ENDOCRINE STRATEGIES FOR INSECT CONTROL

Abstract

Analogs of the insect juvenile hormone III have been successfully applied to the control of several species of insects which are pestiferous in the adult stages. These include insects of economic importance to man and to domestic animals such as mosquitos, manure breeding flies and fleas. However, the juvenile hormone analogs are ineffective for the control of the immature stages of insects which are most important in agriculture through their feeding damage to crops. Thus by the time the juvenile hormone analogs can be effective, the immature stages have already completed their feeding damage. It seemed to me that a method of interfering with the biosynthesis, secretion, or action of the juvenile hormone would be a very useful method of insect control against insects which do their damage as feeding immature stages. Whereas a number of insect hormone mimics have been discovered in plants it seemed possible that plants might be a useful resource to investigate for insect hormone antagonists. Since the juvenile hormones control immature development and adult reproduction, I believed that a juvenile hormone antagonist would be a more suitable endocrine strategy for the control of insects of importance in agriculture. We searched for and discovered two naturally-occurring anti-juvenile hormonal compounds in plants. These anti-hormones (precocenes) induce a lethal, precocious metamorphosis in the immature stages of many insects and also sterilize the adult females.