Abstract
When leaves of the mulberry tree, Morus alba L., were dried at high temperature (615°C), a diet containing those leaves (HT diet) caused 5th instar larvae of Bombyx mori L. (Lepidoptera : Bombycidae) to become permanent larvae. These larvae attained a large body size and developed huge silkglands. Their failure to spin cocoons may be related partly to the whitening and hardening of the middle silkglands. Normal development and pupation occurred when larvae were reared on a standard diet containing low-temperature (100°C) treated leaves (LT diet). When larvae kept on the HT diet for several days were transferred to the LT diet, some formed large cocoons and pupated and others failed to do so and diet at different stages of the larval-pupal transformation proces. Pupae obtained from larvae kept longer on the HT diet during the 5th instar took longer ot emerge as adults and produced fewer adults. It is thus likely that the HT diet contained some factor inhibiting metamorphosis in B. mori. Rearing on mixtures of the two diets indicated that the factor appeared to influence growth and development of 5th instars in a dose-dependent manner.
