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1.
Parasite ; 28: 42, 2021.
Article in English | MEDLINE | ID: mdl-33944775

ABSTRACT

Several studies have assessed the potential of essential oils as substitutes for synthetic pesticides, in order to counter insect resistance to commercial pesticides. Piper aduncum L. is a very common shrub in the Amazon Rainforest and in other subtropical areas. The objective of this review was to analyse the existing information on P. aduncum essential oil as a raw material for new bioproducts for sustainable pest disease management. With this review, we collected and critically analysed 59 papers, representing all the studies that aimed to evaluate the essential oil properties of this species as an insecticide, acaricide and antiparasitic. The chemical composition differs depending on the origin, although phenylpropanoid dillapiole is the most cited component, followed by myristicin, 1,8-cineole and ß-ocimene. Between the acaricidal, antiparasitic and synergistic activities, the insecticidal effects are highly promising, with optimal results against the malaria vector Aedes aegypti, with an LC50 that ranges between 57 and 200µg/mL. Acaricidal activity has mainly been reported against Tetranychus urticae, showing an LC50 that ranges between 5.83 and 7.17µg/mL. Antiparasitic activity has predominately been found on Leishmania amazonensis, and antipromastigote activity has been found to be between 23.8 and 25.9µg/mL. Concerning the synergistic effect between dillapiole and synthetic insecticides, four studies on Spodoptera frugiperda found promising results with cypermethrin. In this review, we highlighted the potential of P. aduncum essential oil as a biopesticide, also focusing on the lack of information about applied research. We also provide suggestions for future investigations.


Subject(s)
Acaricides , Anopheles , Insecticides , Malaria , Oils, Volatile , Piper , Animals , Antiparasitic Agents , Insecticides/pharmacology , Mosquito Vectors , Oils, Volatile/pharmacology
2.
Article in English | MEDLINE | ID: mdl-33801616

ABSTRACT

The recent spread of invasive mosquito species, such as Aedes albopictus and the seasonal sporadic transmission of autochthonous cases of arboviral diseases (e.g., dengue, chikungunya, Zika) in temperate areas, such as Europe and North America, highlight the importance of effective mosquito-control interventions to reduce not only nuisance, but also major threats for public health. Local, regional, and even national mosquito control programs have been established in many countries and are executed on a seasonal basis by either public or private bodies. In order for these interventions to be worthwhile, funding authorities should ensure that mosquito control is (a) planned by competent scientific institutions addressing the local demands, (b) executed following the plan that is based on recommended and effective methods and strategies, (c) monitored regularly by checking the efficacy of the implemented actions, (d) evaluated against the set of targets, and (e) regularly improved according to the results of the monitoring. Adherence to these conditions can only be assured if a formal quality management system is adopted and enforced that ensures the transparency of effectiveness of the control operation. The current paper aims at defining the two components of this quality management system, quality assurance and quality control for mosquito control programs with special emphasis on Europe, but applicable over temperate areas.


Subject(s)
Aedes , Zika Virus Infection , Zika Virus , Animals , Europe , Mosquito Control , Mosquito Vectors , North America
3.
Parasite ; 28: 37, 2021.
Article in English | MEDLINE | ID: mdl-33861197

ABSTRACT

Mosquitoes transmit several agents of diseases and the presence of different species represents a threat to animal and public health. Aedes and Culex mosquitoes are of particular concern giving their potential vector competence for Arbovirus transmission. In Morocco, the lack of detailed information related to their spatial distribution raises major concerns and hampers effective vector surveillance and control. Using maximum entropy (Maxent) modeling, we generated prediction models for the potential distribution of Arboviruses vectors (Aedes aegypti, Ae. vexans, Ae. caspius, Ae. detritus, and Culex pipiens) in Morocco, under current climatic conditions. Also, we investigated the habitat suitability for the potential occurrence and establishment of Ae. albopictus and Ae. vittatus recorded only once in the country. Prediction models for these last two species were generated considering occurrence datasets from close countries of the Mediterranean Basin, where Ae. albopictus is well established, and from a worldwide database for the case of Ae. vittatus (model transferability). With the exception of Ae. vittatus, the results identify potential habitat suitability in Morocco for all mosquitos considered. Existing areas with maximum risk of establishment and high potential distribution were mainly located in the northwestern and central parts of Morocco. Our results essentially underline the assumption that Ae. albopictus, if not quickly controlled, might find suitable habitats and has the potential to become established, especially in the northwest of the country. These findings may help to better understand the potential distribution of each species and enhance surveillance efforts in areas identified as high risk.


Subject(s)
Aedes , Arboviruses , Animals , Ecosystem , Morocco , Mosquito Vectors
4.
Rev Soc Bras Med Trop ; 54: e0835, 2021.
Article in English | MEDLINE | ID: mdl-33886820

ABSTRACT

INTRODUCTION: Bioprospection of plant products is used to discover new insecticides. METHODS: The larvicidal activity of ethanolic extract and triterpene (tingenone B) from the bark of Maytenus guianensis and their effect on pupation and emergence were evaluated against Aedes aegypti. RESULTS: Crude extract LC50 was 11.3 ppm and caused ejection of the larvae intestine; tingenone B LC50 was 14.8 ppm. Pupation was reduced by 20% and 10%, respectively; however, the emergence was not affected. CONCLUSIONS: The crude bark extract exhibited a higher larvicidal effect against the vector.


Subject(s)
Aedes , Anopheles , Celastraceae , Insecticides , Maytenus , Animals , Insecticides/pharmacology , Larva , Mosquito Vectors , Plant Extracts/pharmacology , Plant Leaves
5.
Pestic Biochem Physiol ; 174: 104823, 2021 May.
Article in English | MEDLINE | ID: mdl-33838716

ABSTRACT

Conventional and volatile pyrethroids are widely used to control the vectors of dengue arboviral diseases, Aedes albopictus in China. The development of resistance to conventional pyrethroids has become an increasing problem, potentially affecting the use of volatile pyrethroid. The Ae. albopictus dimefluthrin-resistant (R) strain by selecting the field population with dimefluthrin were investigated the multiple and cross-resistance levels between conventional and volatile pyrethroids and analyzed both target-site and metabolic resistant mechanisms to dimefluthrin compared with three volatile pyrethroids metofluthrin, meperfluthrin and esbiothrin and type II pyrethroid deltamethrin. The R strain displayed moderate to low resistance to selected pyrethroids (dimefluthrin, metofluthrin, meperfluthrin, esbiothrin and deltamethrin) associated with metabolic enzymes, but less distinctly to selected pyrethroids (dimefluthrin and metofluthrin) associated with a high frequency of sodium channel gene mutation (F1534S). Profiles of the multiple and cross-resistance of the R strain to other three volatile pyrethroids and type II pyrethroid deltamethrin were detected. Both synergistic and enzyme activity studies indicated that multifunctional oxidase (MFO) played an important role in this resistance.


Subject(s)
Aedes , Insecticides , Pyrethrins , Aedes/genetics , Animals , China , Insecticide Resistance/genetics , Insecticides/pharmacology , Mosquito Vectors , Pyrethrins/pharmacology
6.
Nat Commun ; 12(1): 2290, 2021 04 16.
Article in English | MEDLINE | ID: mdl-33863888

ABSTRACT

Arthropod-borne viruses pose a major threat to global public health. Thus, innovative strategies for their control and prevention are urgently needed. Here, we exploit the natural capacity of viruses to generate defective viral genomes (DVGs) to their detriment. While DVGs have been described for most viruses, identifying which, if any, can be used as therapeutic agents remains a challenge. We present a combined experimental evolution and computational approach to triage DVG sequence space and pinpoint the fittest deletions, using Zika virus as an arbovirus model. This approach identifies fit DVGs that optimally interfere with wild-type virus infection. We show that the most fit DVGs conserve the open reading frame to maintain the translation of the remaining non-structural proteins, a characteristic that is fundamental across the flavivirus genus. Finally, we demonstrate that the high fitness DVG is antiviral in vivo both in the mammalian host and the mosquito vector, reducing transmission in the latter by up to 90%. Our approach establishes the method to interrogate the DVG fitness landscape, and enables the systematic identification of DVGs that show promise as human therapeutics and vector control strategies to mitigate arbovirus transmission and disease.


Subject(s)
Antiviral Agents/administration & dosage , Defective Viruses/genetics , Mosquito Vectors/drug effects , Zika Virus Infection/drug therapy , Zika Virus/genetics , Aedes/drug effects , Aedes/virology , Animals , Chlorocebus aethiops , Computational Biology , Directed Molecular Evolution , Disease Models, Animal , Female , Genetic Fitness , Genome, Viral/genetics , HEK293 Cells , Humans , Mice , Mosquito Control/methods , Mosquito Vectors/virology , Open Reading Frames/genetics , RNA, Viral/genetics , Vero Cells , Zika Virus Infection/transmission , Zika Virus Infection/virology
7.
Pan Afr Med J ; 38: 119, 2021.
Article in French | MEDLINE | ID: mdl-33912289

ABSTRACT

Long-lasting insecticidal mosquito nets (LLIMNs) are needed for malaria vector control. However, their distribution is not yet optimal in sub-Saharan regions. According to projections, COVID-19 pandemic will further delay the distribution of LLIMNs. In Niger, a distribution campaign of LLIMNs with a multi-sectoral approach (state-partner-civil society) was organized in compliance with barrier measures for preventing transmission of COVID-19. A door-to-door strategy was chosen to implement this campaign, in order to avoid entry into confined spaces and to engage community. A total of 13,994,681 people received LLIMNs (reflecting a success rate of 101%) in six targeted regions. A collective effort is needed to sustain the fight against malaria in the COVID-19 era.


Subject(s)
/prevention & control , Insecticide-Treated Bednets/supply & distribution , Malaria/prevention & control , /epidemiology , Humans , Mosquito Control , Mosquito Vectors , Niger
8.
Article in English | MEDLINE | ID: mdl-33668472

ABSTRACT

The emergence and spread of vector-borne diseases (VBDs) is a function of biotic, abiotic and socio-economic drivers of disease while their economic and societal burden depends upon a number of time-varying factors. This work is concerned with the development of an early warning system that can act as a predictive tool for public health preparedness and response. We employ a host-vector model that combines entomological (mosquito data), social (immigration rate, demographic data), environmental (temperature) and geographical data (risk areas). The output consists of appropriate maps depicting suitable risk measures such as the basic reproduction number, R0, and the probability of getting infected by the disease. These tools consist of the backbone of a semi-automatic early warning system tool which can potentially aid the monitoring and control of VBDs in different settings. In addition, it can be used for optimizing the cost-effectiveness of distinct control measures and the integration of open geospatial and climatological data. The R code used to generate the risk indicators and the corresponding spatial maps along with the data is made available.


Subject(s)
Mosquito Vectors , Vector Borne Diseases , Animals , Basic Reproduction Number , Disease Vectors , Risk Factors
9.
Article in English | MEDLINE | ID: mdl-33673292

ABSTRACT

Mosquitoes have been a nuisance and health threat to humans for centuries due to their ability to transmit different infectious diseases. Biological control methods have emerged as an alternative or complementary approach to contain vector populations in light of the current spread of insecticide resistance in mosquitoes. Thus, this study aimed to evaluate the predation efficacy of selected potential predators against Anopheles mosquito larvae. Potential invertebrate predators and Anopheles larvae were collected from natural habitats, mainly (temporary) wetlands and ponds in southwest Ethiopia and experiments were conducted under laboratory conditions. Optimal predation conditions with respect to larval instar, water volume and number of predators were determined for each of the seven studied predators. Data analyses were carried out using the Poisson regression model using one way ANOVA at the 5% significant level. The backswimmer (Notonectidae) was the most aggressive predator on Anopheles mosquito larvae with a daily mean predation of 71.5 larvae (95% CI: [65.04;78.59]). Our study shows that larval instar, water volume and number of predators have a significant effect on each predator, except for dragonflies (Libellulidae), with regard to the preference of the larval instar. A selection of mosquito predators has the potential to control Anopheles mosquito larvae, suggesting that they can be used as complementary approach in an integrated malaria vector control strategy.


Subject(s)
Anopheles , Malaria , Odonata , Animals , Ecosystem , Ethiopia , Humans , Larva , Malaria/prevention & control , Mosquito Control , Mosquito Vectors
10.
Pestic Biochem Physiol ; 173: 104772, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33771251

ABSTRACT

Metabolic resistance driven by multiple P450 genes is worsening insecticide resistance in malaria vectors. However, it remains unclear whether such multiple over-expression imposes an additive fitness cost in the vectors. Here, we showed that two highly over-expressed P450 genes (CYP6P9a and CYP6P9b) combine to impose additive fitness costs in pyrethroid-resistant Anopheles funestus. Genotyping of the CYP6P9b resistance allele in hybrid mosquitoes from a pyrethroid-resistant FUMOZ-R and the susceptible FANG strains revealed that this gene imposes a fitness cost in resistant mosquitoes similar to CYP6P9a. Homozygote susceptible CYP6P9b_S (SS) significantly lay more eggs than the resistant (OR = 2.2, P = 0.04) and with greater hatching rate (p < 0.04). Homozygote resistant larvae CYP6P9b_R (RR) developed significantly slower than homozygote susceptible from L1-L4 (χ2 = 7.2; P = 0.007) with a late pupation observed for RR compared to both heterozygotes and homozygotes susceptible (χ2 = 11.17; P = 0.0008). No difference was observed between genotypes for adult longevity with no change in allele frequency and gene expression across the lifespan. Furthermore, we established that CYP6P9b combines with CYP6P9a to additively exacerbate the fitness cost of pyrethroid resistance with a greater reduction in fecundity/fertility and increased developmental time of double homozygote resistant mosquitoes. Moreover, an increased proportion of double homozygote susceptible individuals was noted over 10 generations in the insecticide-free environment (χ2 = 6.3; P = 0.01) suggesting a reversal to susceptibility in the absence of selection. Such greater fitness cost imposed by multiple P450 genes shows that resistance management strategy based on rotation could help slow the spread of resistance.


Subject(s)
Anopheles , Insecticides , Malaria , Pyrethrins , Animals , Anopheles/genetics , Cytochrome P-450 Enzyme System/genetics , Insecticide Resistance/genetics , Insecticides/pharmacology , Malaria/genetics , Mosquito Vectors/genetics , Pyrethrins/toxicity
11.
Nat Commun ; 12(1): 1750, 2021 03 19.
Article in English | MEDLINE | ID: mdl-33741942

ABSTRACT

Malaria elimination requires tools that interrupt parasite transmission. Here, we characterize B cell receptor responses among Malian adults vaccinated against the first domain of the cysteine-rich 230 kDa gamete surface protein Pfs230, a key protein in sexual stage development of P. falciparum parasites. Among nine Pfs230 human monoclonal antibodies (mAbs) that we generated, one potently blocks transmission to mosquitoes in a complement-dependent manner and reacts to the gamete surface; the other eight show only low or no blocking activity. The structure of the transmission-blocking mAb in complex with vaccine antigen reveals a large discontinuous conformational epitope, specific to domain 1 of Pfs230 and comprising six structural elements in the protein. The epitope is conserved, suggesting the transmission-blocking mAb is broadly functional. This study provides a rational basis to improve malaria vaccines and develop therapeutic antibodies for malaria elimination.


Subject(s)
Antibodies, Monoclonal/pharmacology , Antibodies, Protozoan/pharmacology , Epitopes/immunology , Germ Cells/immunology , Malaria, Falciparum/prevention & control , Plasmodium falciparum/drug effects , Adult , Animals , Antibodies, Monoclonal/immunology , Antibodies, Protozoan/immunology , Antigens, Protozoan/chemistry , Antigens, Protozoan/immunology , Binding Sites , Cells, Cultured , Epitopes/chemistry , Host-Parasite Interactions/drug effects , Host-Parasite Interactions/immunology , Humans , Malaria Vaccines/administration & dosage , Malaria Vaccines/immunology , Malaria, Falciparum/parasitology , Malaria, Falciparum/transmission , Mosquito Vectors/parasitology , Plasmodium falciparum/immunology , Plasmodium falciparum/physiology , Protein Conformation , Protozoan Proteins/chemistry , Protozoan Proteins/immunology
12.
Article in English | MEDLINE | ID: mdl-33787737

ABSTRACT

Dengue virus, the etiological agent of dengue fever (DF) occurs in four genetically distinct serotypes (DENV1-4), being transmitted by female Aedes mosquitoes. DF incidence is increasing in Brazil, following vector dispersal, proliferation and DENV serotypes introduction, co-circulation and substitution. Medium- and small-sized cities in Sao Paulo State, such as Marilia (Midwest region), have been affected by huge epidemics. To understand the evolution of DENV epidemics in medium-sized cities, in this study a historical data on DENV incidence (2000-2015) in Marilia, was evaluated. Previous studies disclosed regional and specific DF outcomes associated with 2007 outbreak in that city, when co-circulating DENV1 and DENV3 presented different hematological profiles. In this study, characteristics of 2007 DENV epidemics were compared to the epidemiological, hematological and demographic outlines of the major outbreak of DENV1 in Marilia in 2015. DENV1 genetic diversity was assessed through capsid and pre-membrane junction encoding gene (CprM) sequencing. The results revealed circulation of DENV1 serotype from 2007 to 2015, with epidemics occurring every three-years until 2013 and then, increasing yearly. There were significant differences in hematological profiles of DENV1 patients between 2015 and 2007. CprM showed DENV1 genetic variability in 2015, contrasting with the unique sequence pattern in 2007. These results reinforce the regional and temporal characteristics of DENV epidemics that need local public health research to improve care for people and to limit the spread of new serotypes/genotypes to uninfected areas.


Subject(s)
Dengue Virus/genetics , Dengue/epidemiology , Disease Outbreaks , Adolescent , Adult , Aged , Animals , Brazil/epidemiology , Child , Dengue/transmission , Dengue Virus/classification , Dengue Virus/isolation & purification , Female , Humans , Immunoglobulin M/blood , Male , Middle Aged , Mosquito Vectors , RNA, Viral/genetics , Reverse Transcriptase Polymerase Chain Reaction , Serogroup , Serotyping , Young Adult
13.
Article in English | MEDLINE | ID: mdl-33787744

ABSTRACT

A few studies have carried out the taxonomic and molecular characterization of sylvatic mosquito species in Latin America, where some species have been incriminated as vectors for arboviruses and parasites transmission. The present study reports the molecular characterization of mosquito species in the Sierra Nevada de Santa Marta, a natural ecosystem in the Northern coast of Colombia. Manual capture methods were used to collect mosquitoes, and the specimens were identified via classical taxonomy. The COI marker was used for species confirmation, and phylogenetic analysis was performed using the neighbor-joining method, with the Kimura-2-Parameters model. Aedes serratus , Psorophora ferox , Johnbelkinia ulopus , Sabethes chloropterus , Sabethes cyaneus , Wyeomyia aporonoma , Wyeomyia pseudopecten , Wyeomyia ulocoma and Wyeomyia luteoventralis were identified. We assessed the genetic variability of mosquitoes in this area and phylogenetic reconstructions allowed the identification at the species level. Classical and molecular taxonomy demonstrated to be useful and complementary when morphological characteristics are not well preserved, or the taxonomic group is not represented in public molecular databases.


Subject(s)
Culicidae/genetics , Phylogeny , Rainforest , Animals , Colombia , DNA Barcoding, Taxonomic , Ecosystem , Mosquito Vectors
14.
PLoS Negl Trop Dis ; 15(3): e0009259, 2021 03.
Article in English | MEDLINE | ID: mdl-33705409

ABSTRACT

Dengue, Zika and chikungunya are diseases of global health significance caused by arboviruses and transmitted by the mosquito Aedes aegypti, which is of worldwide circulation. The arrival of the Zika and chikungunya viruses to South America increased the complexity of transmission and morbidity caused by these viruses co-circulating in the same vector mosquito species. Here we present an integrated analysis of the reported arbovirus cases between 2007 and 2017 and local climate and socio-economic profiles of three distinct Colombian municipalities (Bello, Cúcuta and Moniquirá). These locations were confirmed as three different ecosystems given their contrasted geographic, climatic and socio-economic profiles. Correlational analyses were conducted with both generalised linear models and generalised additive models for the geographical data. Average temperature, minimum temperature and wind speed were strongly correlated with disease incidence. The transmission of Zika during the 2016 epidemic appeared to decrease circulation of dengue in Cúcuta, an area of sustained high incidence of dengue. Socio-economic factors such as barriers to health and childhood services, inadequate sanitation and poor water supply suggested an unfavourable impact on the transmission of dengue, Zika and chikungunya in all three ecosystems. Socio-demographic influencers were also discussed including the influx of people to Cúcuta, fleeing political and economic instability from neighbouring Venezuela. Aedes aegypti is expanding its range and increasing the global threat of these diseases. It is therefore vital that we learn from the epidemiology of these arboviruses and translate it into an actionable local knowledge base. This is even more acute given the recent historical high of dengue cases in the Americas in 2019, preceding the COVID-19 pandemic, which is itself hampering mosquito control efforts.


Subject(s)
Chikungunya Fever/epidemiology , Dengue/epidemiology , Zika Virus Infection/epidemiology , Aedes/physiology , Aedes/virology , Animals , Chikungunya Fever/economics , Chikungunya Fever/virology , Chikungunya virus/physiology , Climate , Colombia/epidemiology , Dengue/economics , Dengue/virology , Dengue Virus/physiology , Ecosystem , Humans , Mosquito Vectors/physiology , Mosquito Vectors/virology , South America , Temperature , Zika Virus/physiology , Zika Virus Infection/economics , Zika Virus Infection/virology
15.
J Vis Exp ; (169)2021 03 10.
Article in English | MEDLINE | ID: mdl-33779607

ABSTRACT

Female mosquitoes are the deadliest animals on earth, claiming the lives of more than 1 million people every year due to pathogens they transmit when acquiring a blood-meal. To locate a host to feed on, mosquitoes rely on a wide range of sensory cues, including visual, mechanical, thermal, and olfactory. The study details a technique, electroantennography (EAG), that allows researchers to assess whether the mosquitoes can detect individual chemicals and blends of chemicals in a concentration-dependent manner. When coupled with gas-chromatography (GC-EAG), this technique allows to expose the antennae to a full headspace/complex mixture and determines which chemicals present in the sample of interest, the mosquito can detect. This is applicable to host body odors as well as plant floral bouquets or other ecologically relevant odors (e.g., oviposition sites odorants). Here, we described a protocol that permits long durations of preparation responsiveness time and is applicable to both female and male mosquitoes from multiple genera, including Aedes, Culex, Anopheles, and Toxorhynchites mosquitoes. As olfaction plays a major part in mosquito-host interactions and mosquito biology in general, EAGs and GC-EAG can reveal compounds of interest for the development of new disease vector control strategies (e.g., baits). Complemented with behavioral assays, the valence (e.g., attractant, repellent) of each chemical can be determined.


Subject(s)
Biosensing Techniques/instrumentation , Animals , Mosquito Vectors
16.
Nat Commun ; 12(1): 1810, 2021 03 22.
Article in English | MEDLINE | ID: mdl-33753725

ABSTRACT

For most pathogens, transmission is driven by interactions between the behaviours of infectious individuals, the behaviours of the wider population, the local environment, and immunity. Phylogeographic approaches are currently unable to disentangle the relative effects of these competing factors. We develop a spatiotemporally structured phylogenetic framework that addresses these limitations by considering individual transmission events, reconstructed across spatial scales. We apply it to geocoded dengue virus sequences from Thailand (N = 726 over 18 years). We find infected individuals spend 96% of their time in their home community compared to 76% for the susceptible population (mainly children) and 42% for adults. Dynamic pockets of local immunity make transmission more likely in places with high heterotypic immunity and less likely where high homotypic immunity exists. Age-dependent mixing of individuals and vector distributions are not important in determining spread. This approach provides previously unknown insights into one of the most complex disease systems known and will be applicable to other pathogens.


Subject(s)
Algorithms , Dengue Virus/genetics , Dengue/transmission , Models, Theoretical , Adult , Aedes/virology , Animals , Child , Dengue/epidemiology , Dengue/virology , Dengue Virus/classification , Dengue Virus/physiology , Genome, Viral/genetics , Host-Pathogen Interactions , Humans , Mosquito Vectors/virology , Phylogeny , Phylogeography/methods , Phylogeography/statistics & numerical data , Population Dynamics , Thailand/epidemiology
17.
J Vis Exp ; (169)2021 03 12.
Article in English | MEDLINE | ID: mdl-33779612

ABSTRACT

The control of such human diseases as dengue, Zika, and chikungunya relies on the control of their vector, the Aedes aegypti mosquito, because there is no prevention. Control of mosquito vectors can rely on chemicals applied to the immature and adult stages, which can contribute to the mortality of non-targets and more importantly, lead to insecticide resistance in the vector. The sterile insect technique (SIT) is a method of controlling populations of pests through the release of sterilized adult males that mate with wild females to produce non-viable offspring. This paper describes the process of producing sterile males for use in an operational SIT program for the control of Aedes aegypti mosquitoes. Outlined here are the steps used in the program including rearing and maintaining a colony, separating male and female pupae, irradiating and marking adult males, and shipping Aedes aegypti males to the release site. Also discussed are procedural caveats, program limitations, and future objectives.


Subject(s)
Aedes/physiology , Fertility/radiation effects , Insecticide Resistance , Mosquito Control/methods , Mosquito Vectors/physiology , Pupa/physiology , Sterilization, Reproductive/methods , Aedes/radiation effects , Animals , Female , Humans , Male , Mosquito Vectors/radiation effects , Pupa/radiation effects
18.
Rev Soc Bras Med Trop ; 54: e05762020, 2021.
Article in English | MEDLINE | ID: mdl-33656151

ABSTRACT

INTRODUCTION: Aedes aegypti is the main vector of dengue and yellow fever. Recently, the use of plant-sourced larvicides has gained momentum. METHODS: The hydroethanolic extracts and fractions ofOcotea nutansleaves and stems were bioassayed to determine the larvicidal efficacy of these samples. RESULTS: S-HEX (hexane fraction from the crude stem extract) demonstrated high potential for controlling third-stage larvae, with an LC50 of 14.14 µg.mL-1 (concentration required to inhibit 50% of the treated larvae). CONCLUSIONS: Extracts from O. nutans were effective against third-stage larvae ofA. aegyptiafter 24 h of exposure.


Subject(s)
Aedes , Insecticides , Ocotea , Animals , Insecticides/pharmacology , Larva , Mosquito Vectors , Plant Extracts/pharmacology , Plant Leaves
19.
Mem Inst Oswaldo Cruz ; 116: e200497, 2021.
Article in English | MEDLINE | ID: mdl-33729397

ABSTRACT

BACKGROUND: Flight tones play important roles in mosquito reproduction. Several mosquito species utilise flight tones for mate localisation and attraction. Typically, the female wingbeat frequency (WBF) is lower than males, and stereotypic acoustic behaviors are instrumental for successful copulation. Mosquito WBFs are usually an important species characteristic, with female flight tones used as male attractants in surveillance traps for species identification. Anopheles darlingi is an important Latin American malaria vector, but we know little about its mating behaviors. OBJECTIVES: We characterised An. darlingi WBFs and examined male acoustic responses to immobilised females. METHODS: Tethered and free flying male and female An. darlingi were recorded individually to determine their WBF distributions. Male-female acoustic interactions were analysed using tethered females and free flying males. FINDINGS: Contrary to most mosquito species, An. darlingi females are smaller than males. However, the male's WBF is ~1.5 times higher than the females, a common ratio in species with larger females. When in proximity to a female, males displayed rapid frequency modulations that decreased upon genitalia engagement. Tethered females also modulated their frequency upon male approach, being distinct if the interaction ended in copulation or only contact. MAIN CONCLUSIONS: This is the first report of An. darlingi flight acoustics, showing that its precopulatory acoustics are similar to other mosquitoes despite the uncommon male:female size ratio, suggesting that WBF ratios are common communication strategies rather than a physical constraint imposed by size.


Subject(s)
Anopheles , Malaria , Mosquito Vectors , Animals , Female , Malaria/transmission , Male , Reproduction
20.
Nat Commun ; 12(1): 1671, 2021 03 15.
Article in English | MEDLINE | ID: mdl-33723237

ABSTRACT

Zika virus (ZIKV) has caused large, brief outbreaks in isolated populations, however ZIKV can also persist at low levels over multiple years. The reasons for these diverse transmission dynamics remain poorly understood. In Fiji, which has experienced multiple large single-season dengue epidemics, there was evidence of multi-year transmission of ZIKV between 2013 and 2017. To identify factors that could explain these differences in dynamics between closely related mosquito-borne flaviviruses, we jointly fit a transmission dynamic model to surveillance, serological and molecular data. We estimate that the observed dynamics of ZIKV were the result of two key factors: strong seasonal effects, which created an ecologically optimal time of year for outbreaks; and introduction of ZIKV after this optimal time, which allowed ZIKV transmission to persist over multiple seasons. The ability to jointly fit to multiple data sources could help identify a similar range of possible outbreak dynamics in other settings.


Subject(s)
Flavivirus Infections/epidemiology , Flavivirus Infections/transmission , Animals , Culicidae , Dengue/transmission , Dengue Virus , Disease Outbreaks , Epidemics , Fiji/epidemiology , Flavivirus , Humans , Mosquito Vectors/virology , Seasons , Zika Virus , Zika Virus Infection/epidemiology , Zika Virus Infection/transmission
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