Mosquitoes (Diptera: Culicidae) Distribution in Thailand

Study Extent

Mosquito collection has been carried out across Thailand from 2007 to 2023 by experienced researches, skilled public health professionals, and ambitious graduate students, all of whom have worked in close collaboration with the invaluable assistance and support provided by the local residents residing in the various communities across the country.

Sampling

Mosquitoes were collected as part of various search projects and routine mosquito collections, employing appropriate collection techniques. After the collection, all mosquito specimens, including both immatures and adults, were transferred to the laboratory for further rearing or identification to the lowest possible taxonomic rank using well-established morphological keys or molecular techniques.

Method steps

1. Immature stages of mosquito were collected as part of routine larval surveys using dipping technique. Both larvae and pupae were transferred to climate-controlled insectary for further rearing into adult stage. Adults were then identified using well-established morphological keys. Light-emitting diodes (LEDs) (blue, green, yellow, and red) and 2 fluorescents (ultraviolet [UV] and white) lights were used in the light traps for collecting mosquitoes in urban Bangkok and field site of Kanchanaburi Province. Adult mosquitoes were collected as part of ‘mosquito surveillance projects’ research project primarily intended to compare the effectiveness of light traps equipped with different bulbs across the wavelength spectrum. Six light traps equipped with different lights were set-up in a Latin square experimental design and rotated between 6 trap site locations. Traps were operated simultaneously (18:00 to 06:00 h), with captured mosquitoes removed at 3-h intervals. Over 36 collection nights, 6 replications were conducted for each location with a total of 216 trap-nights. The collected mosquitoes were placed in freezer and then morphologically identified. All primary Anopheles species, including the Anopheles minimus complex, Anopheles maculatus group, and Anopheles dirus complex, were then further identified using molecular identification techniques. As part of ‘mosquito surveillance projects’, the effectiveness of the ‘gold standard’ outdoor human landing collection (OHLC) was also compared with alternative mosquito collection methods, namely human double net trap (HDNT), human decoy trap (HDT) and UV light trap (UVLT). The study was conducted in Sai Yok District, Kanchanaburi Province. All mosquito collection methods were performed during night-time (18:00 to 06:00 h). Similarly, the collected mosquitoes were initially identified using well-established morphological keys. Most of adult mosquito data were extracted from the public domain of the Thailand Malaria Elimination Program database. Mosquitoes were collected as part of routine mosquito surveys of Thailand Malaria Elimination Program using HLC technique across Thailand. The collection was performed during night-time (possibly 18:00 to 06:00 h) by experienced researches and skilled public health professionals. However, the collected mosquitoes were primarily identified using only well-established morphological keys.

Every mosquito specimen (belonging to the family Culicidae within the order Diptera) collected in Thailand underwent identification to determine their lowest specific taxonomic classification. The dataset contains 12,278 records of mainly Aedes, Anopheles, Armigeres, Culex, and Mansonia genus.

1. Aedes
   rank: genus
2. Anopheles
   rank: genus
3. Armigeres
   rank: genus
4. Culex
   rank: genus
5. Mansonia
   rank: genus

Mosquitoes were collected from 1,725 locations in 66 provinces across Thailand. The World Geodetic System 1984 (WGS84) was used as the standard reference for determining the precise geographic coordinates (latitude and longitude) in the dataset. However, in case of no geographic coordinates provided, the GPS coordinates were then indicated by the village/sub-district name found in the original dataset file using Google Earth. As a result, these coordinates do not represent precise geographic locations, but rather serve as representative locations within the corresponding village/sub-district.