Effects of web chemical signatures on intraspecific recognition in a subsocial spider, Coelotes terrestris (Araneae)

For web-building spiders, a current hypothesis states that silk structure is involved in intraspecific communication, and could play a major role in regulating social relations. To test this hypothesis, we studied a subsocial spider, Coelotes terrestris (Araneae). During their lifetime, individuals of this species successively experience a social period (parental female and young stages, from hatching to dispersal) and a solitary period (postdispersal young to adult stage). We therefore expected the link between an individual and its web to change depending on whether it was in its subsocial or solitary period. We conducted two complementary studies. Behavioural tests showed that the webs of incubating females were attractive to mated females and the webs of parental females repelled virgin spiders. Dispersal of young spiders was accompanied by characteristic changes in the chemical components of the mother's web. Chromatographic analyses of individual webs revealed the presence of 48 different compounds. The components were alcohol, fatty acids and long-chain aliphatic hydrocarbons. Quantitative as well as qualitative changes in chemical profiles correlated strongly with the physiological state of the spiders that made them. Bioassays showed that the spatial distribution of the spider was influenced by these chemical compounds.