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

Abstract

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 F8Anopheles funestusstrains 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 withL119F-GSTe2genotypes. In contrast, forCYP6P9a_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 thatCYP6P9agene affects the feeding success and blood meal size ofAn. funestus. However, no correlation was found in the expression ofCYP6P9aand 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.