How to spoil the taste of insect prey? A novel feeding deterrent against ants released by larvae of the alder leaf beetle, Agelastica alni.
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.
Hilker
Monika
M
Institute of Biology, Freie Universität Berlin, Haderslebener Strasse 9, 12163 Berlin, Germany. hilker@zedat.fu-berlin.de
Häberlein
Christopher
C
Trauer
Ute
U
Bünnige
Martina
M
Vicentini
Mark-Oliver
MO
Schulz
Stefan
S
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
D004151:Dipeptides