The level of chitinolytic enzymes and ecdysteroids during larval-pupal development in Ephestia cautella and their modifications by a juvenile hormone analogue

Abstract

The influence of the juvenoid methoprene on ecdysteroid titre and enzymatic activity of N- acetylglucosaminidase and chitinase in Ephestia cautella was examined. Treatment of the larvae in the early fourth larval instar prevents not only the normal rise in ecdysteroid titre but also the increase in activity of both enzymes. Treatment of pupae has no effect on either the ecdysteroid titre or on the enzymatic activities. Larvae treated with methoprene during the last quarter of the larval stage show intermediate values in ecdysteroid titre as well as in chitinolytic enzyme activities. A causal relationship between moulting hormone titre and activity of chitin-degrading enzyme is proposed.