Potential distribution area of the Mexican bean beetle, Epilachna varivestis (Coleoptera : Coccinellidae) in Japan, estimated from its high-temperature tolerance

Thermal responses in regard to female oviposition and larval development we re investigated in the invasion population of the Mexican bean beetle, Epil achna varivestis whose presence was initially confirmed in Yamanashi and Na gano Prefectures, central Japan in 1997. Oogenesis in the female was inhibi ted when exposed to 27.5 degreesC for five continuous days. Larval developm ent was inhibited markedly at 30 degreesC, and survival rate declined to ne arly 0% when exposed to 32.5 degreesC for more than five days. Based on the se high-temperature stresses and the 30-year average temperature data in Ja pan (1961-1990), we estimated the potential distribution area of E. varives tis in Japan. It is predicted that E. varivestis will be less abundant in t he south-western areas of central Japan, while this beetle could survive ef ficiently and maintain a high population level in the mountainous areas of central Japan, and in almost all of northern Japan (Tohoku and Hokkaido).