دراسة حيوية لعزلات محلية من الفطر Beauveria bassiana (Balsamo)‎ Vuill. عند درجات حرارة مختلفة و طبيعة تأثيرها في إناث عثة درنات البطاطا البطاطس Phthorimaea operculella (Zeller)‎

Abstract EN

A comparative study among three native Syrian isolates of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuill.

collected from different geographical locations (isolate B from Latakia, isolate C from Aleppo, isolate D from Damascus) was carried out.

Isolates' vitality was evaluated under four constant temperatures: 20, 25, 30 and 35°C.

Effect of temperature on isolates characteristics (growth, spore production and germination) was also studied.

The best performance for all isolates was at 25°C and the least at 35°C.

Variation among the isolates were insignificant at all studied temperatures, except for isolate C at 35°C, which surpassed other isolates.

The effect of three spore concentrations of the three isolates at 104, 105 and 106 spore/ml was tested at 25°C and R.H 60%±5 on accumulative mortality and the fecundity of potato tuber moth Phthorimaea operculella (Zeller).

All three isolates were effective in controlling the pest at the concentration of 106 spore/ml, where the mortality of females was increased significantly in comparison with the control, on the 6th day after treatment, and reached 100% for females of all isolates, in contrast to 77.7% in the control.

Isolate B was the most virulent one, it surpassed the other isolates in causing moth mortality.

All three isolates caused a decrease in fecundity and was highest at the concentration of 106 spore/ml, and reached 3.33, 3, 6 egg/female after treatment with isolates B, C, D, respectively, compared to 28.33 egg/female for the control.

Results obtained suggest that using native isolates of B.

bassiana is effective in controling the potato tuber moth and decrease its population in the field.