LIFE HISTORY OF THE RED PALM WEEVIL, RHYNCHOPHORUS FERRUGINEUS (COLEOPTERA: DRYOPHTORIDAE), IN SOUTHERN JAPAN

We surveyed the life history of the red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae), in southern Japan, including seasonal changes in the flight activity of adults and composition of R. ferrugineus in different developmental stages in a total of 17 infested Phoenix canariensis trees which were cut down in 2003-2005. The flight of adults began in Mar, showed some peaks in summer and autumn, and ceased in mid-Dec. Various stages of individuals inhabited infested R canariensis trees throughout the year. The composition of individuals at different stages in late fall was dependent on the resource (white intact tissue) availability in R canariensis trees. In R canariensis trees where considerable resource remained, all stages of larvae, pupae, and adults were found, whereas in palm trees with no resource, few young- and medium-stage larvae were observed. The temperature in the infested part of a palm trunk was 30 degrees C or higher even in winter. From these results, we view the life history of R. ferrugineus in southern Japan as follows: Adults emerge from host trees in spring and continue to attack host trees until late fall. Rhynchophorus ferrugineus grows even in winter if intact tissue remains at the peripheral part of trunks, and there may be 3 or 4 generations per year. A cold winter probably does not have any negative effects on successful colonization of R. ferrugineus in Japan.