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Pyrethroids and DDT tolerance of Anopheles gambiae s.l. from Sengerema District, an area of intensive pesticide usage in north‐western Tanzania
Author(s) -
Philbert Anitha,
Lyantagaye Sylvester Leonard,
Pradel Gabriele,
Ngwa Che Julius,
Nkwengulila Gamba
Publication year - 2017
Publication title -
tropical medicine and international health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.056
H-Index - 114
eISSN - 1365-3156
pISSN - 1360-2276
DOI - 10.1111/tmi.12850
Subject(s) - deltamethrin , anopheles gambiae , permethrin , biology , pesticide , malaria , cyfluthrin , population , anopheles , toxicology , veterinary medicine , larva , tanzania , ecology , environmental health , environmental science , medicine , environmental planning , immunology
Abstract Objective To assess the susceptibility status of malaria vectors to pyrethroids and dichlorodiphenyltrichloroethane ( DDT ), characterise the mechanisms underlying resistance and evaluate the role of agro‐chemical use in resistance selection among malaria vectors in Sengerema agro‐ecosystem zone, Tanzania. Methods Mosquito larvae were collected from farms and reared to obtain adults. The susceptibility status of An. gambiae s.l. was assessed using WHO bioassay tests to permethrin, deltamethrin, lambdacyhalothrin, etofenprox, cyfluthrin and DDT . Resistant specimens were screened for knock‐down resistance gene (kdr), followed by sequencing both Western and Eastern African variants. A gas chromatography–mass spectrophotometer ( GC ‐ MS ) was used to determine pesticide residues in soil and sediments from mosquitoes’ breeding habitats. Results Anopheles gambiae s.l. was resistant to all the insecticides tested. The population of Anopheles gambiae s.l was composed of Anopheles arabiensis by 91%. The East African kdr (L1014S) allele was found in 13 of 305 specimens that survived insecticide exposure, with an allele frequency from 0.9% to 50%. DDT s residues were found in soils at a concentration up to 9.90 ng/g (dry weight). Conclusion The observed high resistance levels of An. gambiae s.l., the detection of kdr mutations and pesticide residues in mosquito breeding habitats demonstrate vector resistance mediated by pesticide usage. An integrated intervention through collaboration of agricultural, livestock and vector control units is vital.