LEAF AGE AFFECTS COMPOSITION OF HERBIVORE-INDUCED SYNOMONES AND ATTRACTION OF PREDATORY MITES

We investigated the olfactory response of the predatory mite Phytoseiulus persimilis to cucumber leaves infested with prey, the herbivorous spider mite Tetranychus urticae. The predators responded to volatiles from young rather than old infested cucumber leaves. GC-MS analysis of the headspace of spider mite-infested, artificially damaged and undamaged cucumber plants showed that herbivore-induced plant volatiles were present among the volatiles of both old and young infested cucumber leaves. The major components of the herbivore-induced plant volatiles were (3E)-4,8-dimethyl-1,3,7-nonatriene and (E)-beta-ocimene: these compounds are known to attract the predatory mites. In addition, we found three oximes (2-methylbutanal O-methyloxime, 3-methylbutanal O-methyloxime, and an unknown oxime) in the headspace of both old and young infested cucumber leaves. 3-Methylbutanal O-methyloxime and the unknown oxime were much more abundant in the headspace of infested old cucumber leaves. The potential adaptive value of differential attractiveness of cucumber plant leaves of different age is discussed.