Efficacy of commercial products of Bacillus thuringiensis (B.t) Berliner against teak defoliator, Hyblaea puera Cramer

Effectiveness of four commercial products of Bacillus thuringiensis viz., Biobit WP®, Dipel DF®, Delfin WG® and Halt WP® were evaluated at 0.1, 0.2, 0.5, 1.0 and 1.5 g/l against first to fifth instars larvae of H. puera. The test insect was highly susceptible to B. thuringiensis irrespective of products. Larval death started after 24h and maximum larval mortality occurred after 48h of continuous feeding of B. thuringiensis sprayed leaves. Among the tested products, all the products were found to be best in killing larvae at higher concentrations, i.e, 1.0 and 1.5 g/l. Higher larval mortality up to 100 per cent was observed irrespective of concentrations and products in younger larvae up to third instars than later ones.