author(s)
Dinesh Swami, Bishwajeet Paul and S K Dotasara

abstract
Effect of carriers on the efficacy of new wettable powder (WP) formulations of Bacillus thuringiensis var. kurstaki (HD-1) was evaluated at Division of Entomology, Indian Agricultural Research Institute, New Delhi during 2006-2008. Sixteen wettable powder (WP) formulations of B. thuringiensis var. kurstaki (HD-1) were developed using eight carriers namely barium sulphate, bentonite, dolomite, fuller’s earth, kaoline, talc, precipitate of silica and pyrophyllite. Six physico-chemical properties i.e. bulk density, carrier reaction (pH), cation exchange capacity, moisture content, sorptivity and specific surface area of the carriers were studied. Among the carrier tested, precipitate of silica was found to be the most suitable for preparation of WP formulation of HD-1. Efficacy of new formulations was evaluated. LC₅₀ values of formulation-7 (0.018%) and formulation-15 (0.015%) were highly effective against III instar larvae of H. armigera (Hubner).