Book Description

The practice of growing varieties, lines or hybrids resistant to attack by insects, and their subsequenty effectiveness in reducing pest populations and corresponding crop losses, is well documented for several agricultural crops and pest species. The development of many of these resitant cultivars has resulted from or been facilitated by many years of study of the insect pests, the development of techniques to mass rear the insects, artificially infest the crop species, and screen the germplasm of the species (or their wild relatives) for resistance, and the successful application of appropriate breending procedures for improvement of the resistance characteristic over succeeding cycles or generations of population improvement (Guthrie, 1974, 1980). The basic components necessary to identify or developed germaplasm with resitance, or with higher levels of resistance than present cultivars utilized by farmer/producers, include: (1) A colony of the insect species, which exhibits the vigor and vitality of the damaging pest population within the geographical area that is affected. (2) The capability to efficiently mass culture the species, including the rearing facility, trained personnel, natural, meridic, or defined diets, and rearing procedures and containers. (3) Germaplasm resources that area representative of the genetic variation within the crop and/or its closely related species. (4) Methods for uniform artificial infestation. (5) Methods for assessing resultant damage, or lack of damage, to the plants subjected to deliberate infestation (rating scales to determine classes or categories of resistance or susceptibility). (6) Screening to determine whether adequate levels of resistance exist within suitable agronomic types (equivalent or better than currently grown cultivars), and effective selection/breeding scheme established to improve either the resistance levels or agronomic characteristics of the "improved" materials.