Abstract: is paper is a review on recent progress in the researches on the role played by plant volatiles in tritrophic interactions among phytophagous insects, their host plants and natural enemies. It summarizes information in the following areas: 1. The physical and chemical characteristics of plant volatiles, 2. The role of plant volatiles in host selection of phytophagous insects and their natural enemies, their reception by olfactory receptors, and the olfactory code and information processing of stimulating signals, 3. Synergism of plant volatiles with insect pheromones, 4. Production ofplant volatiles induced by herbivore-feeding and their ignificance in the indirect defence of host plants, and 5. Odor learning of phytophagous insects and their natural enemies. Presumably to understand the plant volatiles and their role in the interactions can provide the basis in the design of some types of program for insect pest control. Possible application in future pest control is discussed.

Key words: plant volatiles&mdash, &mdash, host selection&mdash, &mdash, olfactory perception&mdash, &mdash, odor learning