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1.
Mem. Inst. Oswaldo Cruz ; 115: e200271, 2020. tab, graf
Article in English | LILACS, SES-SP | ID: biblio-1135271

ABSTRACT

BACKGROUND Aedes aegypti is the primary transmitter of several arbovirus with great impact in human health. Controlling vector mosquitoes is an essential and complex task. One promising control method is to use mosquitoes as a vehicle to disseminate tiny particles of juvenile-killing insecticides, such as pyriproxyfen (PPF), to breeding sites. OBJECTIVES We aimed to investigate the capacity of Ae. aegypti to disseminate two new formulations of PPF in two sites of Rio de Janeiro city for assessment of the efficacy of these products. METHODS Dissemination stations impregnated with powder and liquid new formulations of PPF were installed in two test sites. Ovitraps were used in the test sites and in a control site for monitoring the presence of Ae. aegypti throughout eggs collection. FINDINGS Entomological indices indicated that the new formulations of PPF were efficient in reducing eggs abundance. Liquid formulation performed better than powder formulation. Ready-to-use formulations of PPF can be quickly applied in the field and can be replaced after a few months. MAIN CONCLUSIONS New formulations of PPF associated with mosquito dissemination approach make a valuable vector control strategy, managing to cover places of difficult access for whatever reason. New formulations application requires less labour, being economically attractive.


Subject(s)
Humans , Animals , Adolescent , Pyridines/pharmacology , Mosquito Control/methods , Aedes/drug effects , Insecticides/pharmacology , Larva/drug effects , Cities , Mosquito Vectors/growth & development , Mosquito Vectors/drug effects , Larva/growth & development
2.
Mem. Inst. Oswaldo Cruz ; 115: e200313, 2020. tab, graf
Article in English | LILACS | ID: biblio-1154867

ABSTRACT

BACKGROUND Aedes aegypti is the sole vector of urban arboviruses in French Guiana. Overtime, the species has been responsible for the transmission of viruses during yellow fever, dengue, chikungunya and Zika outbreaks. Decades of vector control have produced resistant populations to deltamethrin, the sole molecule available to control adult mosquitoes in this French Territory. OBJECTIVES Our surveillance aimed to provide public health authorities with data on insecticide resistance in Ae. aegypti populations and other species of interest in French Guiana. Monitoring resistance to the insecticide used for vector control and to other molecule is a key component to develop an insecticide resistance management plan. METHODS In 2009, we started to monitor resistance phenotypes to deltamethrin and target-site mechanisms in Ae. aegypti populations across the territory using the WHO impregnated paper test and allelic discrimination assay. FINDINGS Eight years surveillance revealed well-installed resistance and the dramatic increase of alleles on the sodium voltage-gated gene, known to confer resistance to pyrethroids (PY). In addition, we observed that populations were resistant to malathion (organophosphorous, OP) and alpha-cypermethrin (PY). Some resistance was also detected to molecules from the carbamate family. Finally, those populations somehow recovered susceptibility against fenitrothion (OP). In addition, other species distributed in urban areas revealed to be also resistant to pyrethroids. CONCLUSION The resistance level can jeopardize the efficiency of chemical adult control in absence of other alternatives and conducts to strongly rely on larval control measures to reduce mosquito burden. Vector control strategies need to evolve to maintain or regain efficacy during epidemics.


Subject(s)
Animals , Pyrethrins/pharmacology , Insecticide Resistance/drug effects , Insecticide Resistance/genetics , Aedes/drug effects , Mosquito Vectors/drug effects , Insecticides/pharmacology , Mosquito Control/methods , Aedes/genetics , Spatio-Temporal Analysis , Mosquito Vectors/virology , French Guiana , Insect Vectors/drug effects , Insect Vectors/genetics
3.
Rev. Soc. Bras. Med. Trop ; 53: e20190489, 2020. tab, graf
Article in English | LILACS | ID: biblio-1057274

ABSTRACT

Abstract INTRODUCTION: In Brasilia, pyriproxyfen (PPF; 0.01 mg/L) has been used for the larval control of Aedes aegypti mosquitoes since 2016. Information on the susceptibility of Ae. aegypti to PPF, and the development of resistance in populations from the Federal District of Brazil (FD) is limited. It is essential to monitor the susceptibility of Ae. aegypti to insecticides in order to improve vector control strategies. This study aimed to evaluate the susceptibility of Ae. aegypti populations from five areas of Brasilia to PPF. METHODS: We performed dose-response tests to estimate the emergence inhibition and resistance ratio of each field population, including the Rockefeller reference population. We also analyzed egg positivity, and the density and mortality of larvae and pupae. RESULTS: Populations from Vila Planalto (RR50=1.7), Regiment Guards Cavalry (RR50=2.5), and Sub-secretary of Justice Complex (RR50=3.7) presented high susceptibility to PPF, while the RR values of populations from Lago Norte (RR50=7.7) and Varjão (RR50=5.9) were moderately high, suggesting the emergence of insipient resistance to PPF in Brasilia. At 30 ng/mL, the highest larvae mortality rate was 2.7% for the population from Lago Norte, while that of pupae was 92.1% for Varjão and Vila Planalto. CONCLUSIONS: The five populations of Ae. aegypti from the FD are susceptible to PPF and there is a need to monitor the susceptibility of Ae. aegypti in new areas of the FD.


Subject(s)
Animals , Pyridines/pharmacology , Insecticide Resistance , Aedes/drug effects , Mosquito Vectors/drug effects , Insecticides/pharmacology , Brazil , Larva/drug effects
4.
Rev. Soc. Bras. Med. Trop ; 53: e20190211, 2020. tab, graf
Article in English | LILACS | ID: biblio-1057287

ABSTRACT

Abstract INTRODUCTION Anopheles stephensi is the main malaria vector in Southeast Asia. Recently, plant-sourced larvicides are attracting great interests. METHODS: The essential oil was extracted from the leaf of Cinnamomum camphora (L.), and a bioassay was conducted to determine the larvicidal efficacy. The chemical composition of the essential oil was determined by GC-MS analysis. RESULTS: The oil showed strong, dose-dependent larvicidal activities. The onset of larvicidal efficiency was rapid. The LC50 and LC95 were determined as 0.146% and 1.057% at 1 h, 0.031% and 0.237% at 12 h, 0.026% and 0.128% at 24 h, respectively. The oil contains 32 compounds. CONCLUSIONS The essential oil of C. camphora leaf has an excellent larvicidal potential for the control of A. stephensi.


Subject(s)
Animals , Oils, Volatile/pharmacology , Cinnamomum camphora/chemistry , Mosquito Vectors/drug effects , Insecticides/pharmacology , Larva/drug effects , Anopheles/drug effects , Biological Assay , Oils, Volatile/isolation & purification , Mosquito Vectors/classification , Insecticides/isolation & purification , Lethal Dose 50 , Anopheles/classification
5.
Mem. Inst. Oswaldo Cruz ; 114: e190120, 2019. tab, graf
Article in English | LILACS | ID: biblio-1040624

ABSTRACT

BACKGROUND In recent years, South America has suffered the burden of continuous high impact outbreaks of dengue, chikungunya and Zika. Aedes aegypti is the main mosquito vector of these arboviruses and its control is the only solution to reduce transmission. OBJECTIVES In order to improve vector control it is essential to study mosquito population genetics in order to better estimate the population structures and the geneflow among them. METHODS We have analysed microsatellites and knockdown resistance (kdr) mutations from a trans-border region in Amazonia between the state of Amapá (Brazil) and French Guiana (overseas territory of France), to provide further knowledge on these issues. These two countries have followed distinct vector control policies since last century. For population genetic analyses we evaluated variability in 13 well-established microsatellites loci in Ae. aegypti from French Guiana (Saint Georges and Cayenne) and Brazil (Oiapoque and Macapá). The occurrence and frequency of kdr mutations in these same populations were accessed by TaqMan genotype assays for the sites 1016 (Val/Ile) and 1534 (Phe/Cys). FINDINGS We have detected high levels of gene flow between the closest cross-border samples of Saint-Georges and Oiapoque. These results suggest one common origin of re-colonisation for the populations of French Guiana and Oiapoque in Brazil, and a different source for Macapá, more similar to the other northern Brazilian populations. Genotyping of the kdr mutations revealed distinct patterns for Cayenne and Macapá associated with their different insecticide use history, and an admixture zone between these two patterns in Saint Georges and Oiapoque, in accordance with population genetic results. MAIN CONCLUSIONS The present study highlights the need for regional-local vector surveillance and transnational collaboration between neighboring countries to assess the impact of implemented vector control strategies, promote timely actions and develop preparedness plans.


Subject(s)
Animals , Insecticide Resistance/genetics , Aedes/drug effects , Aedes/genetics , Mosquito Vectors/drug effects , Mosquito Vectors/genetics , Mutation/genetics , Brazil , Insecticide Resistance/drug effects , Biodiversity , French Guiana , Genotype
6.
Rev. Soc. Bras. Med. Trop ; 52: e20180459, 2019. tab, graf
Article in English | LILACS | ID: biblio-1041559

ABSTRACT

Abstract INTRODUCTION: The ability of Vitex trifolia and Vitex negundo essential oils to kill Aedes aegypti and Culex quinquefasciatus larvae was evaluated. METHODS: The larvae were treated with their respective essential oils at 50-125 ppm concentration. RESULTS: LC50 and LC90 for V. trifolia against Ae. aegypti and C. quinquefasciatus, and those for V. negundo against Ae. aegypti were 57.7+0.4, 77.9+0.9 ppm and 55.17+3.14, 78.28+2.23 ppm, and 50.86+0.9, 73.12+1.3 ppm, respectively. Eucalyptol and caryophyllene were the major components in Vitex trifolia and Vitex negundo essential oil, respectively. CONCLUSIONS: This study revealed potential larvicidal properties of essential oil from V. trifolia.


Subject(s)
Animals , Oils, Volatile/pharmacology , Aedes/drug effects , Vitex/chemistry , Mosquito Vectors/drug effects , Insecticides/pharmacology , Larva/drug effects , Oils, Volatile/isolation & purification , Insecticides/isolation & purification , Lethal Dose 50
7.
Mem. Inst. Oswaldo Cruz ; 112(2): 108-115, Feb. 2017. tab
Article in English | LILACS | ID: biblio-841761

ABSTRACT

BACKGROUND New brands of potential long lasting insecticide nets (LLINs) and LLIN treatment kits require field evaluation before they are used in a vector control programme. OBJECTIVES The aim of this study was to evaluate the bio-efficacy, usage, washing practice and physical integrity of nets treated with LLIN treatment kit, ICON MAXX in a phase III field trial in Odisha state, India. METHODS A total of 300 polyester nets treated with ICON MAXX and 140 polyester nets treated conventionally with lambda-cyhalothrin CS 2.5% ITNs were distributed. The bio-efficacy was evaluated with WHO cone bioassay. The chemical analysis of netting pieces was done at the beginning, after 12 and 36 months of the trial. FINDINGS After one year of distribution of nets, the bioassay showed 100% mortality on both ITNs and ICON MAXX treated nets. At 36 months, the overall pass rate was 58.8% and the mean lambda-cyhalothrin content of LLINs was 34.5 mg ai/m2, showing a loss of 44.4% of the original concentration. CONCLUSION ICON MAXX treated LLIN was found to retain bio-efficacy causing 97% knockdown of Anopheles stephensi up to 30 months and met the WHOPES criteria. However, the desired bio-efficacy was not sustained up to 36 months.


Subject(s)
Humans , Animals , Pyrethrins/pharmacology , Mosquito Control/instrumentation , Insecticide-Treated Bednets/statistics & numerical data , Mosquito Vectors/drug effects , Anopheles/drug effects , Time Factors , Biological Assay , India , Laundering/methods , Malaria/prevention & control
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