LABORATORY SCREENING OF DIFFERENT BACILLUS-THURINGIENSIS STRAINS AGAINST CERTAIN LEPIDOPTERAN PESTS AND SUBSEQUENT FIELD-EVALUATION ON THE POD BORING PEST COMPLEX OF PIGEONPEA (CAJANUS-CAJAN)

Laboratory evaluation of different Bacillus thuringiensis subspecies r evealed that B. thuringiensis subsp. kurstaki (NCIM 2514) at 10(8) spo res/ml concentration caused more than 85% mortality to the neonate lar vae of the lepidopteran insects Spodoptera litura (E) and Phthorimaea operculella (Z.). This strain at 10(10) and 10(8) spores/ml concentrat ion was effective against the major lepidopteran pests comprising the pod boring complex of pigeonpea (Cajanus cajan), viz. Helicoverpa armi ger a (H.) and Exelastia atomosa (W.) under the field trials. Total gr ain yield from this treatment was at least 1.5 times more than the unt reated control.