Toxicity of Asteraceae plants from the Anatolian region to the Root-Knot Nematode Meloidogyne incog-nita.

Asteraceae plants from the endemic flora of the Anato-lian region are a reservoir of still unexplored sources of bioactive compounds that may be used for the control of root-knot nematodes (Meloidogyne spp.). The aim of this study was to assess the toxicity to the infective juve-niles (J2s) of the root-knot nematode M. incognita of 2 extracts from Asteraceae spp.: one from Helichrysum noeanum and one from Tanacetum nitens. The nema-tode J2s were exposed for 24 and 48 h to 62.5, 125, 250, 500, 1000 and 2000 μg mL-1 concentrations of each plant extract, including distilled water and a 2% etha-nol solution as controls. J2 motility and mortality were checked microscopically at the end of each exposure time. About 90% of the M. incognita J2s were immobi-lized by a 24-hour exposure to the 3 and 2 highest con-centrations of T. nitens and H. noeanum extracts, respec-tively. At the same concentrations, all the J2s treated with H. noeanum extract recovered their mobility after a 24-hour permanence in water, while 13–26% mortal-ity rates occurred for the J2s exposed to T. nitens extract. Nematode mortality reached 93 and 55% after 48-hour treatment with 1000 μg mL-1 solution of T. nitens and H. noeanum, respectively. Both extracts did not show any toxicity to J2s when used at concentrations ≤ 250 μg mL-1. The results indicate a higher suitability of T. nitens plant extracts to a potential formulation of nematocidal products. This study was carried out within the frame of a bilateral project CNR-TUBITAK “The nematocidal potential of endemic species of Asteraceae in Turkiye”