A study on the susceptibility of maize genotypes against the maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae)

Abstract

Several maize varieties with high-yield potential have recently been created; however, their resistance to storage pests is unknown. This study compares the resistance ability to Sitophilus zeamais of four open-pollinated varieties (OPVs) and thirteen hybrid maize varieties using Dobie's susceptibility index (SI). The genotypes were tested in a completely randomized design with three replications at a temperature of 28°C and a humidity of 65 to 70%. A resistant OP maize variety (Melkassa 6Q) had SI of less than 3.5 (3.43). OPVs evaluated (Gambela, Gibe 2, and Gibe 3) had SI of 4.60, 5.32, and 6.77, respectively, while most hybrid varieties had SI of 3.82, 4.15, 4.22, 4.65, 4.74, 4.92, 5.17, 5.74, 6.00, 6.50, and 7.37 respectively. These include BH547, AMH851, P3812W, HB30G19, MHQ138, SC627, BH546, P3506W, BH549, P2859W, and AMH850. Among the thirteen hybrids, AMH853 had a SI of 8.13. This susceptible variety produced a high number of F1 progenies (2.19), had a low median developmental time (27 days), a high percentage of seed damage (75.00%), a high production of grain dust (0.92 g), a high percentage of seed weight loss (1.1%), and a low percentage of weevil mortality (0.16%). Subsistence farming in developing countries should encourage resistant varieties. Key words: Maize varieties, progeny emergence, susceptibility index, weight loss.