An overview of the mechanisms and bases of insect resistance in maize
1997
Smith, C.M. (Kansas State Univ. (USA). Entomology Dept.)
Many insect resistant maize varieties have been developed during the past 50 years, due to the development of highly efficient techniques for maize insect pest rearing, artificial infestation and damage evaluation. Through the efforts of an international working group of scientists, maize genotypes developed primarily from the Antigua Group 2 gene bank and selected from it at CIMMYT have been shown to be resistant to many of the major lepidopterous pests of maize in the world. In several resistant varieties, resistance is controlled by different allelochemicals. The cyclic hydroxamic acid DIMBOA, and its decomposition product, 6-MBOA, occur in the foliage of some resistance sources. The flavone glycoside maysin and its related luteolin c-glucosides occur in the silks of other resistant varieties. These allelochemicals kill or impair the growth of many of the major insect pests of maize. Several morphological factors, including increased leaf fiber content, increased silica content, increased vascular bundle density, increased husk tightness and decreased leaf trichome density also contribute to some sources of resistance that do not have high levels of DIMBOA or maysin. Insect resistant maize greatly increases farming efficiency since insect control is available for the cost of only the seed. In addition, research on developing resistant varieties provides 100- to 300-fold greater returns on investment than research to develop insecticides. During the past 20 years, insect resistant maize in the United States has helped prevent the application of several million tons of insecticides onto croplands, reduced insecticide rates and applications, and encouraged the use of biological and cultural insect control practices in integrated maize insect pest management programs.
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