Effect of Beauveria bassiana strains on the Ceratitis capitata - Psyttalia concolor system

The effects of a previously selected entomopathogenic fungus, Beauveria bassiana AL1 strain, and the B. bassiana based mycoinsecticide Naturalis (ATCC 74040 Beauveria bassiana strain) were evaluated on the system Ceratitis capitata - Psyttalia concolor in laboratory assays. First, the entomopathogenic fungal strains were tested for their virulence against 2, 4, and 6-days old puparia of C. capitata. Subsequently, P. concolor emergence from C. capitata puparia treated or not with the fungal strains was evaluated at three different time points (2, 4 and 6 days) from the parasitization and the following pupation. Results showed that the entomopathogenic fungal applications affected the medfly survival. The effect of fungal treatments was higher on 2-day puparia (49.16 and 51.33% of mycosed puparia for ATCC 74040 and AL1 strain respectively) while the rate of mycoses was lower and ranged between 39 and 27.16% when fungal treatments were performed on 4 and 6-day puparia. Furthermore, fungal treatments affected the P. concolor emergence (c.a. 80% in the untreated control) particularly when applied 2 days after the parasitization and the C. capitata pupation (43.16 and 47.83% for the ATCC 74040 and the AL1 strains respectively), while when treatments were performed on older puparia, the P.concolor emergence ranged from 63.33 to 68.66%. Results suggest that the entomopathogenic B. bassiana strains are effective against C. capitata puparia but they may be detrimental against its endoparasitoid P. concolor, particularly when applied in the earlier stages of the parasitization process.