The Effects Of Juvenile Hormone On The Early Embryonic Development Of The Fleshfly, Sarcophaga Bullata

Abstract

Juvenile hormone (JH), a sesquiterpene compound, acts as a morphogenetic hormone in insects; JH permits expression of the larval genome and inhibits expression of the adult genome. Previous experiments have indicated that development is arrested prior to blastoderm formation in insect eggs treated with JH during the early stages of embryonic development. In the present study, the effects of a highly active JH analog, methoprene, were tested on the eggs of the fleshfly, Sarcophaga bullata (Diptera). Preliminary studies were performed to establish the membrane permeability of S. bullata eggs to the RNA inhibitors 1% benzamide and actinomycin D. Development of newly fertilized eggs treated with the RNA inhibitors was arrested at the blastoderm stage, indicating that the membrane is permeable. Subsequently, development of eggs treated with 35 μg methoprene/μ1 acetone was also arrested suggesting that the membrane is permeable to methoprene. A volume of 2μ1-35μg methoprene/μ1 acetone per group of 10 eggs represented the critical concentration. The critical time of methoprene effects on embroyonic development appeared to be between 0 hours, ie. fertilization, and 4 hours. These results will be discussed in relation to current hypotheses on JH action.