Effectiveness of Bottle Brush (Callistemon lanceolatus DC.) Leaf Extracts to Control the Nymph of Mealybug (Phenacoccus manihoti Matile-Ferrero)
2018
Sannongmueang, T. | Pumnuan, J. | Insung, A.
Mealybug (Phenacoccus manihoti Matile-Ferrero) poses a threat to cassava-growing regions of the world. A current global interest has focused on the discovery of non-chemical strategies and environmental friendly pest control approaches. The objective of this study was to investigate the efficacy in terms of toxicity and repellent properties of hexane, acetone and ethanol crude extracts from leaf of bottle brush (Callistemon lanceolatus DC.) against the nymph of mealybug (P. manihoti) by using leaf dipping method. Various concentrations of bottle brush extract, 0 (5% tween-20 water) 1, 2, 3, 4 and 5% (w/v) were applied. Then the insect mortality was observed at 24 and 48 hrs whereas, the repellent index (%RI) was observed at 24 hrs. The results showed that acetone extract from bottle brush was highly effective in killing the nymph of mealybug with the LC50 at 24 and 48 hrs as 3.54 and 2.28 %, respectively. Acetone and ethanol extracts of bottle brush at 2-5% concentrations showed very strong effect in repellence when the nymph of mealybug with >75% RI was found within 24 hrs. Therefore, the acetone extract of bottle brush leaf was highly containing insecticidal activity against nymph of mealybug in laboratory, then the next filed condition substance should be developed.
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