A monoterpene; a volatile compound involved in plant-plant signaling and plant defense against pests; emitted by C. sinensis and L. japonicus plants in response to predation; reduces the number of winged aphids (M. persicae) that settle on Chinese cabbage and the feeding time and number of nymphs produced by aphids on leaves; the aphid endoparasitoid A. gifuensis demonstrates a preference for ocimene-treated Chinese cabbage over control plants in a wind tube two-choice test; conditioning of tomato plants using VOCs from transgenic tobacco plants overexpressing β-ocimene synthase increases production of VOCs, reduces the number of aphids (M. euphorbiae) that settle on the plant and the number of nymphs produced by the aphids that settle, as well as increases the number of landings of the aphid parasitoid A. ervi