PLOS NTDs: Aedes aegypti in coastal Kenya is more resistant to permethrin, and the pattern does not follow maternal lineage

A paper of 8 September 2026 in PLOS Neglected Tropical Diseases surveyed mitochondrial DNA and insecticide response of Aedes aegypti in Kenya. Coastal populations were clearly resistant to permethrin and still susceptible to bendiocarb, deltamethrin and fenitrothion.

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Main points

• A team at icipe (Kenya) and the University of Cambridge sequenced 175 new mitochondrial COI fragments from Kenyan mosquitoes and compared them with global reference sequences. Genetic structure is not explained by geographic distance alone.
• Nairobi and Mombasa, more than 400 km apart, were more alike in maternal lineage than expected. Ukunda, about 30 km from Mombasa, was more distinct. Populations in western Kenya were genetically separate.
• No non-African maternal lineage was seen in the mitochondrial samples from Rabai and Mombasa. Part of the Marigat and Ukunda samples sat closer to West African and non-African lineages.
• Bioassays: high susceptibility to bendiocarb, deltamethrin and fenitrothion; marked permethrin resistance, especially on the coast. The kdr allele 1534C was highest in coastal populations, in the same direction as the phenotype. Resistance was not tied to mitochondrial lineage. The authors point to local selection, even though Kenya has no organised control programme aimed at Ae. aegypti.

VPMA’s note

The same mosquito species can be resistant to one active ingredient and still susceptible to another, and a maternal-lineage map does not replace a susceptibility test. Do not use the Kenya result to describe the situation in Vietnam.

Source: PLOS Neglected Tropical Diseases (summarised in English by VPMA). Read the Vietnamese page.

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