Efficacy of<I> Bacillus thuringiensis </I> var. <I>kurstaki </I>(Thai Strain) for Controlling Diamondback Moth, <I>Plutella xylostella </I>L., on Chinese Kale

Abstract

An isolate of Bacillus thuringiensis var. kurstaki natural strain was produced and formulated into a water dispersible granule (WG) form with the concentration of 36,000 IU/mg.  Then its control efficacy was determined on diamondback moth (Plutella xylostella L.) in Chinese kale at Bangbuathong, Nontaburi province and Kratumban, Samutsakorn province. An imported bacteria Bactospeine HP WP was used as a standard.   Randomized completed block design with 6 treatments and 4 replications each was employed in the experiment. A wetting agent, Nujol PGL, was added at 5 ml/20 l of water in every treatment.  Results showed that B. thuringiensis WG at the dosage of 100, 80, 60, and 40 g/20 l of water had an efficiency in controlling diamondback moth at the average of 21.4, 15.9, 7.2, and -2.9% respectively at Bangbuathong and 32.9, 24.3, 17.1, and 14.3% respectively at Kratumban while Bactospeine HP WP from two locations were 27.6 and 20.0%, respectively.