Cannibalism in Pardosa palustris (Araneae, Lycosidae):: effects of alternative prey, habitat structure, and density

We investigated potential driving factors for intraspecific predation in Pardosa palustris conducting two laboratory experiments to evaluate the role of availability of alternative prey, habitat structure and spider density for cannibalism between and within developmental stages. Availability of alternative insect prey strongly reduced cannibalism between adult spiders and juveniles as well as among juveniles. For juvenile spiders habitat complexity reduced predation by adult females, whereas cannibalism among second instar spiderlings was not affected by habitat structure suggesting that complex habitat structure only provides shelter from cannibalism by large conspecifics. High density of juvenile spiders increased cannibalism only when alternative prey was available, suggesting that alternative prey increased aggression and interference at higher density. High mortality and tow growth of spiders in treatments without alternative prey likely resulted from starvation indicating that intraspecific prey is of low food quality and does not allow spider development. (c) 2005 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.