Abstract:
Objective Armeniaca vulgaris is the ancestor of cultivated apricots globally and one of the dominant tree species in the Tianshan wild fruit forests, where it plays a critical role in germplasm conservation and ecosystem services. In recent years, the invasion of Sphaerolecanium prunastri led to a large scale decline of wild apricot population, but there is still a lack of research on the physiological nutrients behind its population decline.
Method Physiological damage caused by S. prunastri was assessed by measuring the phloem nutrients of different damage time (early overwintering stage of 2nd instar nymphs, feeding period of 2nd instar nymphs and maximum feeding period of female insects), damage degree (undamaged, mild, moderate and severe) and different branch ages new shoots, 2nd and 3rd instar branches) of wild apricot, and combining with the nutrient difference analysis of various vegetative organs (new shoots, branches, trunks and fine roots).
Results In the primary damaged branch tissues, phloem total sugar (TS) increased by 10.6%~33.8%, and soluble protein (SP) increased by 24.4%~61.1%, whereas soluble sugar (SS) and amino acid (AA) decreased by 30.9%, and 13.4%~66.5%, respectively. The main nutrients in the phloem of A. vulgaris were generally reduced at different branch ages. The soluble sugar of the 2nd and 3rd branches decreased by 26.7%~30.8%, the soluble protein of the new shoots and 2nd branches decreased by 33.1%~37.1%, and the amino acid decreased by 22.0%~66.5% at each branch age. Nutrient responses varied among vegetative organs and did not follow a uniform pattern; however, certain organs exhibited specific long-term response to infestation. Notably, total carbon of fine roots and soluble sugar of new shoots increased by 10.7% and 63.1%, respectively, while total nitrogen of fine roots decreased by 17.9%.
Conclusion Infested by S. prunastri disrupts carbon and nitrogen metabolism in wild apricot, primarily through impaired transport of photosynthetic assimilates and constraints on nitrogen absorption and assimilation. These findings reveal the disruption of nutrient transport caused by this pest in wild apricot and provide a theoretical basis for the conservation of wild apricot populations.