Research Article

Sensitivity of Meloidogyne incognita second-stage juvenile hatch, motility and viability to pure cucurbitacins and cucurbitacin-containing phytonematicides

Published in: South African Journal of Plant and Soil
Volume 36, issue 1, 2019 , pages: 29–32
DOI: 10.1080/02571862.2018.1464220
Author(s): Zakheleni P DubeGreen Biotechnologies Research Centre, South Africa, Phatu W MashelaGreen Biotechnologies Research Centre, South Africa, Dirk de WaeleGreen Biotechnologies Research Centre, South Africa

Abstract

Previous claims suggested that pure active ingredients from botanicals were less effective in pest management than their fermented crude-extracts. The objective of this study was to compare the toxicity of pure (98%) cucurbitacin A and B on nematode bioactivities with those of their fermented crude-extracts, the Nemarioc-AL and Nemafric-BL phytonematicides, respectively. Purified active ingredients were each diluted to 0.00, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.00, 2.25 and 2.50 μg ml‒1 and their fermented crude-extracts to 0.0%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% and 5.0% phytonematicide. The exposure time for second-stage juveniles (J2) hatch, motility and viability of the J2 to each concentration was 24, 48 and 72 h. The overall sensitivities (Σk) of J2 hatch to Nemarioc-AL, cucurbitacin A, Nemafric-BL and cucurbitacin B were 1, 30, 5 and 2 units, respectively, for motility 7, 12, 2 and 12 units, respectively, and for viability 2, 4, 1 and 4 units, respectively. Generally, nematodes displayed high sensitivities to cucurbitacin-containing phytonematicides than to their respective purified active ingredients (cucurbitacins). In conclusion, the cucurbitacin-containing phytonematicides were more effective in nematode suppression than their purified active ingredients.

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