Evidence of a multiple insecticide resistance in the malaria vector Anopheles funestus in South West Nigeria

The Nigerian Government is scaling up the distribution of insecticide-treated bed nets for malaria control, but the lack of surveillance data, especially in the Sudan/Sahel region of the country, may hinder targeting priority populations. Here, the vectorial role and insecticide resistance profile of a population of a major malaria vector Anopheles funestus sensu stricto from Sahel of Nigeria was characterised. An. funestus s.s. was the only vector found, with a high human blood index (100%) and a biting rate of 5.3/person/night. High Plasmodium falciparum infection was discovered (sporozoite rate = 54.55%). The population is resistant to permethrin (mortality = 48.30%, LT50 = 65.76 min), deltamethrin, DDT (dichlorodiphenyltrichloroethane) and bendiocarb, with mortalities of 29.44%, 56.34% and 54.05%, respectively. Cone-bioassays established loss of efficacy of the pyrethroid-only long-lasting insecticidal nets (LLINs); but 100% recovery of susceptibility was obtained for piperonylbutoxide (PBO)-containing PermaNet®3.0. Synergist bioassays with PBO and diethyl maleate recovered susceptibility, implicating CYP450s (permethrin mortality = 78.73%, χ2 = 22.33, P < 0.0001) and GSTs (DDT mortality = 81.44%, χ2 = 19.12, P < 0.0001). A high frequency of 119F GSTe2 mutation (0.84) was observed (OR = 16, χ2 = 3.40, P = 0.05), suggesting the preeminent role of metabolic resistance. These findings highlight challenges associated with deployment of LLINs and indoor residual spraying (IRS) in Nigeria.

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Multiple insecticide resistance in an infected population of the malaria vector Anopheles funestus in Benin

Parasites & Vectors ◽

10.1186/s13071-016-1723-y ◽

2016 ◽

Vol 9 (1) ◽

Cited By ~ 37

Author(s):

Rousseau Djouaka ◽

Jacob M. Riveron ◽

Akadiri Yessoufou ◽

Genevieve Tchigossou ◽

Romaric Akoton ◽

...

Keyword(s):

Insecticide Resistance ◽

Malaria Vector ◽

Anopheles Funestus ◽

Infected Population

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Influence of GST- and P450-based metabolic resistance to pyrethroids on blood feeding in the major African malaria vector Anopheles funestus

10.1101/2020.03.16.993535 ◽

2020 ◽

Author(s):

Lynda Nouage ◽

Emmanuel Elanga-Ndille ◽

Achille Binyang ◽

Magellan Tchouakui ◽

Tatiane Atsatse ◽

...

Keyword(s):

Insecticide Resistance ◽

Malaria Vector ◽

Resistance Genes ◽

Blood Meal ◽

Anopheles Funestus ◽

Blood Feeding ◽

Meal Size ◽

Metabolic Resistance ◽

Feeding Success ◽

Blood Meal Size

AbstractInsecticide resistance genes are often associated with pleiotropic effects on various mosquito life-history traits. However, very little information is available on the impact of insecticide resistance, especially metabolic resistance, on blood feeding process in mosquitoes. Here, using two recently detected DNA-based metabolic markers in the major malaria vector, An. funestus, we investigated how metabolic resistance genes could affect blood meal intake.After allowing both field F1 and lab F8 Anopheles funestus strains to feed on human arm for 30 minutes, we assessed the association between key parameters of blood meal process including, probing time, feeding duration, blood feeding success and blood meal size, and markers of glutathione S-transferase (L119F-GSTe2) and cytochrome P450 (CYP6P9a_R) - mediated metabolic resistance. None of the parameters of blood meal process was associated with L119F-GSTe2 genotypes. In contrast, for CYP6P9a_R, homozygote resistant mosquitoes were significantly more able to blood-feed than homozygote susceptible (OR = 3.3; CI 95%: 1.4-7.7; P =0.01) mosquitoes. Moreover, the volume of blood meal ingested by CYP6P9a-SS mosquitoes was lower than that of CYP6P9a-RS (P<0.004) and of CYP6P9a-RR (P<0.006). This suggests that CYP6P9a gene affects the feeding success and blood meal size of An. funestus. However, no correlation was found in the expression of CYP6P9a and that of genes encoding for salivary proteins involved in blood meal process.This study suggests that P450-based metabolic resistance may increase the blood feeding ability of malaria vectors and potential impacting their vectorial capacity.

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