Trends affecting research strategies in plant resistance to insects

Abstract

Varieties of crop plants showing resistance to insect pests have been in use in modern agricultural production systems for nearly 40 years. The need for their continued use is especially critical in developing countries today, since both food and food production costs have increased greatly. The expanding populations of some developing countries currently endanger the habitats of the germplasm of several major crop plants. For this reason, major efforts are now necessary to collect, preserve and maintain as much wild germplasm of major crop plants as possible. These efforts may lead to the exchange of advanced biotechnology techniques from developed countries for exotic crop plant germplasm from developing countries. Many varieties of insect-resistant crop plants rely on allelochemicals to convey antibiotic effects on pest insects. However, high levels of allelochemicals can have detrimental effects on beneficial insects, and induce insecticide tolerance in non-target insect pests. Therefore, a need for caution exists in the development of crop varieties which utilize allelochemicals in their resistance. Accurate, reproducible bioassay techniques are essential to the continued development of insect-resistant varieties. This is especially important today, since groups of scientists at different locations may be involved cooperatively in identifying and categorizing plant resistance to insects. Insect, plant and environmental variables should be standardized, since each can greatly affect the validity of bioassay results.