Global phylogeography of Amrasca biguttula (Hemiptera: Cicadellidae) across eight countries reveals a single-haplotype incursion into the United States beyond its putative native range

Abstract

Amrasca biguttula is a pest of cotton, ornamentals, and vegetables, and is invading the southeastern United States. We addressed five questions: (1) Are US populations genetically identical to those in the putative native range? (2) Does the southeastern US outbreak extend the recent Puerto Rico and Florida invasion or represent separate introductions? (3) Does the lineage infesting ornamentals match that on other crops? (4) What is the mitochondrial cytochrome oxidase subunit 1 (mtCOI) diversity of A. biguttula? (5) Which regions constitute its native versus invaded range? Adults were collected from Florida, Georgia, South Carolina, Texas, and Puerto Rico. Species identity was confirmed morphologically and by sequencing mtCOI, where possible, from five individuals per site, yielding consensus haplotypes. We analyzed 11 US, 20 Puerto Rican, and 342 sequences originating from publicly available databases (n = 373). Phylogenetic analysis confirmed monophyly of this species. A haplotype network recovered 70 unique haplotypes, including a star-like core of 68 radiating from Hap01 and two divergent singletons. The mainland US and Chinese populations were fixed for Hap01, indicating recent introductions. Puerto Rico exhibited Hap01, Hap52, and Hap70, reflecting multiple introductions, but could also result from haplotype diversity carried within a single introduction involving many individuals. Furthermore, southeastern US sites were fixed for Hap01, indicating extension from Puerto Rico and Florida. No haplotype was host-specific, confirming a lineage across crops. Diversity metrics indicate recent expansion in Iraq, Hong Kong, and Puerto Rico. South Asia, particularly Bangladesh, India, and Pakistan, showed the highest haplotype diversity, supporting its role as the putative native range. In contrast, low diversity in China and the US is consistent with recent invasion. Curation yielded 373 high-quality sequences, providing a unified database to support quarantine and management strategies.