Mapping of QTL Associated with Maize Weevil Resistance in Tropical Maize

The maize weevil (MW), Sitophilus zeamais (Motsch.), is an important pest of stored maize (Zea mays L.) in tropical areas. Quantitative trait loci (QTL) associated with MW resistance were analyzed. A total of 163 F-2 progeny derived from the cross CML290 (susceptible) x Muneng-8128 CO HC1-18-2-1-1 (resistant), were genotyped with 151 molecular markers. Resistance was evaluated using bioassays or) replicated F-2:3 progenies. Grain damage (GD), grain weight losses (GWL), MW susceptibility index (Dobie index [DI]), and numbers of adult progeny (AP) were evaluated on grain from F, lines across two environments. Grain hardness and pericarp/grain ratio were evaluated as putative components of resistance. Composite interval mapping was used for QTL analysis. Five QTL dispersed across the genome explained 28% of the phenotypic variance (sigma(2) (g)) for GD. Six QTL were detected with effects on GWL and explained 22% of sigma(2) and 47% of sigma(2) (g). Seven QTL (27% sigma(2) (p) and 78% sigma(2) (g)) were identified for DI and three QTL (10% sigma(2) (p) and 23% sigma(2) (g)) for AP. Both parents contributed resistance alleles. Genetic effects were mainly dominant (GD, GWL, and DI) and additive (AP). Quantitative trait loo x environment interaction was significant for 50% of the QTL. Since the identified QTL accounted for less than a third of (TIP, additional mapping populations are required for mapping MW susceptibility.