scholarly journals Identifying permethrin resistance loci in malaria vectors by genetic mapping

Parasitology ◽  
2013 ◽  
Vol 140 (12) ◽  
pp. 1468-1477 ◽  
Author(s):  
CLAUDIA WITZIG ◽  
CHARLES S. WONDJI ◽  
CLARE STRODE ◽  
ROUSSEAU DJOUAKA ◽  
HILARY RANSON
Keyword(s):  
Genetic Mapping ◽  
Insecticide Resistance ◽  
Pyrethroid Resistance ◽  
Association Studies ◽  
Management Strategies ◽  
Resistance Management ◽  
Malaria Vectors ◽  
Genome Wide Association Studies ◽  
Population Structuring ◽  
Genomic Locations

SUMMARYIdentification of the major loci responsible for insecticide resistance in malaria vectors would aid the development and implementation of effective resistance management strategies, which are urgently needed to tackle the growing threat posed by resistance to the limited insecticides available for malaria control. Genome-wide association studies in the major malaria vector, Anopheles gambiae, have been hindered by the high degree of within-population structuring and very low levels of linkage disequilibrium hence we revisited the use of quantitative trait loci (QTL) mapping to study resistance phenotypes in this vector species. Earlier work, identified two major QTL associated with pyrethroid resistance in A. gambiae s.s. from East Africa using genetic crossing of laboratory-colonized resistant and susceptible strains. In this study, we report the results from genetic mapping of pyrethroid resistance in three isofemale pedigrees established from wild-caught female A. gambiae s.s. mosquitoes from Benin. We identified two QTL on chromosomes 2L and 3R in these field populations, in similar genomic locations to the QTL identified in laboratory strains. The relative merits of two alternative study designs are discussed and suggestions made for future genetic mapping studies of insecticide resistance in mosquitoes.

Characterisation of DDT and Pyrethroid Resistance in Trinidad and Tobago populations of Aedes aegypti

2011 ◽  
Vol 101 (4) ◽  
pp. 435-441 ◽  
Author(s):  
K.A. Polson ◽  
S.C. Rawlins ◽  
W.G. Brogdon ◽  
D.D. Chadee
Keyword(s):  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Trinidad And Tobago ◽  
Pyrethroid Resistance ◽  
Management Strategies ◽  
Resistance Management ◽  
Activity Levels ◽  
Biochemical Assays ◽  
The Status ◽  
Control And Prevention

AbstractInsecticide resistance is an important factor in the effectiveness of Aedes aegypti control and the related spread of dengue. The objectives of this study were to investigate the status of the organochlorine dichlorodiphenyltrichloroethane (DDT) and pyrethroid (permethrin and deltamethrin) resistance in Trinidad and Tobago populations of Ae. aegypti and the underlying biochemical mechanisms. Nine populations of Ae. aegypti larvae from Trinidad and Tobago were assayed to DDT and PYs using the Centers for Disease Control and Prevention (CDC) time-mortality-based bioassay method. A diagnostic dosage (DD) was established for each insecticide using the CAREC reference susceptible Ae. aegypti strain and a resistance threshold (RT), time in which 98–100% mortality was observed in the CAREC strain, was calculated for each insecticide. Mosquitoes which survived the DD and RT were considered as resistant, and the resistance status of each population was categorised based on the WHO criteria with mortality <80% indicative of resistance. Biochemical assays were conducted to determine the activities of α and β esterases, mixed function oxidases (MFO) and glutathione-S-transferases (GST) enzymes which are involved in resistance of mosquitoes to DDT and PYs. Enzymatic activity levels in each population were compared with those obtained for the CAREC susceptible strain, and significant differences were determined by Kruskal-Wallis and Tukey's non-parametric tests (P<0.05). The established DDs were 0.01 mg l−1, 0.2 mg l−1 and 1.0 mg l−1 for deltamethrin, permethrin and DDT, respectively; and the RTs for deltamethrin, permethrin and DDT were 30, 75 and 120 min, respectively. All Ae. aegypti populations were resistant to DDT (<80% mortality); two strains were incipiently resistant to deltamethrin and three to permethrin (80–98% mortality). Biochemical assays revealed elevated levels of α-esterase and MFO enzymes in all Ae. aegypti populations. All, except three populations, showed increased levels of β-esterases; and all populations, except Curepe, demonstrated elevated GST levels.Metabolic detoxification of enzymes is correlated with the manifestation of DDT and PY resistance in Trinidad and Tobago populations of Ae. aegypti. The presence of this resistance also suggests that knock down (kdr)-type resistance may be involved, hence the need for further investigations. This information can contribute to the development of an insecticide resistance surveillance programme and improvement of resistance management strategies aimed at combatting the spread of dengue in Trinidad and Tobago.

scholarly journals Review and Meta-Analysis of the Evidence for Choosing between Specific Pyrethroids for Programmatic Purposes

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 826
Author(s):  
Natalie Lissenden ◽  
Mara Kont ◽  
John Essandoh ◽  
Hanafy Ismail ◽  
Thomas Churcher ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Pyrethroid Resistance ◽  
Meta Analysis ◽  
Resistance Management ◽  
Malaria Vectors ◽  
Resistance Testing ◽  
Differential Mortality ◽  
Wild Populations ◽  
Insecticide Resistance Management ◽  
Laboratory Colonies

Pyrethroid resistance is widespread in malaria vectors. However, differential mortality in discriminating dose assays to different pyrethroids is often observed in wild populations. When this occurs, it is unclear if this differential mortality should be interpreted as an indication of differential levels of susceptibility within the pyrethroid class, and if so, if countries should consider selecting one specific pyrethroid for programmatic use over another. A review of evidence from molecular studies, resistance testing with laboratory colonies and wild populations, and mosquito behavioural assays were conducted to answer these questions. Evidence suggested that in areas where pyrethroid resistance exists, different results in insecticide susceptibility assays with specific pyrethroids currently in common use (deltamethrin, permethrin, α-cypermethrin, and λ-cyhalothrin) are not necessarily indicative of an operationally relevant difference in potential performance. Consequently, it is not advisable to use rotation between these pyrethroids as an insecticide-resistance management strategy. Less commonly used pyrethroids (bifenthrin and etofenprox) may have sufficiently different modes of action, though further work is needed to examine how this may apply to insecticide resistance management.

scholarly journals Insecticide resistance exerts significant fitness costs in immature stages of Anopheles gambiae in western Kenya

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Joyce K. Osoro ◽  
Maxwell G. Machani ◽  
Eric Ochomo ◽  
Christine Wanjala ◽  
Elizabeth Omukunda ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Development Time ◽  
Pyrethroid Resistance ◽  
Management Strategies ◽  
Adult Emergence ◽  
Fitness Cost ◽  
Malaria Vectors ◽  
Fitness Costs ◽  
Western Kenya ◽  
First Instar

Abstract Background Despite increasing documentation of insecticide resistance in malaria vectors against public health insecticides in sub-Saharan Africa, there is a paucity of information on the potential fitness costs of pyrethroid resistance in malaria vectors, which is important in improving the current resistant management strategies. This study aimed to assess the fitness cost effects of insecticide resistance on the development and survival of immature Anopheles gambiae from western Kenya. Methods Two-hour old, first instar larvae (L1) were introduced and raised in basins containing soil and rainwater in a semi-field set-up. Each day the number of surviving individuals per larval stage was counted and their stage of development were recorded until they emerged as adults. The larval life-history trait parameters measured include mean larval development time, daily survival and pupal emergence. Pyrethroid-resistant colony of An. gambiae sensu stricto and susceptible colony originating from the same site and with the same genetic background were used. Kisumu laboratory susceptible colony was used as a reference. Results The resistant colony had a significantly longer larval development time through the developmental stages than the susceptible colony. The resistant colony took an average of 2 days longer to develop from first instar (L1) to fourth instar (L4) (8.8 ± 0.2 days) compared to the susceptible colony (6.6 ± 0.2 days). The development time from first instar to pupa formation was significantly longer by 3 days in the resistant colony (10.28 ± 0.3 days) than in susceptible colony (7.5 ± 0.2 days). The time from egg hatching to adult emergence was significantly longer for the resistant colony (12.1 ± 0.3 days) than the susceptible colony (9.6 ± 0.2 days). The pupation rate (80%; 95% (CI: 77.5–83.6) vs 83.5%; 95% (CI: 80.6–86.3)) and adult emergence rate (86.3% vs 92.8%) did not differ between the resistant and susceptible colonies, respectively. The sex ratio of the females to males for the resistant (1:1.2) and susceptible colonies (1:1.07) was significantly different. Conclusion The study showed that pyrethroid resistance in An. gambiae had a fitness cost on their pre-imaginal development time and survival. Insecticide resistance delayed the development and reduced the survivorship of An. gambiae larvae. The study findings are important in understanding the fitness cost of insecticide resistance vectors that could contribute to shaping resistant management strategies.

scholarly journals Evidence of pyrethroid resistance in Anopheles amharicus and Anopheles arabiensis from Arjo-Didessa irrigation scheme, Ethiopia

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0261713
Author(s):  
Assalif Demissew ◽  
Abebe Animut ◽  
Solomon Kibret ◽  
Arega Tsegaye ◽  
Dawit Hawaria ◽  
...  
Keyword(s):  
Malaria Control ◽  
Pyrethroid Resistance ◽  
Management Strategies ◽  
Resistance Management ◽  
Indoor Residual Spraying ◽  
Resistance Mechanisms ◽  
Malaria Vectors ◽  
Insecticide Treated Nets ◽  
Irrigation Area ◽  
Specific Pcr

Background Indoor residual spraying and insecticide-treated nets are among the key malaria control intervention tools. However, their efficacy is declining due to the development and spread of insecticide resistant vectors. In Ethiopia, several studies reported resistance of An. arabiensis to multiple insecticide classes. However, such data is scarce in irrigated areas of the country where insecticides, pesticides and herbicides are intensively used. Susceptibility of An. gambiae s.l. to existing and new insecticides and resistance mechanisms were assessed in Arjo-Didessa sugarcane plantation area, southwestern Ethiopia. Methods Adult An. gambiae s.l. reared from larval/pupal collections of Arjo-Didessa sugarcane irrigation area and its surrounding were tested for their susceptibility to selected insecticides. Randomly selected An. gambiae s.l. (dead and survived) samples were identified to species using species-specific polymerase chain reaction (PCR) and were further analyzed for the presence of knockdown resistance (kdr) alleles using allele-specific PCR. Results Among the 214 An. gambiae s.l. samples analyzed by PCR, 89% (n = 190) were An. amharicus and 9% (n = 20) were An. arabiensis. Mortality rates of the An. gambiae s.l. exposed to deltamethrin and alphacypermethrin were 85% and 86.8%, respectively. On the other hand, mortalities against pirmiphos-methyl, bendiocarb, propoxur and clothianidin were 100%, 99%, 100% and 100%, respectively. Of those sub-samples (An. amharicus and An. arabiensis) examined for presence of kdr gene, none of them were found to carry the L1014F (West African) allelic mutation. Conclusion Anopheles amharicus and An. arabiensis from Arjo-Didessa sugarcane irrigation area were resistant to pyrethroids which might be synergized by extensive use of agricultural chemicals. Occurrence of pyrethroid resistant malaria vectors could challenge the ongoing malaria control and elimination program in the area unless resistance management strategies are implemented. Given the resistance of An. amharicus to pyrethroids, its behavior and vectorial capacity should be further investigated.

scholarly journals Review and Meta-Analysis of the Evidence for Choosing Between Specific Pyrethroids for Programmatic Purposes.

2021 ◽  
Author(s):  
Natalie Lissenden ◽  
Mara Kont ◽  
John Essandoh ◽  
Hanafy M Ismail ◽  
Thomas S Churcher ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Pyrethroid Resistance ◽  
Meta Analysis ◽  
Resistance Management ◽  
Malaria Vectors ◽  
Resistance Testing ◽  
Differential Mortality ◽  
Wild Populations ◽  
Insecticide Resistance Management ◽  
Lambda Cyhalothrin

Pyrethroid resistance is widespread in malaria vectors. However, differential mortality in discriminating dose assays to different pyrethroids is often observed in wild populations. When this occurs, it is unclear if this differential mortality should be interpreted as an indication of differential levels of susceptibility within the pyrethroid class, and if so, if countries should consider selecting one specific pyrethroid for programmatic use over another. A review of evidence from molecular studies, resistance testing with laboratory colonies and wild populations, and mosquito behavioural assays was conducted to answer these questions. Evidence suggests that in areas where pyrethroid resistance exists, different results in insecticide susceptibility assays with specific pyrethroids currently in common use (deltamethrin, permethrin, &alpha;-cypermethrin and &lambda;-cyhalothrin) are not necessarily indicative of an operationally relevant difference in potential performance. Consequently, it is not advisable to use rotation between these pyrethroids as an insecticide resistance management strategy. Less commonly used pyrethroids (bifenthrin and etofenprox) may have sufficiently different modes of action, though further work would be needed to examine how this may apply to insecticide resistance management.

scholarly journals Insecticide Resistance Exerts Significant Fitness Costs in Immature Stages of Anopheles Gambiae in Western Kenya.

2020 ◽  
Author(s):  
Joyce K Osoro ◽  
Maxwell Gesuge Machani ◽  
Eric Ochomo ◽  
Christine Wanjala ◽  
Elizabeth Omukunda ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Development Time ◽  
Pyrethroid Resistance ◽  
Management Strategies ◽  
Adult Emergence ◽  
Fitness Cost ◽  
Malaria Vectors ◽  
Fitness Costs ◽  
Western Kenya ◽  
First Instar

Abstract Background: Despite increasing documentation of insecticide resistance in malaria vectors against public health insecticides in sub-Saharan Africa, there is a paucity of information on the potential fitness costs of pyrethroid resistance in malaria vectors which is important in improving the current resistant management strategies. This study aimed to assess the fitness cost effects of insecticide resistance on the development and survival of immature Anopheles gambiae from western Kenya.Method: Two-hour old first instar larvae (L1) were introduced and raised in basins containing soil and rainwater in a semi-field setup. Each day the number of surviving individuals per larval stage was counted and their stage of development were recorded until they emerged as adults. The larval life history trait parameters measured include mean larval development time, daily survival and pupal emergence. Pyrethroid selected resistant colony of An. gambiae s.s and unselected colony originating from the same site and with same genetic background were used. Kisumu laboratory susceptible colony was used as a reference.Results: The selected resistant colony had a significantly longer larval development time through the developmental stages than the unselected susceptible colony. The selected colony took an average of 2 days longer to develop from first instar (L1) to fourth instar (L4) (8.8 ± 0.2 days) compared to unselected colony (6.6 ± 0.2 days). The development time from first instar to pupa formation was significantly longer by 3 days in the selected colony (10.28 ± 0.3 days) than in unselected colony (7 ± 0.2 days). The time from egg hatching to adult emergence was significantly longer for the selected colony (12.1 ± 0.3 days) than the unselected colony (9.2 ± 0.2 days). The pupation rate (80%; 95% [CI: 77.5-83.6] vs 83.5%; 95% [CI: 80.6-86.3]) and adult emergence rate (86.3% vs 92.5%) did not differ between the selected and unselected colonies respectively. The sex ratio of the females to males for the selected (1:1.21) and unselected colonies (1:1.07) was significantly different.Conclusion: The study showed that pyrethroid resistance in An. gambiae had a fitness cost on their pre-imaginal development time and survival. Insecticide resistance delayed the development and reduced the survivorship of An. gambiae larvae. The study findings are important in understanding the fitness cost of insecticide resistance vectors that could contribute to shaping resistant management strategies.

scholarly journals Fitness Costs of the Glutathione S-Transferase Epsilon 2 (L119F-GSTe2) Mediated Metabolic Resistance to Insecticides in the Major African Malaria Vector Anopheles Funestus

Genes ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 645 ◽  
Author(s):  
Magellan Tchouakui ◽  
Jacob M. Riveron ◽  
Doumani Djonabaye ◽  
Williams Tchapga ◽  
Helen Irving ◽  
...  
Keyword(s):  
Management Strategies ◽  
Resistance Management ◽  
Anopheles Funestus ◽  
Adult Emergence ◽  
Malaria Vectors ◽  
Adult Longevity ◽  
Heterozygote Advantage ◽  
Glutathione S Transferase ◽  
Metabolic Resistance ◽  
Life Traits

Metabolic resistance to insecticides threatens malaria control. However, little is known about its fitness cost in field populations of malaria vectors, thus limiting the design of suitable resistance management strategies. Here, we assessed the association between the glutathione S-transferase GSTe2-mediated metabolic resistance and life-traits of natural populations of Anopheles funestus. A total of 1200 indoor resting blood-fed female An. funestus (F0) were collected in Mibellon, Cameroon (2016/2017), and allowed to lay eggs individually. Genotyping of F1 mosquitoes for the L119F-GSTE2 mutation revealed that L/L119-homozygote susceptible (SS) mosquitoes significantly laid more eggs than heterozygotes L119F-RS (odds ratio (OR) = 2.06; p < 0.0001) and homozygote resistant 119F/F-RR (OR = 2.93; p < 0.0001). L/L119-SS susceptible mosquitoes also showed the higher ability for oviposition than 119F/F-RR resistant (OR = 2.68; p = 0.0002) indicating a reduced fecundity in resistant mosquitoes. Furthermore, L119F-RS larvae developed faster (nine days) than L119F-RR and L119F-SS (11 days) (X2 = 11.052; degree of freedom (df) = 4; p = 0.02) suggesting a heterozygote advantage effect for larval development. Interestingly, L/L119-SS developed faster than 119F/F-RR (OR = 5.3; p < 0.0001) revealing an increased developmental time in resistant mosquitoes. However, genotyping and sequencing revealed that L119F-RR mosquitoes exhibited a higher adult longevity compared to RS (OR > 2.2; p < 0.05) and SS (OR > 2.1; p < 0.05) with an increased frequency of GSTe2-resistant haplotypes in mosquitoes of D30 after adult emergence. Additionally, comparison of the expression of GSTe2 revealed a significantly increased expression from D1-D30 after emergence of adults (Anova test (F) = 8; df= 3; p = 0.008). The negative association between GSTe2 and some life traits of An. funestus could facilitate new resistance management strategies. However, the increased longevity of GSTe2-resistant mosquitoes suggests that an increase in resistance could exacerbate malaria transmission.

scholarly journals Impact of insecticide resistance in Anopheles arabiensis on malaria incidence and prevalence in Sudan and the costs of mitigation

2017 ◽  
Vol 114 (52) ◽  
pp. E11267-E11275 ◽  
Author(s):  
Hmooda Toto Kafy ◽  
Bashir Adam Ismail ◽  
Abraham Peter Mnzava ◽  
Jonathan Lines ◽  
Mogahid Shiekh Eldin Abdin ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Pyrethroid Resistance ◽  
Malaria Incidence ◽  
Disease Incidence ◽  
Indoor Residual Spraying ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Incidence And Mortality ◽  
Additional Protection ◽  
The Impact

Insecticide-based interventions have contributed to ∼78% of the reduction in the malaria burden in sub-Saharan Africa since 2000. Insecticide resistance in malaria vectors could presage a catastrophic rebound in disease incidence and mortality. A major impediment to the implementation of insecticide resistance management strategies is that evidence of the impact of resistance on malaria disease burden is limited. A cluster randomized trial was conducted in Sudan with pyrethroid-resistant and carbamate-susceptible malaria vectors. Clusters were randomly allocated to receive either long-lasting insecticidal nets (LLINs) alone or LLINs in combination with indoor residual spraying (IRS) with a pyrethroid (deltamethrin) insecticide in the first year and a carbamate (bendiocarb) insecticide in the two subsequent years. Malaria incidence was monitored for 3 y through active case detection in cohorts of children aged 1 to <10 y. When deltamethrin was used for IRS, incidence rates in the LLIN + IRS arm and the LLIN-only arm were similar, with the IRS providing no additional protection [incidence rate ratio (IRR) = 1.0 (95% confidence interval [CI]: 0.36–3.0; P = 0.96)]. When bendiocarb was used for IRS, there was some evidence of additional protection [interaction IRR = 0.55 (95% CI: 0.40–0.76; P < 0.001)]. In conclusion, pyrethroid resistance may have had an impact on pyrethroid-based IRS. The study was not designed to assess whether resistance had an impact on LLINs. These data alone should not be used as the basis for any policy change in vector control interventions.

scholarly journals Influence of a Major Mountainous Landscape Barrier (Mount Cameroon) on the Spread of Metabolic (GSTe2) and Target-Site (Rdl) Resistance Alleles in the African Malaria Vector Anopheles funestus

Genes ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1492
Author(s):  
Nathalie Amvongo-Adjia ◽  
Jacob M. Riveron ◽  
Flobert Njiokou ◽  
Samuel Wanji ◽  
Charles S. Wondji
Keyword(s):  
Control Strategies ◽  
Management Strategies ◽  
Resistance Management ◽  
Anopheles Funestus ◽  
Target Site ◽  
Malaria Vectors ◽  
Mount Cameroon ◽  
Parity Rate ◽  
Control Programmes ◽  
Mountainous Landscape

Increased levels of insecticide resistance in major malaria vectors such as Anopheles funestus threaten the effectiveness of insecticide-based control programmes. Understanding the landscape features impacting the spread of resistance makers is necessary to design suitable resistance management strategies. Here, we examined the influence of the highest mountain in West Africa (Mount Cameroon; 4095 m elevation) on the spread of metabolic and target-site resistance alleles in An. funestus populations. Vector composition varied across the four localities surveyed along the altitudinal cline with major vectors exhibiting high parity rate (80.5%). Plasmodium infection rates ranged from 0.79% (An. melas) to 4.67% (An. funestus). High frequencies of GSTe2R (67–81%) and RdlR (49–90%) resistance alleles were observed in An. funestus throughout the study area, with GSTe2R frequency increasing with altitude, whereas the opposite is observed for RdlR. Patterns of genetic diversity and population structure analyses revealed high levels of polymorphisms with 12 and 16 haplotypes respectively for GSTe2 and Rdl. However, the reduced diversity patterns of resistance allele carriers revealed signatures of positive selection on the two genes across the study area irrespective of the altitude. Despite slight variations associated with the altitude, the spread of resistance alleles suggest that control strategies could be implemented against malaria vectors across mountainous landscapes.

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