Abstract: Plant galls, the abnormal outgrowths of plant tissues induced by gallinducing insects, are ideal materials to investigate the co-evolution between plants and insects. Gall-inducing insects are also important pests in agriculture and forestry. Investigations into the effects of gall-inducing insects on their host plants are useful to reveal the relationships between gall-inducing insects and plants, and can also help reveal the growth process of host plants. Besides, investigations into the responses of galled plants to gall-inducing insects are helpful to screen out the resistance indexes, resistance genes and sensitive genes of plants, providing a theoretical basis for resistance breeding. This review focuses mainly on the effects of gall-inducing insects on the photosynthesis, physiology and metabolism of their host plants. Gall-inducing insects generally reduce the photosynthetic pigments and photosynthetic rate of host plants, raise the contents of primary metabolites such as sugars and amino acids in inner tissues of galls, raise the contents of secondary metabolites such as non-volatile phenols and flavonoids and volatile terpenoids in outer tissues of galls, raise the activities of protective enzymes such as POD and SOD, and raise the contents of phytohormones such as IAA, SA and JA in host plants. The current research data indicate that investigations into the influences of gallinducing insects on the physiology and metabolism of host plants are even in their infancy, and the influencing mechanisms still need to be further explore.

Key words: Gall-inducing insects, host plants, photosynthesis, physiology, metabolism, co-evolution