Action of ecdysoids, juvenoids, and non-hormonal agents on termination of pupal diapause in the flesh fly

Abstract

Pupal diapause in Sarcophaga crassipalpis can be immediately terminated with high doses of ecdysterone or 5,β-hydroxyecdysterone. Within a range of lower doses diapause is not immediately terminated, but the duration of diapause is shortened. Injection of small doses at 3-day intervals is more effective than a single application of the same total amount. 5,β-hydroxy-ecdysterone is more effective than ecdysterone. The juvenoid isopropyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate does not cause immediate termination of diapause but diapause is shortened. Simultaneous application of ecdysterone and the juvenoid synergistically produce a shorter duration of diapause than either hormone applied separately. Topical application of acetone and several other organic compounds can cause an immediate break of diapause. Neckligated pupae, however, do not respond to acetone treatment. Temperature shocks caused by brief exposure to high or low temperatures are ineffective. Although high doses of ecdysoids cause immediate termination of diapause, subsequent adult morphogenesis is protracted in direct proportion to the dose of ecdysoid. With the highest doses many flies fail to complete adult morphogenesis. Flies receiving high doses of ecdysoid are characterized by developmental abnormalities such as underdeveloped antennae, compound eyes, and mouthparts. By contrast, adultoids produced with juvenoids are characterized by abdominal abnormalities.