First report of damage in olive orchards in Slovenia caused by Aculus olearius Castagnoli (Prostigmata: Eriophyidae)

During a field survey conducted in olive orchards (Olea europaea L.) in western Slovenia over two consecutive years (2022–2023), severe symptoms of bud browning, flower drying, leaf curling, and shoot deformations were observed. Symptomatic flower buds and leaves were collected in late May and early June for laboratory analysis. Stereomicroscopic examination confirmed a significant infestation of eriophyid mites. Morphological characterization identified the presence of Aculus olearius Castagnoli, marking the first record of this species in Slovenia. A molecular characterization was also performed and sequences were compared with other Aculus spp. High densities of mite populations feeding on flower buds and peduncles led to the premature dropping of flowers and young fruits, a phenomenon increasingly observed in recent years. This study documents the first occurrence of A. olearius in Slovenia and highlights its potential economic impact on olive production.