Genetic variability, heritability and genetic gain of common bean (Phaseolus vulgaris L.) genotypes in response to Mexican bean weevil (Zabrotes subfasciatus Boheman) infestation

Abstract

The aims of the study were to determine expected genetic gains from selection and the extent and pattern of genetic diversity of common bean genotypes to Mexican bean weevil. Three hundred bean genotypes were artificially infested with the Mexican bean weevil. The experiment was laid out in a randomized complete block design with three replications. Data on thirteen insect and seed related traits were recorded and subjected to statistical analysis. The broad-sense heritability values ranged from 68.5%–93.9% for the traits studied. The expected genetic gains from selection ranged from 5.9%-67.1% for insect related traits and from 0.2%-82.2% for seed related traits. Seed weight loss showed significant positive phenotypic and genotypic correlation with number of eggs, number of adults emerged, percent adult emergence, index of susceptibility, number of holes and first and second progeny damage. Cluster analysis classified the 300 genotypes into two major clusters and seven sub-clusters. Mahalanobis’s D2 value calculated among the sub clusters ranged from 5.6 to 191.6. There was no defined relationship between geographic origins and the pattern of genetic diversity in response to Mexican been weevil infestation. Therefore, parental selection should be made based on genetic diversity and other special merits of the genotype for the resistance attributes. The introgression of the resistance gene into the adapted improved varieties and landraces, and increasing the frequency of resistance genes through selection could be used as a strategy to improve bruchid resistance in the future