Agrilus maliMatsumara (Coleoptera: Buprestidae), a new invasive pest of wild apple in western China: DNA barcoding and life cycle

Agrilus maliMatsumara (Coleoptera: Buprestidae) is a wood‐boring beetle distributed to eastern China that occasionally injures apple species. However, this wood‐boring beetle is new to the wild apple forests (Malus sieversii) of the Tianshan Mountains (western China) and has caused extensive tree mortality. The development of a biological control program for these wild apple forests is a high priority that requires exploration of the life cycle, DNA barcoding and taxonomic status ofA. mali. In this study, to determine the diversity of invasive beetles, a fragment of the mitochondrialcytochrome oxidasegene was analyzed. Based on the results, beetles from Gongliu and Xinyuan counties of Xinjiang were identical but differed from those in the apple nursery of Gongliu by a single‐nucleotide substitution. We summarize the taxonomic status, relationships, and genetic distances ofA. maliamong otherAgrilusspecies using the Tajima‐Nei model in maximum likelihood phylogeny. Analysis revealed thatA. maliwas closely related toAgrilus mendaxand both belong to theSinuatiagrulussubgenus. The life cycle ofA. maliwas investigated based on a monthly regular inspection in the wild apple forests of Tianshan. Similar to congeneric species, hosts are injured by larvae ofA. malifeeding on phloem tissue, resulting in serpentine galleries constructed between bark and xylem that prevent nutrient transport and leading to tree mortality. Future studies will focus on plant physiological responses to the invasive beetles and include surveys of natural enemies for a potential classical biological control program.