title: Chemical Defense as a Condition-Dependent Trait in Harvestmen.
abstract: The expression of costly traits often depends on the amount of food available to the individuals. Chemical defenses are costly, thus their production should be condition-dependent. Here, we tested the hypothesis that an increase in food availability and an acetate-supplemented diet will increase the production of chemical defenses by the harvestman Magnispina neptunus, which releases alkylated benzoquinones biosynthesized using acetate as a precursor. We manipulated the diet of the individuals and created four experimental groups: well-fed with acetate, well-fed without acetate, poorly-fed with acetate, and poorly-fed without acetate. Well-fed individuals produced secretions with higher mass and concentration of benzoquinones than poorly-fed individuals, but we detected no significant effect of the acetate supplement. Thus, the production of benzoquinones is condition-dependent, and even short periods of dietary restriction may make individuals more vulnerable to predators, imposing fitness consequences to chemically-protected arthropods that biosynthesize their own defensive compounds.
authors.affiliation: LAGE do Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 05508-090, Brazil.
authors.forename: Taís M
authors.initials: TM
authors.lastname: Nazareth
authors.affiliation: Departamento de Biologia Marinha, Instituto de Biologia, Universidade Federal Fluminense, PO Box 100.644, Niterói, Rio de Janeiro, 24.001-970, Brazil.
authors.forename: Daniela B
authors.initials: DB
authors.lastname: Sudatti
authors.affiliation: LAGE do Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, 05508-090, Brazil. glaucom@ib.usp.br.
authors.forename: Glauco
authors.initials: G
authors.lastname: Machado
mesh_terms: D000085:Acetates / Q000378:metabolism*; D000478:Alkylation; D000818:Animals; D001097:Arachnida / Q000502:physiology*; D016227:Benzoquinones / Q000378:metabolism*; D004032:Diet; D005260:Female; D008297:Male
chemical_list: D000085:Acetates; D016227:Benzoquinones
keywords: Arachnida; Benzoquinone; Costs; Dietary restriction; Food availability; Opiliones; Parental care