Resistance of Selected Sorghum Genotypes to Maize Weevil (Coleoptera: Curculionidae).

Abstract

The maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is a major insect pest of stored grain. This study evaluated resistance of grain of 26 sorghum genotypes, Sorghum bicolor (L.) Moench, to maize weevil under laboratory conditions. Three female and two male newly emerged maize weevils were reared with 5 g of grain in each of 10 vials for each of the 26 sorghum genotypes in a laboratory experiment. The weevils and grain of each genotype were scored once every 3 wk for a total of five times during 105 d. The numbers of live and newly emerged maize weevils, dead weevils from the initial population, damage score (scale of 1-5), and grain weight loss were used to indicate resistance. The least percentage weight loss of 23.9 and 24.1% was recorded for sorghum genotypes Sureño and (5BRON151*Tegemeo)-HG7, respectively. Genotypes B.HF8 and (A964*P850029)-HW6 had the most weight loss, 70.6 and 67.7%, at 105 d after infestation. Genotypes B.HF8 and (A964*P850029)-HW6 consistently exhibited the highest numbers of maize weevil, 63 and 84, per vial at 105 d after infestation. Sorghum genotypes Sureño, (SV1*Sima/IS23250)-LG15, (5BRON151*Tegemeo)-HG7, and (B35*B9501)-HD9 ranked among the top four genotypes with least damage rating more often than any other genotype across the five sampling dates. On the other hand, genotypes B.HF8, (A964*P850029)-HW6, (Segaolane*WM#322)LG2, and (Tx2880*(Tx2880*(Tx2864*(Tx436*(Tx2864*PI550607)))))-PR3-CM1 were more often ranked among the top four genotypes with the highest damage rating. Our results indicate that grain of genotype Sureno is most resistant to the maize weevil among screened genotypes.