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Abstract
The Pink Stem Borer, Sesamia cretica Led. (Lepidoptera: Noctuidae) is a serious pest threatening maize (Zea mays L.) plants in Egypt. The relative susceptibility of 18 recommended maize cultivars to infestation with this pest under natural infestation condition was investigated at 2Wadi Al-Natroon3 and 2Giza3 regions throughout 2011 and 2012 seasons. Criteria used for comparing susceptibility to infestation were the percentage of 2Total Infested Plants3 (% TIP), percentage of 2Dead Hearts3 (% DH) and 2Infestation Rate3 (IR) [which is based on an arbitrary 5-class rating system]. The percentage of 2Yield-Loss3 (% YL) was also considered in the evaluation process. At Wadi Al-Natroon region, maize plantations were subject to relatively higher insect populations than at Giza. According to % TIP at Wadi Al-Natroon in 2011 season (where and when the highest levels of infestation were recorded) tested maize cultivars could be classified into 5 significantly different susceptibility groups. None of the tested cultivars showed immunity or high resistance. Four cultivars were resistant, 4 were relatively resistant, 5 were relatively resistant to susceptible, 2 were susceptible and 3 were highly susceptible. A positive correlation between infestation criteria and % YL was recorded. During the two considered seasons and at the 2 investigation regions, grain-yield ranged 11.0 - 29.4 Ardabs/feddan, and yield-loss ranged 1.0 - 18.0%