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.
Citations
More filters
01 Jan 2015
TL;DR: The Amazon region of Brazil is considered the endemic area of malaria, with more than 99% of cases of malaria reported in this region, and vector control was performed with the indoor application of dichlorodiphenyltrichloroethane, however, in 1987, this insecticide was banned in agriculture and, subsequently, in 1997, it was also banned in public health in Brazil.
Abstract: Introduction: This study aimed to evaluate the susceptibility of Anopheles darlingiAnopheles marajoara Root (1926) and Galvao & Damasceno (1942) to pyrethroids used by the National Malaria Control Program in Brazil. Methods: Mosquitoes from Amapa, Brazilian Amazon, were assessed for resistance to cypermethrin, deltamethrin, and alpha-cypermethrin. Insecticide-impregnated bottles were used as suggested by the CDC/Atlanta. Results: Diagnostic dose for Anopheles darlingi was 12.5µg/bottle during 30 min of exposure. Concentrations for Anopheles marajoara were 20µg/bottle of cypermethrin and deltamethrin and 12.5µg/bottle of alpha-cypermethrin. Conclusions : No resistance was recorded for Anopheles darlingi , but Anopheles marajoara requires attention. Keywords: Insecticide resistance. Pyrethroids. Vector control.The Amazon region of Brazil is considered the endemic area of malaria, with more than 99% of cases of malaria reported in this region (1) . Until the 1980s, vector control was performed with the indoor application of dichlorodiphenyltrichloroethane (DDT). However, in 1987, the use of this insecticide was banned in agriculture and, subsequently, in 1997, it was also banned in public health in Brazil
01 Jan 2009
TL;DR: In this paper, the Aedes aegyptius sensitivity level for cypermethrin 10% (ASLC) study, Those were collected from Chaiyaphoom, Surin, Burirum and Nakhon Ratchasima for care and testing.
Abstract: The objectives of this research was Aedes aegyptius sensitivity level for cypermethrin 10% (ASLC) study, Those were collected from Chaiyaphoom, Surin, Burirum and Nakhon Ratchasima for care and testing. Bioassay technique was employed for fatality rate, knock-down rate and sensitivity level for cypermethrin 10%. The findings showed that had 100% of knock-down rate at any areas, 100% of fatality rate after follow up 24 hours. Conclusion, ASLC had high level at any areas. However, cypermethrin 10% should conduct at endemic area for quickly expel vectors by supervisorus comment. For further, that should study about Aedes aegyptius resistance level for cypermethrin 10% or factor of unsuccessful cypermethrin 10% spraying and efficiency of Dengue Haemorrahgic Fever control. ∫∑π”
TL;DR: The strong presence of resistance alleles kdr in the city is evident, which demonstrates that even with the interruption of the use of pyrethroids by the National Dengue Control Program, resistance may be maintained due to domestic use.
Abstract: Londrina is the fourth most populous city in southern Brazil. Its subtropical weather with rain in all seasons, as well as its high population density, make the city perfect for the Aedes aegypti (Linnaeus, 1762) life cycle. Over the last few years, Londrina presented high infestation indexes and was one of the cities with the most reported cases of dengue. Uncontrolled use of synthetic insecticides may influence the mosquito’s genetic composition. In this paper, we studied mitochondrial DNA and kdr mutations in Aedes aegypti. The analysis of the ND4 gene in 330 specimens showed the presence of 27 haplotypes. The pyrethroid resistance alleles (kdr) evaluated are present in the collected populations, with a 50% frequency of the Val1016Ile and 48% of the Phe1534Cys mutations. Such analysis of the mutations in the populations collected at the State University of Londrina’s campus – a microenvironment that differs from the rest of the city – showed frequencies of 57% and 62%, respectively. The low gene flow observed, Nm = 0.11 and Nm = 0.10, along with the elevated differentiation, Fst = 0.19 and Fst = 0.18, among populations suggest an influence of genetic drift. The strong presence of resistance alleles kdr in the city is evident, which demonstrates that even with the interruption of the use of pyrethroids by the National Dengue Control Program, resistance may be maintained due to domestic use. Thus, the results have shown the need for genetic monitoring, alongside other entomological surveillance monitoring tools, to create strategies of mosquito control. A R T I C L E I N F O Article history: Received 21 August 2020 Accepted 02 January 2021 Associate Editor: Maria Sallum
16 May 2019
TL;DR: The 5-stage structured population model proposed by Schechtman and Souza was modified to comprise insecticide resistance as a recessive trait and allow for additional death rates at the larval and imago stages.
Abstract: The 5-stage structured population model proposed by Schechtman and Souza [1] was modified to comprise insecticide resistance as a recessive trait and allow for additional death rates at the larval and imago stages. Insecticide resistance was assessed by evaluating the total fraction of the allele for resistance present in the population. A very intense insecticide application policy was investigated. It comprised 18 blocks of applications of adult insecticide, with a resting interval of 2 days between any two consecutive block of applications, during the summer season for a period of a 100 years. Each block of application consisted of two daily applications of insecticide for 5 consecutive days. Insecticide resistance as expressed by an increase in the fraction of the allele for resistance occurred for this very intensive policy. The resistance allele, which started at a frequency of 2%, got fixated at 100% after the insecticide application period.
References
More filters
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....
[...]
...According to Brogdon and McAllister (1998) these would be dead mosquitoes....
[...]
...Bioassays were performed with insecticide-coated bottles, as described by Brogdon and McAllister (1998)....
[...]
...This was attained after 30 min exposure, a period considered as the resistance threshold (Brogdon & McAllister 1998)....
[...]
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)....
[...]
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....
[...]
...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)....
[...]
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)....
[...]