THE LIFE-CYCLE OF APATANIA-FIMBRIATA PICTET IN THE BREITENBACH

The life-cycle of Apatania fimbriata (Pictet, 1843) (Trichoptera: Limnephilidae) was studied in the Breitenbach (Hesse, Federal Republic of Germany) and in the laboratory at 6-degrees-C, 10-degrees-C and 14-degrees-C at 14 h day length. Embryogenesis was mainly temperature dependent in the 4-degrees-C-18-degrees-C range. At a constant 22-degrees-C embryos developed to well-differentiated larvae which did not hatch. In the laboratory experiments, developmental rates increased with increasing temperature (6-degrees-C, 10-degrees-C and 14-degrees-C); larvae went through a dormancy in the third and fourth larval instars; in the field this occurred between November and February. The dormancy synchronized the larval development. Laboratory studies led to the conclusion that the dormancy was not temperature dependent but endogenously determined. The emergence pattern of adults showed a clear diurnal pattern, with a maximum emergence approximately two hours after sunset. A comparison of several years emergence studies showed a decreasing number of females with increasing distance from the spring. A comparison of the dry weight of females between two traps at the stream showed a significantly higher weight from the downstream site. For males no between-site differences were observed.