This paper surveys the recent progress in the study on chemical ecology of tritrophic interactions among host\|plants,aphids and natural enemies.The following aspects are included:(1)the role of plant volatiles in host selection behavior of aphids and its natural enemies,(2)the influences of aphid pheromones and its honeydew on host selection behavior of natural enemies,(3)relevance of plant volatiles with aphid pheromones.Understanding the tritrophic interactions of host plants aphids natural enemies ca...