Nematicidal activity of the tropane alkaloids hyoscyamine and scopolamine against the root-knot nematode Meloidogyne incognita

Alkaloids and alkaloid-producing plants have the potential to reduce crop damage by plant-parasitic nematodes. In a series of in vitro experiments, the nematicidal activity of the tropane alkaloids, hyoscyamine and scopolamine, and a mixture of both on the root-knot nematode, Meloidogyne incognita, was tested. Solutions of 16 mg of compound per ml of solvent were used in concentrations of 80-1280 μg ml−1 of water. Inactivity of second-stage juveniles of M. incognita increased with increasing concentration and exposure time. Lethal concentrations (LC50) after 120 min of exposure ranged from 182.4 μg ml−1 for scopolamine to 318.4 μg ml−1 for hyoscyamine and 332.8 μg ml−1 for the combination of both alkaloids. Similarly, the same concentrations of scopolamine inhibited hatching of M. incognita to a greater extent than hyoscyamine. In a glasshouse experiment, M. incognita was not able to penetrate the roots, induce galls and reproduce on Datura stramonium, D. innoxia and D. tatula. Results indicate that the tropane alkaloids hyoscyamine and scopolamine contained in Datura plants express a strong nematicidal activity against M. incognita and could possibly be used for an alternative and sustainable nematode management.