Neonicotinoid and pyrethroid combination: A tool to manage insecticide resistance in malaria vectors? Insights from experimental evolution

Background: The introduction of neonicotinoids for managing insecticide resistance in mosquitoes is of high interest as they interact with a biochemical target not previously used in public health. In this concern, Bayer developed a combination of the neonicotinoid clothianidin and the pyrethroid deltamethrin (brand name Fludora Fusion) as a new vector control tool. Although this combination proved to be efficient against pyrethroid-resistant mosquitoes, its ability to prevent the selection of pyrethroid and neonicotinoid resistance alleles was not investigated. In this context, the objective of this work was to study the dynamics and the molecular mechanisms of resistance of An. gambiae to the separated or combined components of this combination. A field-derived An. gambiae line carrying resistance alleles to multiple insecticides at low frequencies was used as a starting for 33 successive generations of controlled selection. Resistance levels to each insecticide and target site mutation frequencies were monitored throughout the selection process. Cross resistance to other public health insecticides were also investigated. RNA-seq was used to compare gene transcription variations and polymorphisms across all lines. Results: This study confirmed the potential of this insecticide combination to impair the selection of resistance as compared to its two separated components. Deltamethrin selection led to the rapid enrichment of the kdr L1014F target-site mutation while clothianidin selection led to the over-transcription of multiple cytochrome P450s including some showing high homology with the ones conferring neonicotinoid resistance in other insects. A strong selection signature associated with clothianidin selection was observed on a cytochrome P450 gene cluster previously associated with resistance. Within this cluster, the gene CYP6M1 showed the highest selection signature together with a transcription profile supporting a role in clothianidin resistance. Modelling the impact of point mutations selected by clothianidin on CYP6M1 protein structure suggested that the selection of variants affecting its active site can enhance clothianidin metabolism. Conclusions: In the context of the recent deployment of neonicotinoids for mosquito control and their frequent usage in agriculture, the present study highlights the benefit of combining them with other insecticides for preventing the selection of resistance and sustaining vector control activities.

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Experimental evolution supports the potential of neonicotinoid-pyrethroid combination for managing insecticide resistance in malaria vectors

Scientific Reports ◽

10.1038/s41598-021-99061-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marius Gonse Zoh ◽

Jean-Marc Bonneville ◽

Jordan Tutagata ◽

Frederic Laporte ◽

Behi K. Fodjo ◽

...

Keyword(s):

Public Health ◽

Insecticide Resistance ◽

Vector Control ◽

Target Site ◽

Site Mutation ◽

Protein Variant ◽

Selection Signature ◽

The Impact ◽

Selection Of ◽

Selection Of Resistance

AbstractThe introduction of neonicotinoids for managing insecticide resistance in mosquitoes is of high interest as they interact with a biochemical target not previously used in public health. In this concern, Bayer developed a combination of the neonicotinoid clothianidin and the pyrethroid deltamethrin (brand name Fludora Fusion) as a new vector control tool. Although this combination proved to be efficient against pyrethroid-resistant mosquitoes, its ability to prevent the selection of pyrethroid and neonicotinoid resistance alleles was not investigated. In this context, the objective of this work was to study the dynamics and the molecular mechanisms of resistance of An. gambiae to the separated or combined components of this combination. A field-derived An. gambiae line carrying resistance alleles to multiple insecticides at low frequencies was used as a starting for 33 successive generations of controlled selection. Resistance levels to each insecticide and target site mutation frequencies were monitored throughout the selection process. Cross resistance to other public health insecticides were also investigated. RNA-seq was used to compare gene transcription variations and polymorphisms across all lines. This study confirmed the potential of this insecticide combination to impair the selection of resistance as compared to its two separated components. Deltamethrin selection led to the rapid enrichment of the kdr L1014F target-site mutation. Clothianidin selection led to the over-transcription of multiple cytochrome P450s including some showing high homology with those conferring neonicotinoid resistance in other insects. A strong selection signature associated with clothianidin selection was also observed on a P450 gene cluster previously associated with resistance. Within this cluster, the gene CYP6M1 showed the highest selection signature together with a transcription profile supporting a role in clothianidin resistance. Modelling the impact of point mutations selected by clothianidin on CYP6M1 protein structure showed that selection retained a protein variant with a modified active site potentially enhancing clothianidin metabolism. In the context of the recent deployment of neonicotinoids for mosquito control and their frequent usage in agriculture, the present study highlights the benefit of combining them with other insecticides for preventing the selection of resistance and sustaining vector control activities.

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Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya

Parasites & Vectors ◽

10.1186/s13071-021-04833-z ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Pauline Winnie Orondo ◽

Steven G. Nyanjom ◽

Harrysone Atieli ◽

John Githure ◽

Benyl M. Ondeto ◽

...

Keyword(s):

Insecticide Resistance ◽

Vector Control ◽

Anopheles Arabiensis ◽

Crop Protection ◽

Indoor Residual Spraying ◽

Malaria Vectors ◽

Western Kenya ◽

Animal Protection ◽

Selection Of ◽

Selection Of Resistance

Abstract Background Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya. Methods The study was carried out in 2018–2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area. Results Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8–84% to 83.3–78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1–16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection. Conclusion Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides. Graphic abstract

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Insecticide exposure impacts vector–parasite interactions in insecticide-resistant malaria vectors

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.0389 ◽

2014 ◽

Vol 281 (1786) ◽

pp. 20140389 ◽

Cited By ~ 31

Author(s):

Haoues Alout ◽

Innocent Djègbè ◽

Fabrice Chandre ◽

Luc Salako Djogbénou ◽

Roch Kounbobr Dabiré ◽

...

Keyword(s):

Insecticide Resistance ◽

Vector Competence ◽

Resistance Mechanisms ◽

Malaria Vectors ◽

Anopheles Gambiae S.S ◽

Strong Trend ◽

Insecticide Exposure ◽

The Impact ◽

Selection Of ◽

Selection Of Resistance

Currently, there is a strong trend towards increasing insecticide-based vector control coverage in malaria endemic countries. The ecological consequence of insecticide applications has been mainly studied regarding the selection of resistance mechanisms; however, little is known about their impact on vector competence in mosquitoes responsible for malaria transmission. As they have limited toxicity to mosquitoes owing to the selection of resistance mechanisms, insecticides may also interact with pathogens developing in mosquitoes. In this study, we explored the impact of insecticide exposure on Plasmodium falciparum development in insecticide-resistant colonies of Anopheles gambiae s.s. , homozygous for the ace-1 G119S mutation (Acerkis) or the kdr L1014F mutation (Kdrkis). Exposure to bendiocarb insecticide reduced the prevalence and intensity of P. falciparum oocysts developing in the infected midgut of the Acerkis strain, whereas exposure to dichlorodiphenyltrichloroethane reduced only the prevalence of P. falciparum infection in the Kdrkis strain. Thus, insecticide resistance leads to a selective pressure of insecticides on Plasmodium parasites, providing, to our knowledge, the first evidence of genotype by environment interactions on vector competence in a natural Anopheles–Plasmodium combination . Insecticide applications would affect the transmission of malaria in spite of resistance and would reduce to some degree the impact of insecticide resistance on malaria control interventions.

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Antimicrobials and resistant bacteria in global fish farming and the possible risk for public health

Arquivos do Instituto Biológico ◽

10.1590/1808-1657000362019 ◽

2020 ◽

Vol 87 ◽

Author(s):

Luís Eduardo de Souza Gazal ◽

Kelly Cristina Tagliari de Brito ◽

Renata Katsuko Takayama Kobayashi ◽

Gerson Nakazato ◽

Lissandra Souto Cavalli ◽

...

Keyword(s):

Public Health ◽

Infectious Diseases ◽

Pathogenic Bacteria ◽

Bacterial Resistance ◽

Public Health Problem ◽

Fish Farming ◽

Cross Resistance ◽

Resistant Bacteria ◽

The Impact ◽

Selection Of

ABSTRACT: The use of antimicrobials in fish farming is a reflection of the fast aquaculture development worldwide. The intensification of aquaculture to achieve market demands could lead to an increase in infectious diseases by pathogenic bacteria. Consequently, antimicrobials act as controls for emerging infectious diseases, but their use must follow the rules and regulations of the country where the activity is performed. Although the regulations impose limits to the use of antimicrobials in fish farming, many studies show that resistant bacteria are isolated from this system. The selection of resistant bacteria is not limited only to the use of antimicrobials, but also to co-selection of resistance genes or even with cross-resistance processes. Resistant bacteria from fish farming are a serious concern because they can be acquired by humans with handling or food chain, which may represent a public health problem. In the present review, we present an overview of antimicrobials use in aquaculture, the antimicrobial resistance and the impact of antimicrobial and bacterial resistance from a public health perspective.

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Assessing the anti-resistance potential of public health vaporizer formulations and insecticide mixtures with pyrethroids using transgenic Drosophila lines

Parasites & Vectors ◽

10.1186/s13071-021-04997-8 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Hang Ngoc Bao Luong ◽

Arunas Damijonaitis ◽

Ralf Nauen ◽

John Vontas ◽

Sebastian Horstmann

Keyword(s):

Public Health ◽

Insecticide Resistance ◽

Vector Control ◽

Pyrethroid Resistance ◽

Indoor Residual Spraying ◽

Target Site ◽

Detoxification Enzymes ◽

Modes Of Action ◽

Commercial Mixture ◽

Insecticide Mixtures

Abstract Background Insecticide resistance—and especially pyrethroid resistance—is a major challenge for vector control in public health. The use of insecticide mixtures utilizing alternative modes of action, as well as new formulations facilitating their uptake, is likely to break resistance and slow the development of resistance. Methods We used genetically defined highly resistant lines of Drosophila melanogaster with distinct target-site mutations and detoxification enzymes to test the efficacy and anti-resistance potential of novel mixture formulations (i.e. Fludora® Fusion consisting of deltamethrin and clothianidin), as well as emulsifiable concentrate transfluthrin, compared to alternative, currently used pyrethroid insecticide formulations for vector control. Results The commercial mixture Fludora® Fusion, consisting of both a pyrethroid (deltamethrin) and a neonicotinoid (clothianidin), performed better than either of the single active ingredients against resistant transgenic flies. Transfluthrin, a highly volatile active ingredient with a different molecular structure and primary exposure route (respiration), was also efficient and less affected by the combination of metabolic and target-site resistance. Both formulations substantially reduced insecticide resistance across different pyrethroid-resistant Drosophila transgenic strains. Conclusions The use of mixtures containing two unrelated modes of action as well as a formulation based on transfluthrin showed increased efficacy and resistance-breaking potential against genetically defined highly resistant Drosophila flies. The experimental model remains to be validated with mosquito populations in the field. The possible introduction of new transfluthrin-based products and mixtures for indoor residual spraying, in line with other combination and mixture vector control products recently evaluated for use in public health, will provide solutions for better insecticide resistance management. Graphical abstract

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Transcriptomic analysis of insecticide resistance in the lymphatic filariasis vectorCulex quinquefasciatus

10.1101/589028 ◽

2019 ◽

Author(s):

Walter Fabricio Silva Martins ◽

Craig Stephen Wilding ◽

Alison Taylor Isaacs ◽

Emily Joy Rippon ◽

Karine Megy ◽

...

Keyword(s):

Insecticide Resistance ◽

Lymphatic Filariasis ◽

Fold Increase ◽

Target Site ◽

Detoxification Enzymes ◽

Site Mutation ◽

Public Health Importance ◽

Metabolic Resistance ◽

Vector Borne Diseases ◽

Bendiocarb Resistance

ABSTRACTCulex quinquefasciatusplays an important role in transmission of vector-borne diseases of public health importance, including lymphatic filariasis (LF), as well as many arboviral diseases. Currently, efforts to tackleC. quinquefasciatusvectored diseases are based on either mass drug administration (MDA) for LF, or insecticide-based interventions. Widespread and intensive insecticide usage has resulted in increased resistance in mosquito vectors, includingC. quinquefasciatus. Herein, the transcriptome profile of Ugandan bendiocarb-resistantC. quinquefasciatuswas explored to identify candidate genes associated with insecticide resistance. Resistance to bendiocarb in exposed mosquitoes was marked, with 2.04% mortality following 1h exposure and 58.02% after 4h. Genotyping of the G119SAce-1target site mutation detected a highly significant association (p<0.0001; OR=25) between resistance andAce1-119S. However, synergist assays using the P450 inhibitor PBO or the esterase inhibitor TPP resulted in markedly increased mortality (to ≈80%), suggesting a role of metabolic resistance in the resistance phenotype. Using a novel, custom 60K whole-transcriptome microarray 16 genes significantly overexpressed in resistant mosquitoes were detected, with the P450Cyp6z18showing the highest differential gene expression (>8-fold increase vs unexposed controls). These results provide evidence that bendiocarb-resistance in UgandanC. quinquefasciatusis mediated by both target-site mechanisms and over-expression of detoxification enzymes.

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Tenebenal: a meta-diamide with potential for use as a novel mode of action insecticide for public health

Malaria Journal ◽

10.1186/s12936-020-03466-4 ◽

2020 ◽

Vol 19 (1) ◽

Author(s):

Rosemary Susan Lees ◽

Pauline Ambrose ◽

Jessica Williams ◽

John Morgan ◽

Giorgio Praulins ◽

...

Keyword(s):

Public Health ◽

Vector Control ◽

Topical Application ◽

Mode Of Action ◽

Application Rate ◽

Intrinsic Activity ◽

Cross Resistance ◽

Laboratory Assessment ◽

Health Products ◽

Residual Efficacy

Abstract Background There is an urgent need for insecticides with novel modes of action against mosquito vectors. Broflanilide is a meta-diamide, discovered and named Tenebenal™ by Mitsui Chemicals Agro, Inc., which has been identified as a candidate insecticide for use in public health products. Methods To evaluate its potential for use in public health, Tenebenal™ was screened using an array of methodologies against Anopheles and Aedes strains. Initially it was assessed for intrinsic efficacy by topical application. Tarsal contact bioassays were then conducted to further investigate its efficacy, as well as its potency and speed of action. The potential of the compound for use in indoor residual spray (IRS) applications was investigated by testing the residual efficacy of a prototype IRS formulation on a range of typical house building substrates, and its potential for use in long-lasting insecticidal nets (LLIN) was tested using dipped net samples. Finally, bioassays using well-characterized insecticide-resistant mosquito strains and an in silico screen for mutations in the insecticide’s target site were performed to assess the risk of cross-resistance to Tenebenal™. Results Tenebenal™ was effective as a tarsal contact insecticide against both Aedes and Anopheles mosquitoes, with no apparent cross-resistance caused by mechanisms that have evolved to insecticides currently used in vector control. Topical application showed potent intrinsic activity against a Kisumu reference strain and an insecticide-resistant strain of Anopheles gambiae. Applied to filter paper in a WHO tube bioassay, Tenebenal™ was effective in killing 100% of susceptible and resistant strains of An. gambiae and Aedes aegypti at a concentration of 0.01%. The discriminating concentration of 11.91 µg/bottle shows it to be very potent relative to chemistries previously identified as having potential for vector control. Mortality occurs within 24 h of exposure, 80% of this mortality occurring within the first 10 h, a speed of kill somewhat slower than seen with pyrethroids due to the mode of action. The potential of Tenebenal™ for development in LLIN and IRS products was demonstrated. At least 12 months residual efficacy of a prototype IRS formulation applied at concentrations up to 200 mg of AI/sq m was demonstrated on a range of representative wall substrates, and up to 18 months on more inert substrates. A dipped net with an application rate of around 2 g/sq m Tenebenal™ killed 100% of exposed mosquitoes within a 3-min exposure in a WHO cone test. Conclusions Tenebenal™ is a potent insecticide against adult Aedes and Anopheles mosquitoes, including strains resistant to classes of insecticide currently used in vector control. The compound has shown great potential in laboratory assessment and warrants further investigation into development for the control of pyrethroid-resistant mosquitoes.

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Evolution of Drosophila insecticide resistance

Genome ◽

10.1139/g93-001 ◽

1993 ◽

Vol 36 (1) ◽

pp. 1-7 ◽

Cited By ~ 42

Author(s):

R. A. Morton

Keyword(s):

Insecticide Resistance ◽

Quantitative Traits ◽

Molecular Genetic ◽

Resistance Evolution ◽

Target Molecules ◽

Genetic Techniques ◽

The Cost ◽

The Impact ◽

The Relationship ◽

Selection Of

The impact of insecticide resistance is well documented. It includes the toxic effects of pesticides on the environment and the cost of the increased amounts of insecticides required to effectively control resistant insects. Resistance evolves by the selection of genes that confer tolerance to insecticides. Several resistance genes have been identified and cloned in Drosophila, including genes for mutant target molecules and genes that increase insecticide degradation. Drosophila is a useful system to understand the evolution of quantitative traits in general as well as the population genetics of insecticide resistance. Through it, we may hope to understand the relationship between discrete genetic change and continuously varying characters. In addition, molecular genetic techniques developed using Drosophila can eventually be transferred to other insects in order to help control pest populations.Key words: insecticide resistance, evolution of tolerance, selection of resistant genes, molecular genetics, Drosophila.

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Functional genetic validation of key genes conferring insecticide resistance in the major African malaria vector, Anopheles gambiae

10.1101/749457 ◽

2019 ◽

Cited By ~ 1

Author(s):

Adriana Adolfi ◽

Beth Poulton ◽

Amalia Anthousi ◽

Stephanie Macilwee ◽

Hilary Ranson ◽

...

Keyword(s):

Public Health ◽

Insecticide Resistance ◽

Anopheles Gambiae ◽

Pyrethroid Resistance ◽

Control Strategies ◽

Resistance Mechanisms ◽

Effective Control ◽

Cross Resistance ◽

Toxic Metabolite ◽

Control Programs

ABSTRACTResistance in Anopheles gambiae to members of all four major classes (pyrethroids, carbamates, organochlorines and organophosphates) of public health insecticides limits effective control of malaria transmission in Africa. Increased expression of detoxifying enzymes has been associated with resistance, but direct functional validation in An. gambiae has been lacking. Here we perform transgenic analysis using the GAL4/UAS system to examine insecticide resistance phenotypes conferred by increased expression of the three genes - Cyp6m2, Cyp6p3 and Gste2 - most often found upregulated in resistant An. gambiae. We report the first evidence in An. gambiae that organophosphate and organochlorine resistance is conferred by overexpression of GSTE2 in a broad tissue profile. Pyrethroid and carbamate resistance is bestowed by similar Cyp6p3 overexpression, and Cyp6m2 confers only pyrethroid resistance when overexpressed in the same tissues. Conversely, such Cyp6m2 overexpression increases susceptibility to the organophosphate malathion, presumably due to conversion to a more toxic metabolite. No resistant phenotypes are conferred when either Cyp6 gene overexpression is restricted to the midgut or oenocytes, answering long standing questions related to the importance of these tissues in resistance to contact insecticides. Validation of genes conferring resistance provides markers to guide control strategies, and the observed negative cross-resistance due to Cyp6m2 gives credence to proposed dual insecticide strategies to overcome pyrethroid resistance. These trasnsgenic An. gambiae resistant lines are being used to test potential liabilities in new active compounds early in development.SIGNIFICANCE STATEMENTInsecticide resistance in Anopheles gambiae mosquitoes can derail malaria control programs, and to overcome it we need to discover the underlying molecular basis. Here, for the first time, we characterise three genes most often associated with insecticide resistance directly by their overproduction in genetically modified An. gambiae. We show that overexpression of each gene confers resistance to representatives of at least one insecticide class and, taken together, the three genes provide cross-resistance to all four major insecticide classes currently used in public health. These data validate the candidate genes as markers to monitor the spread of resistance in mosquito populations. The modified mosquitoes produced are also valuable tools to pre-screen new insecticides for potential liabilities to existing resistance mechanisms.

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Monitoring of Insecticide Resistance in Anopheles culicifacies in Twelve Districts of Madhya Pradesh, Central India (2017–2019)

Journal of Tropical Medicine ◽

10.1155/2022/4404027 ◽

2022 ◽

Vol 2022 ◽

pp. 1-8

Author(s):

Ashok K. Mishra ◽

Praveen K Bharti ◽

Gyan Chand ◽

Aparup Das ◽

Himanshu Jayswar ◽

...

Keyword(s):

Insecticide Resistance ◽

Vector Control ◽

Indoor Residual Spraying ◽

Central India ◽

Control Programme ◽

Madhya Pradesh ◽

Control Measures ◽

Malaria Vectors ◽

Malaria Vector Control ◽

The Impact

Background. Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) are malaria vector control measures used in India, but the development of insecticide resistance poses major impediments for effective vector control strategies. As per the guidelines of the National Vector Borne Disease Control Programme (NVBDCP), the study was conducted in 12 districts of Madhya Pradesh to generate data on insecticide resistance in malaria vectors. Methods. The susceptibility tests were conducted on adult An. culicifacies as per the WHO standard technique with wild-caught mosquitoes. The blood-fed female mosquitoes were exposed in 3 to 4 replicates on each occasion to the impregnated papers with specified discriminating dosages of the insecticides (DDT: 4%, malathion: 5%, deltamethrin: 0.05%, and alphacypermethrin: 0.05%), for one hour, and mortality was recorded after 24-hour holding. Results. An. culicifacies was found resistant to DDT 4% in all the 12 districts and malathion in 11 districts. The resistance to alphacypermethrin was also observed in two districts, and possible resistance was found to alphacypermethrin in seven districts and to deltamethrin in eight districts, while the vector was found susceptible to both deltamethrin and alphacypermethrin in only 3 districts. Conclusion. An. culicifacies is resistant to DDT and malathion and has emerging resistance to pyrethroids, alphacypermethrin, and deltamethrin. Therefore, regular monitoring of insecticide susceptibility in malaria vectors is needed for implementing effective vector management strategies. However, studies to verify the impact of IRS with good coverage on the transmission of disease are required before deciding on the change of insecticide in conjunction with epidemiological data.

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