trans-β-Ocimene is a monoterpene and isomer of β-ocimene that has been found in a variety of plants, including Cannabis. It is a volatile compound involved in plant-plant signaling and plant defense against pests. Emission of trans-β-ocimene from L. japonicus plants is induced within 24 hours of spider mite (T. urticae) infestation.[1] Conditioning of tomato plants using volatile organic compounds (VOCs) from transgenic tobacco plants overexpressing trans-β-ocimene synthase increases production of VOCs and 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 compared with conditioning using wild-type tobacco VOCs.[2]

Reference:
[1]. Arimura, G., Ozawa, R., Kugimiya, S., et al. Herbivore-induced defense response in a model legume. Two-spotted spider mites induce emission of (E)-β-ocimene and transcript accumulation of (E)-β-ocimene synthase in Lotus japonicus. Plant Physiol. 135(4), 1976-1983 (2004).
[2]. Cascone, P., Iodice, L., Maffei, M.E., et al. Tobacco overexpressing β-ocimene induces direct and indirect responses against aphids in receiver tomato plants. J. Plant Physiol. 173, 28-32 (2015).