Behavioral Ecology and Sociobiology

, Volume 45, Issue 5, pp 349–354 | Cite as

Factors influencing cannibalism in the wolf spider Pardosa agrestis (Araneae, Lycosidae)

  • Ferenc Samu
  • Søren Toft
  • Balázs Kiss
ORIGINAL ARTICLE

Abstract

Cannibalistic tendencies are well known in spiders and may be a significant factor influencing population size. The wolf spider, Pardosa agrestis, is the dominant non-web-building spider in a wide range of central European agricultural habitats. Preliminary field observations indicated an extended reproductive period, which results in a very wide size distribution of juvenile instars. We hypothesised that if cannibalism is enhanced by differences in size, especially during periods when prey is scarce, these populations might be susceptible to cannibalism in an ecologically significant way. Laboratory studies were conducted on juvenile P. agrestis in arenas. We analysed the following specific aspects of cannibalism: (1) the effect of the weight ratio between the opponents; (2) the effect of weight per se, and (3) the role of hunger level in determining cannibalistic tendencies of spiders. The role of weight and hunger were analysed in separate experiments, in both cases by controlling for the other variable. The results showed that cannibalism was strongly positively correlated with both weight ratio and hunger, but absolute size/age of an individual could not predict the occurrence of a cannibalistic event. These experiments generated the plausible hypothesis that cannibalism might be an important phenomenon in the regulation of real populations, which should be tested specifically in future field experiments.

Key words Cannibalism Wolf spider Hunger Size difference Agroecosystem 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Ferenc Samu
    • 1
  • Søren Toft
    • 2
  • Balázs Kiss
    • 1
  1. 1.Plant Protection Institute, Hungarian Academy of Sciences P.O. Box 102, H-1525 Budapest, Hungary e-mail: h2367sam@ella.hu Tel.: +36-1-1769555, Fax: +36-1-37697299 HU
  2. 2.Department of Zoology, University of Aarhus Bldg. 135, Universitetsparken D-8000 Århus C, DenmarkDK

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