Tree-derived stimuli affecting host-selection response of larva and adult peach twig borers, Anarsia lineatella (Zeller) (Lepidoptera: Gelechiidae)

Volatiles from ripening peach fruit reportedly mediate host-finding by adult peach twig borers, Anarsia lineatella (Lepidoptera: Gelechiidae). However, moths were repelled by in-situ ripe peach fruits, and by a blend of 22 synthetic volatiles associated with ripe peach fruits. In laboratory experiments, females preferred hairy and creviced surfaces over glabrous surfaces as oviposition sites. Volatiles from almond and peach shoots induced oviposition, as did volatiles from immature, green mature, and hard-ripe peach fruits. Soft-ripe peach fruits, in contrast, did not induce oviposition, and when tested against immature peach fruits received three times fewer eggs. In laboratory olfactometer experiments, larvae of A. lineatella were found to orient chemoanemotactically toward Porapak Q extracts of peach shoot or almond shoot and fruit volatiles. β-Bourbonene and (E,E)-α-farnesene identified in almond shoot and fruit volatile extracts, and tested as a 2-component blend, were as attractive to larvae as was the entire extract.