Reduced susceptibility to DDT in field populations of Anopheles quadriannulatus and Anopheles arabiensis in Malawi: evidence for larval selection

Mzilahowa, T., Ball, Amanda, Bass, C., Morgan, John, Nyoni, B., Steen, Keith ORCID: https://orcid.org/0000-0002-8933-8643, Donnelly, Martin ORCID: https://orcid.org/0000-0001-5218-1497 and Wilding, Craig (2008) 'Reduced susceptibility to DDT in field populations of Anopheles quadriannulatus and Anopheles arabiensis in Malawi: evidence for larval selection'. Medical and Veterinary Entomology, Vol 22, Issue 3, pp. 258-263.

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Abstract

Bioassays for insecticide resistance in adult mosquitoes were conducted on samples of Anopheles gambiae Giles s.l. (Diptera: Culicidae) species collected as larvae from breeding sites in the lower Shire Valley, Malawi. The results indicate full susceptibility to permethrin, deltamethrin and malathion, but reduced susceptibility to DDT in one sample from Thorn (LT50 of 8.39min for females and 25.09min for males). Polymerase chain reaction-based species identification of the mosquitoes assayed revealed a Mixture of Anopheles arabiensis Patton and Anopheles quandriannulatus (Theobold). The LT50 did not differ significantly between species. Genotyping of the L1014F and L1014S kdr alleles showed all mosquito specimens to be homozygous wild type: thus the reduced Susceptibility detected is not attributable to target site insensitivity and instead is likely to be metabolic in nature. Anopheles quadriannulatus is characteristically zoophagic and exophilic. Indeed. of 82 Anopheles collected through knockdown collections within dwellings. only one was An. quadriannulatus and the rest were An. arabiensis. They are unlikely, therefore, to have been exposed to selection pressure arising from insecticide-treated net Usage or to DDT indoor residual spraying Therefore, it IS Suggested that this example of reduced susceptibility to DDT in An. quandriannulatus reflects selection in the larval stages.

Item Type:	Article
Uncontrolled Keywords:	anopheles arabiensis anopheles quadriannulatus agriculture ddt selection malawi knockdown resistance kdr agricultural use gambiae complex south-africa malaria pyrethroids gene identification insecticides metabolites
Subjects:	WC Communicable Diseases > Tropical and Parasitic Diseases > WC 765 Prevention and control WC Communicable Diseases > Tropical and Parasitic Diseases > WC 750 Malaria QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control QX Parasitology > Insects. Other Parasites > QX 510 Mosquitoes QX Parasitology > Insects. Other Parasites > QX 650 Insect vectors QX Parasitology > Insects. Other Parasites > QX 515 Anopheles
Digital Object Identifer (DOI):	https://doi.org/10.1111/j.1365-2915.2008.00736.x
Depositing User:	Users 183 not found.
Date Deposited:	05 Jul 2010 09:54
Last Modified:	17 Jul 2020 10:58
URI:	https://archive.lstmed.ac.uk/id/eprint/877

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