Phylogenetic Analysis of Hazelnut Big Bud Mite - Phytoptus Avellanae Nal. in the Black Sea Region of Georgia

Abstract

Hazelnut is one of the leading agricultural crops in Georgia. It is cultivated on 8% of the arable area in Georgia and is of great economic importance. Therefore, it is important to protect hazelnut plants from pests in order to produce high quality nuts and minimize losses. In recent years, the ‘big bud mites’ have become major pests of hazelnut plantations in Georgia. Their timely detection and diagnostics will enable the implementation of effective control measures. For this study, 20 orchards in the western Georgia regions of Guria, Samegrelo and Adjara were selected. The species identification and phylogenetic analysis were carried through the sequencing of PCR fragments. The comparison of sequence results to reference isolates of Phytoptus avellanae in Genbank showed high percentage similarity (93-99%). Phylogenetic analysis were conducted in MEGA7 by using UPGMA methods. The phylogenetic trees show that Georgian isolates are grouped in two main clades. First clade contains 15 Georgian and 3 GenBank (KR149013.1, KR149017.1, KT070248.1) isolates of P. avellanae. Microhabitat of all these isolates were buds. The second clade contains 6 Georgian isolates and two isolates from GenBank (KR149026.1 and KR149027.1.), which were isolated from vagrant forms of P. avellanae. The phylogenetic trees show that Georgian isolate GUR1 is separate from Genbank and Georgian isolates. © 2018 Bull. Georg. Natl. Acad. Sci.