The prey of web-building spiders compared with feeding experiments (Araneae: Aranaeidae, Linyphiidae, Pholcidae, Agelenidae)

Feeding experiments with 2520 prey animals show differences in consumption rate and palatability for 4 spider species (Zygiella x-notata, Linyphia triangularis, Tegenaria atrica, Pholcus phalangioides). A possible protection against predators by chemical defense is discussed with special regard to 30 spp. of Heteroptera. Chemical weapons possess and astonishingly low deterrent effect; thick chitinization (Coleoptera) gives very effective protection. Studies of the actual prey of these webbuilding spiders gave similar results in Araneidae and Linyphiidae. Nematocera and Homoptera are the most important prey group. Hymenoptera, Coleoptera and Brachycera were seldom caught. The prey of Tegenaria and Pholcus consists mainly of Brachycera, Coleoptera and Hymemoptera; Nematocera and Homoptera are rarely caught. The prey animals are mostly small. Only Pholcus and Tegenaria catch larger specimens. An ecological classification of the prey of Linyphiidae and Araneidae shows high percentages of phytophagous and detritophagous insects. Compared to the potential prey (trap data), predators, parasites and pollinating insects are underrepresented in the acutal prey.