The nematicidal activity of saponins from Medicago arborea (tops), M. arabica (tops and roots) and M. sativa (tops and roots) against the plantparasitic nematode Xiphinema index was investigated. Nematicidal activity of related prosapogenins and sapogenins on X. index is also described. Saponins from Medicago spp. at different concentrations were all nematicidal, those from M. arborea tops being the less effective. In general, saponins induced 100% mortality at 500 μg ml −1 between 8 and 48 h, while prosapogenins resulted in toxicity starting at 125 μg ml −1 . Differences in the effects on X. index induced by prosapogenins and sapogenins were less pronounced, although prosapogenins displayed a larger range of activity. Assays with purified sapogenins demonstrated the relationship of the observed nematicidal activity of M. sativa and M. arborea to the content of the main aglycones (medicagenic acid and hederagenin, respectively) in the saponin extracts. Hederagenin displayed the highest bioactivity, giving 38% mortality after 1 h at 125 μg ml −1 .

Medicago sativa L., alfalfa, is the most known plant species within the Medicago genus. The plant has been extensively studied for its content of saponins, mainly consisting of triterpene glycosides of medicagenic acid, possessing several biological properties including a biocidal activity on different soil microorganisms. Phytoparasitic nematodes are responsible for heavy economic damages to numerous agricultural crops and, due to their large distribution, they are among the most difficult crop pests to control. Attention on environmental safety and human and animal health has led to the progressive dismission of many synthetic formulations for the control of those pests and to the search of alternative strategies, including the use of natural metabolites from plants. Saponins from M. sativa may be good candidates for natural nematicide formulations, as in our in vitro studies the saponin mixtures from M. sativa tissues have been found effective in vitro against the virus-vector nematode Xiphinema index, the root-knot nematode Meloidogyne incognita and the potato cyst parasite, Globodera rostochiensis. A structure-activity relationship among saponins and related prosapogenins and sapogenin, respectively, has also been analyzed. The nematicidal efficacy differed among the three assayed nematode species, G. rostochiensis being the most susceptible to the active compounds from alfalfa. The in vitro results were also confirmed by experiments in potting mixes infested by M. incognita or G. rostochiensis and amended with dry top and root material from M. sativa, and in field trials on M. incognita and carrot cyst nematode Heterodera carotae with M. sativa pelleted meal. All amendments reduced root and soil population densities of target nematode species compared to non-treated and chemical controls, with a general improvement of plant growth and yield performances

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Brassicaceae Burnett (syn. Cruciferae A. L. de Jussieu) include many important economic plants used as edibile or ornamental. They are commonly known as the “mustard” plant family due to the sharp, potent flavour of their main metabolites, the glucosinolates (GLSs) which contain sulfur. Glucosinolates coexist in vivo with glycosylated thioglucosidases, myrosinase(s), responsible of their hydrolysis with the production of bioactive cognate isothiocyanates (ITC). GLSs and ITCs function as defence bioactive metabolites against plant pathogens, insects and herbivores. The present review paper focus on GLSs role as bionematicides. The current knowledge on the efficacy of these phytochemicals against the most common phytoparasitic nematodes affecting crops of agriculture importance such as tomato, potato and grapevine is reported. Data from our ongoing research on the in vitro biocidal activity of glucosinolate extracts, and their main components, against the virus-vector nematode Xiphinema index Thorne & Allen and the carrot cyst nematode Heterodera carotae Jones are also described

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Content of bioactive saponins of Medicago species suggests that they may also exert, as previously demonstrated on M. sativa, nematicidal properties exploitable for the formulation of new products for sustainable phytoparasitic nematode management. This study was addressed to highlight the bioactivity of saponins from five different Medicago species still poorly known for their biological efficacy, i.e., M. heyniana, M. hybrida, M. lupulina, M. murex and M. truncatula, against the plant parasitic nematodes Meloidogyne incognita, Xiphinema index and Globodera rostochiensis. The bioactivity of the extracts from the five Medicago species was assessed by in vitro assays on the juveniles (J2) and eggs of M. incognita and G. rostochiensis and the adult females of X. index. The suppressiveness to M. incognita of soil treatments with the Medicago plant biomasses was also investigated in a tomato experiment. The nematicidal activity of the five Medicago species was reported and discussed in relation to their phytochemical profile.

The effectiveness of soil fumigation with 50, 100 and 200 μL kg −1 soil of essential oils (EOs) from the plant species Eucalyptus citriodora, Eucalyptus globulus, Mentha piperita, Pelargonium asperum and Ruta graveolens was assessed against the root-knot nematode Meloidogyne incognita on potted tomato. Plant growth parameters and number of galls, nematode eggs and juveniles on tomato roots were evaluated after two months of maintenance of the treated plants at 25 ∘ C in greenhouse. EOs of E. globulus and P. asperum significantly reduced nematode multiplication and gall formation on tomato roots at all the tested rates, whereas the EOs of E. citriodora, M. piperita and R. graveolens were more suppressive at levels greater than 50 μL kg −1 soil. Biofumigation with EOs of E. globulus and P. asperum resulted also in the largest increase of tomato plant top and root biomass. The five samples of EOs had a different chemical composition as determined by GC and GC-MS. Structure-activity relationship based on the main constituents of the tested EOs and their nematicidal effect on M. incognita is discussed.

In this study, the relationship between nematicidal activity and chemical composition of ten essential oils (EOs) from different plant species was investigated both in in vitro assays on juveniles (J2) and eggs of the root-knot nematode Meloidogyne incognita and in experiments on tomato in soil infested by M. incognita. Nematode J2 were exposed for 4, 8 or 24 h to 0.78–100 μg mL−1 concentrations of each EO, whereas 24, 48 or 96 h exposures to 250, 500 and 1000 μg mL−1 solutions were tested on M. incognita egg masses. Treatments with 50, 100 or 200 μg kg soil rates of each EO were applied in the experiment on potted tomato. The highest nematicidal potential resulted for the C. verum EO, as highly toxic to both M. incognitaJ2 and eggs and strongly suppressive on nematode multiplication on tomato roots. The infestation of M. incognita on tomato roots was also strongly reduced by the EOs from E. citriodora and S. aromaticum, both highly toxic to M. incognitaJ2 but less active on nematode eggs. Adversely, R. graveolens EO strongly inhibited the egg hatch but was limitedly toxic to the infective J2. Chemical composition of the EOs was determined by GC-FID and GC-MS. The ten EOs showed a very different chemical composition in terms of major phytochemicals, with one or two dominant components totally amounting up to 85%. The structure–activity relationship based on the main phytochemicals identified in the assayed EOs and their nematicidal effects on M. incognita was also discussed. Results from this study confirmed that the selection of suitable EO raw materials can lead to the formulation on new effective nematicidal products.