Population Fluctuation and Determination of The Economic Injury Level and The Economic Threshold for The Sugarbeet Fly, Pegomia hyo-scyami Curtis, in Nobaria Region, El-Behaira Governorate, Egypt.

Abstract

ABESTRACT: Experiments were conducted in a private farm cultivated with sugarbeet crop (Top cv.) for the two successive seasons of 2013/2014 and 2014/2015 to determine the economic damage threshold levels of Pegomia hyo-scyami Curtis (Diptera: Anthomyidae) under field conditions in Nobaria region, El-Behaira Governorate, Egypt. The results showed that the relationship between the yield of sugarbeet and the infestation of sugarbeet fly, Pegomia hyoscyami Curtis (Pegomyia mixta Vill.) was negative, which is means that an increase in larvae numbers caused a decrease in roots yield and vice-versa.In both seasons, Pegomyia hyo-scyami Curtis larvae registered two seasonal peaks of abundance that occurred in February and March.The determined economic threshold level for Pegomia hyo-scyami Curtis was 19 larvae / plant and the economic injury level was 22 larvae / plant in the first season. But the values were 21 larvae / plant and 22 larvae / plant, in respect, in the second season.