Effects of Eyestalk Removal and Ecdysterone Infusion on Molting in Homarus americanus

Abstract

Techniques of inducing precocious molting by introduction of the steroid ecdysterone were studied on the American lobster, Homarus americanus. The results indicate that ecdysterone, at the dosages used, while accelerating premolt processes, sufficiently disrupts the normal sequence of molting. Destalked intermolt stage C lobsters were infused with ecdysterone, in quantities ranging from 1–6 μg/g body weight. Proecdysis was shortened, particularily in lobsters receiving more than 2 μg/g body weight of the steroid. They reached ecdysis 13.8 days (average) after infusion but showed no increase in limb bud growth and died during or immediately after ecdysis. Lobsters with eyestalks infused with Ringer's solution (3% NaCl), ethyl alcohol, β-Sitosterol, or ecdysterone failed to shorten their intermolt duration near 13.8 days.It appears that, in H. americanus, removal of both eyestalks does not induce precocious molt as in other decapod crustaceans, but this animal exhibits a limb bud growth during the intermolt cycle, similar to what other investigators have found for other decapods.