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Abstract

Diaphorina citri adults collected from Ishigaki Island (southern Ryukyus), Okinawa Island (central Ryukyus) and Amami Island (northern Ryukyus) were reared on Citrus unshiu and Murraya paniculata leaves under the late autumn to spring temperature conditions of 3 areas of Kyushu (south to north: Makurazaki, Akune, Kuchinotsu) located north of their natural habitat. About 60% of adults of Ishigaki population survived until late April at Makurazaki temperatures, at which time the survival rates of Okinawa and Amami populations had decreased below 14%. At temperatures in Akune, 35% of the Ishigaki population on M. paniculata and 10% on C. unshiu survived until late April, but the Okinawa and Amami populations died out before March. Under the conditions at Kuchinotsu with a minimum temperature of −3.3°C, only 4% of the Ishigaki population survived on M. paniculata and 6% on C. unshiu. Ishigaki adults reared on M. paniculata and Citrus limon trees at Makurazaki temperatures oviposited and progeny developed to the nymphal stage by the end of April. These results suggest that winter temperature conditions in parts of Kyushu are not destructive factors for D. citri populations.