Characterizing the insecticide resistance of Anopheles gambiae in Mali

Abstract

BackgroundThe impact of indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs), key components of the national malaria control strategy of Mali, is threatened by vector insecticide resistance. The objective of this study was to assess the level of insecticide resistance in Anopheles gambiae sensu lato populations from Mali against four classes of insecticide recommended for IRS: organochlorines (OCs), pyrethroids (PYs), carbamates (CAs) and organophosphates (OPs). Characterization of resistance was done in 13 sites across southern Mali and assessed presence and distribution of physiological mechanisms that included target-site modifications: knockdown resistance (kdr) and altered acetycholinesterase (AChE), and/or metabolic mechanisms: elevated esterases, glutathione S-transferases (GSTs), and monooxygenases.MethodsThe World Health Organization (WHO) tube test was used to determine phenotypic resistance of An.gambiae s.l. to: dichlorodiphenyltrichloroethane (DDT) (OC), deltamethrin (PY), lambda-cyhalothrin (PY), bendiocarb (CA), and fenitrothion (OP). Identification of sibling species and presence of the ace-1R and Leu-Phe kdr, resistance-associated mutations, were determined using polymerase chain reaction (PCR) technology. Biochemical assays were conducted to detect increased activity of GSTs, oxidases and esterases.ResultsPopulations tested showed high levels of resistance to DDT in all 13 sites, as well as increased resistance to deltamethrin and lambda-cyhalothrin in 12 out of 13 sites. Resistance to fenitrothion and bendiocarb was detected in 1 and 4 out of 13 sites, respectively. Anopheles coluzzii, An. gambiae sensu stricto and Anopheles arabiensis were identified with high allelic frequencies of kdr in all sites where each of the species were found (13, 12 and 10 sites, respectively). Relatively low allelic frequencies of ace-1R were detected in four sites where this assessment was conducted. Evidence of elevated insecticide metabolism, based on oxidase, GSTs and esterase detoxification, was also documented.ConclusionMultiple insecticide-resistance mechanisms have evolved in An. coluzzii, An. gambiae s.s. and An.arabiensis in Mali. These include at least two target site modifications: kdr, and ace-1R, as well as elevated metabolic detoxification systems (monooxygenases and esterases). The selection pressure for resistance could have risen from the use of these insecticides in agriculture, as well as in public health. Resistance management strategies, based on routine resistance monitoring to inform insecticide-based malaria vector control in Mali, are recommended.

Susceptibility profile and metabolic mechanisms involved in Aedes aegypti and Aedes albopictus resistant to DDT and deltamethrin in the Central African Republic

“…CAR has promoted use of long-lasting insecticidal nets as one of the main components of the national malaria control programme, with indoor residual spraying by households with insecticides available on the market, which we noted at nearly every study site. Therefore, insecticides used against other insects of medical or agricultural importance may exert indirect selection pressure on these two mosquito species [63, 64]. Similar observations have been made for resistance of Ae.…”

Putting evolution in elimination: Winning our ongoing battle with evolving malaria mosquitoes and parasites

“…It was probably observed early in this area due to the fact that South Africa already shifted to pyrethroids for indoor spraying in 1996 (Corbel & N′Guessan, ), but can be found in multiple sites across Africa nowadays (Barnes et al., ; Nwane et al., ; Sangba et al., ). Alarmingly, there are now countries reporting resistance to three (Djouaka, Atoyebi, et al., ; Djouaka, Riveron, et al., ; Menze et al., ; Olé Sangba et al., ; Riveron et al., , ) or all four classes of insecticides that we currently have at our disposal (Cisse et al., ; Edi, Koudou, Jones, Weetman, & Ranson, ) (Figure ).…”

A bibliometric analysis of literature on malaria vector resistance: (1996 – 2015)

“…Point mutations in mosquitos described as Knockdown resistance (kdr) was extensively investigated to understand the molecular aspects of Anopheles mosquito resistance. Knockdown resistance (kdr) is the most common form of insecticide resistance and has been reported in many African and Asian countries [20,81,[95][96][97][98][99][100][101][102][103][104]. One of the top cited articles also discussed the role of voltage gated sodium channels in insecticide resistance.…”

“…Most important challenges are the emergence of resistance to the new generation antimalarial drug resistance, artemisinins and the emergence of resistance among malaria vectors to common insecticides [12][13][14][15][16][17][18][19]. Insecticide resistance in malaria vectors is becoming a global concern because of reports on insecticide resistance from many countries in Africa [20][21][22][23][24]. Of particular concern is vector resistance to pyrethroids since they are the only class of insecticides approved for use in ITNs.…”