Genetic Relationship Between Maize Resistance to Corn Borer Attack and Yield

Selection for reduced stalk tunnel length by the Mediterranean corn borer (MCB) (Sesamia nonagrioides Lef.) while maintaining yield under infestation has already been evaluated. Significant reductions for tunnel length were reported, but yield showed a nonsignificant tendency to decrease with selection that could be due to increased inbreeding or significant genetic correlation between yield and resistance. Simultaneously, the presence of major quantitative trait loci (QTL) for resistance in chromosome 4 has been suggested. In the present study, we investigated the genetic relationship between yield and stalk tunneling resistance by conducting one generation of selection each for yield alone, resistance alone, and yield and resistance combined in a broad‐based population. In addition, we tested the effectiveness of marker‐assisted selection at two markers on chromosome 4 for reducing tunnels by MCB. Evaluations were made for 2 yr at two locations under MCB infestation. Unfavorable genetic correlation between stalk tunnel length and yield has been confirmed and could prevent detection of major QTL for tunnel length by using selection mapping. Markers phi076 and umc1329 could be linked to QTL for plant height but are not useful markers for reducing tunnel length and hence damage caused by borers. Finally, results advise against selection for reduced tunnel length by MCB or any index involving yield and tunnel length.