دراسات مختبرية حول تاثير عزلتين محلية للفطرBEAUVERIA BASSIANA في ذبابة البصل الصغيرة

Abstract

Laboratory studies have been conducted at the college of Agriculture, University of Baghdad to evaluate the pathogenicity of two local isolates of Beauveria loassiana on different stages of the onion maggot, Delia alliria Fonseca. Results indicated a significant and high mortality rates on different stages of the maggot from egg to adult, especially during the first days of treatment. Mortalities on eggs reached 100% and 98% after 5 days of treatment for the two isolates BSA3 and BSAI respectively, the symptoms begin to appear on the 1st and 2nd larval instars after 24 hours of treatment, and then increased its influence progressively to 100% for both isolates after 14 days of the treatment. Results indicated a gradual reduction of the impact of fungus isolates in larval ages, the average Mortality of the isolates decreased to 74% for the third larval instars after two weeks. The results indicated significant differences in the percentage of adults emerges from treated pupae with the two isolates, BSA3 treatment reduced the rate of emergence , by (6.00 , 11.67 , 6.67 )% after 5,7 and 15 days of treatment, compared with (11.33 , 21.67 and 20)% for the isolate of BSA1. Results showed that the fungus isolates had a significant impact on the adult insect , and that effect was greater for males than females as the death rate of 85% for males and 75% for females. The possible use of these isolates and the timing of B.bassiana application to conceded with onion maggot oviposition and first larval stages in the IPM program for the Onion maggot, also discussed.