Isolation and characterization of entomopathogenic fungi from walnut fields in Kırşehir and their pathogenicity against the codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae)

Entomopathogenic fungi (EPFs) play an important role for regulating insect pest populations and these fungi, Beauveria and Metarhizium spp. genera include species that are the most commercially important. The aim of this study was to determine the diversity and distribution of Beauveria and Metarhizium spp. in walnut fields of Kırşehir, Turkey, and to evaluate their pathogenicity against Cydia pomonella (L.) (Lepidoptera: Tortricidae). To perform this, 90 soil samples were collected from walnut fields in the vicinityof Kırşehir and its surroundings. Beauveria spp. and Metarhizium spp. were isolated from these soils, using selective media. The isolated 40 fungi were obtained and characterized based on their morphological and molecular characteristics (Bloc and β-tubulin gene sequences). Also, eight selected fungi were tested against C. pomonella larvae under laboratory conditions. Based on morphological and molecular characterications, the fungal isolates were identified as Beauveria pseudobassiana (15), B. bassiana (12), Metarhizium robertsii (10), and M. brunneum (3). M. brunneum ELA-38 caused 83% mortality within 2 weeks after application of 1 × 108 conidia/ml. Consequently, some of fungi obtained from this work might be beneficial in the future biological control programs of C. pomonella.