Destiny of Wild Apricot (Armeniaca vulgaris) at Stake: The Post Invasion Population Dynamics of Globose Scale (Sphaerolecanium prunastri) and Damage Status of Forests in Central Eurasia

The globose scale (GS) Sphaerolecanium prunastri (Boyer de Fonscolombe) (Hemiptera: Coccidae) is a serious pest affecting plants within the Rosaceae, notably wild apricot, Armeniaca vulgaris (Lamarck). Following its initial detection in 2019, more than 80% of valleys with wild apricots have become affected in the Ili River basin of Tianshan Mountains in Xinjiang, China. This study assessed GS population dynamics post invasion and its effects on growth and reproductive traits of wild apricot trees from 2019 to 2024. Nymph densities decreased over the years but remained high, with densities on shoots per 20 cm of 986 (1st instar nymph) and 120 (2nd instar nymph) in 2024, respectively. Damage has declined, with high damage rankings decreasing from 24% to 11% of wild apricot trees. However, mortality of trees was higher (25%) in infested than non-infested areas (13%). Interestingly, GS feeding stimulated the growth of spring shoots but significantly reduced the reproductive capacity of wild apricot. Heavily infested trees exhibited increased shoot length (2-3 times), decreased fruit yield (20-fold), lower flowering percentage (8-fold), and reduced flower bud density (2-fold) compared to non-infested trees. Overall, despite a decrease in damage severity, wild apricot forests remain threatened by GS. Implementing Integrated Pest Management (IPM) strategies is essential for effective GS management and recovery of wild apricot forests.