Evidence map›Paper›PMID 41572323›Full record

ArticleParasites & vectors2026

Insecticide resistance profiles of Anopheles arabiensis and relationship with Microsporidia MB infection in two rice agroecosystems in Kenya.

Winfred K Mutwiri, Ephantus J Muturi, Josephine W Ngunjiri, Jackson W Muthengia, Nancy L M Budambula, Joshua K Muli, Genson Murithi, Franklin N Nyabuga, Njogu M Kimani, Moses M Muraya and 1 more

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Article in Parasites & vectors, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

Authors and funding

11 authors.

Winfred K MutwiriInternational Centre of Insect Physiology and Ecology, Nairobi, Kenya. Winfred.mutwiri@gmail.com.
Ephantus J MuturiU.S. Department of Agriculture, Agricultural Research Service, Crop Bioprotection Research Unit, National Center for Agricultural Utilization Research, Peoria, IL, USA. Ephantus.Muturi@usda.gov.
Josephine W NgunjiriUniversity of Embu, Embu, Kenya.
Jackson W MuthengiaUniversity of Embu, Embu, Kenya.
Nancy L M BudambulaUniversity of Embu, Embu, Kenya.
Joshua K MuliUniversity of Embu, Embu, Kenya.
Genson MurithiUniversity of Embu, Embu, Kenya.
Franklin N NyabugaUniversity of Embu, Embu, Kenya.
Njogu M KimaniUniversity of Embu, Embu, Kenya.
Moses M MurayaChuka University, Chuka, Kenya.
David P TchouassiInternational Centre of Insect Physiology and Ecology, Nairobi, Kenya. dtchouassi@icipe.org.

Funding

Wellcome Trust 222005/Z/20/Z
6 · The paper itself

Abstract

backgroundInsecticide resistance monitoring in vector populations is a key pillar of the Global Plan for Insecticide Resistance Management in malaria vectors. This study assessed the susceptibility of Anopheles arabiensis populations from Mwea and Ahero, Kenya to six insecticides. The association between insecticide resistance and Microsporidia MB infection, a symbiont known to block malaria transmission in An. arabiensis was also investigated.

methodsMosquitoes were exposed to permethrin, deltamethrin, alphacypermethrin, malathion, bendiocarb, and dichlorodiphenyltrichloroethane (DDT) using the Centers for Disease Control and Prevention (CDC) bottle bioassay. Resistance intensity and synergist bioassays for pyrethroids were conducted to evaluate the strength of resistance and the contribution of cytochrome P450s to pyrethroid resistance. Microsporidia MB infection was detected and quantified using qPCR.

resultsA total of 3120 females were tested. Populations from both study sites were susceptible to bendiocarb but resistant to all three pyrethroids. Mortality rates following exposure to alpha-cypermethrin, permethrin, and deltamethrin respectively were 0%, 4.7%, and 25.7% in Ahero, and 25.7%, 6.2%, and 26.6% in Mwea. Mortality increased with increasing permethrin concentration with 1 × , 2 × , 5 × , and 10 × values of 4.7%, 17.2%, 70.8%, and 84.4% respectively in Ahero and 6.2%, 29.4%, 85.3%, and 100% in Mwea. The Ahero population was susceptible to malathion but had reduced susceptibility to DDT (92.7%) while the Mwea population was susceptible to DDT and resistant to malathion (69.2%). Pre-exposure to piperonyl butoxide fully restored pyrethroid susceptibility in the Mwea population, indicating metabolic resistance and partially restored permethrin susceptibility (4.7 to 86.7%) in Ahero population, indicating the presence of other resistance mechanisms. Microsporidia MB was detected in Ahero population and mean (± se) infection density was significantly higher in mosquitoes that survived 2 × and 5 × permethrin doses (1017.6 ± 296.6) compared with those that succumbed to these doses (171.3 ± 78.0).

conclusionsAnopheles arabiensis populations from the two sites exhibit heterogeneous yet high levels of insecticide resistance, particularly to pyrethroids. The findings highlight the need to incorporate synergist-based interventions into resistance management strategies. This study is the first to document an association between Microsporidia MB density and the intensity of insecticide resistance in An. arabiensis, and further studies are needed to clarify this relationship and its significance to malaria control.

Indexed as

AnophelesInsecticide ResistanceInsecticidesMosquito VectorsAnimalsFemaleKenyaMalathionNitrilesPermethrinPyrethrinsInsecticidesMalathionNitrilesPermethrinPyrethrinsInsecticide resistanceIrrigationMalaria vectorsMicrosporidia MBPyrethroids

Identifiers

PMID41572323
PMCPMC12910883

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.