scholarly journals An. gambiae s.l. exhibit high intensity pyrethroid resistance throughout Southern and Central Mali (2016-2018); PBO or next generation LLINs may provide greater control

2020 ◽  
Author(s):  
Arthur Sovi ◽  
Chitan Keita ◽  
Youssouf Sinaba ◽  
Abdourhamane Dicko ◽  
Ibrahim Traore ◽  
...  
Keyword(s):  
High Intensity ◽  
Pyrethroid Resistance ◽  
Fold Increase ◽  
Malaria Vectors ◽  
Effective Control ◽  
The Past ◽  
Pirimiphos Methyl ◽  
Anopheles Gambiae S.L ◽  
Agricultural Use ◽  
Rotation Strategy

Abstract Background: Millions of pyrethroid LLINs have been distributed in Mali during the past 20 years which, along with agricultural use, has increased the selection pressure on malaria vector populations. This study investigated pyrethroid resistance intensity and susceptible status of malaria vectors to alternative insecticides to guide choice of insecticides for LLINs and IRS for effective control of malaria vectors. Methods: For 3 years between 2016 and 2018, susceptibility testing was conducted annually in 14-16 sites covering southern and central Mali. Anopheles gambiae s.l. were collected from larval sites and adult mosquitoes exposed in WHO tube tests to diagnostic doses of bendiocarb (0.1%) and pirimiphos-methyl (0.25%). Resistance intensity tests were conducted using CDC bottle bioassays (2016-17) and WHO tube tests (2018) at 1 × , 2 × , 5 × , and 10 × the diagnostic concentration of permethrin, deltamethrin and alpha-cypermethrin. WHO tube tests were conducted with pre-exposure to the synergist PBO followed by permethrin or deltamethrin. Chlorfenapyr was tested in CDC bottle bioassays at 100µg active ingredient per bottle and clothianidin at 2% in WHO tube tests. PCR was performed to identify species within the An. gambiae complex. Results: In all sites An. gambiae s.l. showed high intensity resistance to permethrin and deltamethrin in CDC bottle bioassay tests in 2016 and 2017. In 2018, WHO intensity tests resulted in survivors at all sites for permethrin, deltamethrin and alpha-cypermethrin when tested at 10× the diagnostic dose. Across all sites mean mortality was 33.7% with permethrin (0.75%) compared with 71.8% when pre-exposed to PBO (4%), representing a 2.13 fold increase in mortality. A similar trend was recorded for deltamethrin. There was susceptibility to pirimiphos-methyl, chlorfenapyr and clothianidin in all surveyed sites, including current IRS sites in Mopti Region. An. coluzzii was the primary species in 4 of 6 regions. Conclusions: Widespread high intensity pyrethroid resistance was recorded during 2016-18 and is likely to compromise the effectiveness of pyrethroid LLINs in Mali. PBO or chlrofenapyr LLINs should provide improved control of An. gambiae s.l. Clothianidin and pirimiphos-methyl insecticides are currently being used for IRS as part of a rotation strategy based on susceptibility being confirmed in this study.

scholarly journals An. gambiae s.l. exhibit high intensity pyrethroid resistance throughout Southern and Central Mali (2016-2018); PBO or next generation LLINs may provide greater control

2020 ◽  
Author(s):  
Arthur Sovi ◽  
Chitan Keita ◽  
Youssouf Sinaba ◽  
Abdourhamane Dicko ◽  
Ibrahim Traore ◽  
...  
Keyword(s):  
High Intensity ◽  
Pyrethroid Resistance ◽  
Fold Increase ◽  
Malaria Vectors ◽  
Effective Control ◽  
The Past ◽  
Pirimiphos Methyl ◽  
Anopheles Gambiae S.L ◽  
Agricultural Use ◽  
Rotation Strategy

Abstract Background: Millions of pyrethroid LLINs have been distributed in Mali during the past 20 years which, along with agricultural use, has increased the selection pressure on malaria vector populations. This study investigated pyrethroid resistance intensity and susceptible status of malaria vectors to alternative insecticides to guide choice of insecticides for LLINs and IRS for effective control of malaria vectors. Methods: For 3 years between 2016 and 2018, susceptibility testing was conducted annually in 14-16 sites covering southern and central Mali. Anopheles gambiae s.l. were collected from larval sites and adult mosquitoes exposed in WHO tube tests to diagnostic doses of bendiocarb (0.1%) and pirimiphos-methyl (0.25%). Resistance intensity tests were conducted using CDC bottle bioassays (2016-17) and WHO tube tests (2018) at 1 × , 2 × , 5 × , and 10 × the diagnostic concentration of permethrin, deltamethrin and alpha-cypermethrin. WHO tube tests were conducted with pre-exposure to the synergist PBO followed by permethrin or deltamethrin. Chlorfenapyr was tested in CDC bottle bioassays at 100µg active ingredient per bottle and clothianidin at 2% in WHO tube tests. PCR was performed to identify species within the An. gambiae complex. Results: In all sites An. gambiae s.l. showed high intensity resistance to permethrin and deltamethrin in CDC bottle bioassay tests in 2016 and 2017. In 2018, WHO intensity tests resulted in survivors at all sites for permethrin, deltamethrin and alpha-cypermethrin when tested at 10× the diagnostic dose. Across all sites mean mortality was 33.7% with permethrin (0.75%) compared with 71.8% when pre-exposed to PBO (4%), representing a 2.13 fold increase in mortality. A similar trend was recorded for deltamethrin. There was susceptibility to pirimiphos-methyl, chlorfenapyr and clothianidin in all surveyed sites, including current IRS sites in Mopti Region. An. coluzzii was the primary species in 4 of 6 regions. Conclusions: Widespread high intensity pyrethroid resistance was recorded during 2016-18 and is likely to compromise the effectiveness of pyrethroid LLINs in Mali. PBO or chlrofenapyr LLINs should provide improved control of An. gambiae s.l. Clothianidin and pirimiphos-methyl insecticides are currently being used for IRS as part of a rotation strategy based on susceptibility being confirmed in this study.

scholarly journals An. gambiae s.l. exhibit high intensity pyrethroid resistance throughout Southern and Central Mali (2016-2018); PBO or next generation LLINs may provide greater control

2020 ◽  
Author(s):  
Arthur Sovi ◽  
Chitan Keita ◽  
Youssouf Sinaba ◽  
Abdourhamane Dicko ◽  
Ibrahim Traore ◽  
...  
Keyword(s):  
High Intensity ◽  
Susceptibility Testing ◽  
Pyrethroid Resistance ◽  
Fold Increase ◽  
Malaria Vectors ◽  
Effective Control ◽  
The Past ◽  
Pirimiphos Methyl ◽  
Agricultural Use ◽  
Rotation Strategy

Abstract Background: Millions of pyrethroid LLINs have been distributed in Mali during the past 20 years which, along with agricultural use, has increased the selection pressure on malaria vector populations. This study investigated pyrethroid resistance intensity and susceptible status of malaria vectors to alternative insecticides to guide choice of insecticides for LLINs and IRS for effective control of malaria vectors.Methods: For 3 years between 2016 and 2018, susceptibility testing was conducted annually in 14-16 sites covering southern and central Mali. Anopheles gambiae s.l. were collected from larval sites and adult mosquitoes exposed in WHO tube tests to diagnostic doses of bendiocarb (0.1%) and pirimiphos-methyl (0.25%). Resistance intensity tests were conducted using CDC bottle bioassays (2016-17) and WHO tube tests (2018) at 1×, 2×, 5×, and 10× the diagnostic concentration of permethrin, deltamethrin and alpha-cypermethrin. WHO tube tests were conducted with pre-exposure to the synergist PBO followed by permethrin or deltamethrin. Chlorfenapyr was tested in CDC bottle bioassays at 100µg active ingredient per bottle and clothianidin at 2% in WHO tube tests. PCR was performed to identify species within the An. gambiae complex.Results: In all sites An. gambiae s.l. showed high intensity resistance to permethrin and deltamethrin in CDC bottle bioassay tests in 2016 and 2017. In 2018, WHO intensity tests resulted in survivors at all sites for permethrin, deltamethrin and alpha-cypermethrin when tested at 10× the diagnostic dose. Across all sites mean mortality was 33.7% with permethrin (0.75%) compared with 71.8% when pre-exposed to PBO (4%), representing a 2.13 fold increase in mortality. A similar trend was recorded for deltamethrin. There was susceptibility to pirimiphos-methyl, chlorfenapyr and clothianidin in all surveyed sites, including current IRS sites in Mopti Region. An. coluzzii was the primary species in 4 of 6 regions.Conclusions: Widespread high intensity pyrethroid resistance was recorded during 2016-18 and is likely to compromise the effectiveness of pyrethroid LLINs in Mali. PBO or chlrofenapyr LLINs should provide improved control of An. gambiae s.l. Clothianidin and pirimiphos-methyl insecticides are currently being used for IRS as part of a rotation strategy based on susceptibility being confirmed in this study.

scholarly journals Anopheles gambiae (s.l.) exhibit high intensity pyrethroid resistance throughout Southern and Central Mali (2016–2018): PBO or next generation LLINs may provide greater control

2020 ◽  
Author(s):  
Arthur Sovi ◽  
Chitan Keita ◽  
Youssouf Sinaba ◽  
Abdourhamane Dicko ◽  
Ibrahim Traore ◽  
...  
Keyword(s):  
Anopheles Gambiae ◽  
High Intensity ◽  
Pyrethroid Resistance ◽  
Fold Increase ◽  
Malaria Vectors ◽  
Effective Control ◽  
Pirimiphos Methyl ◽  
Anopheles Gambiae S.L ◽  
Agricultural Use ◽  
Rotation Strategy

Abstract Background: Millions of pyrethroid LLINs have been distributed in Mali during the past 20 years which, along with agricultural use, has increased the selection pressure on malaria vector populations. This study investigated pyrethroid resistance intensity and susceptible status of malaria vectors to alternative insecticides to guide choice of insecticides for LLINs and IRS for effective control of malaria vectors. Methods: For 3 years between 2016 and 2018, susceptibility testing was conducted annually in 14–16 sites covering southern and central Mali. Anopheles gambiae (s.l.) were collected from larval sites and adult mosquitoes exposed in WHO tube tests to diagnostic doses of bendiocarb (0.1%) and pirimiphos-methyl (0.25%). Resistance intensity tests were conducted using CDC bottle bioassays (2016–2017) and WHO tube tests (2018) at 1×, 2×, 5×, and 10× the diagnostic concentration of permethrin, deltamethrin and alpha-cypermethrin. WHO tube tests were conducted with pre-exposure to the synergist PBO followed by permethrin or deltamethrin. Chlorfenapyr was tested in CDC bottle bioassays at 100 µg active ingredient per bottle and clothianidin at 2% in WHO tube tests. PCR was performed to identify species within the An. gambiae complex. Results: In all sites An. gambiae (s.l.) showed high intensity resistance to permethrin and deltamethrin in CDC bottle bioassay tests in 2016 and 2017. In 2018, the WHO intensity tests resulted in survivors at all sites for permethrin, deltamethrin and alpha-cypermethrin when tested at 10× the diagnostic dose. Across all sites mean mortality was 33.7% with permethrin (0.75%) compared with 71.8% when pre-exposed to PBO (4%), representing a 2.13-fold increase in mortality. A similar trend was recorded for deltamethrin. There was susceptibility to pirimiphos-methyl, chlorfenapyr and clothianidin in all surveyed sites, including current IRS sites in Mopti Region. An. coluzzii was the primary species in 4 of 6 regions. Conclusions: Widespread high intensity pyrethroid resistance was recorded during 2016–2018 and is likely to compromise the effectiveness of pyrethroid LLINs in Mali. PBO or chlrofenapyr LLINs should provide improved control of An. gambiae (s.l.). Clothianidin and pirimiphos-methyl insecticides are currently being used for IRS as part of a rotation strategy based on susceptibility being confirmed in this study.

scholarly journals Phenotypic Insecticide Resistance in Anopheles gambiae (Diptera: Culicidae): Specific Characterization of Underlying Resistance Mechanisms Still Matters

2020 ◽  
Author(s):  
Adandé A Medjigbodo ◽  
Luc S Djogbenou ◽  
Aubin A Koumba ◽  
Laurette Djossou ◽  
Athanase Badolo ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Resistance Mechanisms ◽  
Malaria Vectors ◽  
Effective Control ◽  
Anopheles Coluzzii ◽  
Anopheles Gambiae S.S ◽  
Diagnostic Dose ◽  
Pirimiphos Methyl ◽  
Old Adult

Abstract An effective control of malaria vectors requires an extensive knowledge of mechanisms underlying the resistance-phenotypes developed by these vectors against insecticides. We investigated Anopheles gambiae mosquitoes from Benin and Togo for their intensity of insecticide resistance and we discussed the involvement of genotyped mechanisms in the resistance-phenotypes observed. Three- to five-day-old adult mosquitoes emerged from field and laboratory An. gambiae larvae were assayed using WHO tube intensity tests against various doses of deltamethrin: 1× (0.05%); 2× (0.1%); 5× (0.25%); 7.5× (0.375%) and those of pirimiphos-methyl: 0.5× (0.125%); 1× (0.25%). Members of An. gambiae complex were screened in field populations using polymerase chain reaction (PCR) assays. The presence of kdrR(1014F/1014S) and ace-1R(119S) mutations was also investigated using TaqMan and PCR-RFLP techniques, respectively. Anopheles gambiae from field were very resistant to deltamethrin, whereas KisKdr and AcerKdrKis strains displayed 100% mortality rates at 2× the diagnostic dose. In contrast, the field mosquitoes displayed a low resistance-intensity against 1× the diagnostic dose of pirimiphos-methyl, whereas AcerKis and AcerKdrKis strains showed susceptibility at 0.5× the diagnostic dose. Anopheles gambiae s.s., Anopheles coluzzii, and Anopheles arabiensis were identified. Allelic frequencies of kdrR (1014F) and ace-1R (119S) mutations in the field populations varied from 0.65 to 1 and 0 to 0.84, respectively. The field An. gambiae displayed high-resistance levels against deltamethrin and pirimiphos-methyl when compared with those of the laboratory An. gambiae-resistant strains. These results exhibit the complexity of underlying insecticide resistance mechanisms in these field malaria vectors.

scholarly journals Pyrethroid Resistance Aggravation in Ugandan Malaria Vectors Is Reducing Bednet Efficacy

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 415
Author(s):  
Magellan Tchouakui ◽  
Leon M. J. Mugenzi ◽  
Benjamin D. Menze ◽  
Jude N. T. Khaukha ◽  
Williams Tchapga ◽  
...  
Keyword(s):  
High Intensity ◽  
Pyrethroid Resistance ◽  
Anopheles Funestus ◽  
Resistance Mechanisms ◽  
Malaria Vectors ◽  
Insecticide Treated Nets ◽  
Over Expression ◽  
Cytochrome P450 Genes ◽  
Long Lasting Insecticidal Nets ◽  
Urgent Action

Monitoring cases of insecticide resistance aggravation and the effect on the efficacy of control tools is crucial for successful malaria control. In this study, the resistance intensity of major malaria vectors from Uganda was characterised and its impact on the performance of various insecticide-treated nets elucidated. High intensity of resistance to the discriminating concentration (DC), 5× DC, and 10× DC of pyrethroids was observed in both Anopheles funestus and Anopheles gambiae in Mayuge and Busia leading to significant reduced performance of long-lasting insecticidal nets (LLINs) including the piperonyl butoxide (PBO)-based nets (Olyset Plus). Molecular analysis revealed significant over-expression of cytochrome P450 genes (CYP9K1 and CYP6P9a/b). However, the expression of these genes was not associated with resistance escalation as no difference was observed in the level of expression in mosquitoes resistant to 5× DC and 10× DC compared to 1× DC suggesting that other resistance mechanisms are involved. Such high intensity of pyrethroid resistance in Uganda could have terrible consequences on the effectiveness of insecticide-based interventions and urgent action should be taken to prevent the spread of super-resistance in malaria vectors.

scholarly journals Evidence that agricultural use of pesticides selects pyrethroid resistance within Anopheles gambiae s.l. populations from cotton growing areas in Burkina Faso, West Africa

PLoS ONE ◽  
2017 ◽  
Vol 12 (3) ◽  
pp. e0173098 ◽  
Author(s):  
Aristide Sawdetuo Hien ◽  
Dieudonné Diloma Soma ◽  
Omer Hema ◽  
Bazoma Bayili ◽  
Moussa Namountougou ◽  
...  
Keyword(s):  
West Africa ◽  
Burkina Faso ◽  
Anopheles Gambiae ◽  
Pyrethroid Resistance ◽  
Anopheles Gambiae S.L ◽  
Agricultural Use

scholarly journals Insecticide resistance status of malaria vectors Anopheles gambiae s.l of southwest Burkina Faso and residual efficacy of indoor residual spraying with microencapsulated pirimiphos-methyl insecticide

2020 ◽  
Author(s):  
Dieudonné D. Soma ◽  
Barnabas M. Zogo ◽  
François D. Hien ◽  
Aristide S. Hien ◽  
Didier P.A. Kaboré ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Burkina Faso ◽  
Anopheles Gambiae ◽  
Local Population ◽  
Indoor Residual Spraying ◽  
Susceptible Strain ◽  
Malaria Vectors ◽  
Pirimiphos Methyl ◽  
Anopheles Gambiae S.L ◽  
Residual Efficacy

AbstractThe rapid spread of insecticide resistance in malaria vectors and the rebound in malaria cases observed recently in some endemic areas underscore the urgent need to evaluate and deploy new effective control interventions. A randomized control trial was conducted with the aim to investigate the benefit of deploying complementary strategies, including indoor residual spraying (IRS) with pirimiphos-methyl, in addition to long-lasting insecticidal nets (LLINs) in Diébougou, southwest Burkina Faso. We measured the susceptibility of Anopheles gambiae s.l. population from Diébougou to conventional insecticides. We further monitored the efficacy and residual activity of pirimiphos-methyl on both cement and mud walls using a laboratory susceptible strain (Kisumu) and the local An. gambiae s.l. population. An. Gambiae s.l. from Diébougou was resistant to pyrethroids (deltamethrin, permethrin and alphacypermethrin) and bendiocarb but showed susceptibility to organophosphates (pirimiphos-methyl and chlorpyrimiphos-methyl). A mixed-effect generalized linear model predicted that pirimiphos-methyl applied on cement or mud walls was effective for 210 days against the laboratory susceptible strain and 247 days against the local population. The residual efficacy of pirimiphos-methyl against the local population on walls made of mud was similar to that of cement (OR=0.792, [0.55-1.12], Tukey’s test p-value =0.19). This study showed that one round of IRS with pirimiphos-methyl CS has the potential to control the multi-resistant An. gambiae s.l. population from Southwest Burkina Faso for at least 7 months, regardless of the type of wall.

scholarly journals Etude De L’efficacité De L’huile De Thevetia Neriifolia Pour Le Contrôle De Anopheles Gambiae S.L Résistant Aux Pyréthrinoïdes

2017 ◽  
Vol 13 (24) ◽  
pp. 231
Author(s):  
Armand A. Akpo ◽  
Daniel C. Chougourou ◽  
Razaki A. Osse ◽  
Joseph Dossou ◽  
Bruno Akinro ◽  
...  
Keyword(s):  
Resistance Management ◽  
Malaria Vectors ◽  
Effective Control ◽  
Wild Type ◽  
Stage 4 ◽  
Sensitivity Tests ◽  
Anopheles Gambiae S.L ◽  
Alternative Measures ◽  
Probit Method ◽  
Different Strains

Effective control of pyrethroid-resistant malaria vectors requires new alternative measures. The purpose of this study is to test the effectiveness of Thevetia oil extracted from seed kernels to control malaria transmission by An. gambiae s.l. Sensitivity tests were carried out on larvae of Stages 3 and 4 of An. gambiae s.s of wild-type and pyrethroid-resistant Kis-kdr. The susceptible reference strain "Kisumu" served as a control. Mortality was read 24 hours and 48 hours after exposure. LD50 and 90 for 24 hours and 48 hours were determined using the log-probit method of determining the dose corresponding to a proportion. The high LD50s determined in 24 hours and 48 hours correspond to doses that kill 50% of Stage 3 larvae in wild populations in 24 hours and 48 hours. Low LD50s refer to stage 4 "Kisumu" larvae. The strong DL90 in 24 hours and 48 hours correspond respectively to stage 3 larvae of the Kis-kdr and wild-type strains. The comparison of the LD between the different strains shows the influence of the resistance on the sensitivity of the larvae of the strains resistant to the oil tested. However, the larvicidal effect of Thevetia oil on the larvae of resistant strains may elicit formulations for alternative measures in vector resistance management to pyrethroids.

scholarly journals Malaria vector species composition and entomological indices following several years of indoor residual spraying in regions bordering Lake Victoria, Tanzania

2020 ◽  
Author(s):  
Charles Elias Kakilla ◽  
Alphaxard Manjurano ◽  
Karen Nelwin ◽  
Jackline Martin ◽  
Fabian Mashauri ◽  
...  
Keyword(s):  
Pyrethroid Resistance ◽  
Lake Victoria ◽  
Indoor Residual Spraying ◽  
Malaria Vectors ◽  
Lake Victoria Basin ◽  
Species Identity ◽  
Substantial Impact ◽  
Sporozoite Rate ◽  
Cone Bioassay ◽  
Pirimiphos Methyl

Abstract Background Vector control through long lasting insecticidal nets and focal indoor residual spraying (IRS) is a major component of the Tanzania national malaria control strategy. In mainland Tanzania, IRS has been conducted annually around Lake Victoria basin since 2007. Due to pyrethroid resistance in malaria vectors, use of pyrethroids for IRS was phased out and from 2014 to 2017 pirimiphos-methyl (Actellic 300CS) was sprayed in regions of Kagera, Geita, Mwanza and Mara. Methods WHO Cone bioassays were conducted monthly on interior house walls to determine residual efficacy of pirimiphos-methyl CS. Indoor CDC light traps with or without bottle rotator were hung next to protected sleepers indoors and also set outdoors (un-baited) as a proxy measure for indoor and outdoor biting rate and time of biting. A sub-sample of Anopheles were tested by PCR to determine species identity and ELISA for sporozoite rate. Results Annual IRS with Actellic® CS between 2015 and 2017 was effective on sprayed walls for a mean of 7 months in cone bioassay. PCR of 2016 and 2017 samples showed vector populations were predominantly An. arabiensis (58.1%, n=4,403 IRS sites, 58%, n=2,441 unsprayed sites). There was a greater proportion of An. funestus s.s. in unsprayed sites (20.4%, n=858) than sprayed sites (7.9%, n=595) and fewer An. parensis (2%, n=85 unsprayed, 7.8%, n=591 sprayed). Biting peaks of An. gambiae s.l. followed periods of rainfall occurring between October and April, but were generally lower in sprayed sites than unsprayed. In most sprayed sites, An. gambiae s.l. indoor densities increased between January and February, i.e. 10-12 months after IRS. Based on these data and malaria case data, the timing of IRS was changed to November in Kagera and Geita Regions in 2018. The predominant species An. arabiensis had a sporozoite rate in 2017 of 2.0% (95% CI: 1.4-2.9) in unsprayed sites compared to 0.8% (95% CI: 0.5-1.3) in sprayed sites (p=0.003). Sporozoite rates also appeared to be lower for An. funestus collected in sprayed sites. Conclusion IRS appeared to have substantial impact on malaria transmission, with sporozoite rate in An. arabiensis being 59% lower in sprayed sites than in unsprayed sites in 2017.

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