Control of Meloidogyne incognita Using Aqueous Extracts and Solanum stramonifolium Jacq. Dialisates

Root-knot nematodes (Meloidogyne spp.) considerably affect their plant hosts, causing extensive damage in the world agriculture. The most widely used method to control these pathogens is through the intensive application of nematicides, despite being highly toxic to humans, animals, and the environment. The urgent search for alternative forms of control based on natural resources that are effective, provide a targeted strategy that is less toxic and less harmful to the environment. The species Solanum stramonifolium Jacq. (Solanaceae) have been described as resistant to root-knot nematode infection and other diseases, such as fungi and bacteria. Nematotoxic assays here presented demonstrated that aqueous crude seed extract from S. stramonifolium is very effective against second stage juveniles (J2) of M. incognita even at very low concentrations such 100µg mL-1 during in vitro bioassays. Furthermore, this extract also demonstrated a nematicidal effect after a heating process at 50 °C, killing more than 90% of M. incognita J2. No toxic activity was observed against non-target organisms, like bacteria, and the free-living nematode Caenorhabditis elegans at concentrations varying from 25 to 512 µg mL-1. Finally, greenhouse assays showed that external dialysate (ED) can be used to control nematodes in the soil, and that the plants treated with the dialysates display a reproduction factor lower than the synthetic nematicide used as positive control.