Evidence of multiple insecticide resistance mechanisms in Anopheles gambiae populations in Bangui, Central African Republic

Abstract

BackgroundKnowledge of insecticide resistance status in the main malaria vectors is an essential component of effective malaria vector control. This study presents the first evaluation of the status of insecticide resistance in Anopheles gambiae populations from Bangui, the Central African Republic.Methods Anopheles mosquitoes were reared from larvae collected in seven districts of Bangui between September to November 2014. The World Health Organisation’s bioassay susceptibility tests to lambda-cyhalothrin (0.05%), deltamethrin (0.05%), DDT (4%), malathion (5%), fenitrothion (1%) and bendiocarb (0.1%) were performed on adult females. Species and molecular forms as well as the presence of L1014F kdr and Ace-1 R mutations were assessed by PCR. Additional tests were conducted to assess metabolic resistance status.ResultsAfter 1 h exposure, a significant difference of knockdown effect was observed between districts in all insecticides tested except deltamethrin and malathion. The mortality rate (MR) of pyrethroids group ranging from 27% (CI: 19–37.5) in Petevo to 86% (CI: 77.6–92.1) in Gbanikola; while for DDT, MR ranged from 5% (CI: 1.6–11.3) in Centre-ville to 39% (CI: 29.4–49.3) in Ouango. For the organophosphate group a MR of 100% was observed in all districts except Gbanikola where a MR of 96% (CI: 90–98.9) was recorded. The mortality induced by bendiocarb was very heterogeneous, ranging from 75% (CI: 62.8–82.8) in Yapele to 99% (CI: 84.5–100) in Centre-ville. A high level of kdr-w (L1014F) frequency was observed in all districts ranging from 93 to 100%; however, no kdr-e (L1014S) and Ace-1 R mutation were found in all tested mosquitoes. Data of biochemical analysis showed significant overexpression activities of cytochrome P450, GST and esterases in Gbanikola and Yapele (χ 2 = 31.85, df = 2, P < 0.001). By contrast, esterases activities using α and β-naphthyl acetate were significantly low in mosquitoes from PK10 and Ouango in comparison to Kisumu strain (χ 2 = 17.34, df = 2, P < 0.005).ConclusionsEvidence of resistance to DDT and pyrethroids as well as precocious emergence of resistance to carbamates were detected among A. gambiae mosquitoes from Bangui, including target-site mutations and metabolic mechanisms. The co-existence of these resistance mechanisms in A. gambiae may be a serious obstacle for the future success of malaria control programmes in this region.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1965-8) contains supplementary material, which is available to authorized users.

Exploring insecticide resistance mechanisms in three major malaria vectors from Bangui in Central African Republic

“…culuzzii are highly resistant to pyrethroids and DDT Both species were fully resistant to both types of pyrethroid: deltamethrin (type II) and permethrin (type I), and highly resistant to DDT. These findings are in contrast with the results of previous study performed at Bangui in 2014 indicating the moderate level of resistance to deltamethrin with mortality rate varying from 68.1% to 74.6% [25]. The high pyrethroid resistance reported in this study in Bangui An.…”

“…This is in contrast with the previous work done at Bangui where An. coluzzii was not collected from seven districts in Bangui [25]. However, our findings are consistent with previous results in Central Africa notably in Cameroon showing that An.…”

“…funestus s.l. in Bangui [25,26]. To implement an optimal strategy to prevent malaria and reduce its burden in this country, up-to-date information is required about vector characterization as well as the molecular basis of insecticide resistance.…”

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 ).…”

Piperonyl Butoxide: An Enhancing Arsenal for an Adomant Foe

“…At present, LLINs are no longer showing the impact it has shown few decades ago in Africa where there has been reports of rapid decline of child mortality and mobidirty [7] due to mosquitoes insecticides resistance problem [8][9][10][11]. Changing of IRS compound have caused some resistant mosquitoes to be susceptible but with time they have built resistance [9,[12][13][14][15]. Inseticides detoxification enzymes have been expressed in higher level and caused insecticides tolerance which increases the survivorship of mosquitoes and increase the disease risk [16].…”