Induced systemic resistance to rice blast fungus in rice plants infested by white‐backed planthopper

Many of the studies on herbivorous insects and also on pathogens have been conducted to clarify the relationship of insects to plants and of pathogens to plants. Studies on the relationship between insects and pathogens via host plants, however, have seldom been conducted (Karban et al., 1987). The white-backed planthopper, Sogatella furcifera Horvas (Homoptera: Delphacidae), and the rice blast disease caused by Pyricularia grisea Cooke, are an economically important insect pest and fungal disease of rice throughout south-east and far-east Asia, including Japan. In general, S. furcifera does not hibernate in Japan. The entire original S. furcifera population emigrates from mainland China into Japan during the rainy season from early June to early July. The population of the next generation of S. furcifera then increases rapidly in rice fields, and the highest peak of the population appears around late July or early August (Watanabe et al., 1991; Watanabe, 1996). At the same time, the rice blast disease caused by P. grisea develops commonly in rice fields in Japan and occasionally causes serious damage to the rice plants (Iwano, 1999). The authors therefore were interested in the interspecific relationships between S. furcifera and P. grisea via the host plants. In this paper, the results of experiments elucidating such interspecific relationships are discussed, in particular the effect of S. furcifera infestation in rice on the incidence of rice blast disease caused by P. grisea . Materials and methods