Sexual Differences in the Behavior of the Harvestman Leiobunum vittatum (Opiliones, Sclerosomatidae) Towards Conspecific Cues

Preliminary observations of the harvestman Leiobunum vittatum found that individuals rub their bodies against the substrate, presenting the possibility of chemical marking. To determine whether or not L. vittatum individuals can detect substrate-borne chemical cues, we compared responses of L. vittatum males and females to substrate-borne male and female cues. We found that individuals of L. vittatum do respond to conspecific cues and that their responses are sex-specific. In response to substrate-borne conspecific cues, male L. vittatum spent more time, engaged in more scraping with their sensory legs I, and engaged in pedipalpal tapping more often in the presence versus absence of conspecific cues (male and female equally). Furthermore, in the presence of conspecific cues, males engaged in two behaviors never observed in females-(a) "fast approach" and (b) "jerking", the latter of which was never observed in the presence of cricket cues. In contrast to males, females did not spend more time on conspecific cues, but did spend more time tapping their pedipalps in the presence of male vs female cues, suggesting an ability to distinguish between them. A final experiment explored the possibility that females could discriminate among males of varying histories of agonistic interactions based upon their chemical cues. We found no support for this hypothesis. Our results demonstrate that L. vitattum do respond to conspecific cues, and introduce the possibility that intraspecific communication may be mediated in part by chemical cues.

The scent of stress: Pintado catfish differentially respond to chemical cues from stressed conspecifics

We examined whether pintado catfish (Pseudoplatystoma corruscans) can discriminate between scents of non-injured conspecifics stressed by a predator or by confinement and how fish use this information in the trade-off between feeding and predator avoidance. In the confinement stress condition, fish ingested the food, whereas in the predator stress condition, fish did not eat. This finding and comparisons of the latency to food ingestion and the time spent swimming between the confinement and predator-stress conditions indicated that pintado catfish can discriminate between conspecifics stressed by a predator or confinement using chemical cues, and use this information for adjusting the trade-off between food intake and predator avoidance.