Ballooning of spiders (Araneae) in Switzerland: general results from an eleven-year survey

摘要

A survey of ballooning spiders was carried out over a period of eleven years between 1994 and 2004. Altogether, 15,398 ballooning spiders, representing 103 species and 16 families, were caught with a 12.2 m high suction trap in an agricultural landscape of Switzerland. The families Linyphi-idae, Araneidae, Philodromidae and Theridiidae were numerically dominant. Linyphiids represented 60% of the total, and were the most diverse family. Of the total captures, 31% were adults, and 52% of the adults were females. The diversity of species caught as males (78) was higher than that of females (68). We observed 11 species frequently ballooning: Meioneta rurestris, by far the most frequent, Araeoncus humilis, Erigone dentipalpis, Porrhomma microphthalmum, Erigone atra, Tenuiphantes tennis, Nuctenea umbratica, Bathyphantes gracilis, Eperigone trilobata, Mangora acalypha and Oedothorax apicatus. Of the 103 species recorded, 28 species , (27%) and two genera had not previously been recorded in ballooning studies, and 22 species are rare in Switzerland. Although the proportions of species from open areas and from areas with bushes and trees were almost identical, the proportion of individuals of species from open areas was much higher; 46% were ground-livingspecies and the others were from higher vegetation layers. Dispersal by ballooning showed two main peaks: the first between the end of May and mid-August and the second from the beginning of October until the beginning of November. The maximal diversitywas found in June (34 species). The percentage of adults varied between 12 and 65% during the year. The percentage of adult females varied between 32 and 100%. Phenological patterns for the main families are presented.