Efficacy of indigenous entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin, isolates against the rose aphid, Macrosiphum rosae L. (Hemiptera: Aphididae) in rose production

The rose aphid, Macrosiphum rosae L. (Hemiptera: Aphididae), is an important insect pest of rose plants because it damages the leaves and flowers. The entomopathogenic fungus, Beauveria bassiana Balsamo (Vuillemin), is environmentally safe in comparison with the chemical pesticides. The indigenous fungal isolates can be the best options in biological control because they are more adapted to the local environment. In the present study, four genetically different isolates of B. bassiana (isolates 1, 2, 3, and 4) were used to estimate LC50 for the rose aphid. Also, the same isolates were used to control the aphid’s infestation on rose plants in the field, and the efficacy was compared with a commercial strain (Naturalis®) with two concentrations for each isolate (2.3 × 106 and 4.6 × 106 conidia/ml). Bioassay results indicated that isolate 1 differed significantly (LC50 = 6.46 × 104) than the other three ones (LC50 = 1.46 × 105, 1.52 × 105, and 1.71 × 105). In field trials, the concentration of 4.6 × 106 conidia/ml, for indigenous as well as commercial strains, achieved the highest reductions of rose aphid infestation and the highest extraction of rose oil. Thus, this fungus can be recommended in organic rose production. Further investigations are needed for the improvement in utilization of these isolates with regard to UV radiations in the field.