No abstract

Mated females of the tropical warehouse moth, Ephestia cautella, start laying eggs shortly after adult emergence. All eggs are laid within 4 days and the adult's total life span is 5 to 6 days. If mating i s prevented, egg laying is drastically delayed and the life span is extended to approximately 10 to 11 days. Virgin females lay fewer eggs than mated insects. If the juvenile hormone analogue methoprene is applied topically (100 ng/pupa) 2 to 3 days prior to adult emergence, the number of eggs per virgin female increases and the life span is reduced, as compared with nontreated virgins, and reaches values similar to control (mated) females. Changes in the ecdysteroid titer of females are related to egg laying. The concentrations increase and reach a maximum before most of the eggs are laid. Accordingly, the peak maximum is delayed in virgins as compared with mated females. This delay i s prevented after application of methoprene. Mated and virgin females have lower ecdysteroid levels than treated virgins. In contrast to mated females, males have much lower ecdysteroid levels throughout their adult life.

No abstract

A dou ble-antibody ecdysone-specific radioimmunoassay was used to clarify whether the effects on metamorphosis of the juvenile hormone analogue methoprene are correlated with changes in ecdysteroids level. It appears that a small ecdysteroids peak, 5 days before pupation, i s responsible for the transition from inhibition to defective metamorphosis. Study of the changes in ecdysteroid titer in last-instar larvae treated with the JHA 2 days prior to the appearance of the above small ecdysteroids' peak showed an immediate reduction in ecdysteroid level, followed by cyclic, successively reduced titer for about 20 days. After this period the larvae ceased to feed and entered to a diapauselike stage which ended in the death of the larvae. A similar effect on ecdysteroid titer and developmental arrest was exhibited by JHA-treated first-instar larvae. The mechanism of the interactions between JHA and ecdysteroid level deserves further investigation.