Granular matrix formulation of Bacillus thuringiensis for control of the European corn borer (Lepidoptera: Pyralidae)

A low-cost, granular matrix formulation of Bacillus thuringiensis Berliner var. kurstaki, composed primarily of corn flour and containing a feeding stimulant composed of cottonseed flour and sugars, was developed for use against the European corn borer, Ostrinia nubilalis (Hubner), on whorl-stage corn. Laboratory experiments indicated that a corn flour agricultural commodity product was a suitable carrier, that the feeding stimulant enhanced the activity of B. thuringiensis, and that the granular matrix protected B. thuringiensis from photodegradation. Results of a greenhouse test showed higher mortality of the European corn borer on corn plants treated with the granular matrix than on plants treated with a standard commercial granular formulation of B. thuringiensis. 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 European corn borer with B. thuringiensis should be possible through the use of the granular matrix formulation.