THE FUNDAMENTAL ROLE OF SAMPLING AND SEPARATION SCIENCES IN THE DEFINITION OF MULTITROPHIC PHENOMENA

Multitrophic phenomena can be defined as the plant responses to herbivore feeding damage by producing a volatile fraction differing not only in its quantitative composition per unit of plant biomass but also qualitatively i.e. because of the release of compounds not occurring in the volatile fraction of the intact plant [1]. Multitrophic interactions between plants and insects can therefore be monitored through chemical messages mainly consisting of volatiles. The study of the “chemistry of the interaction” implies the adoption of strategies of analysis enabling to obtain results not only analytically reliable but also biologically meaningful. The importance of the analysis approach will be illustrated through two examples: a) the first one describes the different toxic effect of the volatile fraction from different species belonging to the same genus on an herbivore through HS-SPME-GCxGC-qMS analysis, in particular the interaction between mint leaf beetle (Crysolina herbacea Duftschmid) and peppermint species (Mentha spicata L., Mentha×piperita L., Mentha longifolia L.) [2] b) the second one is the STE-GC-MS study of the dynamics of the reaction of a plant when attacked from an herbivore: in particular the reaction of lima bean leaving leaves (Phaseolus lunatus L.) to the attack of Egyptian cottonworms (Spodoptera littoralis Boisduval).