Heritability of Resistance in Cowpea to the Western Plant Bug1

Abstract

Lygus bugs (Lygus hesperus Knight) reduce both the quality and yield of cowpea [Vigna unguiculata (L.) Walp.]. The objectives this study were to evaluate two expressions of resistance to L. hesperus in cowpea: (i) inhibition of nymphal growth (antibiosis) (ii) level of Lygus‐induced seed damage; and to estimate heritability of resistance. Heritability was estimated in populations derived from crosses between four resistant accessions with ‘California Blackeye 5’ (CBS). For the Cross PI170861 ✕ CBS, heritabilities of antibiosis estimated from the F2 variance and from the variance of F4 family means were 40 and 43%, respectively, whereas the estimate from the parent‐offspring regression (F4 on F2) was only 4%. Thus, single plant evaluations did not provide reliable estimates of nymphal growth‐inhibition. Selection for antibiosis requires progeny testing and/or family selection. Heritability of resistance to Lygus‐induced seed damage was investigated among progenies of the crosses New Era✕CBS, CBS✕PI227829 and CBS✕CR17‐1‐13 (Crosses 1, 2, and 3, respectively). Heritabilities estimated from F2 variances were 49, 65, and 63%, respectively. Heritabilities estimated from variances of F3 family means for Crosses 1 and 2 were 75 and 54%,respectively. For Cross 3, heritability estimated from the variance of F4 family means was 72%. Heritability of resistance to Lygus‐induced seed damage was sufficiently high to indicate probable effectiveness of single plant selection. Seed weight and percent seed damage were not significantly correlated indicating that simultaneous selection for both characters is feasible.