INVITRO ACTIVITY OF SOME GLUCOSINOLATES AND THEIR REACTION-PRODUCTS TOWARD A POPULATION OF THE NEMATODE HETERODERA-SCHACHTII

An in vitro study was conducted of the nematocidal effect of some glucosinolates and the products of their myrosinase-mediated enzymatic hydrolysis on second-stage juveniles of the sugar beet cyst nematode Heterodera schachtii. The glucosinolates tested were purified from the seeds or from plant organs of some crucifers cited as hosts of the nematode: Brassica napus, Lepidium sativum, Brassica rapa, Brassica carinata, Raphanus sativus, and Sinapis alba. The glucosinolates were dissolved in various concentrations in both the absence and presence of the enzyme myrosinase, and their nematocidal effect in time on second-stage juveniles was then determined. All of the glucosinolates tested as such (i.e., in their native form) showed no nematocidal effect, whereas the products of the enzymatic hydrolysis at pH 7.0 (essentially isothiocyanate) of some of them (sinigrin, gluconapin, glucotropeolin, glucodehydroerucin, and the whole glucosinolate group extracted from rapeseed) demonstrated a mortality rate that varied as a function of both the concentration of product and the exposure time. The reaction products of glucoraphenin and sinalbin did not show any nematocidal activity at the concentrations tested.