Methods for developing maize resistant to the corn leaf aphid.
1989
Dicke F.F.
The corn leaf aphid, Rhopalosiphum maidis (Fitch), is a cosmopolitan insect that has been recorded on many species of Gramineae, of which maize, Zea mays L., is a preferred cultivated host. In addition to direct injury to plants, it has a long history as a vector of mosaic virus disease. Extremes in temperature and turbulent rainy periods have a limiting effect on seasonal populations. Alate populations can infest such crops as maize and sorghum in seedling and early whorl stages of growth at considerable distances from their origin. Evaluations of inbred lines and hybrid combinations thereof for relative resistance began in the 1930s as openpollinated varieties were replaced by hybrids. Resistance indices were based on counts of apterae, percentage of plants infested, degree of resistance. Because of sporadic populations and lack of consistent artificial infestation procedures, studies on the genetic nature and inheritance of resistance factors have received little attention. Several studies in the central Corn Belt of the United States have shown that delayed plantings attract ample populations of alatae to initiate apterous populations adequate for genetic and inheritance studies.
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