Insecticides Susceptibility Status of Malaria Vectors in a High Malaria Endemic Tribal District Gadchiroli (Maharashtra) of India

Background and Objective: The current study was undertaken to determine insecticide susceptibility of malaria vectors in various villages of high malaria endemic PHCs of Gadchiroli district of Maharashtra. Methods: Adult malaria vectors were collected from the human dwellings/ cattle sheds of 156 villages of 18 malaria endemic PHCs. Susceptibility tests were carried out for different insecticides against An. culicifacies and An. fluviatilis mosquitoes as per the World Health Organization (WHO) procedure. Cone bioassays were also done to assess the quality and efficacy of indoor residual spray. Results:An. fluviatilis could be collected from 23 villages only and all the populations were fully susceptible to synthetic pyrethroid (deltamethrin) while being tolerant to organophosphorous (malathion). Susceptibility of An. culicifacies from 156 villages indicated that only 3 populations of An. culicifacies were resistant to deltamethrin while 57 populations were fully susceptible and other 96 populations were tolerant to deltamethrin. Resistance was recorded in 25 populations of An. culicifacies against malathion and 30 populations were tolerant to malathion insecticide. Remaining populations of An. fluviatilis and An. culicifacies were highly resistant to organochlorine. Results of cone bioassay revealed the mortality ranged from 32.5-51.1% on cemented and 27.5-43.3% on the mud wall sprayed with lambda cyhalothrin. Conclusion: The current study indicates that resistance has developed to synthetic pyrethroids in the major malaria vector An. culicifacies. Therefore, there is an urgent need for the evaluation of new insecticide molecules for better control of malaria vectors.

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Investigation of Susceptibility Levels of Culex pipiens L. (Diptera: Culicidae) Populations to Synthetic Pyrethroids in Antalya Province of Turkey

Journal of Arthropod-Borne Diseases ◽

10.18502/jad.v13i3.1535 ◽

2019 ◽

Author(s):

Onder Ser ◽

Huseyin Cetin

Keyword(s):

Public Health ◽

Culex Pipiens ◽

World Health ◽

Chemical Pollution ◽

Synthetic Pyrethroids ◽

Pyrethroid Insecticides ◽

Pollution Levels ◽

Lambda Cyhalothrin ◽

The World ◽

Susceptibility Tests

Background: Culex pipiens L. (Diptera: Culicidae) is an important vector of several pathogens. This mosquito is widely distributed throughout the world. We aimed to determine the susceptibility levels of Cx. pipiens populations to some synthetic pyrethroid insecticides in Antalya, Turkey. Methods: The immature stages of mosquitoes were collected from eight locations in Alanya, Döşemealtı, Kemer, Kumluca, and Manavgat districts of Antalya between Apr and Oct of 2017. Adult susceptibility tests were carried out according to a modified version of the Centers for Disease Control and Prevention bottle bioassay. In the tests, the World Health Organization recommended diagnostic doses; permethrin (0.75%), etofenprox (0.5%), deltamethrin (0.05%) and lambda-cyhalothrin (0.05%) were used. Results: As a result of the susceptibility tests, deltamethrin was the least effective insecticide and it caused 58.78–97.56% mortalities on Cx. pipiens populations while permethrin was the most effective substance that caused 100% mortality on all populations. While all of the tested populations were found susceptible to permethrin, and possible resistant or resistant to deltamethrin. Etofenprox and lambda-cyhalothrin led to 91.54–100% and 93.1–100% mortalities, respectively. Conclusion: The possible resistance or resistance to deltamethrin in all the areas is caused by the widespread use of this chemical against pests in agriculture and public health applications for long-term. Moreover, a concordance was found between resistance levels and the intensity of pesticide application in agriculture and public health, and organic and chemical pollution levels in the sampled habitats.

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The Efficacy of Vectron 20 WP, Etofenprox, for Indoor Residual Spraying in Areas of High Vector Resistance to Pyrethroids and Organochlorines in Zambia

ISRN Preventive Medicine ◽

10.5402/2013/371934 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

Emmanuel Chanda ◽

Alister Kandyata ◽

Javan Chanda ◽

Faustina N. Phiri ◽

Lucy Muzia ◽

...

Keyword(s):

Insecticide Resistance ◽

World Health Organization ◽

Indoor Residual Spraying ◽

Control Programme ◽

World Health ◽

Malaria Vectors ◽

Insecticide Treated Nets ◽

Lambda Cyhalothrin ◽

Residual Efficacy ◽

Health Organization

The selection of insecticide resistance in malaria vectors has the potential to compromise any insecticide-based vector control programme. To ensure that the insecticides used for indoor residual spraying and insecticide-treated nets in Zambia remain effective and their choice is evidence based, insecticide resistance surveillance and monitoring are essential. This study assessed and compared the residual efficacy of etofenprox (Vectron 20 WP), an ether pyrethroid, at 0.1 g/m2 with pyrethroids: bifenthrin (Bistar 10 WP) and lambda-cyhalothrin (Icon 10 CS) at 25 mg/m2 for indoor residual spraying. We also assessed the resistance status of etofenprox to local malaria vectors, An. funestus s.s and An. gambiae s.s, using World Health Organization standard protocols. The residual efficacy of Vectron 20 WP on cement, rendered walls of houses lasted for four months with 100% mortality. By the eighth month, the killing effect had reduced to 73.8% compared to 63.3% for bifenthrin and 77.0% for lambda-cyhalothrin. Susceptibility tests using standard World Health Organization assays on An. gambiae s.s showed susceptibility to etofenprox (0.1%) but some resistance was detected to Anopheles funestus s.s. The product is recommended as an ideal insecticide for indoor residual spraying for malaria control in Zambia as part of a resistance management programme in selected areas of the country.

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Insecticide susceptibility tests conducted in Kamhororo, Masakadza and Chilonga villages in Zimbabwe during the 2011 malaria period

Journal of Entomological and Acarological Research ◽

10.4081/jear.2012.e19 ◽

2012 ◽

Vol 44 (3) ◽

pp. 19 ◽

Cited By ~ 2

Author(s):

N. Lukwa ◽

S. Sande ◽

P. Munosiyei ◽

M. Zimba

Keyword(s):

Insecticide Resistance ◽

World Health Organization ◽

Anopheles Gambiae ◽

World Health ◽

Insecticide Susceptibility ◽

Lambda Cyhalothrin ◽

Percent Mortality ◽

Susceptibility Tests ◽

Health Organization ◽

Observation Times

Insecticide susceptibility tests using World Health Organization papers treated with 4% dichloro-diphenyl-trichloro-ethane (DDT), 0.05% deltamethrin, 0.05% lambda-cyhalothrin, 0.5% etofenprox, 0.15% cyfluthrin and 0.75% permethrin were conducted in Kamhororo, Masakadza and Chilonga villages, Zimbabwe. Three to 5-day old female Anopheles gambiae sensu lato adult mosquitoes were used. Deltamethrin knocked down 100% of the mosquitoes from Kamhororo, Masakadza and Chilonga at 35 min exposure. DDT did not knock down 100% of the mosquitoes from Kamhororo and Masakadza but did so in Chilonga. One hundred percent knockdown was achieved for cyfluthrin when exposed to mosquitoes from Kamhororo (60 min), Masakadza (25 min) and Chilonga (25 min). Etofenprox knocked down 100% of the mosquitoes collected from Kamhororo (30 min), Masakadza (30 min) and Chilonga (55 min). Knockdown of mosquitoes due to deltamethrin, DDT, cyfluthrin, permethrin; lambda-cyhalothrin and etofenprox were different at different observation times. One hundred percent mortality due to deltamethrin, DDT, etofenprox, lambdacyhalothrin and cyfluthrin was recorded for mosquitoes collected from all the 3 sites. One hundred percent mortality due to pemethrin was recorded for mosquitoes collected from Kamhororo and Chilonga but mortality was 98.5% for those collected from Masakadza. No knockdown or mortality occurred in the controls from each locality. The kd50 (knockdown of 50% of the mosquitoes) values were 24.4-73.7 min (DDT), 8-13 min (pemethrin), 9.4-16.3 min (cyfluthrin), 9.4-14.4 min (etofenprox), 8.7-13 min (lambda-cyhalothrin) and 12.1-15.9 min (deltamethrin). The kd90 (knockdown of 90% of the mosquitoes) values were 45.6-199.5 min (DDT), 14.7-26.5 min (pemethrin), 16.5-34.9 min (cyfluthrin), 21.8-24.4 min (etofenprox), 16.3-31.6 min (lambdacyhalothrin) and 21-25.3 min (deltamethrin). No insecticide resistance was recorded from the 3 sites.

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Evaluation of organophosphorus and synthetic pyrethroid insecticides against six vector mosquitoe species

Revista de Saúde Pública ◽

10.1590/s0034-89101993000600001 ◽

1993 ◽

Vol 27 (6) ◽

pp. 391-397 ◽

Cited By ~ 18

Author(s):

Domingo Montada Dorta ◽

V. Vasuki ◽

A. Rajavel

Keyword(s):

Organophosphorus Compounds ◽

Mosquito Species ◽

Residual Effect ◽

World Health ◽

Synthetic Pyrethroids ◽

Pyrethroid Insecticides ◽

Residual Efficacy ◽

Health Organization ◽

Integrated Vector Control ◽

Susceptibility Status

Three organophosphorus compounds- malathion, folithion and temephos- and two synthetic pyrethroids- alphamethrin and deltamethrin- were used for monitoring the susceptibility status of larvae and adults of six vector mosquitoe species: Culex quinquefasciatus (Filariasis) and Aedes albopictus (Dengue) (both laboratory and field strains); laboratory strains of Aedes aegypti (Dengue), Anopheles slephensi and Anopheles culicifacies (Malaria), and Culex tritaeniorhynchus (Japanese encephalitis) in India. From the LC50 values obtained for these insecticides, it was found that all mosquito species including the field strains of Cx. quinquefasciatus and Ae. albopictus were highly susceptible Except for Cx. quinquefasciatus (field strain) against malathion, 100% mortality was observed at the discriminating dosages recommended by World Health Organization. The residual effect of alphamethrin, deltamethrin, malathion and folithion at 25 mg (ai)/m² on different surfaces against six species of vector mosquitoes showed that alphamethrin was the most effective on all four treated surfaces (mud, plywood, cement and thatch). Nevertheless, residual efficacy lasted longer on thatch than on the other surfaces. Therefore, synthetic pyrethroids such as alphamethrin can be effectively employed in integrated vector control operations.

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Personal protection with PBO-pyrethroid synergist-treated nets after 2 years of household use against pyrethroid-resistant Anopheles in Tanzania

Parasites & Vectors ◽

10.1186/s13071-021-04641-5 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Jackline L. Martin ◽

Franklin W. Mosha ◽

Eliud Lukole ◽

Mark Rowland ◽

Jim Todd ◽

...

Keyword(s):

Pyrethroid Resistance ◽

Density Ratio ◽

Household Survey ◽

Sensu Stricto ◽

World Health ◽

Malaria Vectors ◽

Personal Protection ◽

North West ◽

Hole Index ◽

Health Organization

Abstract Background The spread of pyrethroid resistance in malaria vectors threatens the effectiveness of standard long-lasting insecticidal nets (LLIN). Synergist nets combine pyrethroid (Py) and piperonyl-butoxide (PBO) to enhance potency against resistance mediated by mono-oxygenase mechanisms. Our project assessed personal protection of the World Health Organization first-in-class PBO-Py LLIN (Olyset Plus) versus the standard LLIN (Olyset net) against pyrethroid-resistant Anopheles gambiae sensu lato (s.l.) and An. funestus in North-West Tanzania after 20 months of household use. Methods From a household survey, 39 standard Olyset net and 39 Olyset Plus houses were selected. The physical integrity and hole index (HI) of the nets were assessed, and resting mosquitoes were collected from inside nets and from room walls. The indoor abundance was estimated using CDC light traps and species identified using PCR. The bioefficacy of PBO and standard LLINs against wild Anopheles was assessed using 30-minute cylinder bioassays. Results Of 2397 Anopheles collected, 8.9% (n = 213) were resting inside standard Olyset nets, while none were found inside Olyset Plus nets (PBO-Py LLINs) of any HI category. Resting density of blood-fed mosquitoes was higher on walls of sleeping rooms with Olyset nets compared to Olyset Plus (0.62 vs 0.10, density ratio [DR]: 0.03, 95% CI 0.01–0.13, p < 0.001). Mosquitoes were found inside Olyset nets of all WHO HI categories, but more were collected inside the more damaged nets (HI ≥ 643) than in less damaged (HI 0–64) nets (DR: 6.4, 95% CI 1.1–36.0, p = 0.037). In bioassay, mortality of An. gambiae s.l. was higher with Olyset Plus than with Olyset nets for new nets (76.8% vs 27.5%) and nets used for 20 months (56.8% vs 12.8%); similar trends were observed with An. funestus. Conclusion The PBO-Py LLINs provided improved protection after 20 months of household use, as demonstrated by the higher bioassay mortality and absence of pyrethroid-resistant An. gambiae sensu stricto (s.s.) and An. funestus collected from inside Olyset Plus nets, irrespective of HI category, as compared to Olyset nets.

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Insecticide Resistance in Anopheles stephensi in Somali Region, Eastern Ethiopia

10.21203/rs.2.18020/v2 ◽

2020 ◽

Cited By ~ 1

Author(s):

Solomon Yared ◽

Araya Gebressielasie ◽

Lambodhar Damodaran ◽

Victoria Bonnell ◽

Karen Lopez ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Stephensi ◽

Mortality Rates ◽

Resistance Mechanisms ◽

World Health ◽

Malaria Vectors ◽

Eastern Ethiopia ◽

Pyrethroid Insecticides ◽

Pirimiphos Methyl ◽

Health Organization

Abstract Background: The movement of malaria vectors into new areas is a growing concern in the efforts to control malaria. The recent report of Anopheles stephensi in eastern Ethiopia has raised the necessity to understand the insecticide resistance status of the vector in the region to better inform vector-based interventions. The aim of this study was to evaluate insecticide resistance in An. stephensi in eastern Ethiopia using two approaches: 1) World Health Organization (WHO) bioassay tests in An. stephensi and 2) genetic analysis of insecticide resistance genes in An. stephensi in eastern Ethiopia. Methods: Mosquito larvae and pupae were collected from Kebridehar. Insecticide susceptibility of An. stephensi was tested with malathion 5%, bendiocarb 0.1%, propoxur 0.1%, deltamethrin 0.05%, permethrin 0.75%, Pirimiphos-methyl 0.25% and DDT 4%, according to WHO standard protocols. Results: All An. stephensi samples were resistant to carbamates, with mortality rates 23% and 21% for bendiocarb and propoxur, respectively. Adult An. stephensi was also resistant to pyrethroid insecticides with mortality rates 67% for deltamethrin and 53% for permethrin. Resistance to DDT and malathion was detected in An. stephensi with mortality rates of 32% as well as An. stephensi was resistance to pirimiphos-methyl with mortality rates 14%. Analysis of the voltage gate sodium channel gene (vgsc) revealed the absence of kdr L1014 mutations. Conclusion: Overall, these findings support that An. stephensi is resistant to several classes of insecticides, most notably pyrethroids. However, the absence of the kdr L1014 gene may suggest non-target site resistance mechanisms. Continuous insecticide resistance monitoring should be carried out in the region to confirm the documented resistance and exploring mechanisms conferring resistance in An. stephensi in Ethiopia.

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Assessment of the susceptibility status of Aedes aegypti (Diptera: Culicidae) populations to pyriproxyfen and malathion in a nation-wide monitoring of insecticide resistance performed in Brazil from 2017 to 2018

Parasites & Vectors ◽

10.1186/s13071-020-04406-6 ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Kauara Brito Campos ◽

Ademir Jesus Martins ◽

Cynara de Melo Rodovalho ◽

Diogo Fernandes Bellinato ◽

Luciana dos Santos Dias ◽

...

Keyword(s):

Insecticide Resistance ◽

Mosquito Control ◽

Natural Populations ◽

Adult Emergence ◽

World Health ◽

Two Generations ◽

Wide Scale ◽

Susceptibility Tests ◽

The One ◽

Health Organization

Abstract Background Chemical mosquito control using malathion has been applied in Brazil since 1985. To obtain chemical control effectiveness, vector susceptibility insecticide monitoring is required. This study aimed to describe bioassay standardizations and determine the susceptibility profile of Ae. aegypti populations to malathion and pyriproxyfen, used on a national scale in Brazil between 2017 and 2018, and discuss the observed impacts in arbovirus control. Methods The diagnostic-doses (DD) of pyriproxyfen and malathion were determined as the double of adult emergence inhibition (EI) and lethal doses for 99% of the Rockefeller reference strain, respectively. To monitor natural populations, sampling was performed in 132 Brazilian cities, using egg traps. Colonies were raised in the laboratory for one or two generations (F1 or F2) and submitted to susceptibility tests, where larvae were exposed to the pyriproxyfen DD (0.03 µg/l) and adults, to the malathion DD determined in the present study (20 µg), in addition to the one established by the World Health Organization (WHO) DD (50 µg) in a bottle assay. Dose-response (DR) bioassays with pyriproxyfen were performed on populations that did not achieve 98% EI in the DD assays. Results Susceptibility alterations to pyriproxyfen were recorded in six (4.5%) Ae. aegypti populations from the states of Bahia and Ceará, with Resistance Ratios (RR95) ranging from 1.51 to 3.58. Concerning malathion, 73 (55.3%) populations distributed throughout the country were resistant when exposed to the local DD 20 µg/bottle. On the other hand, no population was resistant, and only 10 (7.6%) populations in eight states were considered as exhibiting decreased susceptibility (mortality ratios between 90 and 98%) when exposed to the WHO DD (50 µg/bottle). Conclusions The feasibility of conducting an insecticide resistance monitoring action on a nation-wide scale was confirmed herein, employing standardized and strongly coordinated sampling methods and laboratory bioassays. Brazilian Ae. aegypti populations exhibiting decreased susceptibility to pyriproxyfen were identified. The local DD for malathion was more sensitive than the WHO DD for early decreased susceptibility detection.

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Evaluating insecticide resistance across African districts to aid malaria control decisions

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2006781117 ◽

2020 ◽

Vol 117 (36) ◽

pp. 22042-22050 ◽

Cited By ~ 1

Author(s):

Catherine L. Moyes ◽

Duncan K. Athinya ◽

Tara Seethaler ◽

Katherine E. Battle ◽

Marianne Sinka ◽

...

Keyword(s):

Cytochrome P450 ◽

Pyrethroid Resistance ◽

Resistance Mechanisms ◽

World Health ◽

Malaria Vector Control ◽

Ensemble Model ◽

Metabolic Resistance ◽

The World ◽

Susceptibility Tests ◽

Health Organization

Malaria vector control may be compromised by resistance to insecticides in vector populations. Actions to mitigate against resistance rely on surveillance using standard susceptibility tests, but there are large gaps in the monitoring data across Africa. Using a published geostatistical ensemble model, we have generated maps that bridge these gaps and consider the likelihood that resistance exceeds recommended thresholds. Our results show that this model provides more accurate next-year predictions than two simpler approaches. We have used the model to generate district-level maps for the probability that pyrethroid resistance inAnopheles gambiaes.l. exceeds the World Health Organization thresholds for susceptibility and confirmed resistance. In addition, we have mapped the three criteria for the deployment of piperonyl butoxide-treated nets that mitigate against the effects of metabolic resistance to pyrethroids. This includes a critical review of the evidence for presence of cytochrome P450-mediated metabolic resistance mechanisms across Africa. The maps for pyrethroid resistance are available on the IR Mapper website, where they can be viewed alongside the latest survey data.

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Bio-efficacy and Wash-fastness of a Lamda-cyhalothrin Long-lasting Insecticide Treatment Kit (ICON® Maxx) Against Mosquitoes on Various Polymer Materials

10.21203/rs.3.rs-564533/v1 ◽

2021 ◽

Author(s):

Patrick Tungu ◽

Wema Sudi ◽

Harparkash Kaur ◽

Stephen Magesa ◽

Mark Rowland

Keyword(s):

Malaria Prevention ◽

Home Treatment ◽

Polymer Materials ◽

World Health ◽

Insecticide Treated Nets ◽

Pyrethroid Insecticides ◽

Wash Fastness ◽

Lambda Cyhalothrin ◽

Efficacy Criteria ◽

Health Organization

Abstract BackgroundLong-lasting efficacy of insecticide treated nets is a balance between adhesion, retention and migration of insecticide to the surface of netting fibres. ICON® Maxx is a twin-sachet ‘home-treatment kit’ of pyrethroid plus binding agent, recommended by the World Health Organization for long-lasting, wash-fast treatment of polyester nets. While knitted polyester netting is widely used, fine woven polyethylene netting is increasingly available and nets made of cotton and nylon are common in Africa and Asia. It is important to investigate whether ICON Maxx is able to fulfill the WHO criteria of long-lasting treatment on a range of domestic fabrics to widen the scope for malaria protection.Method This study was a controlled comparison of the bio-efficacy and wash-fastness of lambda-cyhalothrin CS, with or without binder, on nets made of cotton, polyethylene, nylon, dyed and undyed polyester. Evaluation compared an array of bioassays, WHO cone and cylinder, median time to knockdown and WHO tunnel tests using Anopheles mosquitoes. Chemical assay revealed further insight. ResultsICON Maxx treated polyethylene and polyester netting met the WHO cone and tunnel test bio-efficacy criteria for LLIN after 20 standardized washes. Although nylon and cotton netting failed to meet the WHO cone and cylinder criteria, both materials passed the WHO tunnel test criterion of 80% mortality after 20 washes. All materials treated with standard lambda-cyhalothrin CS without binder failed to meet any of the WHO bio-efficacy criteria within 5 washes. ConclusionThe bio-efficacy of ICON Maxx against mosquitoes on netting washed up to 20 times demonstrated wash durability on a range of synthetic polymer and natural fibres: polyester, polyethylene, nylon and cotton. This raises the prospect of making the insecticide-binder kit into an effective approach for turning untreated nets, curtains, military clothing, blankets - and tents and tarpaulins as used in disasters and humanitarian emergencies - into effective malaria prevention products. It may provide a solution to the problem of reduced LLIN coverage between campaigns by converting commercially sourced untreated nets into LLINs through community or home treatment. It may also open the door to binding of non-pyrethroid insecticides to nets and textiles for control of pyrethroid resistant vectors.

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Insecticide resistance characteristic of Anopheles vector species successfully controlled by deployment of pyrethroid and PBO long lasting insecticidal treated nets (LLINs) in Tanzania

10.1101/2021.03.19.436139 ◽

2021 ◽

Author(s):

Johnson Matowo ◽

David Weetman ◽

Patricia Pignatell ◽

Alexandra Wright ◽

Jacques Charlwood ◽

...

Keyword(s):

Insecticide Resistance ◽

Pyrethroid Resistance ◽

Cluster Randomized Trial ◽

World Health ◽

Malaria Vectors ◽

Metabolizing Enzymes ◽

Sub Saharan ◽

Underlying Mechanisms ◽

Cluster Randomized ◽

Health Organization

Long lasting insecticidal nets (LLINs) are a proven tool to reduce malaria transmission, but in Africa efficacy is being reduced by pyrethroid resistance in the major vectors. A cluster randomized trial in Muleba district, Tanzania demonstrated that permethrin LLINs co-treated with piperonyl butoxide (PBO), a synergist that can block pyrethroid-metabolizing enzymes in the mosquito, had much greater efficacy than pyrethroid-only nets. Insecticide resistance profiles and underlying mechanisms were investigated in Anopheles gambiae and An. funestus from Muleba during the trial. Diagnostic dose bioassays using permethrin, together with intensity assays, suggest pyrethroid resistance that is both strong and very common, but not extreme. Transcriptomic analysis found multiple P450 genes over expressed including CYP6M2, CYP6Z3, CYP6P3, CYP6P4, CYP6AA1 and CYP9K1 in An. gambiae and CYP6N1, CYP6M7, CYP6M1 and CYP6Z3 in An. funestus. Indeed, very similar suites of P450 enzymes commonly associated with resistant populations elsewhere in Africa were detected as over expressed suggesting a convergence of mechanisms across Sub-Saharan African malaria vectors. The findings give insight into factors that may correlate with pyrethroid PBO LLIN success, broadly supporting model predictions, but revision to guidelines previously issued by the World Health Organization is warranted.

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