Isolation and characterization of Beauveria and Metarhizium spp. from walnut fields and their pathogenicity against the codling moth, Cydia pomonella (NL.) (Lepidoptera: Tortricidae)

Abstract

Entomopathogenic fungi (EPFs) play an important role for regulating insect pest populations, as they exist in many different ecosystems. Within 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 Kirsehir, Turkey, and to evaluate their pathogenicity against Cydia pomonella (L.) (Lepidoptera: Tortricidae). To perform this, 90 soil samples were collected from walnut fields where Beauveria and Metarhizium spp. were isolated from these soils, using selective media. The isolated 40 fungi were characterized based on their morphological and molecular characteristics including Bloc and beta-tubulin gene sequences. Also, eight selected fungi were tested against C. pomonella larvae under laboratory conditions. The fungal isolates were identified as Beauveria pseudobassiana (15), B. bassiana (12), Metarhizium robertsii (11), and M. brunneum (13). M. brunneum ELA-38 caused 83% mortality within 2 weeks after application of 1 x 10(8) conidia/ml. Consequently, Beauveria and Metarhizium spp. are the common component of the soils collected from walnut fields and some of fungi obtained from this work might be beneficial in the future biological control programs of C. pomonella.