ABSTRACT Since volatiles do not leave residues in food and cause low toxicity to humans, they can act as a skeleton for new nematicidal molecules, once they have demonstrated activity against phytonematodes. The aim of this study was to evaluate the effect of volatile organic compounds (VOCs) released by wood-associated fungi on controling second-stage juveniles (J2) of Meloidogyne incognita. All 28 wood-associated fungi isolates produced VOCs which caused in excess of 76 % immobility in exposed J2 of M. incognita. The fungus isolate VOCs also caused significant mortality compared to control when J2 were exposed to them. After 6 h of exposure, the fungus species Epicoccum nigrum and Schizophyllum commune produced VOCs that immobilized exposed J2 compounds, in relation to the control. When J2 were inoculated into tomato under greenhouse conditions, the M. incognita infectivity and reproduction were reduced by exposure to the VOCs. Volatiles produced by most of the fungi isolates and analyzed by gas chromatograph coupled to a mass spectrometer (CG-MS), included alcohols, esters, terpenes, and ketones. Certain compounds appeared only in S. commune or in E. nigrum suggesting their involvement in the high level of damage caused to nematode reproduction on tomato. Volatiles emitted by wood fungi demonstrated another mode of action of these microorganisms in nature.

This paper presents the fundamental principles, instrumentation and selected applications of comprehensive two-dimensional gas chromatography (GC × GC). In this technique, introduced in 1991, two capillary columns are coupled and proper modulating interfaces continuously collect the eluate from the first column, transferring it to the second column. The result is a geometric increment in the chromatographic resolution, ensuring separation of extremely complex mixtures in time periods shorter or comparable to those of analysis using conventional gas chromatography and with better detectabilities and sensitivities.