Studies on the embryogenesis of Aulocara elliotti (Thomas) (Orthoptera, Acrididae). II. Developmental variability and the effects of maternal age and environment.

Abstract

AbstractThe stages of diapause embryos of A. elliotti reared in the laboratory were described, and the lengths of embryos of stage 19 were compared with a second group of diapause embryos of advanced ages. Collections of diapause embryos of the same species were made from wild populations during the autumn and winter of two consecutive years. The stages of embryos present in these samples were found to vary widely. The mean lengths of embryos in stage 19 from different populations were compared and found to differ with statistical significance. The numbers of retarded embryos in different populations were found to vary significantly between populations of diapause embryos. In two populations, mean lengths of embryos of stage 19 were found to differ from one year to the next.Post‐diapause embryos were collected from wild populations in the spring of two consecutive years and their stages described. No significant difference was found in the incidence of retardation in post‐diapause samples. Results of these studies and those of other authors indicate that there may be wide developmental variation between populations of acridid embryos as well as in one population in two different years.Rearing adult A. elliotti in varying numbers under two different environmental conditions was found to produce significant effects upon the rate of development and variability of their embryonic progeny. Embryos laid by young females were found to be more variable, in general, and to develop more slowly than those laid by older females.