Monitoring of resistance to the pyrethroid cypermethrin in Brazilian Aedes aegypti (Diptera: Culicidae) populations collected between 2001 and 2003
TL;DR: Although this pyrethroid was recently started to be used in the country to control the dengue vector, a decrease in susceptibility was noted between both periods analyzed, particularly in the city of Rio de Janeiro, indicating that resistance is due at least in part to a target site alteration.
Abstract: Resistance to cypermethrin of different Aedes aegypti Brazilian populations, collected at two successive periods (2001 and 2002/2003), was monitored using the insecticide-coated bottles bioassay. Slight modifications were included in the method to discriminate between mortality and the knock down effect. Although this pyrethroid was recently started to be used in the country to control the dengue vector, a decrease in susceptibility was noted between both periods analyzed, particularly in the city of Rio de Janeiro. The results indicate that resistance is due at least in part to a target site alteration.
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TL;DR: 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.
Abstract: 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. 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. Susceptibility alterations to pyriproxyfen were recorded in six (4.5%) Ae. aegypti populations from the states of Bahia and Ceara, 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). 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.
19 citations
Cites background from "Monitoring of resistance to the pyr..."
...3 Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, Rua Francisco Manuel no 102, Bairro Benfica, Rio de Janeiro/Rio de Janeiro State CEP 20911-270, Brasil....
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...In 2001, resistance to the adulticide pyrethroid (PY) cypermethrin was detected in populations from the state of Rio de Janeiro [10]....
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...Rio de Janeiro: Fiocruz; 2015. p. 93–126....
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...Rio de Janeiro: Fiocruz; 2005. https ://www. incte m.bioqm ed.ufrj.br/index .php/pt/bibli oteca /2964-param etros -de-bioss egura nca-para-inset arios -e-infec torio s-de-vetor es-do-insti tutooswal do-cruz....
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...The paddles were then shipped to the Physiology and Arthropod Vector Control Laboratory (Laboratório de Fisiologia e Controle de Artrópodes Vetores, LAFICAVE), at the Oswaldo Cruz Institute (IOC/Fiocruz), Rio de Janeiro/ RJ, where the arrivals were recorded, forms were stored and populations labeled with a code known only by the study director, in order to maintain origin confidentiality....
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Journal Article•
TL;DR: The resistance/susceptible status of Aedes aegypti (field strain) from slum area of Misri Shah Lahore, Pakistan was determined during May 2009 to January 2011 and indicated the tested population was less resistant against cypermethrin as compared to deltamethrin.
Abstract: The resistance/susceptible status of Aedes aegypti (field strain) from slum area of Misri Shah Lahore, Pakistan was determined during May 2009 to January 2011. Two insecticides i.e. deltamethrin 1. 5% EC and cypermethrin 10% EC which were sprayed in various localities of Lahore from the last ten years we re used to evaluate resistance/ susceptible status of field collected adult females of Aedes aegypti by CDC bottle bioassays. The resistance level was expressed as resistance ratio (RR) of lethal time at 50% death determined using field collected and susceptible strain s. Current study indicated RR LT50 1.95 and 1.47 against deltamethrin and cypermethrin in adult females of Aedes aegypti respectively. In addition, the tested population was less resistant against cypermethrin as compared to deltamethrin. In comparison of percent mortalities, there was no significant difference between the two insecticides against adult fema les.
18 citations
TL;DR: Diagnostic doses and diagnostic times can be incorporated into vector management programs that use the CDC bottle bioassay to assess insecticide resistance in field populations of Lu and P. papatasi.
Abstract: Insecticide resistance to synthetic chemical insecticides is a worldwide concern in phlebotomine sand flies (Diptera: Psychodidae), the vectors of Leishmania spp. parasites. The CDC bottle bioassay assesses resistance by testing populations against verified diagnostic doses and diagnostic times for an insecticide, but the assay has been used limitedly with sand flies. The objective of this study was to determine diagnostic doses and diagnostic times for laboratory Lutzomyia longipalpis (Lutz & Nieva) and Phlebotomus papatasi (Scopoli) to ten insecticides, including pyrethroids, organophosphates, carbamates, and DDT, that are used worldwide to control vectors. Bioassays were conducted in 1,000-ml glass bottles each containing 10–25 sand flies from laboratory colonies of L. longipalpis or P. papatasi. Four pyrethroids, three organophosphates, two carbamates and one organochlorine, were evaluated. A series of concentrations were tested for each insecticide, and four replicates were conducted for each concentration. Diagnostic doses were determined only during the exposure bioassay for the organophosphates and carbamates. For the pyrethroids and DDT, diagnostic doses were determined for both the exposure bioassay and after a 24-hour recovery period. Both species are highly susceptible to the carbamates as their diagnostic doses are under 7.0 μg/ml. Both species are also highly susceptible to DDT during the exposure assay as their diagnostic doses are 7.5 μg/ml, yet their diagnostic doses for the 24-h recovery period are 650.0 μg/ml for Lu. longipalpis and 470.0 μg/ml for P. papatasi. Diagnostic doses and diagnostic times can now be incorporated into vector management programs that use the CDC bottle bioassay to assess insecticide resistance in field populations of Lu. longipalpis and P. papatasi. These findings provide initial starting points for determining diagnostic doses and diagnostic times for other sand fly vector species and wild populations using the CDC bottle bioassay.
18 citations
TL;DR: Aedes aegypti populations in the Goiânia area are highly resistant to deltamethrin, presumably due to high frequencies of kdr(knockdown-resistance) mutations.
Abstract: The mosquito Aedes aegypti has evolved resistance to pyrethroid insecticides. The present study evaluated
Ae. aegypti from Goiânia for the resistant phenotype and for mutations associated with resistance. Methods: Insecticide
dose-response bioassays were conducted on mosquitoes descended from fi eld-collected eggs, and polymerase chain reaction
(PCR) was used to genotype 90 individuals at sites implicated in pyrethroid resistance. Results: All mosquito populations
displayed high levels of resistance to deltamethrin, as well as high frequencies of the 1016Ilekdr and 1534Cyskdr mutations.
Conclusions: Aedes aegypti populations in the Goiânia area are highly resistant to deltamethrin, presumably due to high
frequencies of kdr (knockdown-resistance) mutations.
17 citations
Patent•
13 Jul 2012
TL;DR: In this paper, the active agent can include perilla oil, a component found in perilla oils, or a perillaldehyde or carvone analog, and the insecticide can include a pyrethrum, pyrethrin, pyrin, neonicotinoid, chlofenapyr, ethiprole, sulfoxoflor, carbamate, organophosphate, or organochlorine.
Abstract: Insecticidal compositions have at least one active agent and at least one insecticide. The active agent can include perilla oil, a component found in perilla oil, or a perillaldehyde or carvone analog. The insecticide can include a pyrethrum, pyrethrin, pyrethroid, neonicotinoid, chlofenapyr, ethiprole, sulfoxoflor, carbamate, organophosphate, or organochlorine. Methods for controlling insects include contacting an insect with an effective amount of a composition described in this specification. Modified plants that produce an active agent can be contacted with an insecticide.
17 citations
References
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TL;DR: At field-use rates, a neurotoxic effect of the ecdysteroid agonist RH-5849 is observed that involves blockage of both muscle and neuronal potassium channels, and the future use of ion channels as targets for chemical and genetically engineered insecticides is discussed.
Abstract: Ion channels are the primary target sites for several classes of natural and synthetic insecticidal compounds. The voltage-sensitive sodium channel is the major target site for DDT and pyrethroids, the veratrum alkaloids, andN-alkylamides. Recently, neurotoxic proteins from arthropod venoms, some of which specifically attack insect sodium channels, have been engineered into baculoviruses to act as biopesticides. The synthetic pyrazolines also primarily affect the sodium channel, although some members of this group target neuronal calcium channels as well. The ryanoids have also found use as insecticides, and these materials induce muscle contracture by irreversible activation of the calcium-release channel of the sarcoplasmic reticulum. The arylheterocycles (e.g. endosulfan and fipronil) are potent convulsants and insecticides that block the GABA-gated chloride channel. In contrast, the avermectins activate both ligand and voltage-gated chloride channels, which leads to paralysis. At field-use rates, a ne...
418 citations
Journal Article•
TL;DR: A simple method is described for treating 250-ml glass Wheaton bottles with insecticide, and using them as test chambers for detecting insecticide resistance in mosquito and sandfly populations.
Abstract: A simple method is described for treating 250-ml glass Wheaton bottles with insecticide, and using them as test chambers for detecting insecticide resistance in mosquito and sandfly populations. The methods for treating bottles, obtaining baseline data, and applying this technique to insects from the field are described. Sample data are presented from tests run on different vector species using a variety of insecticides. Time-mortality data from the bottle bioassay are presented alongside results from biochemical detection methods applied to the same mosquito population. The potential role, advantages, and limitations of the time-mortality bottle method are discussed.
265 citations
"Monitoring of resistance to the pyr..." refers background or methods in this paper
...According to the original methodology (Brogdon & McAllister 1998), the criterion for mortality was that mosquitoes were not able to fly or to right themselves when the bottle is gently rotated....
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...According to Brogdon and McAllister (1998) these would be dead mosquitoes....
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...Bioassays were performed with insecticide-coated bottles, as described by Brogdon and McAllister (1998)....
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...This was attained after 30 min exposure, a period considered as the resistance threshold (Brogdon & McAllister 1998)....
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TL;DR: Exposure of larvae to a diagnostic dose of temephos showed in alterations in susceptibility in all populations, and adults from only one municipality remained susceptible to both fenitrothion and malathion.
Abstract: Chemical insecticides have been widely used in Brazil for several years. This exposes mosquito populations to an intense selection pressure for resistance to insecticides. In 1999, the Brazilian National Health Foundation started the first program designed to monitor the resistance of Aedes aegypti to insecticides. We analyzed populations from 10 municipalities (from 84 selected in Brazil) in the states of Rio de Janeiro and Espirito Santo. Exposure of larvae to a diagnostic dose of temephos showed in alterations in susceptibility in all populations. Mosquitoes from eight municipalities exhibited resistance, with mortality levels ranging from 74% (Campos dos Goytacazes, Rio de Janeiro) to 23.5% (Sao Goncalo, Rio de Janeiro). The resistance ratios of mosquitoes from three municipalities ranged from 3.59 to 12.41. Adults from only one municipality (Nova Iguacu, Rio de Janeiro) remained susceptible to both fenitrothion and malathion. These results are being used to define new local vector control strategies.
234 citations
"Monitoring of resistance to the pyr..." refers background in this paper
...The use of organophosphates, employed since 1967 throughout the country against Ae. aegypti larvae and adults, was intensified after the 1986 epidemics, that started at Rio de Janeiro and spread over several other regions (Lima et al. 2003, Braga et al. 2004)....
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Journal Article•
TL;DR: The method with which the percentage of sodium channel population that needs to be modified to cause repetitive after-discharges can be measured accurately is developed and is applicable to other neuroactive drugs that act through the threshold phenomenon.
Abstract: Most insecticides are neurotoxicants causing various forms of hyperexcitation and paralysis in animals. A variety of neuroreceptors and ion channels have been identified as the major target sites of these neurotoxic insecticides. This paper gives the highlights of some of the recent development in this area. Pyrethroids keep the sodium channel open for unusually long times causing a prolonged flow of sodium current. The prolonged sodium current elevates and prolongs the depolarizing after-potential which reaches the threshold membrane potential to initiate repetitive after-discharges. We have developed the method with which the percentage of sodium channel population that needs to be modified to cause repetitive after-discharges can be measured accurately. In rat cerebellar Purkinje neurons, only 0.6% of sodium channels needs to be modified for hyperexcitation resulting in a large toxicity amplification. This concept is applicable to other neuroactive drugs that act through the threshold phenomenon. 'The mechanisms of selective toxicity of pyrethroids in mammals and insects have been quantitatively determined to be due mainly to the different sensitivity of the sodium channels to pyrethroids and the negative temperature dependence of pyrethroid action on the sodium channels. The degradation of pyrethroids play only a minor role. The negative temperature dependence of pyrethroid action is due to the increased sodium current flow at low temperature. The major site of action of dieldrin and hexachlorocyclohexane is the GABA A receptor chloride channel complex. Dieldrin exerts a dual action, initial stimulation and subsequent suppression, and the latter is responsible for hyperexcitation of animals. Dieldrin stimulation requires the γ2s subunit in the GABA receptor, whereas dieldrin suppression occurs in the presence or absence of the γ2s subunit.
202 citations
"Monitoring of resistance to the pyr..." refers background or methods in this paper
...After linkage to pyrethroids, the sodium channels in the neurons are maintained for a longer length of time in their opened conformation, which results in a continuous nervous impulse that causes bursts of contractions, culminating with paralysis (Bloomquist 1996). Depending on the insecticide’s dosage, this effect, known as the “knock down” mechanism, is reversible if contact with the insecticide is interrupted. Resistant individuals that have a kdr mutation exhibit the knock down effect but can recover from pyrethroid dosages that are lethal to susceptible insects (Milani 1954, Pauron et al. 1989). Sodium channels are also the target site for organochlorines, an insecticide class that has not been used in the Public Health at Brazil since the reintroduction of Ae. aegypti in 1967 (Franco 1976). We report on the monitoring of Ae. aegypti resistance to cypermethrin in municipalities of three Brazilian states: Sergipe (SE) and Alagoas (AL), located at Northeast Brazil and Rio de Janeiro (RJ), at the Southeast (Figure). Bioassays were performed with insecticide-coated bottles, as described by Brogdon and McAllister (1998). We first calibrated the bottles with different dosages of cypermethrin, by testing mosquitoes from the Rockefeller strain....
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...After linkage to pyrethroids, the sodium channels in the neurons are maintained for a longer length of time in their opened conformation, which results in a continuous nervous impulse that causes bursts of contractions, culminating with paralysis (Bloomquist 1996)....
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TL;DR: Exposure of larvae to the diagnostic dose of temephos revealed resistance in all localities examined, with mortality levels ranging from 4% (Pilares district, Rio de Janeiro, RJ) to 61.9% (Campos dos Goytacazes, RJ).
Abstract: For more than 30 years temephos, an organophosphate insecticide, has been the sole larvicide used in Brazil in the control of Aedes aegypti. Organophosphates were also used for adult control, being replaced by pyrethroids since l999. In this same year, the Brazilian Health Foundation started the coordination of the Ae. aegypti Insecticide Resistance Monitoring Program. In the context of this program, our group was responsible for the detection of temephos resistance in a total of 12 municipalities in the states of Rio de Janeiro (RJ), Alagoas (AL), and Sergipe (SE) during 2001. In each municipality, a pool of mosquitoes collected from different districts was used, with the exception of Rio de Janeiro city, where eight districts have been separately evaluated. Exposure of larvae to the diagnostic dose of temephos revealed resistance in all localities examined, with mortality levels ranging from 4% (Pilares district, Rio de Janeiro, RJ) to 61.9% (Campos dos Goytacazes, RJ). Quantification of mortality showed resistance ratios from 6.1 (Aracaju, SE) to 16.8 (Sao Goncalo, RJ and Penha district, Rio de Janeiro, RJ). The national dengue control program is presently using these data to subside insecticide resistance management.
194 citations
"Monitoring of resistance to the pyr..." refers background in this paper
...The use of organophosphates, employed since 1967 throughout the country against Ae. aegypti larvae and adults, was intensified after the 1986 epidemics, that started at Rio de Janeiro and spread over several other regions (Lima et al. 2003, Braga et al. 2004)....
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