late fruit growth stage, both peach fruit and apple fruit were highly attractive, whereas a twig with leaves from either an apple or a peach tree was neither attractive nor repellent to the female moths. This changing female olfactory response to volatiles emitted by vegetative tissue and fruits from the two host plant species with progressing season is discussed with respect to the biology and the dispersal of this moth species.