Plants as biocontrol agents against phytoparasite nematodes

Overuse of synthetic pesticides has generated a series of environmental problems and human and animal health concerns which have led to their progressive withdrawn from the European market [1]. The reasons given are related to high toxicity of these type of biocides, their nonbiodegradable properties and the presence of residues in soil, water resources and food crops. As an alternative to synthetic pesticides, the use of phytochemicals is a very promising tool for pest control and for reducing the negative impact on health and environment. Management of soil-borne phytonematodes affecting the yield and quality of important food crops such as potatoes, tomatoes, grapes, etc is of economic importance and in the recent years the interest in the application of botanical nematicides has been enormously growing [2]. Groups of plant secondary metabolites most promising in the development of pesticidal formulations are glucosinolates, saponins and terpenoid phytoconstituents. As a continuation of our studies [3,4], we will here describe our latest results on the nematicidal effects of selected plant natural products with particular attention to essential oils (EOs), largely containing terpene components, against the highly crop destructive root-knot nematode Meloidogyne incognita and the ectoparasite dagger nematode Xiphinema index. Results obtained from in vitro and in soil experiments suggest that the biocidal activity of the selected EOs mainly depends upon the chemical type and individual concentration of their constituents. Structure-activity relationship based on the main terpenes composing the assayed EOs is also discussed. In conclusion, the present study indicates that specific plant EOs have a high potential for developing new nematicides sustainable to environment and human health. In addition, our results suggest that priority should be given to EOs with a high content of specific active components.