Reserva Nacional Tambopata animals invertebrates arthropods Arachnida spiders animal behavior parasites parasitism Anelosimus eximius Araneae theridiidae Argyrodes ululans predation small spatial scales ecology Madre de Dios Bibliography
Because of the large amount of webbing they provide, social spider colonies often host other satellite spider species referred to as kleptoparasites or food stealers. Such kleptoparasites may take advantage of increased prey capture rates associated with larger spider aggregates. This study investigates the relationship between a cooperatively social spider species, Anelosimus eximius (Araneae: Theridiidae), which lives in the undergrowth of tropical rainforest in Peru and its kleptoparasite Argyrodes ululans (Araneae: Theridiidae) which specializes in foraging in An. eximius webs. Although large aggregates of spiders may be more attractive to kleptoparasites, the benefits of group defense may offset this cost. The aim was to determine whether kleptoparasite succes is afected by the number of social spiders that are available for defense. Prey was less likely to be stolen when a greater number of host An. eximius spiders were involved in prey capture. When host detected a kleptoparasite earlier and chased it more often, prey was more likely to be successfully defended. Ar. ululans was more successful in stealing small prey items in all colonies and gave up more readily on very large prey (>11mm). It is possible to conclude that communal living and group defense in An. eximius confer protection from this kleptoparasite.