Multiple Insecticide Resistance in Anopheles gambiae s.l. Populations from Burkina Faso, West Africa

Abstract

Malaria control programs are being jeopardized by the spread of insecticide resistance in mosquito vector populations. The situation in Burkina Faso is emblematic with Anopheles gambiae populations showing high levels of resistance to most available compounds. Although the frequency of insecticide target-site mutations including knockdown resistance (kdr) and insensitive acetylcholinesterase (Ace-1 R) alleles has been regularly monitored in the area, it is not known whether detoxifying enzymes contribute to the diversity of resistance phenotypes observed in the field. Here, we propose an update on the phenotypic diversity of insecticide resistance in An. gambiae populations sampled from 10 sites in Burkina Faso in 2010. Susceptibility to deltamethrin, permethrin, DDT, bendiocarb and fenithrotion was assessed. Test specimens (N = 30 per locality) were identified to species and molecular form and their genotype at the kdr and Ace-1 loci was determined. Detoxifying enzymes activities including non-specific esterases (NSEs), oxydases (cytochrome P450) and Glutathione S-Transferases (GSTs) were measured on single mosquitoes (N = 50) from each test locality and compared with the An. gambiae Kisumu susceptible reference strain. In all sites, mosquitoes demonstrated multiple resistance phenotypes, showing reduced mortality to several insecticidal compounds at the same time, although with considerable site-to-site variation. Both the kdr 1014L and Ace-1 R 119S resistant alleles were detected in the M and the S forms of An. gambiae, and were found together in specimens of the S form. Variation in detoxifying enzyme activities was observed within and between vector populations. Elevated levels of NSEs and GSTs were widespread, suggesting multiple resistance mechanisms segregate within An. gambiae populations from this country. By documenting the extent and diversity of insecticide resistance phenotypes and the putative combination of their underlying mechanisms in An. gambiae mosquitoes, our work prompts for new alternative strategies to be urgently developed for the control of major malaria vectors in Burkina Faso.

Multiple Resistances and Complex Mechanisms of Anopheles sinensis Mosquito: A Major Obstacle to Mosquito-Borne Diseases Control and Elimination in China

“…Previous investigations on metabolic activity in African An. gambiae confirmed that monooxygenases played an important role in the resistance to pyrethroids while COE was the major metabolic mechanism for organophosphates [47]–[49]. This correlates with our findings.…”

Baseline drivers of lymphatic filariasis in Burkina Faso

“…The lower levels of prevalence in 2000 could be explained by this coupled with the use of ivermectin close to the Dienkoa River (Borsboom et al, 2003). The intensive use of insecticide has, however, would contribute to the development of insecticide resistance in these cotton growing areas, and may have already done so (Diabate et al, 2002;Dabiré et al, 2009;Namountougou et al, 2012). LF risk in these areas may increase over time and should be therefore be monitored.…”

“…gambiae M form is potentially the more efficient vector than the S form (de Souza et al, 2012). Due to this region being very wet (annual rainfall of 800-1000 mm) and at a slightly higher elevation (300-500 m above the mean sea level) compared to the rest of the country, it is likely to be favoured by the S form, which may also contribute to the low prevalence of LF in this area (Bayoh et al, 2001;Kelly-Hope et al, 2006;Namountougou et al, 2012).…”

New approaches for integrated and cost-effective malaria vector control

“…After decades of optimism to further curb malaria, which was largely nurtured by the success of bed net campaigns, today vector control faces increased headwind once again. Although new research indicates that resistances of mosquitoes against insecticides might not compromise bed net and spraying campaigns as much as often reported [5][6][7] , those developments together with changes in vector behavior and alterations of vector species compositions may adversely affect current control efforts [7][8][9][10][11] . Improved biological larval control methods are a promising approach to fill in at the weak spots of adult control interventions that are currently in place.…”