Evidence of Metabolic Resistance in Pyrethroid Resistant Aedes aegypti Population from Lagos, Nigeria

Abstract

Background: Pyrethroid resistance in Aedes aegypti is of major concern to the control of several arboviral infections. The major mechanisms of Pyrethroid resistance in mosquitoes are target-site insensitivity and elevation in the activity of detoxification enzymes. In this study, we assessed the susceptibility status of Aedes aegypti population from Lagos to Pyrethroid and the impact of metabolic enzymes on resistance development. Methods: Larvae of Aedes aegypti were collected from differ ent habitats in Lagos Mainland Local Government Area, Lagos state. Adult mosquitoes of 2-5 days were exposed to diagnostic dose of permethrin and Deltamethrin using the CDC method. Synergist assay was done with pre-exposure of samples to PBO before exposure to insecticide. Esterase and GST activities were measured using standard protocol. Regression Probit was used to compute the KDT50 and KDT95. Analysis of variance was used to compare the difference in mean of enzymes activities. Results: Aedes aegypti population from the study location is resistant to permethrin (33% ) and Deltamethrin (80%) within the diagnostic time. PBO pre-exposure increases percentage knockdown from 33% to 82% and 80% to 87% for permethrin and Deltamethrin respectively. The activity of GST was higher (P<0.05) in permethrin exposed mosquitoes in comparison with unexposed. Conclusion: A robust insecticide resistance management (IRM) plan in Lagos should take into consideration strategies for addressing the effects of metabolic enzymes in resistance development .

First Detection and Co-occurrence of kdr (F1534C and S989P) Mutations in Multiple Insecticides Resistant Aedes aegypti in Nigeria

“…Results from this study showed resistance to DDT and pyrethroid in the two study communities, similar to previous reports from Lagos State and other parts of southern Nigeria where resistance to DDT has been recorded in Aedes aegypti [6][7][8]. Resistance to bendiocarb was reported in Majidun community similar to previous report from Kwara State, north-central Nigeria [6] though a similar study in Lagos had reported susceptibility of Aedes aegypti in Lagos State to carbamates [7].…”

“…However, resistance to insecticides is being reported in different mosquito species including Aedes aegypti in various parts of the world. In Nigeria, resistance to DDT, pyrethroids and carbamates have been reported in Aedes aegypti from different parts of the country [5][6][7][8]. Insecticide resistances in mosquitoes in mainly as a result of the activities of detoxifying enzymes and mutation of the target sites.…”

“…Detoxification enzymes that have been linked to insecticide resistance include, cytochrome P450 monooxygenases (P450s), carboxylesterases (COEs), and glutathione S-transferases (GSTs). The impact of these detoxifying enzymes in the resistance phenotype expressed by Aedes mosquitoes has been highlighted in some studies in different parts of the world [7][8][9][10][11]. Knockdown resistance (kdr) has been described and associated in DDT and pyrethroid resistance in Aedes [12].…”