Biofficacy of lion’s ear and African basil extracts in management of adult twospotted spider mite on french beans

Methanol extracts of Lion’s ear, Leonotis nepetifolia L. (LN) and African basil, Ocimum gratissimum L. (OG), were evaluated for their toxic and ovicidal effects against the female adult two-spotted spider mite, Tetranychus urticae Koch. Laboratory bioassays were conducted at Egerton University using five concentrations (0.0, 1.5, 3.0, 6.0 and 12.0 % w/ v) of each plant extract and methanol and Abamectin (0.6 ml/L) as negative and positive controls, respectively, arranged in completely randomized design replicated four times. Data on adult mite mortality and number of eggs laid were collected 24, 48 and 72 hours after treatment (HAT) and subjected to analysis of variance (ANOVA) and means separated using Tukey’s HSD test (P< 0.05). Preliminary results showed concentration- and exposure time-dependent increase in efficacy of LN and OG extracts against adult mite. At 12% w/ v and 72 HAT, LN and OG extracts produced 93.8 and 96.4% mortality of adult TSSM, respectively. Similarly, both extracts produced 100% reduction in the number of eggs laid by the female adult TSSM. Synthetic acaricide, abamectin had 43.5 and 45.3% mortality, 34.4 and 62.9% reduction in number of eggs laid respectively. These findings demonstrate the potential use of L. nepetifolia and O. gratissimum extracts for the management of twospotted spider mite on French beans.