Observations on the nematicidal properties of some mycotoxins.

Secondary metabolites produced by species of Fusarium and other soil fungi were tested against sorne plant parasitic nematodes. Assays were conducted in vitTO using toxin concentrations of 0.02,0.2,2,20, and 200 ppm in 4 % methanol. T2-toxin, moniliforrnin, verrucarin A and cytochalasin B significanùy reduced the viability of Meloidogyne javanica juveniles at 2 ppm or higher concentrations after 72 hours exposure at 22.5 oc. Enniatin B showed a significant increase in M. javanica mortaliry at 20 ppm. T2-toxin also showed a nematicidal effect on M. hapla and Pratylenchus neglectus at 0.2 and 2 ppm, respectively. When tested in soi! against M. javanica parasitizing tomato plants, T2-toxin and moniliformin did not affect nematode densiry. In the treated pots a larger number of galls per g of root was a1so observed. Data suggest that mycotoxins can interact with nematodes through antagonistic or synergistic effects related to the concentration levels present in the plant rhizosphere.