TRANSGENIC POTATO EXPRESSING THE BACILLUS-THURINGIENSIS CRYIA(C) GENEEFFECTS ON THE SURVIVAL AND FOOD-CONSUMPTION OF PHTHORIMEA-OPERCULELLA (LEPIDOPTERA, GELECHIIDAE) AND OSTRINIA-NUBILALIS (LEPIDOPTERA, NOCHUIDAE)

Second generation transgenic potatoes were grown from tubers of transg enic plants expressing the Bacillus thuringiensis CryIA(c) gene. Leaf disks from transgenic and untransformed potato plants were tested agai nst the tubermoth Phthotimea operculella (Zeller), a major pest of pot ato, and European com borer, Ostrinia nubilalis (Hubner), which can us e potato as an alternative host. Ten percentage of mortality of first- instar P. operculella was observed after 48 h of feeding on leaf disks from transgenic plants. Bioassays also showed that second-instar P. o perrulella is slightly less capable of surviving on leaf disks from tr ansgenic plants than on untransformed plants after 240 h of feeding. T he amount of feeding of P. operculella larvae was also less, as indica ted by lighter weight of the dried frass. Bioassay showed that second- instar European com borer is less capable of surviving on leaf disks f rom transgenic plants than those from untransformed plants. Preference tests showed that leaf disks from transgenic plants were less preferr ed than those from untransformed plants by third-instar com borer afte r 24 h of exposure. Prolonged exposure showed that leaf disks from tra nsgenic and untransformed plants were equally preferred by com borer l arvae. These transgenic plants can be used together with untransformed plants or transgenic plants (or both) expressing high quantity of B. thuringiensis insecticidal protein to devise insect resistance managem ent strategies.