Hidden Mosquito Diversity Surfaces in Mexico’s Celestún Mangrove Reserve

Deep in the mangrove swamps of Mexico’s Yucatán Peninsula, where pelicans and frigatebirds crowd a tiny islet and tourists flock to flamingo-lined lagoons, entomologists have quietly rewritten the mosquito map of one of the country’s most important protected areas. A new survey of the Ría Celestún Biosphere Reserve has documented 17 mosquito species across six genera, including one species never before recorded in the state of Yucatán and eight species new to the reserve itself. The findings, published in the open-access journal Discover Animals, carry implications that stretch far beyond insect catalogs: several of the newly documented mosquitoes are known vectors of arboviruses, and the reserve already has a documented history of viral circulation among its insects and birds.

The research team, led by Diana G. Argaez-Sierra and colleagues at the Universidad Autónoma de Yucatán’s Arbovirology Laboratory, set out to inventory the mosquito fauna of a reserve that had received surprisingly little focused entomological attention despite its ecological prominence. The Ría Celestún Biosphere Reserve is one of the largest of Yucatán’s twelve protected natural areas, encompassing roughly 81,482 hectares of mangroves, coastal dune vegetation, salt marshes, petenes, and lowland floodplain forest on the Gulf of Mexico. The region’s warm, semi-arid climate brings about 767 millimeters of annual rainfall, with relative humidity ranging from 65 to 95 percent and maximum monthly temperatures climbing to 40 degrees Celsius—a combination that creates ideal conditions for mosquito breeding across a mosaic of brackish and freshwater habitats.

Sampling took place during the rainy season in October and November 2024, when the researchers deployed a cross-sectional design across 27 sites representing seven distinct habitat types, including mangrove swamp, salt flats, water surge zones, the bird-nesting islet known as Isla de los Pájaros, coastal scrub, disturbed vegetation, and coastal halophytic vegetation. Working from 19:00 to 22:00 and again from 05:00 to 08:00, the team used two backpack-mounted Prokopack aspirators per night to vacuum adult mosquitoes directly from shaded areas and dense vegetation. They supplemented this active collection with BG-Sentinel traps baited with synthetic human-scent attractant, five traps per site running overnight. Captured insects were immediately preserved in liquid nitrogen and transported to the laboratory, where stereomicroscopes and standard taxonomic keys were used to identify species morphologically.

The results were dominated by a single, familiar face. Of the 3,755 adult mosquitoes captured, females of Aedes taeniorhynchus—the black salt-marsh mosquito—accounted for 95.26 percent of the entire collection and turned up in every habitat sampled. This species is famously associated with coastal wetlands and mangroves throughout the Americas, ovipositing in brackish-water environments and displaying a remarkable tolerance for salinity that few other mosquitoes can match. Its larvae can even colonize artificial containers, allowing the insect to bridge wild and human-modified landscapes. While Ae. taeniorhynchus is primarily a biting nuisance in much of its range, its epidemiological resume is sobering: Venezuelan equine encephalitis virus has been isolated from this species in Guatemala and Costa Rica, eastern equine encephalitis virus in South Carolina, and the Itaqui virus, which causes fever and headache in humans, in Venezuela.

The headline discovery of the survey, however, was Anopheles gabaldoni, a mosquito first described in Tabasco, Mexico in 1941 and subsequently reported in Veracruz and Chiapas, as well as in the neighboring Yucatán Peninsula states of Campeche and Quintana Roo. Its capture in the disturbed vegetation area and on Isla de los Pájaros marks the first record for Yucatán state, raising the state’s documented mosquito tally to 60 species. The identification rests on distinctive abdominal morphology—tufts of posterolateral scales on the tergites and numerous light and dark scales on the sternites—features that the team documented photographically. Intriguingly, all Anopheles species in the study except An. vestitipennis were collected on the islet, including An. albimanus, An. crucians, An. punctipennis, and An. pseudopunctipennis, suggesting that this mangrove-covered bird sanctuary functions as an anopheline hotspot within the reserve.

Habitat type proved to be a strong predictor of mosquito diversity. The disturbed vegetation area yielded the richest assemblage with 12 species, followed by Isla de los Pájaros and the floodable area with seven species each. Although forest modification is generally associated with reduced species diversity, the authors propose that the convergence of disturbed vegetation and highly conserved mangrove may actually amplify mosquito richness by creating edge habitats that satisfy the breeding requirements of multiple species simultaneously. Six of the 27 sampling sites produced no mosquitoes at all, including two sites in the saltworks and three on the islet, underscoring how patchy mosquito distributions can be even within favorable landscapes.

Because morphology alone can mislead—Coquillettidia venezuelensis resembles Cq. nigricans, Anopheles vestitipennis resembles An. neivai, and species of the Aedes subgenus Ochlerotatus are notoriously similar—the team turned to DNA barcoding to confirm the identities of three species. Using the Folmer primers LCO1490 and HC02198, they amplified roughly 700-base-pair fragments of the mitochondrial cytochrome c oxidase subunit I gene. The 704-base-pair COI sequence of An. vestitipennis showed 99.56 percent nucleotide identity with reference sequences in GenBank, and the 687-base-pair sequence of Cq. venezuelensis reached 99.85 percent identity. For Ae. angustivittatus, the 707-base-pair COI sequence showed 98.50 percent identity with a specimen from neighboring Quintana Roo, and a complementary 377-base-pair fragment of the nuclear ITS2 region was also generated. All sequences were deposited in GenBank under accession numbers PZ154394, PZ154395, PZ154396, and PZ158059, adding a permanent molecular reference resource for future mosquito work in the region.

The phylogenetic analysis added a tantalizing evolutionary twist. Bayesian inference conducted in MrBayes, using a 46-sequence dataset of 579 nucleotide positions and Culex quinquefasciatus as an outgroup, revealed that the Celestún Ae. angustivittatus forms a strongly supported lineage with the Quintana Roo specimen, with 98 percent posterior support. But when the researchers calculated pairwise genetic distances, the Yucatán sequences diverged by 3.11 to 4.15 percent from Ae. angustivittatus collected in Chiapas, the State of Mexico, Colombia, and Ecuador. Divergence values in the 3 percent range are often taken as evidence of distinct evolutionary lineages in mosquito DNA barcoding, and the authors suggest that what is currently called Ae. angustivittatus may actually comprise multiple species or distinct subpopulations across its range. They ruled out confusion with the closely related Aedes infirmatus, since interspecific divergence between the two species measured only 2.76 to 2.77 percent, and they note that the ITS2 marker was of limited use here because public databases contain too few ITS2 sequences from closely related Aedes species. Resolving the question will require broader sampling, diagnostic morphological comparisons, and potentially complete mitochondrial genome analysis.

The public health stakes of the inventory are considerable. The Ría Celestún Biosphere Reserve has previously yielded Cache Valley and South River viruses and alphavirus RNA from Ae. taeniorhynchus, alphavirus RNA from An. pseudopunctipennis and An. crucians, and St. Louis encephalitis virus isolated from the bird Cyanocorax yncas. Females of Ae. taeniorhynchus captured at the Mérida zoo tested positive for Cache Valley and Kairi viruses, both of which primarily infect livestock and wildlife but can incidentally infect humans. In Colombian mangrove forests, RNA from St. Louis encephalitis, yellow fever, dengue, Venezuelan equine encephalitis, and West Nile viruses has been detected in mosquitoes, and Venezuelan equine encephalitis virus and St. Louis encephalitis virus have been found in Mansonia titillans—one of the eight species newly recorded at Celestún. With the reserve attracting heavy tourism and hosting dense communities of birds and mammals, the presence of competent vector species creates precisely the ecological conditions under which zoonotic arboviruses can circulate undetected until they spill over into human populations.

Methodologically, the study also delivered a practical lesson for surveillance design: the backpack aspirator captured 94.70 percent of all mosquitoes across 15 species, while the BG-Sentinel traps, which excel at collecting human-biting species like Ae. aegypti, accounted for just 5.30 percent across nine species. For rare species such as Ae. angustivittatus, An. vestitipennis, Cq. venezuelensis, and Ma. titillans, both methods contributed in similar proportions, suggesting that combining techniques remains essential for a complete picture of diversity. The authors are candid about the limitations of a single wet-season pass through the reserve; each site was inspected only once, and dry-season sampling will be needed to capture seasonal shifts in species composition. They also call for intensified arbovirus testing on Isla de los Pájaros, whose hundreds of nesting pelicans, herons, frigatebirds, and cormorants make it a natural laboratory for understanding how mosquitoes, birds, and viruses interact in one of the Yucatán’s most ecologically vital corners. With 24 species now documented across the reserve—40 percent of Yucatán state’s entire mosquito fauna—Celestún has firmly established itself as a frontier for entomological discovery on Mexico’s Gulf coast.

Subject of Research: Mosquito species inventory and DNA barcoding in a Mexican mangrove biosphere reserve

Article Title: Mosquito fauna (Diptera: Culicidae) in the Ria Celestún Biosphere Reserve (RCBR) with a new record for Yucatán, México

Article References: Argaez-Sierra, D. G., Cigarroa-Toledo, N., Baak-Baak, C. M., Tzuc-Dzul, J. C., Cetina-Trejo, R. C., Talavera-Aguilar, L. G., Chi-Chim, W. A., Arana-Guardia, R., & García-Rejón, J. E. (2026). Mosquito fauna (Diptera: Culicidae) in the Ria Celestún Biosphere Reserve (RCBR) with a new record for Yucatán, México. Discover Animals, 3(1), Article 93. https://doi.org/10.1007/s44338-026-00253-4

Image Credits: AI Generated

DOI: 10.1007/s44338-026-00253-4

Keywords: mosquitoes, Culicidae, Anopheles gabaldoni, Ría Celestún Biosphere Reserve, Yucatán, DNA barcoding, COI gene, arboviruses, Aedes taeniorhynchus, mangroves, biodiversity, vector surveillance