This study was designed to assess whether churches in endemic dengue districts in Merida, Mexico provide suitable breeding habitats for mosquitoes and are potential sites for dengue virus (DENV) transmission. Churches were inspected for immature and adult mosquitoes once every week from November 2015 to October 2016. A total of 10,997 immatures of five species were collected. The most abundant species were Aedes aegypti (6,051) and Culex quinquefasciatus (3,018). The most common source of immature Ae. aegypti were buckets followed by disposable containers. Adult collections yielded 21,226 mosquitoes of nine species. The most common species were Cx. quinquefasciatus (15,215) and Ae. aegypti (3,902). Aedes aegypti were found all year long. Female Ae. aegypti (1,380) were sorted into pools (166) and assayed for flavivirus RNA by RT-PCR and Sanger sequencing. Two pools were positive for DENV (DENV-1 and 2). In conclusion, we demonstrated that some churches in Merida are infested with mosquitoes all year long and they potentially serve as sites for DENV transmission and should therefore be considered for inclusion in mosquito and arboviruses control and surveillance efforts.

Introducción. Aedes taeniorhynchus es un mosquito nativo de América. Es vector potencial de arbovirus de origen zoonótico. Los estados inmaduros se desarrollan en hábitats costeros inundables, principalmente en aguas salobres y pantanos. En temporada de lluvia generalmente invaden comunidades rurales y urbanas.Objetivo. Determinar la distribución temporal y el estado trófico de Ae. taeniorhynchus en la ciudad de Mérida, Yucatán, México.Materiales y Métodos. Entre agosto de 2016 y mayo de 2017 se visitaron casas (n = 40) para capturar mosquitos adultos. El estado trófico de los mosquitos fue determinado por examinación externa del abdomen de las hembras y se clasificó como no alimentados, alimentados, sub-grávidos y grávidos.Resultados. En las casas de la ciudad de Mérida, se capturaron 1,747 adultos de Ae. taeniorhynchus, de los cuales, 570 son machos y 1,177 son hembras. Hubo diferencia estadística significativa en el número de hembras capturadas por temporada (p≤0.01). En temporada de lluvia se capturó el 93.80% de las hembras de Ae. taeniorhynchus. El estado trófico estuvo constituido principalmente por hembras no alimentadas (n= 492) y grávidas (n= 363).Conclusión. Aedes taeniorhynchus fue capturado frecuentemente en temporada de lluvias. Aunque es mejor conocido por la agresividad de su picadura, representa un riesgo potencial para transmitir patógenos zoonóticos.

Aedes albopictus (Skuse) is a competent vector of dengue and Zika viruses in Mexico. Monitoring the level of resistance of local population is essential due to its epidemiological significance. This study aimed to identify mutations in the voltage-gated sodium channel (VGSC) as one of the mechanisms responsible for pyrethroid insecticide resistance in Ae. albopictus. Immature samples were collected in a rural town in Yucatan, Mexico, from May to October 2021. The pyrethroid insecticide lambda-cyhalothrin was impregnated in CDC bottles and bioassays were conducted on Ae. albopictus populations 3–5 days after emergence. The mosquitoes were susceptible to the insecticide. Females were taken for total DNA extraction. Fragments of domains II, III, and IV of the voltage-gated sodium channel (VGSC) were amplified and sequenced. The presence of synonymous and non-synonymous mutations was found in positions 1532 and 1534 of domain III of the sodium channel gene (VGSC). No mutant alleles in domain IV were detected. A homozygous mutant (ACG) coding for the amino acid threonine (1008Thr) was identified in domain II. Domain III included three heterozygous alleles (P1528S, L1530S, and Ile1410Thr). This last heterozygous allele is reported for the first time in Mexico. Homozygous mutants encoding the amino acids serine/serine and serine/proline in domain III were observed. These have been reported in Aedes aegypti from Mexico, but not yet in Ae. albopictus. This represents new findings for the region, as Ae. albopictus has only been introduced there for approximately five years. In conclusion, non-synonymous mutations were found in Ae. albopictus in a rural area of Yucatan, emphasizing the importance of integrated vector control to prevent Asian tiger mosquitoes from spreading these resistant alleles.

The genus Flavivirus (Family: Flaviviridae) comprises arboviruses with the capacity to infect humans and animals. It also integrates insect-specific viruses. This study aimed to identify Flavivirus in mosquitoes captured in 17 municipalities in Yucatan State, Mexico. The mosquitoes were caught in households from November 2021 to May 2022. A total of 4,321 adult mosquitoes from five species were caught. The most abundant were Culex quinquefasciatus (n = 3,563) and Aedes aegypti (n = 734). For molecular investigations, 600 female mosquitoes were split into groups of 10, mostly for species and site location. Reverse transcriptase polymerase chain reaction (RT-PCR) amplified a region of the NS5 gene to find the Flavivirus ribonucleic acids (RNA). A total of 24 pools that were positive for Flavivirus were detected in Ae. aegypti specimens and subsequently subjected to sequencing using the Sanger method. A total of 12 sequences matched the established quality criteria and were subsequently employed for sequence homology analysis. We found that one sequence corresponded to the Zika virus (ZIKV), and 11 sequences had sequence similarity with Phlebotomus-associated flavivirus (PAFV), an insect-specific virus (ISF). In conclusion, we found ZIKV in the Merida municipality, Yucatan State, which suggests that the virus is silently circulating. Phlebotomus-associated flavivirus is distributed in five municipalities in Yucatan State, Mexico. Future studies could focus on isolating this virus and studying its biological role within Ae. aegypti.

Taxonomic studies on mosquitoes are based on the morphological description of larvae and adults. However, few studies have focused on the morphological description of eggs despite their taxonomic value. The description of mosquito eggs by scanning electron microscopy (SEM) allows more detailed descriptions of the ornamentation of the egg, which can provide diagnostic characters of the species. The objective of the work was to describe the eggs of Psorophora cyanescens by SEM and provide fecundity data for the species. In general, Ps. cyanescens eggs are elliptical and very wide. The exochorion is characterized by polygon pattern, where each polygon consists of longitudinal ridges joined by cross-ridges defining regular "hexagonal" areas. Each longitudinal ridge consisting by a small tubercle. The small tubercles are irregular, rectangular, rounded, or tubular. The ornamentation of the exochorion also has long and conical tubercles throughout the egg region. The micropylar apparatus located in the anterior region of the egg has a prominent, continuous and thickness collar. Psorophora cyanescens laid mature eggs at 2.5 days post-feeding. The mean number of eggs per female was 82.20 (± 13.31). This is the first study that describes the ultrastructure of the morphology of the eggs of Ps. cyanescens by SEM. With the contribution of the present work, there are five species of the genus Psorophora whose eggs morphology is described by SEM: Ps. albigenu, Ps. albipes, Ps. columbiae, Ps. cyanescens, and Ps. ferox.

Aedes (Fredwardsius) vittatus (Bigot, 1861) has a native geographical distribution that encompasses tropical areas of Asia, Africa, and the Mediterranean region of Europe. In its natural range, this mosquito species is a potential vector of the dengue, chikungunya, Zika, and yellow fever viruses. Currently, Ae. vittatus is reported in the Caribbean countries of Cuba, Jamaica, and the Dominican Republic in América. We report the discovery of one female Ae. vittatuscaptured on September 11, 2024, in X-Calakoop, Tinum, located near a tourist site in Yucatán. Additionally, 11 mosquito species were found: Aedes aegypti(Linnaeus), Aedes albopictus (Skuse), Aedes bimaculatusCoquillett, Aedes cozumelensis Díaz Nájera, Aedes podographicusDyar and Knab, Aedes taeniorhynchus (Wiedemann), Culex coronatorDyar and Knab, Culex nigripalpus Theobald, Haemagogus mesodentatusKomp & Kumm, Limatus durhamii Theobald, and Toxorhynchites moctezuma (Dyar & Knab). Notably, Ae. albopictus was the most abundant mosquito in the collection, representing 77.5% in the adult stage and 63.5% in the larval stage. The identification of Ae. vittatus in México represents the first record for a mainland country. The discovery represents the 252nd species in the country and 49th in Yucatán. The increase in the distribution pattern may have implications for public health in tropical America.