title: How to spoil the taste of insect prey? A novel feeding deterrent against ants released by larvae of the alder leaf beetle, Agelastica alni.
abstract: Chemical defense of leaf beetle larvae (Chrysomelidae) against enemies is provided by secretions containing a wide range of deterrent compounds or by unpalatable hemolymph constituents. Here we report a new, very strong feeding deterrent against ants released by larvae of the alder leaf beetle Agelastica alni when attacked. The larvae release a defensive fluid from openings of pairwise, dorsolaterally located tubercles on the first to the eighth abdominal segments. The fluid, consisting of hemolymph and probably a glandular cell secretion, has previously been shown to contain a very stable, non-volatile feeding deterrent. The major deterrent component was isolated by repeated HPLC separation and analyzed by NMR and MS. The compound proved to be gamma-L-glutamyl-L-2-furylalanine (1), a novel dipeptide containing the unusual amino acid L-2-furylalanine. This amino acid, although synthetically well known, has not previously been reported from natural sources. The absolute configuration of the natural compound was elucidated by enantioselective gas chromatography after derivatization. The structure of the dipeptide was verified by the synthesis of several isomeric dipeptides. In bioassays a concentration of 1 microg microL(-1) was sufficient to deter polyphagous Myrmica rubra ants from feeding.
authors.affiliation: Institute of Biology, Freie Universität Berlin, Haderslebener Strasse 9, 12163 Berlin, Germany. hilker@zedat.fu-berlin.de
authors.forename: Monika
authors.initials: M
authors.lastname: Hilker
authors.forename: Christopher
authors.initials: C
authors.lastname: Häberlein
authors.forename: Ute
authors.initials: U
authors.lastname: Trauer
authors.forename: Martina
authors.initials: M
authors.lastname: Bünnige
authors.forename: Mark-Oliver
authors.initials: MO
authors.lastname: Vicentini
authors.forename: Stefan
authors.initials: S
authors.lastname: Schulz
mesh_terms: D029661:Alnus; D000818:Animals; D001000:Ants / Q000254:growth & development*; D001681:Biological Assay; D001517:Coleoptera / Q000378:metabolism*; D004151:Dipeptides / Q000032:analysis*; D006458:Hemolymph / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D010935:Plant Diseases / Q000469:parasitology* / Q000517:prevention & control
chemical_list: D004151:Dipeptides