The effects of environmental light on the role of male chemotactile cues in wolf spider mating interactions

Abstract

Many animals communicate using multiple sensory channels simultaneously and this ability enables them to overcome the challenges of living in variable environments. Studies of wolf spiders have been important in understanding complex communication with a primary focus on the roles of visual and vibratory signals during mating. However, it is well documented that wolf spiders leave silk draglines behind that are often associated with additional chemical residues such as pheromones. We verified that females detect the silk and secretions left on a substrate by male wolf spiders in the species, Tigrosa helluo. We hypothesized that male chemotactile cues play different roles when vision is limited and so we explored the effects of adding male cues prior to courtship in light vs dark situations. Aggression was lower when male chemotactile cues were augmented and when vision was reduced. Males and females came together more quickly and had higher mating success when male cues were augmented under red light, which simulated darkness for these spiders, whereas contact was delayed and mating success was lower in the treatment with added male cues in white light. Thus, the availability of visual signals adjusted the importance of male chemotactile cues either through a shift in sensory priorities of the female or in the evaluative criteria used to make decisions. Chemotactile cues potentially allow for sophisticated information to be conveyed about the male, as such, may be an important communication modality on their own as well as in concert with other signaling channels.

Significance statement

Selecting the right mate depends on effective communication so that the prospective partner can detect and accurately evaluate key traits. Animals living in variable habitats must overcome the communication challenges by presenting information through multiple sensory channels. The understanding of multimodal communication has been advanced by studies of visual and vibratory signaling in wolf spiders. We found that females detect male silk and chemical secretions and that they alter mating interactions in the wolf spider, Tigrosa helluo. Allowing males to deposit silk and chemical cues before virgin males and females were allowed to interact reduced aggression and increased mating success in red light (low vision) conditions. These results broaden the possibilities for the types of interacting signals that might influence the efficacy of multimodal communication in animals live and mate in dynamic environments.