New tree hosts of xylophagous beetles (Insecta: Coleoptera) in Bulgaria

During 2024-2025, xylophagous beetles were studied in the field-protected forest belts of South Dobrudzha in Northeastern Bulgaria and in solitary trees in Borisova Gradina Park, Sofia. Parts of stems and branches infected by these beetles were collected and transported to the Forest Research Institute in Sofia and the State Forest Enterprise General Toshevo. In laboratory conditions, the cuttings were placed in plastic boxes and photoeclectors and reared at room temperatures (18-22°C). As a result, 12 taxa from 4 beetle families were identified: Chrysobothris (Chrysobothris) affinis affinis, Agrilus (Quercuagrilus) graminis graminis, A. (Q.) hastulifer, A. (Q.) laticornis, A. (Q.) litura (Coleoptera: Buprestidae), Melasis buprestoides (Coleoptera: Eucnemidae), Lichenophanes varius (Coleoptera: Bostrichidae), Plagionotus detritus detritus, Xylotrechus (Xylotrechus) antilope antilope, Exocentrus adspersus, E. lusitanus, and Mesosa (Aplocnemia) nebulosa nebulosa (Coleoptera: Cerambycidae). In this study, 3 new insect-host associations were established: Agrilus (Q.) graminis graminis was reared for the first time from Juglans regia, Agrilus (Q.) hastulifer from Quercus rubra, and Agrilus (Q.) litura from Quercus cerris. Additionally, 15 insect-host associations were newly recorded for Bulgaria. The majority of the xylophages (103 out of 158 specimens reared, 65.2%) belong to the genus Agrilus. Within this group, A. (Q.) hastulifer and A. (Q.) graminis graminis were the most abundant, accounting for 56.3% and 39.8%, respectively. These species have the most significant impact on oak mortality in the field-protective forest belts of Northeastern Bulgaria.