Phenotypic and genetic variation of <i>Aedes albopictus</i> (Diptera: Culicidae) in Thailand and its global relationships: Insights from wing morphometric and mitochondrial <i>COI</i> gene analyses

Aedes albopictus (Diptera: Culicidae), commonly known as the Asian tiger mosquito, is an important vector transmitting dangerous arboviruses to humans. This study investigated the phenotypic and genetic variation of this species in Thailand through wing geometric morphometric (GM) and mitochondrial cytochrome c oxidase subunit I (COI) gene sequence analyses. A total of 236 Ae. albopictus specimens from 12 populations in Thailand and 89 specimens from invasive populations in Florida, Hawaii and Brazil underwent wing GM analysis. The centroid size (CS) of Ae. albopictus populations in Thailand ranged from 2.00 mm in Bangkok to 2.36 mm in Chanthaburi, while in invasive populations, CS varied from 2.25 mm in Brazil to 2.47 mm in Florida. Pairwise comparisons of wing shape revealed significant differences for most population pairs, with distances ranging from 1.63 to 10.02. The clustering tree indicated distant relationships in wing shape between native and invasive populations. Additionally, partial COI gene sequences were amplified from 108 specimens, revealing a mean haplotype diversity of 0.842 ± 0.025 and a mean nucleotide diversity of 0.002 ± 0.001. The results from neutral Tajima's D and Fu's Fs tests indicated negative and statistically significant values (-2.159 and -33.846, respectively), suggesting population expansion. Further examination of haplotype relationships between Thailand and other countries identified two distinct groups: a Southeast Asia group, with Thai haplotypes clustered exclusively within it, and a non-Southeast Asia group. These findings highlight the phenotypic and genetic variation of Ae. albopictus in Thailand, providing essential insights for disease control strategies and tracing the mosquito's origins across regions.