Abstract:
An animals’ habitat defines the resources that are available for its use, such as host plants or
food sources, and the use of these resources are critical for optimizing fitness. Spiders are abundant
in all terrestrial habitats and are often associated with vegetation, which may provide structure for
anchoring capture webs, attract insect prey, or provide protective function. Social spiders construct
sedentary communal silk nests on host plants, but we know little about whether and how they make
nest-site decisions. We examined host plant use in relation to host plant availability in the social
spider Stegodyphus dumicola Pocock, 1898 (Eresidae) across different arid biomes in Namibia and
analysed the role of host plant characteristics (height, spines, scent, sturdiness) on nest occurrence.
Host plant communities and densities differed between locations. Spider nests were relatively more
abundant on Acacia spp., Boscia foetida, Combretum spp., Dichrostachys cinerea, Parkinsonia africana,
Tarchonanthus camphoratus, and Ziziphus mucronatus, and nests survived longer on preferred plant
genera Acacia, Boscia and Combretum. Spider nests were relatively more abundant on plants higher
than 2 m, and on plants with thorns and with a rigid structure. Our results suggest that spiders
display differential use of host plant species, and that characteristics such as rigidity and thorns
confer benefits such as protection from browsing animals.
Description:
SUPPLEMENTARY MATERIALS : Table S1. Proportion of potential host plant species (Plant) and Stegodyphus
dumicola Pocock, 1898 nests (Nest) for each plant species, per study site. Empty cells indicate that the
species was not found in the study sites. Total sample size (Sample size line) is given both for the
number of plants (Plants (N=)) and the number of plants with a nest (Nests (N=)) for each study site.
OT = unknown host plant species in Otavi, WH = unknown host plant species in Windhoek.
