Prevalence of rice stripe virus can be altered by temperature and the virus mediated development of insect vector, Laodelphax striatellus, in Korea

Abstract

Since the 2000's in Korea, the regional hotspots of rice stripe virus (genus Tenuivirus, RSV), transmitted by small brown planthopper (Laodelphax striatellus (Fallen), SBPH), have changed from the southeastern to the western coastal regions. The reasons for this are as yet unknown, but recent changes in temperatures in spring, the time at which the vectors migrate from overwintering sites to rice fields, are thought to be an important factor. In this study, we investigated the differences in the development of RSV-infected and RSV-free SBPH populations and further investigated how spring temperatures affect RSV transmission to rice (Otyza sativa). Two temperature conditions (15 and 20 degrees C) were chosen based on the average temperature in April-May and May-June in Korea, respectively, at which the SBPHs begin to migrate from Gramineae weeds to rice during the spring season. The nymphal developmental period in the RSV-infected SBPH was significantly shorter than that in the RSV-free SBPH. The body weight of males was significantly higher in the RSV -infected SBPH than in the RSV-free SBPH at early nymphal stage (1st day of 5th instar). The transmission of RSV to the rice seedlings was higher at 20 degrees C than at 15 degrees C. Rapid nymphal development of the RSV-infected SBPH with higher RSV transmission rate at high temperature is considered to be related to the geographical shift of RSV hotspots from the southeastern to the western coastal regions of Korea.