FIELD-EVALUATION OF TRANSGENIC TOBACCO CONTAINING A BACILLUS-THURINGIENSIS INSECTICIDAL PROTEIN GENE

Six transgenic tobacco lines expressing the CryIA(b) insecticidal protein from Bacillus thuringiensis var. kurstaki HD-1 were tested in 1990 to evaluate their efficacy under normal field conditions. Five of the six CryIA(b) lines tested kept laboratory-reared populations and natural populations of tobacco budworm, Heliothis virescens F., and tobacco hornworm, Manduca sexta L., below their respective economic threshold for the duration of the trial. Little or no economic damage from tobacco hornworm was sustained by any CryIA(b) line and only two lines sustained significant damage from tobacco budworm. Insect control with some CryIA(b) lines was equal to or better than control by standard Orthene and Dipel treatments. In addition, data obtained suggest there may be a positive interaction between CryIA(b) protein expression within a plant and parasitism of Heliothis spp.