Development and developmental stages of the mite Glycyphagus domesticus (De Geer 1778): Scanning electron microscopic studies

Glycyphagus domesticus (Gd) is an abundant mite in the environment of Germa n farms and a frequent mite species in urban dwellings. De Geer was the fir st to describe Gd in 1778, at that time still using the name Acarus domesti cus. Another synonym was Oudemansium domesticus [24]. Nowadays Gd is added to the genus Glycyphagus (Hering 1938 s. str.). The life-cycle of Gd consis ts of egg, larva, prelarva, proto-, tritonymph and adult. All motile develo pmental stages are similiar in their appearence. Identification of the prot onymphe-tritonymphe stage is only possible by the distinctly different geni tal folds. Identification of sexes is only possible in the adult stage. Add itionally, Gd possesses a third nymphal stage, which is produced as a respo nse to environmental stress. This deutonymph (hypopus) is clearly distingui shed from the other stages and acts as a permanent stage. The production of the deutonymph is a variable genetic manifestation to a temporary changing environment, whereby this stage has a survival potential under lethal evir onmental conditions. Depending on the environmental conditions (temperature , relative humidity, food) the duration of the different developmental stag es varies. At constant 25 degrees C and 75% relative humidity Gd takes 17 d ays to develop from egg to adult.