Susceptibility of Egg Stage of Potato Tuber Moth Phthorimaea operculella to Native Isolates of Beauveria bassiana

The pathogenicity of three local isolates of the entomopathogenic fungus Beauveria bassiana (Bals.) Vuill was evaluated on eggs of potato tuber moth P. operculella (Zeller). The three isolates were coded as the following: B (isolate from Latakia), C (isolate from ICARDA) and D (isolate from Damascus). Three concentrations 10 4 , 10 5 , and 10 6 , respectively, conidia/ml were used for each isolate. Eggs in the control were sprayed by sterilized water. All tests were done under laboratory conditions of temperature 28 ± 2°C and relative humidity 40 ± 5%. Susceptibility tests showed significant differences in averages of hatching rate between the control and both isolates B and C when 1 × 10 6 conidia/ml was applied, with averages 18.3 and 26.6% for previous isolates respectively, in contrast to 38.3 for isolate D and 66.6% for control. Findings indicated that eggs of P. operculella seemed sensible to local isolates of B. bassiana in varying degree, but further studies are required about the efficiency of effective isolates for controlling eggs of this pest in natural conditions. C respectively. Susceptibility tests showed significant differences in averages of hatching rate between the control and both isolates B and C when 1 × 10 6 conidia/ml was applied, with averages 18.3 and 26.6% for previous isolates respectively, in contrast 38.3% for isolate D and 66.6% for control. Findings indicated that eggs of P. operculella seemed sensible to local isolates of B. bassiana in varying degree. Results encourage further studies about the efficiency of effective isolates for controlling eggs of this pest in natural conditions of store and field and testing the local isolates on the other stages (adults and larvae) under better condition than this research condition.