Chemical Screening and Nematicidal Activity of Essential Oils from Macaronesian and Mediterranean Plants for Controlling Plant-Parasitic Nematodes.

Plant-parasitic nematodes are highly damaging pests responsible for heavy losses in a considerable number of plant crops. Common pest management strategies rely on the use of synthetic chemical nematicides, which have led to serious concerns regarding their impact on human health and the environment. The essential oils (EOs) obtained from aromatic plant species can provide a good source of agents for the sustainable control of nematodes, due to higher biodegradability, generally low toxicity for mammals, fish, and birds, and lower bioaccumulation in the environment. This study aimed to evaluate the nematicidal and nematostatic properties of EOs extracted from plant species relevant to Macaronesia flora or with widespread use as culinary herbs in Mediterranean cuisine. Eighteen EOs were chemically characterized and evaluated by direct contact and hatching bioassays on the root-knot nematode The EOs that showed a significant effect on second-stage juveniles' (J2) mortality (≥40%) were also used in chemotaxis assays. From the eighteen EOs, seven showed strong nematicidal activity (>80%) and hatching inhibition. The chemotaxis assays revealed that only exhibited repellent behavior for J2, and the rest of EOs had attractive behavior. Furthermore, EOs were assessed against the root-lesion nematode and the pinewood nematode . was the EO with the highest nematicidal activity for the three nematode species. Among the terpene-rich EOs, high mortality values and hatching inhibition for were observed for the carvacrol chemotype , albeit with low activity for and . , mainly composed of monoterpene ketones and monoterpenoids, demonstrated moderate-to-high mortality activity (from 30% for to 99% for ) for the three nematode species.