title: Cuticular antifungals in spiders: density- and condition dependence.
abstract: Animals living in groups face a high risk of disease contagion. In many arthropod species, cuticular antimicrobials constitute the first protective barrier that prevents infections. Here we report that group-living spiders produce cuticular chemicals which inhibit fungal growth. Given that cuticular antifungals may be costly to produce, we explored whether they can be modulated according to the risk of contagion (i.e. under high densities). For this purpose, we quantified cuticular antifungal activity in the subsocial crab spider Diaea ergandros in both natural nests and experimentally manipulated nests of varying density. We quantified the body-condition of spiders to test whether antifungal activity is condition dependent, as well as the effect of spider density on body-condition. We predicted cuticular antifungal activity to increase and body-condition to decrease with high spider densities, and that antifungal activity would be inversely related to body-condition. Contrary to our predictions, antifungal activity was neither density- nor condition-dependent. However, body-condition decreased with density in natural nests, but increased in experimental nests. We suggest that pathogen pressure is so important in nature that it maintains high levels of cuticular antifungal activity in spiders, impacting negatively on individual energetic condition. Future studies should identify the chemical structure of the isolated antifungal compounds in order to understand the physiological basis of a trade-off between disease prevention and energetic condition caused by group living, and its consequences in the evolution of sociality in spiders.
authors.affiliation: Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, México D. F., México.
authors.forename: Daniel
authors.initials: D
authors.lastname: González-Tokman
authors.affiliation: Biocenter Grindel & Zoological Museum, University of Hamburg, Hamburg, Germany; Department of Biological Sciences, Macquarie University, Sydney, Australia.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Ruch
authors.affiliation: School of Biological Sciences, The University of Sydney, Sydney, Australia.
authors.forename: Tamara
authors.initials: T
authors.lastname: Pulpitel
authors.affiliation: School of Biological Sciences, The University of Sydney, Sydney, Australia; Charles Perkins Centre, The University of Sydney, Sydney, Australia.
authors.forename: Fleur
authors.initials: F
authors.lastname: Ponton
mesh_terms: D000818:Animals; D060467:Disease Resistance; D005260:Female; D005658:Fungi; D054884:Host-Pathogen Interactions; D008297:Male; D013112:Spiders / Q000382:microbiology* / Q000502:physiology*