Distribution and biology of caddisflies (Trichoptera) in Dovrefjell mountains, Central Norway

Abstract

Encuentran A. Obscurata en menor porcentaje en zona subalpina (Driva River, 870 m.) The caddisfly fauna of the middle, low, and sub-alpine zones, ranging from 1630 m to 870 m a.s.l., in the Dovrefjell National Park, was investigated. Only three species, Apatania zonella Zetterstedt, Chaetopteryx villosa (Fabricius), and Asynarchus lapponicus (Zetterstedt) inhabited the middle alpine zone, 23 species the low alpine zone, and 60 species the sub-alpine zone. The caddisfly community of the lake outlets in the middle and low alpine zone did not differ markedly from the typical stream fauna, and consisted of limnephilids, except at one lake where the phryganeid Agrypnia obsoleta (Hagen) was present. At the lake outlet in the sub-alpine zone polycentropodids, leptocerids, hydroptilids, and phryganeids, but no hydropsychids, accompanied the limnephilids. Temporary vernal pools were inhabited by Asynarchus contumax McLachlan, A. lapponicus (Zetterstedt), Grammotaulius signatipennis McLachlan, and Limnephilus stigma Curtis. Pools that have water during the entire warm season, but freeze solid deep down into the bottom substrate in wintertime, were inhabited by A. obsoleta, Oecetis ochracea (Curtis), and Molanna albicans (Zetterstedt). Emergence, Malaise, and light trap data showed that most species peaked early in the flight period. Based on the flight periods the caddisflies can be grouped as follows: (1) Late winter species, with adults in April, May; (2) Summer and autumn species, with adults in June to September (Rhyacophila nubila into October); (3) Autumn species, with adults in late August, September, October. In emergence traps the sex ratio was close to 1:1 in most species. Significantly more females emerged of Halesus digitatus (Schrank) and Ecclisopteryx dalecarlica Kolenati, and significantly more males emerged of Parachiona picicornis (Pictet) and Plectrocnemia conspersa (Curtis). The dominant feeding group in the middle alpine zone were scrapers, represented by A. zonella.