Nematicidal Activity of the Essential Oils of Several Argentina Plants Against the Root-Knot Nematode

The nematicidal activity of the essential oils isolated from Aloysia triphylla, A. polystachya, A. gratissima, Lippia juneliana, L. turbinata (from two locations of San Luis: Lujan and Merlo) and Heterotheca latifolia from San Luis, Argentina, were evaluated using in vitro experiments. The oils of A. triphylla, L. juneliana and L. turbinata showed the highest nematicidal activity among the tested oils, killing more than 80% of the juveniles of the root-knot nematode Meloidogyne sp. at 667 μL/L concentration. Analysis of the oils revealed that they possess the following main components: Aloysia triphylla—α-thujone (22.9%), cis-carveol (17.5%), carvone (13.2%) and limonene (12.7%); A. polystachya—α-thujone (80.0%) and sabinene (5.1%); A. gratissima—cadinol (17.4%), caryophyllene oxide (15.8%), limonene oxide (5.3%), chrysanthenyl acetate (5.6%) and β-caryophyllene (4.8%); L. juneliana—piperitenone oxide (36.5%), limonene (23.1%), camphor (8%) and spathulenol (6.5%); L. turbinata—limonene (43.3–60.6%) and piperitenone oxide (39.3–17.8%); and Heterotheca latifolia—borneol (32.5%) and camphor (26.3%). The results suggest that the oils, or perhaps their main components, may serve as nematicides.