ISSN: 0041-3216

ISSN: 0041-3216 (Online), 0041-3216 (Print)
Volume 83 Number 3
Research Notes
Antibiosis in cowpea genotypes for corn earworm (Helicoverpa zea Boddie). (101)
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Corn earworm (Helicoverpa zea Boddie) is a potential pest of cowpea in the U.S.A. Crop resistance is one of the strategies which could be used for the management of corn earworm in cowpea (Vigna unguiculata L. Walp.). A study was conducted to evaluate 22 cowpea genotypes for antibiosis type of resistance to corn earworm in various cowpea genotypes grown in a replicated field trial. Neonatal larvae of corn earworm were reared on newly formed top leaflets of each genotype. There were significant differences among the weights of larvae after 10 days of rearing on various cowpea genotypes. The cowpea genotypes on which the larvae weighed the heaviest, were regarded as susceptible, and those on which they weighed the lowest, were regarded as having higher degree of antibiosis. Genotypes Champion, Texas Cream 12, Texas Cream 6, California Blackeye 5, and California Blackeye 46 were found to be significantly susceptible compared with the other genotypes. Genotypes Colossus and Quickpick Pinkeye showed higher antibiosis type of resistance, and were not significantly different from most of the genotypes included in this study.
Keywords: Antibiosis; Corn earworm; Pest resistance; Cowpea; Delmarva region