The Biology and Survival Rate of the Coffee Stem Borer, Xylotrechus quadripes CHEVLORAT (Coleoptera, Cerambycidae) in Nothern Thailand

Investigation on the biology and survival rate of the coffee stem borer Xylotrechus quadripes CHEVROLAT was carried during 1990-1992. The adult borers emerged during the daytime from infested arabica coffee trees (Coffea arabica LINNE) which confined in the cages. The adults were very active in the daytime and usally mated on the same emergence day. The sex ratio was 0.62. Female adults lived for 29 days including incubation period of 5 days on an average. The preoviposition period were about 2 days. They laid an average of 103 eggs on the bark of coffee trees throughout their life span. The eggs hatched in 5 days. The larvae tunneled into the stem in all directions and sometimes into the roots. The tunnels were tightly packed with larval excreta. The precise measurement of the head capsule of larvae indicated that they elapsed six instars. The mean developmental period from the eggs to adults when they were reared with coffee sticks in the laboratory were 95 days and 172 days in the screen house when the larvae were fed on young living coffee tree. The mean duration of pupal stage were 11 days. The callow adults remained in the pupal chamber for 5 days of incubation period, then the full grown adults emerged via the exit holes. Before emergence the adults chewed the bark and made the round exit holes. The exit holes occurred on the main stems 84% and on the roots 16%. The survivorship curve of the present species seemed to belong to DEEVEY's C-type. The mortalities in the larval period were relatively high at the early instars. The rate of survival at the end of the developmental period was about 25%.