Genetic Engineering of Insect Control Agents and Production of Insect-Resistant Plants

Natural defense mechanisms against herbivorous insects appear to have evolved in many plants. One such mechanism is the synthesis of proteinase inhibitors. Plants containing high levels of serine proteinase inhibitors can be consumed by the insects. Colorado potato beetles, for example, readily consume potato tubers which contain serine proteinase inhibitors. A Bt endotoxin gene with insecticidal activity against lepidopteran larvae was reported to be introduced successfully into tobacco plants in July 1987 by Plant Genetic Systems, a Belgian biotechnology company. Genetic engineering techniques could produce plants that kill a variable proportion of a pest population, slow the pest’s growth rate, and decrease the pest’s reproductive capacity. A major difficulty in the release of genetically engineered plants may be the adaptation of insects to such insecticides as happened with chemical pesticides. If additive genetic variance in the pest for adaptation to strong resistance and partial resistance were equal, this would result in more rapid pest adaptation to the strong resistance.