ABSTRACT
Because of the development of insect resistance to insecticides, adverse effects of insecticides on natural enemies, and environmental pollution, there has been a renewed interest in the development of insect-resistant cultivars for pest management (N. Panda and Khush, 1995; Sharma and Ortiz, 2002; Smith, 2005). Many crop species possess genetic variation, which can be exploited to produce varieties that are less susceptible to insect pests. However, the development of varieties resistant to insects has not been as rapid as for disease resistance. Slow progress in developing insect-resistant cultivars has been due mainly to the diffi culties involved in ensuring adequate insect infestation for resistance screening in addition to low levels of resistance to certain insect species in the cultivated germplasm. Under natural conditions, the insect infestation is either too low or too high and, as a result, it becomes diffi cult to make a meaningful selection. Therefore, it is important to develop techniques to screen for resistance to insect pests under optimum levels of infestation and under similar environmental conditions. Insects reared on artifi cial diets can be used to test the material under uniform infestation. However, insect-rearing programs are expensive, technology development requires several years, and may not produce the behavioral or metabolic equivalent of an insect population in nature.
