Molecular Characterization of Native Entomopathogenic Fungi from Ambrosia Beetles in Hazelnut Orchards of Turkey and Evaluation of Their In Vitro Efficacy

Abstract

Simple Summary Turkey is the world's largest producer and exporter of hazelnut. Ambrosia beetle species are the most common species of pests for hazelnut in the orchards of Turkey. These beetles cause enormous economic losses by draining hazelnut branches and trees. The techniques for managing ambrosia beetles are limited. The more effective and eco-friendly alternative control methods, including the use of entomopathogenic fungi (EPF), should be included in integrated pest management programs to suppress ambrosia beetle populations. The objectives of the current study were (i) to isolate EPF from individual ambrosia beetles that were obtained from Turkey's main hazelnut production areas; (ii) to characterize EPF isolates using DNA sequencing and iPBS profiling; and (iii) to assess the effectiveness of the isolates against three ambrosia beetle species under laboratory conditions. A total of 47 EPF isolates were obtained from beetle cadavers and classified into eight EPF species. For the first time, the primer binding site (PBS) marker system was used to successfully discriminate among the EPF species. Some isolates caused 100% mortality of the beetle species within 7 to 9 days, depending on the beetle species, demonstrating their effectiveness in managing the pests. The major EPF species in this study provided an important basis for developing bioproducts and a possible alternative approach in controlling these ambrosia beetles. Ambrosia beetles, Anisandrus dispar Fabricius, Xylosandrus germanus Blandford, and Xyleborinus saxesenii Ratzeburg (Coleoptera: Curculionidae: Scolytinae) are among the most significant hazelnut pests in Turkey. The control of these pests is difficult and expensive due to their biology. The present study aimed to isolate entomopathogenic fungi (EPF) from A. dispar, X. germanus, and X. saxesenii individuals that were obtained from the main hazelnut production areas of Turkey, characterize the EPF isolates using internal transcribed spacer (ITS)-DNA sequencing and iPBS profiling, and determine the efficacy of the isolates against A. dispar, X. germanus, and X. saxesenii under laboratory conditions. Phylogenetic analyses based on ITS revealed that the 47 native isolates were Beauveria bassiana (11), B. pseudobassiana (8), Cordyceps fumosorosea (6), Cordyceps farinosa (1), Akanthomyces lecanii (13), Purpureocillium lilacinum (3), Clonostachys rosea (2) and Metarhizium anisopliae (3). For the first time, the primer binding site (PBS) marker system, based on retrotransposons, was used to discriminate successfully among the EPF species. Some isolates of B. bassiana, B. pseudobassiana, C. fumosorosea, A. lecanii, and M. anisopliae caused 100% mortality of the beetle species within 7 to 9 days. The findings of this study indicated that some isolated entomopathogenic fungi provide an essential basis for the development of bioproducts, as well as a promising alternative method for controlling these ambrosia beetles.