Gönül DEMIR, Nursen ÜSTÜN and Asiye DERIN
Plant Protection Research Institute, 35040 Bornova, Izmir, TURKEY

This study aimed to isolate Bacillus thuringiensis varieties from Maize Stem Borers; to determine these varieties; to select virulent ones; to produce them; and to test their insecticidal activity against Ostrinia nubilalis.

17 isolates obtained from 55 dead/diseased O. nubilalis instars and 2 Sesamia nonagrioides isolates were identified as B. thuringiensis var. kurstaki on the basis of biochemical and serological tests.

In the pathogenicity tests performed with 6 isolates selected from O. nubilalis isolates at the end of the fourth day 9 of 10 ten alive instars were exist in negative control, but instar number varied from 0 to 0,6 in other characters, showing high insecticidal effect on the pest.

Spore-crystal complexes of 2 O.nubilalis isolates (Bt/5 and Bt/26) which were formulated by HD-1 technique and produced by deep fermentation method controlled O. nubilalis larvae at the rate of 67.8 and 92.8 % at 3000 µg/ml respectively while Lobesia botrana isolate (Bt/21) was 92.8% effective at 1000 µg/ml dosage on O. nubilalis larvae. L. botrana isolate was also found to be superior to the others by having high spor productivity of 1.6 x10 12 spore/gram.

It would be useful to continue the studies on by optimizing fermentation condition by finding new very well adapted varieties to the environment as well as by solving pilot production pit falls.