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.

Recent Advances in Plant Early Signaling in Response to Herbivory

“…In addition, egg deposition might also elicit plant responses [15]. Induction of plant defensive responses by insect egg deposition is caused by the egg or egg-associated components of several insects, although the responsible chemistry has been identified only in bruchid beetles: long-chain α, γ-monounsaturated C 22 diols and α, γ-mono- and di-unsaturated C 24 diols, mono- or diesterified with 3-hydroxypropanoic acid [16].…”

“…Induction of plant defensive responses by insect egg deposition is caused by the egg or egg-associated components of several insects, although the responsible chemistry has been identified only in bruchid beetles: long-chain α, γ-monounsaturated C 22 diols and α, γ-mono- and di-unsaturated C 24 diols, mono- or diesterified with 3-hydroxypropanoic acid [16]. Similarly, it is possible that there are potent elicitors released by herbivorous arthropods during tarsal contact with a plant but they have not so far been found [15]. …”

Ammonium ionic liquids with anions of natural origin

“…This allows for obtaining products with lower toxicity compared to synthetic chemicals. Synthesis of terpenoid lactones from perillyl alcohols 19 or dialkoxybenzenes from benzenediols 20 as well as use of quinones, 21 cinnamic aldehyde 22 or even aminoacids 23 may lead to non-toxic antifeedants. As a consequence, recent literature reports describe ILs as a new class of antifeedants.…”

Sigillin A, eine einzigartige polychlorierte Wehrsubstanz gegen Arthropoden aus dem Schneefloh Ceratophysella sigillata

“…Neben weit verbreiteten Verbindungen, wie Fettsäuren, Cholesterol und kutikularen Kohlenwasserstoffen fand sich die Hauptverbindung A mit einem ungewçhnlichen Massenspektrum (Abbildung 1). GC/HR-MS Untersuchungen lieferten die Summenformel C 14 [9] Tw ist-Boot-Konformation, während der Cyclohexanring die erwartete Sessel-Konformation einnimmt (Abbildung 2). Wirs chlagen den Namen Sigillin Af ür den Naturstoff A vor.…”

“…Sie wurde schon oft für Biotests herangezogen wurde,u md ie abschreckende Wirkung von Naturstoffen aus Hexapoden zu untersuchen. [13,14] Collembolen sind eine potenzielle Beute von M. rubra, [15] Die Synthese startete von dem Schlüssel-Lacton 13,d as entweder ausgehend von Chloral in Anlehnung an eine von Shimizu et al [16] vorgestellte Strategie aufgebaut werden konnte (siehe die Hintergrundinformationen), oder auch…”