INSECT HORMONES AND BIOANALOGUES: THEIR EFFECT ON RESPIRATORY METABOLISM IN DERMESTES VULPINUS L. (COLEOPTERA)

¹ Institute of Entomology, Czechoslovak Academy of Sciences, Prague

1. Treatment of the early last instar larvae with juvenoids caused enormous increase in respiratory metabolism which is referred to as hypermetabolism. During this process the larvae consumed as much as 10 ml of oxygen per gram live weight per hour. It is anticipated that hypermetabolism constitutes part of a physiological "anti-juvenile" mechanism in Dermestes. The effect is associated with considerably enhanced food consumption and excretion. The phenomenon was virtually absent when juvenoids were applied to non-feeding larvae or pupae.

2. Single treatment of prepupal stages with large doses of juvenoids induced the formation of several extra-pupal instars. Each of them exhibited a slightly modified type of the U-shaped metabolic course.

3. Ecdysterone caused an indirect inhibition of the total body metabolism in the feeding larvae. In the non-feeding, immobile dauerlarvae it slowly increased the metabolic rate over the low maintenance level. In connection with stimulation of the molt cycles by ecdysterone there were specific patterns in respiratory metabolism which corresponded to the larval-larval or larval-pupal development.

4. Both the hormonal bioanalogues, i.e., juvenoids and ecdysterone, are believed to have an indirect effect on the total body metabolism. The effect depends on the quality and degree of morphological and physiological changes conditioned by the hormonal milieu and on certain feed-back reactions. It has been confirmed that each of the developmental cycles in insects, such as are larval-larval, larval-pupal, and pupal-adult molt cycles, can be also characterized by a specific pattern in the course of respiratory metabolism.