Dietary niche and cooperative foraging strategies in social spider
Background: Social spiders are faced with the challenge of increasing foraging success to fulfil the needs of the group and counter the cost of prey sharing. Hence social spiders are expected to subdue increasingly larger prey to acquire sufficient energy for all consumers, however there is an increased danger of engaging with large prey. To overcome these costs, cooperative foraging should allow for widening of the dietary niche by increasing prey capture rate or prey size range - thereby optimizing foraging for the whole group. It has been proposed that social spiders reside in areas where larger prey are relatively more abundant, suggesting that cooperation in prey capture allows for expansion of the foraging niche to exploit prey of a larger size.
Project: The aim of my study was to explore whether a similar expansion of the dietary niche may apply for a social spider of the Stegodyphus genus. By studying a social (S. dumicola) and subsocial (S. lineatus) species in their native habitat I examined prey availability and prey size preference as factors that may affect their foraging and in particular increase the dietary niche of the social species. Differences between the level of sociality in the way the spiders exploit prey will provide insights into how cooperative societies increase foraging success to reduce resource competition. I found that social spiders have a broader dietary niche compared to the subsocial congener. This suggests that social spiders are able to exploit more of the available prey in habitat by cooperative prey capture. The data also suggest preference among both spider species for certain insect orders over others.