Mitogenomic insights into Sarcoptes scabiei in American black bears (Ursus americanus): COI utility for regional surveillance and mite genetic structure

Sarcoptic mange is a skin disease caused by the parasitic mite Sarcoptes scabiei that affects humans and over 150 species of domestic animals and wildlife worldwide. For the American black bear ( Ursus americanus ), sarcoptic mange is considered a significant emerging disease and case numbers have increased dramatically over the past four decades. While molecular techniques, such as DNA sequencing, are commonly used for diagnosis of clinical cases, they remain underutilized for studying cross-species transmission and regional mite variation. We captured complete mitochondrial genomes from S. scabiei mites ( n = 17) collected from infested black bears in the Eastern United States (U.S.) using custom-designed oligonucleotide baits. These full mitogenomes were then used to refine primers targeting the cytochrome c oxidase subunit I ( COI ) gene. We then amplified and analyzed 285 COI sequences from S. scabiei collected across multiple North American wildlife hosts to assess their utility in inferring regional diversity and host-associated genetic structure. Full mitogenome comparisons with sequences from the U.S., Japan, and Australia revealed three major global S. scabiei clades, with two circulating among North American black bears. The COI haplotype networks showed regional clustering rather than host-specific patterns, suggesting that ecological or geographic factors influence transmission dynamics. Our findings confirm the presence of multiple S. scabiei lineages in American black bears and other U.S. wildlife and support the use of the COI gene for large-scale, cost-effective screening of genetic variation and shared haplotypes across host species. The integration of mitogenome and COI data offers a scalable model for investigating S. scabiei diversity in wildlife and domestic hosts.