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Sensitivity of Meloidogyne javanica and Tylenchulus semipenetrans to Isothiocyanates in Laboratory Assays

Isothiocyanates are released through enzymatic degradation of glucosinolates produced by plants in the family Brassicaceae. Glucosinolate profiles differ among plant species and the isothiocyanate derivatives differ in their toxicity to nematodes. Control of plant-parasitic nematodes in soil by isothiocyanates released from incorporated brassicaceous plant material has been inconsistent. Success might be improved with knowledge of the relative toxicities of various isothiocyanates against nematodes. Laboratory assays were conducted to determine lethal concentration (LC) values in sand of seven commercially available isothiocyanates against Tylenchulus semipenetrans and Meloidogyne javanica. The LC₉₀ values were 0.01 and 0.03 μmol/ml for 2-phenylethyl isothiocyanate and 0.48 and 0.35 μmol/ml for phenyl isothiocyanate for T. semipenetrans and M. javanica, respectively. Brassicaceous sources of benzyl or 2-phenylethyl isothiocyanate and, to a lesser extent allyl isothiocyanate, are the most promising candidates for plant-parasitic nematode management. The broader context of this research is the development of approaches for consistent and reliable use of plant-derived chemicals for nematode management. The strategy is to select plants in the family Brassicaceae based on their glucosinolate profiles and the sensitivity of the target nematode species to the associated isothiocyanates.