Isolation and Identification of Entomopathogenic Fungi from of Green Peach Aphid Myzus Persicae and Evaluation of Their Activity for Insect Control

Abstract

Twenty-one different fungal isolates were isolated from samples of infected insects from different areas in Salah El-Din Governorate. A preliminary screening of the isolated fungi was carried out using different stages of green peach insect for the purpose of estimating its pathogenicity. The results showed that the fungal spores suspension and fungal filtrates of isolates (RA-4, RA-5, RA-9, RA-10, RA-12, RA-13, RA-14, RA-16, RA-23, RA-24) significantly superior on other isolates in killing green peach insects, the isolate (RA-5) achieved the highest mortality rate of 95.3% during the 72 hours period. All the selected (highest pathogenic) isolates showed their production of chitinase, the fungal isolates (RA-24, RA-4, RA-12, RA-14) superior on other isolates in the activity of chitinase, reaching 6.62, 3.31, 2.53, and 2.15 units/ml, respectively compared to 1.76 units/ml in the commercial fungicide strain B.bassiana. The isolates (RA-5, RA-24, RA-4, RA-9) were significantly superior to the protease activity, which reached 2.42, 1.88, 1.86, and 1.83 units/ml, respectively, compared to 1.64 units/ml in the commercial fungicide strain B. bassiana. These isolates were phenotypically and molecularly identified to the species level based on the nucleotide sequences of the ITS1 and ITS4 region within the 5.8 S rRNA gene. To study the compatibility of the highest pathogenic fungal isolates with different concentrations of the chemical pesticide Dominant, the results showed that all fungal isolates were able to grow in the presence of this pesticide, the highest compatibility was in present of Dominant at 1%, with P. oxalicum (RA-13), M. anisopliae(RA-24) and T. longibrachiatum (RA-5) in which the fungal growth rate reached 89, 88.57and 83.44%, respectively. The results also showed that there was a significant superiority of all treatments that included M. anisopliae (RA-24) and T. longibrachiatum (RA-5) with the pesticide Dominant (0.5%) in the mortality rate of green peach insect stages compared with the other treatments, the highest mortality rate reached 100% after 3 days of treatment (M.anisopliae + Dominant 0.5) and (T. longibrachiatum + Dominant 0.5) while the lowest mortality rate was 66.66% in the treatment of M.anisopliae.