Indigenous entomopathogenic fungi as potential biological control agents of rose sawfly, Arge rosae L. (Hymenoptera: Argidae)

The rose sawfly, Arge rosae L. (Hymenoptera: Argidae), is one of the most destructive pests of roses grown both indoors and outdoors in Antalya province (south-western part of Turkey). Especially in greenhouse rose cultivation, growers depend heavily on synthetic pesticides to control this pest along with other arthropod pests in their crops. The aim of this study was to evaluate biocontrol potential of some indigenous soil-borne entomopathogenic fungi (EPF) against the pest. In pathogenicity assays, a total of 17 EPP isolates, belonging to three species [Beauveria bassiana (Gals.) Vuill. - 14, clonostachys rosea (Link) Schroers - 2 and Isaria farinosa (Holmsk.) Fr. - 1] were tested against the 4th instar larvae of A. rosae under laboratory conditions. All the isolates were applied at a conidial suspension of 1 x 10(7) conidia/mL, using the spray method. The results from the assays showed that bio-efficacy of tested isolates increased significantly with elapsed time up to 9 days after inoculation. Of the 17 isolates tested, 5 isolates of B. bassiana (BbDm-1, BbKp-1, BbMp-1, BbSr-1 and BbMg-2) and 1 isolate of I. farinosa (IfGp-1) appeared to be most promising, causing mortalities between 76.7 and 86.7% 3 days post treatment. Probit analysis of mortality data showed that there were significant differences in the susceptibility of 4th instar larvae of A. rosae to tested EPF isolates. The above-mentioned six isolates had the lowest LT50 and LT95 values (ranged from 1.66 to 7.50 and 4.81 to 8.49 days, respectively), implying their high virulence and their biocontrol potential against the pest. Phylogenetic analysis based on the ITS region sequence revealed that all tested isolates showed high similarities (ranged from 99 to 100%) with other isolates of their respective fungal species in GenBank. Overall results suggested that the most virulent above-mentioned six isolates had significant potential as biological control agents against A. rosae.