Journal of Ecophysiology & Occupational Health

Growth and development during larval-larval ecdysis and larval-pupal metamorphosis vis-à-vis ecdysone titre in the haemolymph of tropical tasar silkworm, Antheraea mylitta Drury (Daba bi-voltine ecorace) in between non-diapause destined (NDD) and diapausing destined (DD) generations has been studied. The entire larval duration (= phagoperiods) was observed 28 days in NDD generation and 39 days in DD generation. A decreasing trend in growth rate during the development of larval instars occurs and instar durations are inversely related to the weight at the time of initiation of a larval instar. A growth compensation mechanism exists during course of development of larval instars. The first half of the each instar exhibits higher growth rate, the relative growth rate is the highest in the first instar and lowest in final. In early instar from 1st to 4th the larval ecdysis are characterized by an increase in ecdysone titre before ecdysis both in NDD and DD generation than DD. The programme for undergoing diapause is initiated during third instar larval development and supported with a sudden decrease in the level of ecdysone titre in DD generation. Each developmental symptom is preceded by a larger or smaller peak of ecdysone titre in the haemolymph. The two major peaks of ecdysone titre are required for larval-pupal transformations first before initiation of wandering stage and second at pharate pupal stage. No significant difference was observed in ecdysone level in NDD and DD in post-feeding larvae but titre was higher in DD than in NDD larvae.