ACTIVITY OF BACILLUS-THURINGIENSIS ISOLATES ON THE CORN BORERS, CHILOAGAMEMNON BLES (CRAMBIDAE) AND OSTRINIA-NUBILALIS HBN (PYRAUSTIDAE)

The potential activity of different varieties of Bacillus thuringiensi s was evaluated against the second instar larvae of the two lepidopter ous corn borers Chilo agamemnon and Ostrinia nubilalis. Data on the LC 50, slopes, 95% confidence limits and potencies of the tested varietie s were determined. With O. nubilalis, Dipel 2X (Bacillus thuringiensis var, kurstaki HD-1) was the most potent and the LC50 was 2.68 mu g/g diet. The LC50 for other varieties ranged between 3.12 and 31.95 mu g/ g. In the case of C. agamemnon, the lowest LC50 was also determined wi th Dipel 2X bring 3.68 mu g/g diet; this ranged between 6.2-15.11 mu g /g for other tested varieties.