Inheritance and combining ability estimates for cowpea resistance to bruchid (Callosobruchus maculatus Fab.) in Benin cowpea

Abstract

Cowpea bruchid (Callosobruchus maculatus Fab.) is the most important storage pest causing significant economic losses. Development of bruchid resistant cowpea varieties is the most sustainable strategy for controlling bruchid. However, information regarding the nature of gene action governing the resistance to bruchid is limited for cowpea genotypes in Benin. This study aimed to understand the genetic basis of cowpea resistance to C. maculatus. Eight parents were crossed in a full diallel mating design. 56 F2 progenies were tested with the eight parental genotypes in alpha lattice design with three replications in laboratory. Data were recorded on bruchid emergence (BE); weight loss (WL); median development period (MDP); Dobie susceptibility index (DSI); number of eggs laid (NEL); average number of holes (ANH); seed damage (SD). Combining ability analysis was performed using Griffn’s method 1, model 1 in AGD-R software. The results showed that general combining ability (GCA) effects were highly significant (p < 0.001) and negative for BE, WL, DSI, NEL, ANH, and SD on the parents. Significant positive GCA effects were observed for MDP. Thus, the parents TVU13677, IT84S2246-4, WC36 and WC66*5T were the best combiners for bruchid resistant. High narrow sense heritability was observed for BE (0.75), WL (0.69), DSI (0.72), ANH (0.77) and SD (0.69). These results showed that both additive and on additive gene action govern the resistance to bruchid in cowpea. The genotypes (TVU13677; IT84S2246-4; WC36; WC66*5T) and the resistant crosses were the promising genotypes and can be used in breeding programs seeking to develop bruchid resistant cowpea varieties.