Nematotoxic and phytotoxic activity of Satureja montana and Ruta graveolens essential oils on Pinus pinaster shoot cultures and P. pinaster with Bursaphelenchus xylophilus in vitro co-cultures

•Satureja montana and Ruta graveolens essential oils were added to plant/nematode co-cultures.•Essential oils nematotoxicity and phytotoxicity was assessed at 0.5 μl/ml culture medium.•Pinus pinaster shoots and P. pinaster with Bursaphelenchus xylophilus co-cultures were the test systems.•S. montana essential oil showed phytotoxicity, inducing in vitro shoot chlorosis and drooping.•R. graveolens essential oil induced no detectable morphological changes.

Satureja montana (winter savory) and Ruta graveolens (rue) nematotoxic essential oils (EOs) (0.5 μl EO/ml culture medium) were assessed for the first time in Pinus pinaster in vitro shoot cultures (Ppi) and P. pinaster shoots with Bursaphelenchus xylophilus co-cultures (PpiBx). The EOs nematotoxic effect was evaluated on B. xylophilus population density in PpiBx co-cultures and the phytotoxic activity to the host was assessed by evaluating relative water content and volatile profiles both on Ppi cultures and on PpiBx co-cultures. Carvacrol-rich S. montana EO showed phytotoxicity, by inducing shoot chlorosis and drooping, whereas no major morphological changes were detected on R. graveolens EO-added Ppi and PpiBx in vitro cultures. Both EOs maintained the nematotoxicity during all experimental phases. R. graveolens EO proved to be an effective PWN antagonist to be further evaluated for pine wilt disease control, given its less phytotoxicity while maintaining nematoxicity.

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