Preferential prey sharing among kin not found in the social huntsman spider, Delena cancerides (Araneae: Sparassidae)

Although the benefits of group foraging are important for evolution of sociality in spiders, the factors that influence group-level benefits of prey sharing in social spiders are still poorly understood. In the unusual transitional social spider Delena cancerides Walckenaer 1837 (Sparassidae), prey sharing almost certainly occurs occasionally among non-kin in the wild, and so we tested the effects of kin relationships and familiarity on the amount of prey consumed in this species. To determine whether the amount of prey sharing increased with relatedness or with familiarity, we fed treatment groups containing spiderlings of varying relatedness and familiarity a single prey item and measured the amount of weight gained by sharing groups. We found no effect of relatedness or familiarity on the amount of prey consumed by prey-sharing groups of D. cancerides. Increased duration of sharing, number and age of the spiders involved, and size of the prey item all increased the amount of prey consumed. The benefits of prey sharing in this species likely overwhelm any possible inclusive fitness benefits derived from kin discrimination in this highly outbred social spider. Hence, we reject the hypothesis that groups of kin consumed proportionately larger amounts of prey biomass than groups of non-kin, as proposed by Schneider and Bilde in 2008 with Stegodyphus lineatus Latreille 1817 (Eresidae).