Comparative In Vitro Nematicidal Activity of Aqueous Leaf Extracts of Datura stramonium and Lantana camara Against Meloidogyne incognita

Abstract

Root-knot nematodes have reduced crop production and increased the interest in botanical sources of nematode management. In the present study, the in vitro activity of aqueous leaf extracts of Datura stramonium and Lantana camara against second stage juveniles of Meloidogyne incognita was compared under a common experimental framework. The shade dried leaf powder was extracted in water (1:10 w/v) at 60-70 °C for 3 hours. Three trials were conducted using nominal extract concentrations of 2%, 4% and 6% and juvenile mortality was assessed after 24, 48, 72 and 96 h. Distilled water was used as negative control and carbosulfan as positive control. Prior to two-way analysis of variance, mortality was adjusted for contemporaneous water-control mortality. Lantana camara had the quickest response. At 72 h, observed mortality was 36.00 ± 22.27%, 44.00 ± 24.33%, and 50.67 ± 27.23% at 2%, 4%, and 6%, respectively, compared with 14.67 ± 2.31%, 17.33 ± 4.62%, and 21.87 ± 3.70% for Datura stramonium. By 96 h, observed mortality reached 84.00 ± 14.42%, 96.00 ± 4.00%, and 100.00 ± 0.00% for Lantana camara and 85.87 ± 3.70%, 94.67 ± 9.24%, and 100.00 ± 0.00% for Datura stramonium. After control adjustment, 96-h mortality remained 76.47-100.00% and 80.37-100.00%, respectively. The effects of the plants were significant at 24, 48 and 72 h, the effects of the concentrations were significant at 24, 48 and 96 h, and no plant × concentration interaction was observed. Carbosulfan produced 60-64% mortality at 24 h, 84-88% at 48 h, and 100% by 72 h. Both extracts thus showed distinct exposure- and concentration-dependent activity; Lantana camara was more fast acting and both botanicals were 100% effective at 6% at 96 h. These results aid in formulation, recovery and greenhouse investigations.