Entomological status of Anopheles sergentii and the first molecular investigation of its insecticide-resistant genes, kdr and ace-1 in Morocco.

Background & objectives: Prior to their elimination in 1974 and 2004, respectively, Plasmodium falciparum and P. vivax were the main native malaria parasites involved in disease transmission in Morocco. Imported cases of human malaria are still reported from the country. Anopheles labranchiae in northern Morocco and An. sergentii in the southern regions are the main malaria vectors. The bionomics and insecticide susceptibility of An. sergentii are poorly understood and need to be further studied to enhance the epidemiological surveillance of this important malaria vector. Methods: The adults and larvae of Anopheles sergentii were collected during the mosquito breeding season in 2015 and 2016 and environmental characteristics of their breeding sites were recorded. Blood meals were analyzed using PCR-RFLP. Alongside, the WHO routine susceptibility tests with DDT (4%) and malathion (5%) were conducted and An. sergentii specimens were screened for knockdown resistance (kdr) and acetyl cholinesterase encoding (ace-1) gene mutations. Results: Anopheles sergentii was observed during the summer and autumn seasons, feeding mainly on sheep, cows and also on humans. The WHO bioassays revealed complete susceptibility to DDT and malathion. Analysis of the sequences of the voltage-gated sodium channel gene revealed the absence of the kdr “Leu-Phe” mutation and PCR-RFLP revealed the absence of the G119S mutation in the ace-1. Interpretation & conclusion: With the increasing number of imported cases of human malaria in Morocco, the indiscriminate feeding behavior of this species may pose an infectious medical threat. Fortunately, the absence of insecticide resistance can ensure, for now, the efficiency of insecticides, as a part of the vector control program in controlling An. sergentii in Morocco.