The Economic Thresholds and Injury Levels for the English Grain Aphid, Sitobion avenae (F.) (Hemiptera- Aphididae) on Wheat Crop

A yield loss 28.66, 47.35, 61.77 and 79.86% caused due to introduce 1, 3, 5 and 7 individuals/ spike of aphid species Sitobion avenea Fabricius (Hemiptera- Aphididae) as abundant wheat insect pests to fifteen tillers under cages. A market price of 2017 the wheat crop (420 E.L/Aradab) and costs of control measures 90 E.L/feddan was standard, during flowering and heading stage. The calculated economic injury level (EIL) and economic threshold (ETL) in average were 7.03 and 2.26 aphid/ spike/ feddan, respectively. Calculated gain threshold was 0.21 Ardab/feddan.