Resistance of selected Mozambican local and improved maize genotypes to maize weevil, Sitophilus zeamais (Motschulsky)

Evaluation of early-generation tropical maize testcrosses for grain-yield potential and weevil (Sitophilus zeamais Motschulsky) resistance

“…Maize weevil mortality was not significantly different among the genotypes. This is consistent with results by Dhliwayo et al (2005) and Kasozi et al (2015) but in contrast to findings by Nhamucho et al (2017) who reported significant differences in maize weevil mortality among Mozambican local and improved maize genotypes. Mortality maybe attributed to presence of a fluorescent pericarp with high concentration of hydroxycinnamic acid ( Serratos et al, 1987 ).…”

“…Grain samples from the field for each genotype at each environment were dried in paper bags to avoid direct heat on the kernels and to attain near uniform moisture content of 12%. In order to destroy adult insects and eggs that might have been present due to natural infestation in the field, grains were kept in a fumigated plastic drum containing phosphine-fumigant (Gastoxin™) ( Nhamucho et al, 2017 ). Dust, dirt and broken grains were sieved and a sub sample (50 g) of each entry was weighed and left for 24 h in a jar at room temperature before infestation with weevils.…”

“…A no choice test was carried out on each entry. In this test, 50 mature, active and unsexed 20–25 days old adult weevils were used for infestation in a 250 ml glass jar containing 50 g of grains ( Dobie, 1974 ; Nhamucho et al, 2017 ; Siwale et al, 2010 ). The glass jars were covered with a wire mesh lid to allow air circulation and prevent the insects from escaping.…”

“…In the process, weevils and grains were collected on the 1.0 mm and 4.75 mm mesh respectively. The dead and live weevils were identified and counted with tweezers and a tally counter ( Nhamucho et al, 2017 ). Tweezers was used to probe the weevils for immobility in order to establish whether they were alive or dead ( Nhamucho et al, 2017 ; Siwale et al, 2010 ).…”

“…The dead and live weevils were identified and counted with tweezers and a tally counter ( Nhamucho et al, 2017 ). Tweezers was used to probe the weevils for immobility in order to establish whether they were alive or dead ( Nhamucho et al, 2017 ; Siwale et al, 2010 ). Then the parent mortality was calculated from the number of dead parental stock and, using a precision electronic scale, the weight of the flour/dust produced during insect feeding and the grains was determined.…”