Plant odor analysis of apple: Antennal response of codling moth females toapple volatiles during phenological development

Volatile compounds were collected from apple branches (Malus domestica) at different developmental stages, and the antennal response of codling moth f emales (Cydia pomonella) to these compounds was recorded by electroantennog raphy coupled to gas chromatography. Presence of a range of terpenoid compo unds, many of which had antennal activity, was characteristic for volatile collections from branches with leaves, and from small green apples. Nine co mpounds from branches with leaves and green fruit consistently elicited an antennal response: methyl salicylate, (E)-beta -farnesene, fi-caryophyllene , 4,8-dimethyl-1,3(E),7-nonatriene, (Z)3-hexenol, (Z,E)-alpha -farnesene, l inalool, germacrene D, and (EE)-alpha -farnesene. The bouquet emitted from flowering branches contained in addition several benzenoid compounds which were not found after bloom. Small green apples, which are the main target o f codling moth oviposition during the first seasonal flight period, release d very few esters. In comparison, fully grown apples released a large numbe r of esters, but fewer terpenoids. The study of apple volatiles eliciting a n antennal response, together with a survey of the seasonal change in the r elease of these compounds, is the first step toward the identification of v olatiles mediating host-finding and oviposition in codling moth females.