Behavioral Responses of Pyrethroid-resistant Anopheles Gambiae Mosquitoes to Insecticide-treated Bed Net

Abstract Background: Long-lasting insecticidal nets are an effective tool in reducing malaria transmission. However, with increasing insecticide resistance little is known about how physiologically resistant malaria vectors behave around a human-occupied bed net, despite their importance in malaria transmission. We assessed the host-seeking behavior of the major malaria vector Anopheles gambiae s.s, when an intact human-occupied treated bed net is in place, with respect to their insecticide resistance status under semi-field conditions. Methods: Pyrethroid resistant and susceptible colonies of female Anopheles gambiae s.s aged 3-5 days that have been bred in our insectary, were color-marked with fluorescent powder and released inside a semi-field environment housing a hut which was occupied by a human host. Inside the hut, the occupant slept under an insecticide-treated bed net trap or untreated bed net trap. The window exit trap was installed to catch mosquitoes exiting the hut. A prokopack aspirator was used to collect indoor and outdoor resting mosquitoes in the morning. Clay pots were placed outside the hut to collect mosquitoes resting outdoors. Results: The proportion of resistant mosquitoes caught in the treated bed net trap was higher 43% (95% CI= [40.6-45.3]) compared to the susceptible mosquitoes 28.3% (OR=1.445; P<0.00019). The proportion of susceptible mosquitoes caught in the untreated bed net trap was higher 51.3% (95% CI= [48.8-53.6]) compared to the treated bed net trap 28.3% (95% CI= [26.3-30.5]) (OR=2.65; P<0.0001). Resistant mosquitoes were less likely to exit the house when a treated bed net was present (5.2%; 95% CI= [4.2-6.4]) compared to the susceptible mosquitoes (11.5%; 95% CI= [9.6-12.6]). The proportion of susceptible mosquitoes avoiding contact with the treated bed net and caught resting indoors in the hut (53.8%) and outdoors (64.5%) was higher compared to the resistant mosquitoes (indoors: 46.2%, outdoor: 35.4%). The susceptible females were 2.3 times more likely to stay outdoors away from the treated bed net (OR=2.25; 95% CI= [1.7-2.9]; P<0.0001).Conclusion: The results show that in the presence of a treated net, the host-seeking performance was not altered for the resistant mosquitoes, unlike the susceptible females that were observed to exit the house and remained outdoors when a treated net was used. However, further investigations of the behavior of resistant mosquitoes under natural conditions should be undertaken to confirm these observations and improve the current intervention which are threatened by insecticide resistance and altered vector behavior.

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A pyrethroïd-treated bed net increases host attractiveness for Anopheles gambiae s.s. carrying the kdr allele in a dual-choice olfactometer

10.1101/077552 ◽

2016 ◽

Cited By ~ 1

Author(s):

Angélique Porciani ◽

Malal Diop ◽

Nicolas Moiroux ◽

Tatiana Kadoke-Lambi ◽

Anna Cohuet ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Sub Saharan Africa ◽

Malaria Vectors ◽

Malaria Vector Control ◽

Anopheles Gambiae S.S ◽

Host Seeking ◽

Seeking Behavior ◽

Sub Saharan ◽

The Impact

AbstractThe use of long lasting insecticide nets (LLINs) treated with pyrethroïd is known for its major contribution in malaria control. However, LLINs are suspected to induce behavioral changes in malaria vectors, which may in turn drastically affect their efficacy against Plasmodium sp. transmission. In sub Saharan Africa, where malaria imposes the heaviest burden, the main malaria vectors are widely resistant to pyrethroïds, the insecticide family used on LLINs, which also threatens LLIN efficiency. There is therefore a crucial need for deciphering how insecticide-impregnated materials might affect the host-seeking behavior of malaria vectors in regards to insecticide resistance. In this study, we explored the impact of permethrin-impregnated net on the host attractiveness for Anopheles gambiae mosquitoes, either susceptible to insecticides, or carrying the insecticide resistance conferring allele kdr. Groups of female mosquitoes were released in a dual-choice olfactometer and their movements towards an attractive odor source (a rabbit) protected by insecticide-treated (ITN) or untreated nets (UTN) were monitored. Kdr homozygous mosquitoes, resistant to insecticides, were more attracted by a host behind an ITN than an UTN, while the presence of insecticide on the net did not affect the choice of susceptible mosquitoes. These results suggest that permethrin-impregnated net is detectable by malaria vectors and that the kdr mutation impacts their response to a LLIN protected host. We discuss the implication of these results for malaria vector control.

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Influence of pyrethroïd-treated bed net on host seeking behavior of Anopheles gambiae s.s. carrying the kdr allele

PLoS ONE ◽

10.1371/journal.pone.0164518 ◽

2017 ◽

Vol 12 (7) ◽

pp. e0164518 ◽

Cited By ~ 8

Author(s):

Angélique Porciani ◽

Malal Diop ◽

Nicolas Moiroux ◽

Tatiana Kadoke-Lambi ◽

Anna Cohuet ◽

...

Keyword(s):

Anopheles Gambiae ◽

Bed Net ◽

Anopheles Gambiae S.S ◽

Host Seeking ◽

Seeking Behavior

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Malaria Transmission, Vector Diversity, and Insecticide Resistance at a Peri-Urban Site in the Forest Zone of Ghana

Frontiers in Tropical Diseases ◽

10.3389/fitd.2021.739771 ◽

2021 ◽

Vol 2 ◽

Author(s):

Yaw Akuamoah-Boateng ◽

Ruth C. Brenyah ◽

Sandra A. Kwarteng ◽

Patrick Obuam ◽

Isaac Owusu-Frimpong ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Malaria Transmission ◽

Urban Setting ◽

World Health ◽

Malaria Vectors ◽

Urban Site ◽

Human Landing Catch ◽

Anopheles Coluzzii ◽

Anopheles Gambiae S.S

IntroductionRecent surge of Anopheles resistance to major classes of World Health Organization (WHO)-approved insecticides globally necessitates the need for information about local malaria vector populations. It is believed that insecticide efficacy loss may lead to operational failure of control interventions and an increase in malaria infection transmission. We investigated the susceptibility levels of malaria vectors to all classes of WHO-approved vector control insecticides and described the dynamics of malaria transmission in a peri-urban setting.MethodsFit 3–5-day-old adults that emerged from Anopheles larvae collected from several different sites in the study area were subjected to the WHO bioassay for detecting insecticide resistance. The knockdown resistance gene (kdr) mutations within the vector populations were detected using PCR. Entomological inoculation rates were determined using the human landing catch technique and Plasmodium falciparum circumsporozoite ELISA.ResultsThe malaria vectors from the study area were resistant to all classes of insecticides tested. Out of the 284 Anopheles complex specimen assayed for the resistance study, 265 (93.30%) were identified as Anopheles gambiae s.s. The kdr gene was detected in 90% of the Anopheles gambiae s.s. assayed. In an area where Anopheles coluzzii resistance to insecticides had never been reported, the kdr gene was detected in 78% of the Anopheles coluzzii sampled. The entomological inoculation rate (EIR) for the dry season was 1.44 ib/m/n, whereas the EIR for the rainy season was 2.69 ib/m/n.ConclusionsThis study provides information on the high parasite inoculation rate and insecticide resistance of malaria vectors in a peri-urban community, which is critical in the development of an insecticide resistance management program for the community.

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

Journal of Medical Entomology ◽

10.1093/jme/tjaa195 ◽

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.

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Elevated Plasmodium infection and multiple insecticide resistance in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the airport of Yaoundé, the Capital city of Cameroon

10.21203/rs.2.23277/v1 ◽

2020 ◽

Author(s):

Nkemngo Francis Nongley ◽

Jean Leon Mugenzi Mbugulize ◽

Ebai Terence ◽

Abdoulaye Niang ◽

Murielle Wondji ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Gambiae ◽

Infection Rate ◽

Transcriptional Profiling ◽

Anopheles Funestus ◽

Capital City ◽

Malaria Vectors ◽

Resistance Allele ◽

Test Procedures ◽

Anopheles Gambiae S.S

Abstract Background Reducing the burden of malaria requires better understanding of vector populations particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the international airport of Yaoundé, the capital city of Cameroon, including species composition, abundance, Plasmodium infection rate; insecticide resistance profiles and underlying resistance mechanisms. Methods Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a village located 2km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F 1 adult progeny. WHO bioassays were performed to assess resistance profile to insecticides. The threshold of insecticide susceptibility was fixed above 98% mortality rate and mortality rates below 90% were considered indicative of confirmed insecticide resistance according to the WHO test procedures for insecticide resistance monitoring. Furthermore, the molecular basis of resistance and Plasmodium infection rates were investigated.Results Anopheles funestus s.s. was most abundant species in Elende (85%) followed by Anopheles gambiae s.s. (15%) with both having a similar sporozoite infection rate. Both species exhibited high levels of resistance to pyrethroids (<40% mortality). An. gambiae s.s. was also resistant to DDT (9.9% mortality) and bendiocarb (54% mortality) while susceptible to organophosphate. An. funestus s.s. was resistant to dieldrin (1% mortality), DDT (86% mortality) but susceptible to carbamates and organophosphates. The DDT/pyrethroid L119F-GSTe2 resistance allele (8%) and G119S ace -1 resistance allele (15%) were detected in An. funestus s.s. and An. gambiae s.s. respectively. Furthermore, the high pyrethroid/DDT resistances in An. gambiae s.s. corresponded with an increase frequency of 1014F kdr allele (95%). The CYP6P9a P450 resistance allele was absent in the An. funestus s.s. population meanwhile transcriptional profiling of candidate cytochrome P450 genes reveals the over-expression of CYP6P5 , CYP6P9a and CYP6P9b. Conclusion The resistance to multiple insecticide classes observed in these vector populations alongside the high Plasmodium infection rate highlights the challenges that public health vector control programs encounter in sustaining the regular effectiveness of contemporary insecticide-based control interventions in forested areas. More particularly, the resistance observed against the carbamates and possible resistance against the organophosphates constitutes a major concern for IRS.

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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

Parasites & Vectors ◽

10.1186/s13071-020-04563-8 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Dieudonné Diloma Soma ◽

Barnabas Zogo ◽

Domonbabele François de Sales Hien ◽

Aristide Sawdetuo Hien ◽

Didier Alexandre Kaboré ◽

...

Keyword(s):

Insecticide Resistance ◽

Burkina Faso ◽

Anopheles Gambiae ◽

Local Population ◽

Residual Activity ◽

Indoor Residual Spraying ◽

Susceptible Strain ◽

Malaria Vectors ◽

Pirimiphos Methyl ◽

Residual Efficacy

Abstract Background The 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 (RCT) 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. Methods We measured the susceptibility of the 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. Results An. gambiae (s.l.) from Diébougou was resistant to DDT, 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). Conclusions If data on malaria transmission and malaria cases (as measured trough the RCT) are consistent with data on residual activity of pirimiphos-methyl regardless of the type of wall, one round of IRS with pirimiphos-methyl would have the potential to control malaria in a context of multi-resistant An. gambiae (s.l.) for at least 7 months.

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