Evaluation of the Performance of Different Maize Varieties against Sitophilus Zeamais Motsch ( Coleoptera , Curculionidae ): Infestation in the Niger Delta Region of Nigeria

The performance of different maize varieties aginst Sitophilus zeamais infestation was evaluated in a laboratory. Seventeen maize varieties comprising fourteen hybrids (ACR.97 TZL COMP.1-W, ACR.8328 BNC7, TZL COMP.4C2, OBA SUPER 1 and 2, SINE 9449-SR, IWD SYN C3F2, TZL COMP. 1SYN STR-Y, TZSR White and Yellow ; 95TZEE-W, MASYN VAR-3 F2, ADV.NCRE-STR and BG 97 TZE COMP.3XL) and three local cultivars (Akparike, Bende and Ogbia muno) were screened to ascertain their level of susceptibility to S. zeamais in the study area. Number of adults that emerged from the 17 varieties differed significantly (P ≤ 0.05) and ranged from 2.00 for the improved variety ADV.NCRE-STR to 62.0 in the local cultivar Bende. Significantly higher weight losses were recorded on local cultivars. Heavier males emerged from the local cultivars Akparike and Bende and lighter (P ≤ 0.05) weights were recorded on Oba super 1, TZL Comp.4C2, TZSR White, ADV.NCRE-STR and MASYN VAR-3F2. Grain hardness test showed that the hybrid variety MASYN VAR-3F2 (275.12N) was the hardest followed by TZSR-Y (259.42N) and the softest were local varieties Akparike (116.62N) and Bende (91.65N). Seed coat thickness result indicated that the local variety Akparike (0.38mm) had the highest value of seed coat thickness followed by MASYN VAR-3F2 (0.22mm) and the least seed coat thickness was BG 97 TZE COMP.3XL (0.03mm). Results indicated that the local cultivars commonly cultivated in the Niger Delta (Bende, Akparike and Ogbia muno) supported higher S. zeamais adult progeny than the improved varieties which had harder seeds and thicker coats. The fact that Akparike which has thick testa was susceptible shows that physical factors alone are not responsible for the observed resistance.