Defensive secretion of Eurycantha calcarata - chemical composition and method of collection

Abstract

Abstract Chemical defense in insects is becoming an increasingly interesting topic and has the potential for providing unexplored compounds with unknown properties for drug and repellent discovery, so the secretions of different species of insects are being studied and new ways of collecting these secretions are being sought. Silica gel and activated carbon are absorbents that were used to collect the gaseous defensive secretion of Eurycantha calcarata. Using gas chromatography coupled with mass spectrometry, 52 compounds were identified, including 19 carboxylic acids, 14 esters, 10 alcohols, 5 hydrocarbons and other organic compounds. The most abundant two compounds from each group are: hexadecenoic acid, octadecanoic acids, 9-hexadecanoic acid octadecyl ester, hexadecanoic acid tetradecyl ester, octacosanol, triacontanol, tridecane and tetradecane. The silica gel turned out to be a better absorbent because it captured more compounds than the activated carbon. The mass of the absorbent did not affect the quality of the analyses. This paper is the first describing the volatile secretions emitted by Phasmid representatives, not originating from the prothoracic glands. The presented results of the analyses and the known properties of found compounds give grounds for the conclusion that these secretions are of importance for defense in this species of phasmid.