The wolf spider Pardosa milvina varies silk deposition in response to self and same-sex conspecific silk

Silk is an important communication medium for spiders with roles in species recognition, sex identification, and mating status assessment. Spiders may benefit by discriminating between their own or another same-sex conspecific's silk. Silk-mediated self-recognition could allow spiders to identify areas that they have previously visited, competitively block silk advertisements from sexual rivals or minimize redundant signaling in an area. Silk deposition behavior may also be contingent upon silk cues detected from same-sex conspecifics. We tested if males and females of the wolf spider Pardosa milvina show different silk deposition patterns when encountering their own silk versus the silk of another spider of the same sex. Using a within-between-subjects design, we quantified male and female deposition of three silk types: draglines, cord silk, and attachment disks on substrates containing either their own silk or the silk of an adult same-sex conspecific (N = 23 males, 28 females). Both males and females significantly increased dragline and cord silk deposition on substrates containing conspecific rather than their own silk with males producing more cord silk than females. Males significantly increased attachment disk deposition on conspecific male silk compared to their own while females showed the opposite response, decreasing attachment disk deposition on conspecific female silk. Both male and female P. milvina can recognize their own silk, but we found significant qualitative and quantitative sex differences in silk deposition suggesting sex-specific functions for attachment disks compared to cord or dragline silk.