PROSTAGLANDINS DO NOT RELEASE EGG-LAYING BEHAVIOR IN THE SILKMOTH, BOMBYX-MORI

A re-evaluation of the role of prostaglandins (PGs) in releasing egg-l aying behaviour in the silkmoth, Bombyx, was performed. The results re vealed that PGs do not play a crucial role as oviposition behaviour st imulants. Injection of prostaglandin E-2 (PGE(2)) had no effect on egg -laying behaviour of virgin females. The oviposition behaviour of fema les which were injected with PG biosynthesis inhibitors such as indome thacin, quinacrine and NDGA was not interrupted or suppressed. Sterili zed males of Bombyx can be induced by heat treatment (32 degrees C) fo r 72 hr during the wandering stage. The rate of oviposition of female moths mated with sterilized males was suppressed at a great deal, comp ared to the control group, in the ensuing mating period of 24 hr. PGE( 2) injection into the females mated with the sterilized males had no e ffect on the restoration of oviposition behaviour. There were no signi ficant difference in the PGE(2) content in the testes of normal and st erilized males. After mating, the amount of PGE(2) increased with age in the bursa copulatrix of females which had mated with either normal or sterilized males. These results indicate that PGs do not seem to be directly involved in the egg-laying behaviour of Bombyx.