ENVIRONMENTAL PERSISTENCE OF BACILLUS-THURINGIENSIS SPORES FOLLOWING AERIAL APPLICATION

Soil and leaf populations of Bacillus thuringiensis (Bt) were monitore d following aerial application of commercial Bt formulations at the ra te of 72 billion international units per acre per year during a 5-year period. Data from soil sample spore counts suggested that Bt spores p ersisted in Wasatch forest soils for up to 2 years but they did not pr oliferate. Bt isolates were recovered from leaf samples 12 months post application from sprayed, previously sprayed and from nonsprayed area s. The frequency and diversity of Bt isolates recovered from leaves wa s independent of sample area spray history. In accordance with U.S. Fo rest Service criteria, aerial application of Bt during a B-year period resulted in the eradication of gypsy moth (Lymantria dispar, L) from the Wasatch Front region of the Wasatch Mountain Range, Utah. (C) 1998 Academic Press.