QUANTITATIVE ANALYSIS OF LARVAL BODY GROWTH IN THE SILKWORM, BOMBYX MORI (LEPIDOPTERA: BOMBYCIDAE)

Abstract

Quantity-wise and rate-wise growth changes in the larval body mass vis-à-vis log-based growth curves were analyzed in Bombyx mori. The body mass accumulation followed a progressively increasing trend from third to fth instar, registering higher values in growth index (GI) and mean growth rate (MGR). But, the corresponding compound periodical growth rates and mean specic growth rates declined remarkably during the same period. The growth increments in body mass are in consonance with Hutchinson's investment policy and accordingly the silkworm accumulates energy reserves and structures that are necessary for future use during metamorphosis. Higher growth ratios recorded in the present study indicate that the silkworm systematically violates the Dyar's constant rule throughout the growth regime. The logbased growth curves were further analyzed to determine the critical and threshold body sizes that trigger moulting and metamorphosis in the silkworm.