Prediction of long distance migration of rice planthoppers to northern Kyushu considering low-level jet stream.

Abstract

Rice planthoppers are major pest for rice plants in Asian countries. They immigrates from overseas to Kyushu in Japan in the Baiu season every year. To predict the long distance migration of rice planthoppers to northern Kyushu, a migration model was developed with a hypothesis that rice planthoppers were transported by low-level jet stream at 1, 000-2, 000m heights. The weather conditions for the migration period (June to July) were analyzed with the 850 mb chart at 21h in 1980-1985 and at 09h and 21h in 1986, and possible migration days were decided. On the other hand, actual migration flight waves were decided with the number of catches by two nets. The possible migration flights decided by the weather chart agreed approximately with the actual flights. The accuracy of this prediction method was improved by using the 850mb chart at 09h additionaly. Finally, the prediction procedure was described.