title: The chemical defense in larvae of the earwig Forficula auricularia.
abstract: Larvae of the European earwig, Forficula auricularia, possess a paired pygidial gland with yet unknown content and function. We used gas chromatography-mass spectrometry to analyze the larval secretions revealing the presence of 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone, n-tridecane and n-pentadecane. Based on our recent discovery that the morphologically-distinct abdominal glands of adult earwigs produce secretions with antibacterial, antifungal and nematicidal activity, we propose that the pygidial glands mediate chemical defenses in the larvae. We next considered whether the defensive functions of larval secretions include repellent activity against sympatric predators. Therefore, we tested the effects of larval secretions on foraging workers of the ant species Myrmica rubra, the actively hunting spiders Anyphaena accentuata and Philodromus aureolus and the net-hunting spider Pholcus phalangioides in laboratory feeding assays. The secretion is released in response to ant attacks, and discourages feeding in M. rubra, however, it does not discourage feeding in spiders. Our results suggest that earwigs use different glands during ontogenesis to produce secretions that play roles in chemical defense against predators such as ants.
authors.affiliation: Institute of Phytopathology and Applied Zoology, Justus Liebig University of Giessen, Giessen, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Gasch
authors.affiliation: Institute of Phytopathology and Applied Zoology, Justus Liebig University of Giessen, Giessen, Germany. Electronic address: Andreas.Vilcinskas@agrar.uni-giessen.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
mesh_terms: D000473:Alkanes / Q000302:isolation & purification / Q000494:pharmacology; D000819:Animal Communication; D000818:Animals; D001000:Ants / Q000187:drug effects*; D016227:Benzoquinones / Q000302:isolation & purification / Q000494:pharmacology; D012634:Bodily Secretions / Q000737:chemistry*; D007313:Insecta / Q000737:chemistry*; D007814:Larva / Q000737:chemistry*; D011235:Predatory Behavior / Q000187:drug effects*; D013112:Spiders / Q000187:drug effects*
chemical_list: D000473:Alkanes; D016227:Benzoquinones
keywords: Chemical defense; Chemical ecology; Dermaptera; Earwigs; Glandular secretions