Effect of constant temperature on development and survival of Lymantria albescens Hori and Umeno and Lymantria xylina Swinhoe (Lepidoptera: Lymantriinae) from Okinawa, Japan

We investigated the effect of temperature on the developmental and survival rates in the life stages of the Okinawan gypsy moth, Lymantria albescens, and the casuarina tussock moth L. xylina, from Okinawa, Japan. Under laboratory conditions at constant temperatures of 17.5, 20.0, 22.5, 25.0, 27.5 and 30.0°C, the thermal threshold and thermal constant from larva to adult for L. albescens and L. xylina were 9.1–9.9 and 8.4–11.0°C and 780.8–872.2 and 731.8–1,053.8 degree-days, respectively. Last-instar larvae of males of both species were mostly 6th instars, whereas a large number of female last-instar larvae were 6th and 7th instars. Survival rates of L. albescens and L. xylina were very low at 30.0°C, indicating that these species in Okinawa are not resistant to temperatures higher than 30°C. Our results provide information for predicting the appearance of field populations of L. albescens and L. xylina in Okinawa.