Susceptibility of Certain Maize Varieties to Tetranychus urticae Koch Infestation in Relation to Leaf Chemical Contents

Field studies were carried out to evaluate six single cross maize hybrids namely; Giza 129, Giza 10 & Giza 125 (white ~1aize varieties) and Giza 168, Giza 162 & Giza 166 (yellow maize varieties) for their relative susceptibility to the twospotted spider mite, Tetranychus urticae Koch infestation, during 2008 and 2009 growing seasons at Sharkia Governorate, Egypt.Giza 125 and Giza 162 proved to be the most susceptible hybrids to spider mite infestation in white and yellow maize varieties, respectively, while Giza 129 and Giza 166 were the most tolerant in the two varieties, ~espectively .In both tested seasons, mite population reached its peak on maize during the fourth and the third weeks of July, respectively, for all tested hybrids.A significant positive correlation was found between mite infestation and both nitrogen and protein contents in maize leaves.