Infection stress and mate assessment in wolf spiders: female mate choice varies with sensory mode of male courtship

Fighting infection is energetically costly and can result in resource trade-offs with other life history processes, including reproduction. Studies investigating parasite-mediated sexual selection are more common than those investigating pathogen-induced effects. Moreover, these studies focus more often on costs of infection for obvious male characteristics (e.g. secondary sex traits, courtship behaviour) and less on responses of healthy females to infected males. This experimental study examined the trade-offs between infection stress and female mate choice in a well-studied wolf spider, Schizocosa ocreata, in which choosy females selected males displaying condition-dependent traits indicating high mate quality (larger/more symmetrical tufts of foreleg bristles, higher peak amplitude vibratory signals). Female S. ocreata were tested to determine whether recent infection by Pseudomonas aeruginosa , a common pathogenic bacterium in their habitat, impacts choosiness when presented with video and/or vibratory playback of courting male stimuli with manipulated leg tuft size and vibration amplitude. Three sensory modes were tested (visual, vibratory, multimodal) and two treatment groups were utilized (infected, control). Females were presented with a two-choice test between high- and low-quality potential mates, utilizing video and/or vibratory playback of male courtship signals manipulated to reflect the quality differential (large versus small foreleg tufts; high versus low peak amplitude of vibratory signals). Female behaviour was scored using the number of receptivity displays to either of the two screens within 5 min trials. Results show that female receptivity behaviour varied based on sensory mode of male courtship and infection treatment. In the visual sensory mode, uninfected females showed significantly greater receptivity than their infected counterparts (but not in the isolated vibratory mode or multimodal treatments). These results suggest that infection stress affects mate choice and may impact the visual sensory pathway more than vibration perception. • We tested whether recent bacterial infection affects female wolf spiders' choosiness. • Females chose between high- vs low-quality signals (visual, vibratory, multimodal). • Female receptivity varied with infection status and sensory mode of male courtship. • Uninfected females showed greater visual receptivity than infected females. • Infection affects mate choice and may impact the visual sensory pathway.