SURVIVAL OF OSTRINIA-NUBILALIS (HUBNER) AFTER EXPOSURE TO BACILLUS-THURINGIENSIS BERLINER ENCAPSULATED IN FLOUR MATRICES

Two types of pregelatinized corn flour were used to produce granules c ontaining Bacillus thuringiensis Berliner subsp. kurstaki and various additives for control of the European corn borer, Ostrinia nubilalis ( Hubner), in the whorl of corn plants. Laboratory-reared larvae were ap plied to corn whorls in the greenhouse and field, and a high natural i nfestation occurred at one field site (Champaign). In the greenhouse a nd at all three field sites, five of these formulations were just as e ffective as Dipel 10G, a commercially available B. thuringiensis produ ct, for control of European corn borer larvae. In all greenhouse studi es and at one of the three field sites (Champaign), the dose of B. thu ringiensis could be reduced by as much as 75% when a phagostimulant wa s added to flour granules without significant loss of corn borer contr ol. The phagostimulant dose response was not observed at the other two field sites in which larval infestations were relatively low. Flour t ype had no significant effect on European corn borer control under gre enhouse and field conditions. Greenhouse evaluations provided results significantly similar to results from two of the field sites indicatin g the usefulness of the technique. The data presented highlight the ve rsatility and potential for using novel formulation techniques for enh ancing the efficacy of B. thuringiensis.