JUVENILE HORMONE-LIKE EFFECTS OF RETINOIC ACID IN INSECT METAMORPHOSIS, EMBRYOGENESIS AND REPRODUCTION

Retinoic acid exerted juvenilizing effect on the last instar larvae of bugs, Pyrrhocoris apterus (L.), Dysdercus cingulatus (F.) and on fres hly moulted pupae of Tenebrio molitor (L.) when applied in doses rangi ng from 0.003 ng to 3 mu g per specimen. Doses higher than 0.3 mu g pe r specimen were toxic for all tested species. Larvae of P. apterus wer e responding to retinoic acid only when it was applied by injection, o ther species were also sensitive to topical treatments. The acid appli ed to the eggs caused embryonic malformations and further exhibited th e capacity to restore reproduction in the allatectomized adults of P. apterus and D. cingulatus. Doses of about 0.003 mu g per female induce d deposition of fertile eggs which provided normal progeny, and also s timulated synthesis of vitelogenins.