تاثیر جدایه‌ی قارچی Beauveria bassiana بر روی مینوز گوجه‌فرنگی، Tuta absoluta (Lep.: Gelechiidae) تحت شرایط آزمایشگاهی

Tomato leafminer moth, Tuta absoluta Meyrick (Lep : Gelechiidae),is one of the most important and destructive pests of tomatoes, and if not controlled, it causes the loss of 50-100% of the tomato crop. Considering the disadvantages and dangers of chemical toxins, alternative methods such as the use of biological agents such as fungal pathogens are considered as a suitable solution. Beauveria bassiana is one of the important agents of microbial control, today many commercial formulations of this fungi are used in integrated pest management worldwide. It is important to isolate and check the toxicity level of native isolates of this fungi. In this research, the lethal effect of different concentrations of a native strain of B.bassiana fungi (IRAN 1217) on the second instar larvae of tomato leafminer was investigated. In order to estimate the lethality of B. bassiana fungi strain, immersion bioassay method was used. After preparing the desired concentrations of fungal spores, ten 2nd larvae were treated for each repetition by immersing them in the fungal suspension for 5 seconds. The treatments included 5 concentrations (2.5 x 106, 106, 5 x 105, 2.5 x 105, 105) and each concentration was repeated three times, and the experiment was repeated three times. Control insects were treated only with sterile distilled water and 0. 1 %Tween 80. The treated insects were kept at a temperature of 25 C, a relative humidity of 70 ± 5% and a photoperiod of 16 hours of light and 8 hours of darkness. Counting of casualties continued until day 7 and data analysis was done with SAS software. The highest and lowest mortality percentages were 76% and 20%, respectively, and the lethal concentration values ​​of 50% LC50 on the fifth day and the seventh day were 9.7x105, 3.9x105 conidia per ml, respectively. The lethal time of 50% LT50 of the fungus was also calculated as 2.16 days. The results show that the fungal isolate used in this research has a high insecticidal ability against tomato moth larvae, and after conducting additional studies in field conditions, it can be used in the form of integrated control, along with other methods against the pest.