Outbreaks of the brown planthopper, Nilaparvata Iugens STAl, and the whitebacked planthopper, Sogatella furcifera Horvath, have been occurring in Japan for a long time. However, the factors causing these outbreaks have not yet been clarified, At present, it is considered that the planthoppers (N. Iugens and S. furcifera) spread from Southeast Asia, where they reproduce throughout the year, to subtropical and temperate zones (Kisimoto and Dyck, 1976). Recently, the El Nino/Southern Oscillation (ENSO) phenomenon has been the focus of attention as a factor in global climatic change. Ropelewskiand Halpert (1987) found that precipitation patterns changed in Southeast Asia during the ENSO phenomenon. The objective of the present paper was to investigate the statistical relationship between the outbreaks of the planthoppers in Japan and the climate changes associated with the ENSO phenomenon during 1890–1989. © 1992, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.
