Preliminary results of Beauveria bassiana (Bb024) use for the biological control of big bud mite, Phytoptus avellanae (Acari: Eriophyoidea)

Abstract: It is important to protect hazelnut from pests, minimize the losses and maintain the best quality. The aim of our study was to establish a biocontrol strategy to use the entomopathogenic fungus, such as Beauveria bassiana (Bb-024) against big bud mites, which are the most widespread arthropod pests of hazelnut throughout the world. Phytoptus avellanae was collected in hazelnut orchards of west Georgia (Chokhatauri Village) in 2015. In laboratory, mycosis by Bb-024 was observed on 4th day after treatment of mites. The mortality was indicated late on 5th-15th days. Maximum mortality was marked on 12-15 days after treatment. Infection caused by fungi was confirmed by microscopic examination, of spores on the surface of the mites. In a semi-field experiment B. bassiana (Bb024) was used against P. avellanae. The fungus suspension with the concentration 5 × 107 conidia/ml was applied on the infested hazelnuts buds. Fourteen days after the treatment, the buds were removed from trees and checked under binocular microscope. The obtained results showed that the fungal strain Bb-024 was pathogenic to P. avellanae and 83.5% of biological effectiveness was achieved 15 days after the treatment. The results show that the B. bassiana (Bb-024) isolate can be used for the control of P. avellanae.