Nematicidal Activity of Stevia rebaudiana (Bertoni) Assisted by Phytochemical Analysis

Abstract

To date, there has been great demand for ecofriendly nematicides with beneficial properties to the nematode hosting plants. Great efforts are made towards the chemical characterization of botanical extracts exhibiting nematicidal activity against Meloidogyne spp., but only a small percentage of these data are actually used by the chemical industry in order to develop new formulates. On the other hand, the ready to use farmer produced water extracts based on edible plants could be a sustainable and economic solution for low income countries. Herein, we evaluate the nematicidal potential of Stevia rebaudiana grown in Greece against Meloidogyne incognita and Meloidogyne javanica, two most notorious phytoparasitic nematode species causing great losses in tomato cultivation worldwide. In an effort to recycle the plant’s remnants, after leaves selection for commercial use, we use both leaves and wooden stems to test for activity. In vitro tests demonstrate significant paralysis activity of both plant parts’ water extracts against the second-stage juvenile (J2) of the parasites; while, in vivo bioassays demonstrated the substantial efficacy of leaves’ powder (95% at 1 g kg−1) followed by stems. Interestingly, the incorporation of up to 50 g powder/kg of soil is not phytotoxic, which demonstrates the ability to elevate the applied concentration of the nematicidal stevia powder under high inoculum level. Last but not least, the chemical composition analyses using cutting edge analytical methodologies, demonstrated amongst components molecules of already proven nematicidal activity, was exemplified by several flavonoids and essential oil components. Interestingly, and to our knowledge, for the flavonoids, morin and robinin, the anthocyanidin, keracyanin, and a napthalen-2-ol derivative is their first report in Stevia species.

Evaluation of Solanum linnaeanum and S. sisymbriifolium extracts for the management of Meloidogyne chitwoodi

“…For easer production, a simple preparation method can be used with water as the extraction solvent, such as was done by Pestana et al (2008, 2014) and Ntalli et al (2020a, 2020b) [ 15 , 31 , 50 , 56 ]. The utilization of water rather than other solvents reduces the risk of secondary effects on the nematodes.…”

Chemical Characterization of Plant Extracts and Evaluation of their Nematicidal and Phytotoxic Potential

“…Among these strategies, natural product usage represents a vital option for controlling phytopathogenic nematodes because of their low impact on the environment and non-target organisms. In the search for botanic nematicides, some of the most recent proposals are using Stevia rebaudiana and Origanum vulgare to control Meloidogyne ; in vivo experiments showed this effect [ 7 , 8 ]. In the case of N. aberrans , crude herbal extracts from T. lunulate [ 9 ], Cosmos sulphureus [ 6 ], Senecio salignus [ 6 ], Witheringia stramoniifolia [ 6 ], and Lantana cámara [ 6 ] showed in vitro nematicidal activity at 500 µg mL −1 (>70%) to second-stage juvenile (J2) individuals.…”

Identification and Functional Characterization of Plant Toxins

“…The toxicity of plant-derived substances against pests is a topic that attracts numerous groups of researchers. Ntalli et al [ 5 ] described Stevia rebaudiana (Bertoni) Bertoni water extracts’ chemical composition against important agricultural pests as nematodes— Meloidogyne incognita and Meloidogyne javanica —and proved that the extracts and leaves’ powder might successfully control them. To the authors’ knowledge, they reported, for the first time, some metabolites in Stevia species.…”