Multiple introductions shaped genomic diversity and demographic history of invasive box tree moth (Cydalima perspectalis) populations in North America

The box tree moth, a pest of boxwood plants, has rapidly spread across Europe and North America since its first detection in Canada in 2018. To understand its invasion history, researchers combined genome-wide single nucleotide polymorphism (SNP) data, mitochondrial cytochrome c oxidase I (COI) data, and morphological information. Their analyses revealed significant genetic differentiation between North American and European populations, as well as substantial structure within North America.

Delaware emerged as a distinct population genetically, showing a closer relationship with European populations than other North American groups. Conversely, New York, Massachusetts, Michigan, Ohio, and Ontario displayed greater genetic similarity, suggesting shared ancestry or regional connectivity. Virginia and West Virginia, on the other hand, exhibited additional genetic differentiation.

Mitochondrial data indicated shared ancestry among most North American populations, with Delaware sharing a haplotype group with the Croatian European population. D-statistic analyses identified asymmetric allele sharing among various European and North American populations, suggesting multiple introductions followed by admixture.

Morphometric analyses further revealed significant geographic variation in several body and wing traits. Overall, these findings demonstrate that multiple introductions, regional genetic structuring, and admixture have shaped the distribution of the box tree moth in North America. The study underscores the importance of integrating genomic approaches with surveillance efforts at nurseries and borders to identify introduction pathways and guide targeted management strategies for this emerging horticultural pest.