Genes involved in multiple insecticide resistance in anopheles gambiae and anopheles coluzzii from kpomé a tomatoes growing area in the southern benin

Authors:Rousseau Djouaka , Innocent Djègbè *, Romaric Akoton , Razack Adéoti , Genevieve Tchigossou
Int J Biol Med Res. 2018; 9(1): 6224-6231  |  PDF File


Background and objectives: Long lasting Insecticidal Nets (LLINs) and Indoor Residual Spraying (IRS) are used to control malaria vectors in Benin. It is known that the main threat to effective malaria vector control is the selection of insecticide resistance in field Anopheles population. This study aimed to generate baseline data on the mechanisms involved in insecticide resistance in An. gambiae s.l. population from Kpomé. This information is useful for a proper evaluation of new formulations of vector control tools expected to be deployed in resistance management. Methods: Indoor-resting Anopheles mosquitoes were collected using electric aspirators. The insecticide susceptibility level of F1 adult offspring of An. gambiae s.l. was assessed using the WHO standardprotocol. Genotyping of insecticide resistant alleles and Plasmodium detections were carried out using TaqMan assays. Results: WHO susceptibility test showed that An. gambiae s.l. from Kpome is highly resistant to DDT and permethrin. Moderate resistance level was recorded with deltamethrin and dieldrin, whereas full susceptibility was observed with bendiocarb and malathion. Molecular analysis of Plasmodium infections showed an infection rate of 13.2 % for An. gambiae s.l. Both L1014F and L1014S kdr mutations were found in this population of An. gambiae s.l. with high distribution of the L1014F resistant allele. Rdl and GSTe2 mutations were also detected in this population. The allelic frequencies of 22% and 37.5% were recorded for Rdl mutation (A296S) in An. coluzzii and An. gambiae s.s. respectively. In these same species, the allelic frequencies of GSTe2 mutation (L119S) were 26.47% and 7.14% respectively. Interpretation and conclusion: The observed co-occurrence of L1014F, L1014S, A296S and L119S mutations in both An. coluzzii and An. gambiae s.s. is worrisome. The presence of L1014S allele in this mosquito population suggested the spreading of this gene across Benin. The operational impact of these resistance genes on malaria control strategies needs further exploration in other malaria endemic areas.