Two mosquitoes can look alike and still belong to different species. This makes them difficult to identify by appearance alone, especially when a mosquito is damaged or when closely related species share similar features.

In Limpopo, malaria control teams monitor which mosquitoes are present to guide control efforts. The Anopheles group includes the main mosquitoes that spread malaria. Different species can behave differently and respond differently to insecticides, so knowing which species are present matters.

In a study funded by the NRF, researchers set out to find out whether a short section of mosquito DNA, called 18S rDNA, could support the usual method of identifying mosquitoes by their visible features.

The researchers examined 42 adult mosquitoes supplied by the Malaria Institute in Tzaneen. The institute had raised them from larvae collected in malaria-affected areas of Limpopo during routine mosquito monitoring between January and March 2022.

The mosquitoes had already been classified by their visible features. The researchers read the selected section of each mosquito’s DNA, looked for the closest matches in a public database and compared those matches with the original identifications. The test examined the mosquitoes’ own DNA to help identify them.

The paper lists the closest DNA matches for 36 mosquitoes. Of these, 21 most closely matched Anopheles gambiae, 10 matched Anopheles maculipalpis, four matched Anopheles squamosus and one matched Anopheles funestus. Both Anopheles gambiae and Anopheles funestus are known to spread malaria in South Africa.

The DNA results supported some of the original identifications and gave the researchers a reason to revisit others. For example, one mosquito had been classified as Culex by appearance, but its closest DNA match was Anopheles funestus. The DNA test helped identify the broader Anopheles group. Identifying the exact species was harder because some closely related mosquitoes shared very similar sequences in the section tested.

Overall, the DNA test helped narrow down the mosquitoes’ identities. For malaria teams, it could provide a second check when a mosquito is damaged or its features are hard to distinguish. The researchers recommend examining more mosquitoes and combining identification by appearance with tests that use additional sections of DNA. This could help teams identify which species are present with greater confidence and use that information to guide malaria control.