Role of Husk Cover and Physical Properties of Maize Grains Towards Resistance to Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae)

Abstract

This study evaluated twenty maize varieties for tlieir resistance to Sitotroga cerealella under both free and no-choice tests. Ear damage score, developmental period, total progeny emerged, susceptibility index, percent grain damage and grain weight loss were evaluated susceptibility parameters. Ear husk and grain biophysical characteristics which may influence infestation by S. cerealella were also investigated and correlated with susceptibility parameters. Majority of die varieties were resistant and moderately resistant under free choice test. However, under no-choice test, only three varieties, i.e., Pratap Makka-5, EH-2101 andEH-2253 were categorized as resistant and moderately resistant, while the remaining varieties showed susceptible to highly susceptible reaction. Under both free and no-choice tests Pratap Makka-5, EH-2101 and EH-2253 were grouped under the same category. We found an inverse relationship between husk extension and ear damage (-0.610*), husk leaf number and ear damage (-0.785**), and percent grain damage and grain hardness (-0.648**); while strong positive relationship between grain size and susceptibility index (r=0.673**) and ear damage score and grain texture (r = 0.698**) were observed. Additionally, a strong negative correlation was found between progeny emerged and grain hardness (-0.696**). Our study leads to the conclusion that of the different husk cover and grain physical variables used to assess S. cerealella behaviour and biology; husk extension, husk tightness, grain hardness, grain size, and grain texture were better indicators of resistance for practical application. Such information could be used to establish a baseline for developing agronomically and biophysically elite maize gennplasm that confers resistance against S. cerealella in the field and storage.