Egg Morphology and Stages of Embryonic Development of the Glassy-Winged Sharpshooter (Hemiptera: Cicadellidae)

Abstract

AbstractThe structure of the egg and embryonic developmental stages of glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera Cicadellidae), an important vector of Xyhlla fastidiosa are described and illustrated. This sharpshooter has narrow, flattened elliptical eggs with the anterior end less broad and more pointed than the posterior end. The anterior portion of the egg contains a keel-shaped structure with a ridge that stretches backward for a short distance and then transforms into a groove stretching longitudinally along the ventral surface of the egg. The eggshell apparently has two layers: an outer shell layer that peels off easily when handling the egg, and an inner layer that appears intact, tightly surrounding the yolk and other liquid contents of the egg. There were six discernible stages of embryonic development (195 h at 25°C): an initial undifferentiated stage at 0–90 h, appearance of the head cap at 90–100 h, eye spot migration at 100–130 h, active physiological stage at 130–180 h, a head cap ballooning stage at 180–190 h, and emergence of the first-instar nymph at 185–195 h. It was found that the general structure of the egg and embryonic developmental stages are similar to that of other cicadellids. However, the present work breaks down the embryonic development of leafhopper] eggs into more stages than previously described. The timing of H. vitripennis embryonic developmental stages could be used to improve the design of host-age effect experiments aimed at developing more efficient rearing methods for egg parasitoids to be released for control of H. vitripennis.