Monitoring the distribution of the Asian chestnut gall wasp, <i>Dryocosmus kuriphilus</i> (Hymenoptera: Cynipidae), and its parasitoid, <i>Torymus sinensis</i> (Hymenoptera: Torymidae), in Albania

Abstract The Asian chestnut gall wasp ( Dryocosmus kuriphilus Yasumatsu) is one of the most damaging invasive pests of chestnut trees worldwide. To assess its distribution and the presence of its parasitoid Torymus sinensis Kamijo in Albania, extensive field surveys were conducted in 2023–2025 across major chestnut‐growing regions. Sampling was carried out in 39 localities covering the municipalities of Elbasan, Fushë Arrëz, Klos, Malësi e Madhe, Mat, Pukë, Shkodër, Tirana, Tropoja and Vau i Dejës. By 2025, D. kuriphilus was recorded in all surveyed municipalities and in nearly all localities except Blerim in Fushë Arrëz, confirming its rapid spread throughout northern Albania. The highest infestation levels reached 18.8 galls per 50 cm of twig in Vilzë in Shkodër. In 2023–2024 the range of the pest exhibited significant expansion in the northernmost chestnut stands of Tropoja, advancing towards the north‐eastern border. The parasitoid T. sinensis was detected in all but five localities, mainly in areas with low or absent pest populations, indicating a temporal lag between host establishment and parasitoid colonization. This study provides the first scientific publication on the presence of D. kuriphilus and distribution of T. sinensis in Albania. The results highlight the pest's strong invasive potential and adaptability, as well as the successful establishment of its biological control agent. Continued monitoring is essential to assess the dynamics of the parasitoid‐host interaction, particularly under changing climatic conditions that may affect their phenological synchronization. Considering the imminent risk of transboundary spread of the pest into neighbouring countries, coordinated regional efforts are strongly recommended to safeguard chestnut ecosystems across the western Balkans.