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