Haplotypes of Aedes aegypti and Aedes albopictus larvae detected in 18 districts of Costa Rica

Background Aedes aegypti and Aedes albopictus are key vectors of arboviruses such as dengue, chikungunya, and Zika. Monitoring the genetic diversity of these mosquito species is essential for understanding their adaptation, distribution, and implications for disease control. This study aimed to identify and compare the haplotypes of Aedes aegypti and Aedes albopictus larvae in 18 districts of Costa Rica. Methods A cross-sectional, descriptive study was conducted from August to November 2021. Larvae were collected from 26 locations across 18 districts at elevations below 900 m above sea level. Morphological identification was followed by DNA extraction and amplification of the cytochrome oxidase I (COI) mitochondrial gene by Polymerase Chain Reaction. Sequences were aligned and compared with GenBank references. Phylogenetic analysis was conducted using the unweighted pair-group method with arithmetic averages (UPGMA) clustering method. Results Ae. aegypti was detected in all districts, and Aedes albopictus in 11. Three haplotypes of Ae. aegypti (H1, H2, H4) and five of Ae. albopictus (H3, H6, H26, H37, H67) were identified. H1 ( Ae. aegypti ) and H67 ( Ae. albopictus ) were the most widespread. Several haplotypes not previously reported in Costa Rica were found. Amino acid polymorphisms were noted at key COI positions, with distinct clades observed in phylogenetic trees. Conclusions This study confirms the genetic diversity of Aedes populations in Costa Rica and identifies previously unreported haplotypes. Further seasonal and geographically broader studies are recommended to track vector population dynamics and inform vector control strategies.