Induction of volatile emissions from ripening apple fruits infested with Cydia pomonella and the attraction of adult females

We studied the effect of herbivory by Cydia pomonella L. (Lepidoptera: Tortricidae) first instar larvae on the volatile emissions from immature apples collected at the end of August. Volatiles from infested, artificially damaged, and healthy fruit were collected using solid-phase microextraction and analysed using combined gas chromatography mass spectrometry. The results show that neonate C. pomonella larvae induce the release of E-beta-ocimene from immature fruit compared to healthy or artificially damaged fruit. Seven further compounds, a terpene, an alcohol, four aldehydes, and a ketone, were consistently found in all treatments. There were no significant differences amongst these latter compounds, although the amount of the terpene E,E-alpha-farnesene was three to five times higher from the infested as compared to healthy fruits. Headspace volatiles were also collected on Tenax to test for behavioural responses to the volatiles. Volatile collections from infested fruit attracted mated adult females in a Y-tube olfactometer, whereas no preference was evinced for volatiles from healthy or artificially damaged fruits when compared to a solvent control.