THE JUVENILE HORMONE. V. THE SENSITIVITY OF THE BUG, PYRRHOCORIS APTERUS, TO A HORMONALLY ACTIVE FACTOR IN AMERICAN PAPER-PULP

Abstract

1. Materials composed of American paper-pulp contain an extractable, heat-stable lipid which exhibits extremely high juvenile hormone activity when injected or topically applied to the European bug, Pyrrhocoris apterus. The active principle in the paper materials is derived from certain species of pulp trees, more particularly the balsam fir, Abies balsamea. Larvae exposed to the active material ultimately die without completing metamorphosis or attaining sexual maturity.2. Despite its extremely high activity for Pyrrhocoris apterus, the extract is without any detectable effects on silkworm pupae or most other species of laboratory insects; conversely, juvenile hormone extracts prepared from cecropia silkmoths show little or no activity when tested on Pyrrhocoris. These findings point to a diversification of the detailed chemistry of juvenile hormone and to corresponding changes in the conformation of the receptor mechanism at the cellular level.3. The factor extracted from paper materials promises to be an effective agent for the selective control of insect pests which show the same endocrine sensitivities as Pyrrhocoris apterus. It is possible that hormonally active factors for other species may be present in other gymnosperms.