POLYPLOIDY AND PREVITELLOGENIC FOLLICULAR ATRESIA DURING OOGENESIS IN THE EUROPEAN EARWIG FORFICULA AURICULARIA (DERMAPTERA: FORFICULIDAE)

Abstract

AbstractGrowth, number of fusions, and polyploidy of ovarian trophocytes were studied in the European earwig, Forficula auricularia L., from the imaginal moult to oviposition, by examining sections of ovarioles and whole mounts of ovaries. During a reproductive cycle, the nucleus of the basal trophocyte enlarges its mean diameter from 5 to 170 ± 33 μm, successively absorbing the trophocyte nuclei of both adjacent follicles and undergoing seven endoreplications. The nucleus thus increased its DNA content 192 times, which is 66.7% more than in the artioploid type of polyploidy. However, vitellogenesis lasted about three times longer than previtellogenesis. This type of polyploidy accelerates oogenesis, allows an earlier oviposition, and may constitute an adaptation specific for the Montréal population of earwigs.