Yield losses caused to potato plants by potato tuber worm, Phthorimaea operculella (Zeller) and its economic levels at Qalyubyia Governorate

Abstract

Article History Received:28/2/2017 Accepted:1/4/2017 _________________ Keywords: potato tuber moth Phthorimaea operculella Infestation yield losses economic injury level economic threshold The present investigation was carried out at Qalyubyia Governorate, Egypt during 2015 and 2016 summer plantations to estimate the losses in potato yield due to the infestation with Phthorimaea operculella (Zeller) and calculate the economic levels for its infestation. Results revealed that percentage of infested tubers was the most effective variable on potato yield than either number of larvae or number of holes/tuber. The correlation between these three variables and the yield was negatively highly significant. The explained variance values ranged between 89.08 and 92.35% for both years of study, respectively. The calculated economic threshold level (ETL) ranged between 15.68 and 21.50%; while the economic injury level (EIL) ranged between 24.97 and 26.61%.