Volatile organic compounds from cottonseed meal are toxic to Meloidogyne incognita

Abstract

The toxic effects of volatile organic compounds (VOC) emitted from cottonseed meal to plant parasitic nematodes are almost unknown, despite their effectiveness when added to soil. We evaluated in this study the effect of second stage juveniles (J2) of Meloidogyne incognita exposed to VOC from a mixture of soil and cottonseed meal in different concentrations held in cups. VOC trapped in cups sealed with parafilm for 10 days caused higher immobility and mortality of J2 of M. incognita and lowered infectivity and reproduction in tomato than in a 20-day exposure. Under the same conditions, adding nematode eggs to soil containing meal significantly reduced M. incognita reproduction in tomato plants at all meal concentrations at 10 and 20 days exposure to cottonseed volatiles in comparison with planting immediately after incorporation. Cottonseed meal concentrations from 3% to 6% reduced infectivity and reproduction of M. incognita in tomato plants in soil mixed with eggs at all tested periods. Gas chromatography-mass spectrometry analysis identified 25 molecules produced exclusively by soil amended with cottonseed meal at 3 % concentration, the most biologically active being 2-methyl-1-butanol, 3-methyl-1-butanol, phenyl-ethylalcohol, benzene-1-ethyl-4methoxy (p-ethylanisole), and 4-ethyl-1,2-dimethoxybenzene. In conclusion, VOC emitted from cottonseed meal are toxic to M. incognita.