GRANULAR MATRIX FORMULATION OF BACILLUS-THURINGIENSIS FOR CONTROL OF THE EUROPEAN CORN-BORER (LEPIDOPTERA, PYRALIDAE)

A low-cost, granular matrix formulation of Bacillus thuringiensis Berl iner var. kurstaki, composed primarily of corn flour and containing a feeding stimulant composed of cottonseed flour and sugars, was develop ed for use against the European corn borer, Ostrinia nubilalis (Hubner ), on whorl-stage corn. Laboratory experiments indicated that a corn f lour agricultural commodity product was a suitable carrier, that the f eeding stimulant enhanced the activity of B. thuringiensis, and that t he granular matrix protected B. thuringiensis from photodegradation. R esults of a greenhouse lest showed higher mortality of the European co rn borer on corn plants treated with the granular matrix than on plant s treated with a standard commercial granular formulation of B. thurin giensis. Mortality with either treatment was increased by application of simulated rainfall. In a field test, the granular matrix applied at a rate of 5.5 kg/ha gave control comparable with that achieved by the commercial standard applied at a rate of 11 kg/ha. Results indicated that increased efficacy or reduction in costs of management of the Eur opean corn borer with B. thuringiensis should be possible through the use of the granular matrix formulation.