Suitability of woodlice prey for generalist and specialist spider predators: a comparative study

1. Predators select a prey according to its energetic and nutritional composition. Generalist predators avoid, whereas specialists often specialise on well‐defended prey. The aim of this study was to find the suitability of woodlice prey for generalist and specialist predators by comparing their handling efficiency. 2. Laboratory experiments were performed in which specialist and generalist predators were reared on monotypic diets comprising one or other of two woodlice species that differ in their defensive strategies: rollers (Armadillidium) and clingers (Porcellio). A control group was reared on a mixture of arthropods (excluding woodlice). Three spider predators were used that differ in their adaptations to deal with woodlice prey: a woodlice specialist, Dysdera crocata; an oligophagous generalist, Pholcus phalangioides, that also captures woodlice; and a euryphagous generalist, Tegenaria domestica, that does not feed on woodlice. The frequency of capture was recorded and various fitness parameters were measured, namely survival, growth rate, and ontogenetic development. 3. It was found that the specialist, D. crocata, performed best on the Porcellio diet, and similarly well on Armadillidium and mixed diets. The two generalists, P. phalangioides and T. domestica, had poor performance on both woodlice diets but performed well on the mixed diet. 4. The results show that woodlice are unsuitable prey for both oligophagous and euryphagous generalist predators.