الشراسة الإمراضية لعزلتين محليتين من الفطر (Balsmo)‎ Beauveria bassiana على طوري يرقات ما قبل التعذر و بالغات ذبابة ثمار الزيتون Bactrocera oleae (Rossi)‎

Abstract EN

Biological tests were carried out to study the virulence of two local isolates of the entomopathogenic fungus Beauveria bassiana on pre-pupae and newly-emerged adults of the olive fruitfly Bactrocera oleae (Rossi) (Diptera : Tephritidae), under laboratory conditions (25 ± 2ºC and relative humidity 60 ± 5 %) by indirect application of the fungal conidia, at three concentration levels 106, 107 and 108 conidia/ml.

The effect of the tested isolates did not appear on the treated larvae, but was observed on the pupae.

The corrected mortality rate of the pupae, 20 days post treatment, ranged between 52.94 and 47.01% for the isolates H and I (at the concentration 108 conidia/ ml), respectively.

Adults of B.

oleae were sensitive to the tested isolates of B.

bassiana and the corrected mortality rates reached 66.66 and 69.44 % for the isolates H and I, at 108 conidia / ml, respectively, whereas these values 12 days after treatment were 52.77 and 47.22 % at the concentration 107 conidia/ml and 33.33 and 30.5 % at the concentration 106 conidia / ml of the isolates H and I, respectively, with significant differences when compared with the control.

The LT50 value of the isolate H was 17.71 days at the concentration 108 conidia / ml on the pre pupae and 10.8 days on the newly emerged adults.

As for the isolate I, the LT50 value was 18.10 days for the pre pupae and 11.1 days for the newly emerged adults.

The LC50 value on the 12th day after treatment for the isolate H was 1.91 x 107conidia/ml for the pre pupae and 2.1 x 106 conidia/ml for the newly emerged adults.

These values were 2.31 x 107 and 1.7x107 conidia/ml for the isolate I on the pre pupae and the newly emerged adults, respectively.