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1.
Biomed Res Int ; 2021: 6619175, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33884266

RESUMO

Background: To date, dengue is considered an important public health problem in Sri Lanka. Irrational use of insecticides without evidence-based applications has primed the development of resistance in mosquito vectors. Method: The present study investigated the resistance status of Aedes aegypti and Aedes albopictus to commonly used insecticides in three selected Medical Officer of Health (MOH) areas (i.e., Attanagalla, Dompe, and Negombo) in Gampaha District, Western Province of Sri Lanka. Entomological surveys were performed using ovitraps and larval collections. Larval bioassays were carried out to determine the LC50, LC90, and LC95 and susceptibility status for organophosphate temephos, whereas adult bioassays were performed to test the 0.03% deltamethrin and 0.8% malathion susceptibility. Results: The study revealed that the temephos concentrations required to control Ae. aegypti (13.7-17.7 times) and Ae. albopictus (4.6-7.6 times) are higher than the diagnostic concentration (0.012 mg/L) proposed by the World Health Organization. The highest resistance levels were observed for both Ae. aegypti (14 ± 1.87) and Ae. albopictus (36 ± 1.87) collected from the Negombo MOH area. Therefore, the WHO recommended diagnostic concentration is no longer effective in controlling Ae. aegypti and Ae. albopictus larvae in these areas. Both the dengue vectors have evolved a high level of insecticide resistance to malathion and deltamethrin in the Gampaha District except Ae. albopictus mosquitoes in rural areas. Further, vectors in rural areas are indicated susceptible (>98%) to pyrethroids and emergence of resistance (<97%) for organophosphate insecticides. Conclusion: The results of this study warrant the vector management authorities on the proper application of insecticides and rational use in vector control. The susceptibility status of vector mosquitoes should be continuously monitored especially in dengue-endemic areas parallel to the routine surveillance programme. Further molecular studies are strongly recommended to determine the Knockdown Resistance (kdr) mutations among Aedes populations.


Assuntos
Aedes/fisiologia , Dengue/prevenção & controle , Dengue/parasitologia , Vetores de Doenças , Resistência a Inseticidas , Mosquitos Vetores/fisiologia , Animais , Feminino , Geografia , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Sri Lanka , Temefós/toxicidade
2.
J Vis Exp ; (169)2021 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-33779612

RESUMO

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.


Assuntos
Aedes/fisiologia , Fertilidade/efeitos da radiação , Resistência a Inseticidas , Controle de Mosquitos/métodos , Mosquitos Vetores/fisiologia , Pupa/fisiologia , Esterilização Reprodutiva/métodos , Aedes/efeitos da radiação , Animais , Feminino , Humanos , Masculino , Mosquitos Vetores/efeitos da radiação , Pupa/efeitos da radiação
3.
PLoS Negl Trop Dis ; 15(3): e0009259, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33705409

RESUMO

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.


Assuntos
Febre de Chikungunya/epidemiologia , Dengue/epidemiologia , Infecção por Zika virus/epidemiologia , Aedes/fisiologia , Aedes/virologia , Animais , Febre de Chikungunya/economia , Febre de Chikungunya/virologia , Vírus Chikungunya/fisiologia , Clima , Colômbia/epidemiologia , Dengue/economia , Dengue/virologia , Vírus da Dengue/fisiologia , Ecossistema , Humanos , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , América do Sul , Temperatura , Zika virus/fisiologia , Infecção por Zika virus/economia , Infecção por Zika virus/virologia
4.
Acta Trop ; 218: 105885, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33713628

RESUMO

Aedes aegypti and Aedes albopictus are mosquito vectors of numerous arboviruses of sanitary importance. Presently in Argentina, neither Ae. aegypti nor Ae. albopictus, have displaced the other species in the places where they coexist, since the introduction of the latter in 1998. In this study, we evaluated whether these species coexist at different scales (ovitrap, microhabitat and habitat) in the city of Eldorado, Misiones province, northeast Argentina. We also analyzed the seasonal variation and climate variables related to the delay in egg hatching of both species. Mosquitoes were collected weekly, from June 2017 to May 2018, using ovitraps placed in urban areas. We conclude that Ae. aegypti and Ae. albopictus coexist in the study area, at the ovitrap, microhabitat and habitat scales. Furthermore, no pronounced pattern of delayed hatching has been observed for either species; however, eggs of Ae. albopictus laid during colder weeks and less rainfall needed a greater number of immersions to hatch, while for Ae. aegypti those laid during weeks with low rainfall and high temperatures showed the longest delay in hatching response.


Assuntos
Aedes/fisiologia , Aedes/virologia , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Ovulação , Clima Tropical , Animais , Arbovirus/fisiologia , Argentina , Cidades , Ecossistema , Estações do Ano
5.
PLoS Negl Trop Dis ; 15(2): e0008492, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33591988

RESUMO

Vector control largely relies on neurotoxic chemicals, and insecticide resistance (IR) directly threatens their effectiveness. In some cases, specific alleles cause IR, and knowledge of the genetic diversity and gene flow among mosquito populations is crucial to track their arrival, rise, and spread. Here we evaluated Aedes aegypti populations' susceptibility status, collected in 2016 from six different municipalities of Rio de Janeiro state (RJ), to temephos, pyriproxyfen, malathion, and deltamethrin. We collected eggs of Ae. aegypti in Campos dos Goytacazes (Cgy), Itaperuna (Ipn), Iguaba Grande (Igg), Itaboraí (Ibr), Mangaratiba (Mgr), and Vassouras (Vsr). We followed the World Health Organization (WHO) guidelines and investigated the degree of susceptibility/resistance of mosquitoes to these insecticides. We used the Rockefeller strain as a susceptible positive control. We genotyped the V1016I and F1534C knockdown resistance (kdr) alleles using qPCR TaqMan SNP genotyping assay. Besides, with the use of Ae. aegypti SNP-chip, we performed genomic population analyses by genotyping more than 15,000 biallelic SNPs in mosquitoes from each population. We added previous data from populations from other countries to evaluate the ancestry of RJ populations. All RJ Ae. aegypti populations were susceptible to pyriproxyfen and malathion and highly resistant to deltamethrin. The resistance ratios for temephos was below 3,0 in Cgy, Ibr, and Igg populations, representing the lowest rates since IR monitoring started in this Brazilian region. We found the kdr alleles in high frequencies in all populations, partially justifying the observed resistance to pyrethroid. Population genetics analysis showed that Ae. aegypti revealed potential higher migration among some RJ localities and low genetic structure for most of them. Future population genetic studies, together with IR data in Ae aegypti on a broader scale, can help us predict the gene flow within and among the Brazilian States, allowing us to track the dynamics of arrival and changes in the frequency of IR alleles, and providing critical information to improving vector control program.


Assuntos
Aedes/efeitos dos fármacos , Vetores de Doenças , Resistência a Inseticidas , Inseticidas/farmacologia , Aedes/genética , Aedes/fisiologia , Animais , Bioensaio , Brasil , Perfilação da Expressão Gênica , Técnicas de Genotipagem , Cobaias , Larva/efeitos dos fármacos , Malation/farmacologia , Mutação , Nitrilos/farmacologia , Piretrinas/farmacologia , Piridinas/farmacologia , Temefós/farmacologia
6.
Nat Commun ; 12(1): 916, 2021 02 10.
Artigo em Inglês | MEDLINE | ID: mdl-33568638

RESUMO

The global emergence of Zika virus (ZIKV) revealed the unprecedented ability for a mosquito-borne virus to cause congenital birth defects. A puzzling aspect of ZIKV emergence is that all human outbreaks and birth defects to date have been exclusively associated with the Asian ZIKV lineage, despite a growing body of laboratory evidence pointing towards higher transmissibility and pathogenicity of the African ZIKV lineage. Whether this apparent paradox reflects the use of relatively old African ZIKV strains in most laboratory studies is unclear. Here, we experimentally compare seven low-passage ZIKV strains representing the recently circulating viral genetic diversity. We find that recent African ZIKV strains display higher transmissibility in mosquitoes and higher lethality in both adult and fetal mice than their Asian counterparts. We emphasize the high epidemic potential of African ZIKV strains and suggest that they could more easily go unnoticed by public health surveillance systems than Asian strains due to their propensity to cause fetal loss rather than birth defects.


Assuntos
Infecção por Zika virus/mortalidade , Infecção por Zika virus/virologia , Zika virus/fisiologia , Zika virus/patogenicidade , Aedes/fisiologia , Aedes/virologia , África , Animais , Ásia , Feminino , Humanos , Masculino , Camundongos , Filogenia , Virulência , Zika virus/classificação , Zika virus/genética , Infecção por Zika virus/transmissão
7.
PLoS Negl Trop Dis ; 15(1): e0008915, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33406161

RESUMO

The adult females of Aedes aegypti mosquitoes are facultative hematophagous insects but they are unable to feed on blood right after pupae emergence. The maturation process that takes place during the first post-emergence days, hereafter named hematophagic and gonotrophic capacitation, comprises a set of molecular and physiological changes that prepare the females for the first gonotrophic cycle. Notwithstanding, the molecular bases underlying mosquito hematophagic and gonotrophic capacitation remain obscure. Here, we investigated the molecular and biochemical changes in adult Ae. aegypti along the first four days post-emergence, prior to a blood meal. We performed a RNA-Seq analysis of the head and body, comparing male and female gene expression time courses. A total of 811 and 203 genes were differentially expressed, respectively in the body and head, and both body parts showed early, mid, and late female-specific expression profiles. Female-specific up-regulation of genes involved in muscle development and the oxidative phosphorylation pathway were remarkable features observed in the head. Functional assessment of mitochondrial oxygen consumption in heads showed a gradual increase in respiratory capacity and ATP-linked respiration as a consequence of induced mitochondrial biogenesis and content over time. This pattern strongly suggests that boosting oxidative phosphorylation in heads is a required step towards blood sucking habit. Several salivary gland genes, proteases, and genes involved in DNA replication and repair, ribosome biogenesis, and juvenile hormone signaling were up-regulated specifically in the female body, which may reflect the gonotrophic capacitation. This comprehensive description of molecular and biochemical mechanisms of the hematophagic and gonotrophic capacitation in mosquitoes unravels potentially new targets for vector control.


Assuntos
Aedes/fisiologia , Comportamento Alimentar/fisiologia , Transcriptoma , Animais , Replicação do DNA , Feminino , Expressão Gênica , Humanos , Masculino , Mitocôndrias/metabolismo , Mosquitos Vetores/fisiologia , Oxigênio/metabolismo , Fosforilação
8.
J Agric Food Chem ; 69(3): 1091-1106, 2021 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-33432806

RESUMO

Furanocoumarins are photoactive compounds derived from secondary plant metabolites. They possess many bioactivities, including antioxidative, anticancer, insecticidal, and bactericidal activities. Here, we designed a new scheme for synthesizing 2-arylfuranocoumarin derivatives by condensation, esterification, bromination, and Wittig reaction. We found that 2-thiophenylfuranocoumarin (Iy) had excellent photosensitive activity. Three Iy concentrations (LC25, LC50, and LC75) were used to treat the fourth instar larvae of Aedes aegypti (A. aegypti). The photoactivated toxicity, sublethal dose, mitochondrial dysfunction, oxidative stress level, intestinal barrier dysfunction, and apoptosis were studied. The results showed that Iy induced reactive oxygen species (ROS) production in midgut cells under ultraviolet light. Ultrastructural analysis demonstrated that mitochondria were damaged, and the activities of related enzymes were inhibited. Ultimately, Iy exposure led to excessive ROS production followed by the inhibition of antioxidant enzymes, including SOD, CAT, GPx, and GR, which diminished ROS elimination and escalated oxidative stress in midgut cells, aggravating the degree of oxidative damage in these cells. Histopathological changes were observed in the midgut, which led to intestinal barrier dysfunction. When the elimination of ROS was blocked and it accumulated in cells, apoptosis-related genes, including AeDronc, AeCaspase7, and AeCaspase8, were induced and activated. In addition, Iy affected the growth and development of A. aegypti at sublethal concentrations, and there was an obvious post-lethal effect. Thus, we found that Iy caused midgut damage and apoptosis in A. aegypti larvae under ultraviolet light, which preliminarily revealed the mode of action of Iy in A. aegypti.


Assuntos
Aedes/efeitos dos fármacos , Apoptose/efeitos dos fármacos , Furocumarinas/química , Furocumarinas/toxicidade , Inseticidas/síntese química , Inseticidas/toxicidade , Aedes/fisiologia , Animais , Sistema Digestório/efeitos dos fármacos , Sistema Digestório/metabolismo , Inseticidas/química , Larva/efeitos dos fármacos , Larva/fisiologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo
9.
PLoS One ; 16(1): e0244284, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33417600

RESUMO

BACKGROUND: Mosquito-borne diseases remain a significant public health problem in tropical regions. Housing improvements such as screening of doors and windows may be effective in reducing disease transmission, but the impact remains unclear. OBJECTIVES: To examine whether housing interventions were effective in reducing mosquito densities in homes and the impact on the incidence of mosquito-borne diseases. METHODS: In this systematic review and meta-analysis, we searched 16 online databases, including NIH PubMed, CINAHL Complete, LILACS, Ovid MEDLINE, and Cochrane Central Register of Controlled Trials for randomized trials published from database inception to June 30, 2020. The primary outcome was the incidence of any mosquito-borne diseases. Secondary outcomes encompassed entomological indicators of the disease transmission. I2 values were used to explore heterogeneity between studies. A random-effects meta-analysis was used to assess the primary and secondary outcomes, with sub-group analyses for type of interventions on home environment, study settings (rural, urban, or mixed), and overall house type (traditional or modern housing). RESULTS: The literature search yielded 4,869 articles. After screening, 18 studies were included in the qualitative review, of which nine were included in the meta-analysis. The studies enrolled 7,200 households in Africa and South America, reporting on malaria or dengue only. The type of home environmental interventions included modification to ceilings and ribbons to close eaves, screening doors and windows with nets, insecticide-treated wall linings in homes, nettings over gables and eaves openings, mosquito trapping systems, metal-roofed houses with mosquito screening, gable windows and closed eaves, and prototype houses using southeast Asian designs. Pooled analysis depicted a lower risk of mosquito-borne diseases in the housing intervention group (OR = 0.68; 95% CI = 0.48 to 0.95; P = 0.03). Subgroup analysis depicted housing intervention reduced the risk of malaria in all settings (OR = 0.63; 95% CI = 0.39 to 1.01; P = 0.05). In urban environment, housing intervention was found to decrease the risk of both malaria and dengue infections (OR = 0.52; 95% CI = 0.27 to 0.99; P = 0.05).Meta-analysis of pooled odds ratio showed a significant benefit of improved housing in reducing indoor vector densities of both Aedes and Anopheles (OR = 0.35; 95% CI = 0.23 to 0.54; P<0.001). CONCLUSIONS: Housing intervention could reduce transmission of malaria and dengue among people living in the homes. Future research should evaluate the protective effect of specific house features and housing improvements associated with urban development.


Assuntos
Habitação , Malária/prevenção & controle , Controle de Mosquitos/métodos , Doenças Transmitidas por Vetores/prevenção & controle , Aedes/efeitos dos fármacos , Aedes/fisiologia , Animais , Humanos , Inseticidas/farmacologia , Malária/transmissão , Razão de Chances , Fatores de Risco , Doenças Transmitidas por Vetores/transmissão
10.
Parasit Vectors ; 14(1): 21, 2021 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-33407798

RESUMO

BACKGROUND: Aedes aegypti control programs have failed to restrain mosquito population expansion and, consequently, the spread of diseases such as dengue, Zika, and Chikungunya. Wolbachia infection of mosquitoes is a new and promising complementary tool for the control of arbovirus transmission. The use of Wolbachia-infected mosquitoes, mass reared using human blood, is currently being tested in several countries. However, the use of human blood for mass rearing mosquitoes, and thus expansion of this strategy, is problematic. With the aim of overcoming this problem, we tested the effect of different types of blood source on the fitness parameters of female Ae. aegypti and the Wolbachia titer over generations to be able to guarantee the suitability of an alternative source to human blood for mass rearing Wolbachia-infected mosquitoes. METHODS: We investigated and compared essential parameters of the vector capacity of laboratory strains of Ae. aegypti with and without Wolbachia that fed on blood of different types of host (human, guinea pig, and mouse). The parameters analyzed were fecundity, fertility, pupation dynamics, and adult survival. Also, we tested whether it is possible to maintain mosquitoes with Wolbachia on mouse blood over generations without losing the bacterium titer. RESULTS: The average number of eggs per female, egg viability and pupation dynamics in the Wolbachia-infected mosquito (wMelBr) strain were similar, regardless of the blood source. The F1 progenies of females that fed on mouse blood or human blood were analyzed. The longevity of males was lower than that of females. F1 female survival differed depending on the presence of Wolbachia in the mother. In subsequent generations analyzed up until F35, the relative Wolbachia density was even higher when mosquitoes fed on mouse blood in comparison to human blood. CONCLUSIONS: Taken together, our results provide no evidence that the different types of blood influenced the fitness of the Wolbachia-infected mosquitoes. The presence of the bacterium in the colonies of Wolbachia-infected Ae. aegypti after 35 generations under the conditions evaluated indicates that they can be maintained on mouse blood. Based on these results, we show that it is possible to use mouse blood to feed female mosquitoes when using human blood for this purpose is problematic.


Assuntos
Aedes , Sangue , Wolbachia , Aedes/crescimento & desenvolvimento , Aedes/microbiologia , Aedes/fisiologia , Ração Animal , Animais , Infecções por Arbovirus/transmissão , Vetores de Doenças , Fertilidade , Cobaias , Humanos , Controle de Insetos , Longevidade , Camundongos , Mosquitos Vetores/microbiologia , Mosquitos Vetores/fisiologia , Controle Biológico de Vetores/métodos , Reprodução
11.
Carbohydr Polym ; 254: 117381, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33357888

RESUMO

Sulfonated cellulose nanocrystals (S-CNCs) can be used to encapsulate thyme white essential oil (EO) that is volatile and immiscible with water. S-CNCs form a Pickering emulsion (PE) with EOs and the micron-scale PEs are embedded in sodium alginate (SA) to form macroscale hydrogel beads. The incorporation of PEs with SA is confirmed with FTIR, XRD, SEM and confocal microscopic characterizations and the release behavior is monitored to understand the time-dependent biological activity of the EOs. The larvicidal performance of the SA-PE composite hydrogel beads is investigated with Aedes albopictus (Skuse) larvae. The larvicidal activity is higher for SA/PE hydrogel beads prepared at 0.5 % CaCl2 than 0.75 or 1.0 % CaCl2 due to their higher release rate.


Assuntos
Aedes/fisiologia , Alginatos/química , Emulsões/química , Hidrogéis/química , Larva/efeitos dos fármacos , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Thymus (Planta)/química , Animais , Celulose/química , Composição de Medicamentos/métodos , Nanopartículas/química , Volatilização , Água/química
12.
PLoS Negl Trop Dis ; 14(12): e0008971, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33338046

RESUMO

Aedes aegypti is a vector of dengue, chikungunya, and Zika viruses. Current vector control strategies such as community engagement, source reduction, and insecticides have not been sufficient to prevent viral outbreaks. Thus, interest in novel strategies involving genetic engineering is growing. Female mosquitoes rely on flight to mate with males and obtain a bloodmeal from a host. We hypothesized that knockout of genes specifically expressed in female mosquitoes associated with the indirect flight muscles would result in a flightless female mosquito. Using CRISPR-Cas9 we generated loss-of-function mutations in several genes hypothesized to control flight in mosquitoes, including actin (AeAct-4) and myosin (myo-fem) genes expressed specifically in the female flight muscle. Genetic knockout of these genes resulted in 100% flightless females, with homozygous males able to fly, mate, and produce offspring, albeit at a reduced rate when compared to wild type males. Interestingly, we found that while AeAct-4 was haplosufficient, with most heterozygous individuals capable of flight, this was not the case for myo-fem, where about half of individuals carrying only one intact copy could not fly. These findings lay the groundwork for developing novel mechanisms of controlling Ae. aegypti populations, and our results suggest that this mechanism could be applicable to other vector species of mosquito.


Assuntos
Aedes/genética , Sistemas CRISPR-Cas , Inseticidas/farmacologia , Controle de Mosquitos , Mosquitos Vetores/genética , Infecção por Zika virus/prevenção & controle , Zika virus/fisiologia , Aedes/fisiologia , Aedes/virologia , Animais , Feminino , Voo Animal , Técnicas de Inativação de Genes , Humanos , Masculino , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia , Fenótipo , Infecção por Zika virus/transmissão , Infecção por Zika virus/virologia
13.
BMC Med ; 18(1): 399, 2020 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-33327961

RESUMO

BACKGROUND: Zika virus (ZIKV) emerged as a global epidemic in 2015-2016 from Latin America with its true geographical extent remaining unclear due to widely presumed underreporting. The identification of locations with potential and unknown spread of ZIKV is a key yet understudied component for outbreak preparedness. Here, we aim to identify locations at a high risk of cryptic ZIKV spread during 2015-2016 to further the understanding of the global ZIKV epidemiology, which is critical for the mitigation of the risk of future epidemics. METHODS: We developed an importation simulation model to estimate the weekly number of ZIKV infections imported in each susceptible spatial unit (i.e. location that did not report any autochthonous Zika cases during 2015-2016), integrating epidemiological, demographic, and travel data as model inputs. Thereafter, a global risk model was applied to estimate the weekly ZIKV transmissibility during 2015-2016 for each location. Finally, we assessed the risk of onward ZIKV spread following importation in each susceptible spatial unit to identify locations with a high potential for cryptic ZIKV spread during 2015-2016. RESULTS: We have found 24 susceptible spatial units that were likely to have experienced cryptic ZIKV spread during 2015-2016, of which 10 continue to have a high risk estimate within a highly conservative scenario, namely, Luanda in Angola, Banten in Indonesia, Maharashtra in India, Lagos in Nigeria, Taiwan and Guangdong in China, Dakar in Senegal, Maputo in Mozambique, Kinshasa in Congo DRC, and Pool in Congo. Notably, among the 24 susceptible spatial units identified, some have reported their first ZIKV outbreaks since 2017, thus adding to the credibility of our results (derived using 2015-2016 data only). CONCLUSION: Our study has provided valuable insights into the potentially high-risk locations for cryptic ZIKV circulation during the 2015-2016 pandemic and has also laid a foundation for future studies that attempt to further narrow this key knowledge gap. Our modelling framework can be adapted to identify areas with likely unknown spread of other emerging vector-borne diseases, which has important implications for public health readiness especially in resource-limited settings.


Assuntos
Mapeamento Geográfico , Infecção por Zika virus/epidemiologia , Aedes/fisiologia , Aedes/virologia , Animais , Surtos de Doenças/história , Ecologia , Epidemias , Geografia , História do Século XXI , Humanos , Viagem/estatística & dados numéricos , Zika virus/fisiologia , Infecção por Zika virus/história
14.
PLoS One ; 15(10): e0234676, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33006964

RESUMO

Male and female mosquito larvae compete for different subsets of the yeast food resource in laboratory microcosms. Males compete more intensely with males, and females with females. The amount and timing of food inputs alters both growth and competition, but the effects are different between sexes. Increased density increases competition among males. Among females, density operates primarily by changing the food/larva or total food; this affects competition in some interactions and growth in others. Food added earlier in the life span contributes more to mass than the same quantity added later. After a period of starvation larvae appear to use some of the subsequent food input to rebuild physiological reserves in addition to building mass. The timing of pupation is affected by the independent factors and competition, but not in the same way for the two sexes, and not in the same way as mass at pupation for the two sexes. There is an effect of density on the timing of pupation for females independent of competition or changes in food/larva or total food. Male and female larvae have different larval life history strategies. Males grow quickly to a minimum size, then pupate, depending on the amount of food available. Males that do not grow quickly enough may delay pupation further to grow larger, resulting in a bimodal distribution of sizes and ages. Males appear to have a maximum size determined by the early food level. Females grow faster than males and grow larger than males on the same food inputs. Females affect the growth and competition among males by manipulating the number of particles in the microcosm through changes in feeding behavior. Mosquito larvae appear to have evolved to survive periods of starvation and take advantage of intermittent inputs of food into containers.


Assuntos
Aedes/fisiologia , Larva/crescimento & desenvolvimento , Aedes/crescimento & desenvolvimento , Ração Animal , Animais , Tamanho Corporal , Ecossistema , Feminino , Masculino , Densidade Demográfica , Caracteres Sexuais , Especificidade da Espécie
15.
PLoS One ; 15(9): e0239636, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32976497

RESUMO

Animals with complex life cycles have traits related to oviposition and juvenile survival that can respond to environmental factors in similar or dissimilar ways. We examined the preference-performance hypothesis (PPH), which states that females lacking parental care select juvenile habitats that maximize fitness, for two ubiquitous mosquito species, Aedes albopictus and Culex quinquefasciatus. Specifically, we examined if environmental factors known to affect larval abundance patterns in the field played a role in the PPH for these species. We first identified important environmental factors from a field survey that predicted larvae across different spatial scales. We then performed two experiments, the first testing the independent responses of oviposition and larval survival to these environmental factors, followed by a combined experiment where initial oviposition decisions were allowed to affect larval life history measures. We used path analysis for this last experiment to determine important links among factors in explaining egg numbers, larval mass, development time, and survival. For separate trials, Aedes albopictus displayed congruence between oviposition and larval survival, however C. quinquefasciatus did not. For the combined experiment path analysis suggested neither species completely fit predictions of the PPH, with density dependent effects of initial egg number on juvenile performance in A. albopictus. For these species the consequences of female oviposition choices on larval performance do not appear to fit expectations of the PPH.


Assuntos
Adaptação Fisiológica , Comportamento Animal , Mosquitos Vetores/fisiologia , Oviposição , Aedes/fisiologia , Animais , Culex/fisiologia , Ecossistema , Feminino , Larva/fisiologia , Especificidade da Espécie
16.
PLoS Negl Trop Dis ; 14(9): e0008531, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32911504

RESUMO

Pathogens may manipulate their human and mosquito hosts to enhance disease transmission. Dengue, caused by four viral serotypes, is the fastest-growing transmissible disease globally resulting in 50-100 million infections annually. Transmission of the disease relies on the interaction between humans and the vector Aedes aegypti and is largely dependent on the odor-mediated host seeking of female mosquitoes. In this study, we use activity monitors to demonstrate that dengue virus-1 affects the locomotion and odor-mediated behavior of Ae. aegypti, reflecting the progression of infection within the mosquito. Mosquitoes 4-6 days post-infection increase locomotion, but do not alter their odor-driven host-seeking response. In contrast, females 14-16 days post-infection are less active, yet more sensitive to human odors as assessed by behavioral and electrophysiological assays. Such an increase in physiological and behavioral sensitivity is reflected by the antennal-specific increase in abundance of neural signaling transcripts in 14 days post-infection females, as determined by transcriptome analysis. This suggests that the sensitivity of the mosquito peripheral olfactory system is altered by the dengue virus by enhancing the overall neural responsiveness of the antenna, rather than the selective regulation of chemosensory-related genes. Our study reveals that dengue virus-1 enhances vector-related behaviors in the early stages post-infection that aid in avoiding predation and increasing spatial exploration. On the other hand, at the later stages of infection, the virus enhances the host-seeking capacity of the vector, thereby increasing the risk of virus transmission. A potential mechanism is discussed.


Assuntos
Aedes/virologia , Dengue , Comportamento de Busca por Hospedeiro , Aedes/genética , Aedes/metabolismo , Aedes/fisiologia , Animais , Antenas de Artrópodes/fisiologia , Comportamento Animal , Vírus da Dengue/fisiologia , Feminino , Perfilação da Expressão Gênica , Humanos , Locomoção , Mosquitos Vetores/fisiologia , Mosquitos Vetores/virologia
17.
PLoS Negl Trop Dis ; 14(9): e0008705, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32986704

RESUMO

Over the past three decades, Europe has witnessed an increased spread of invasive aedine mosquito species, most notably Aedes albopictus, a key vector of chikungunya, dengue and Zika virus. While its distribution in southern Europe is well documented, its dispersal modes across the Alps remain poorly investigated, preventing a projection of future scenarios beyond its current range in order to target mosquito control. To monitor the presence and frequency of invasive Aedes mosquitoes across and beyond the Alps we set oviposition and BG-Sentinel traps at potential points of entry with a focus on motorway service areas across Switzerland. We placed the traps from June to September and controlled them for the presence of mosquitoes every other week between 2013 and 2018. Over the six years of surveillance we identified three invasive Aedes species, including Ae. albopictus, Ae. japonicus and Ae. koreicus. Based on the frequency and distribution patterns we conclude that Ae. albopictus and Ae. koreicus are being passively spread primarily along the European route E35 from Italy to Germany, crossing the Alps, while Ae. japonicus has been expanding its range from northern Switzerland across the country most likely through active dispersal.


Assuntos
Aedes/classificação , Aedes/fisiologia , Monitoramento Epidemiológico , Mosquitos Vetores/fisiologia , Aedes/virologia , Animais , Europa (Continente) , Feminino , Espécies Introduzidas , Itália , Controle de Mosquitos/instrumentação , Oviposição/fisiologia , Suíça , Zika virus
18.
PLoS Negl Trop Dis ; 14(9): e0008576, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32881865

RESUMO

BACKGROUND: The ability of cluster-randomized trials to capture mass or indirect effects is one reason for their increasing use to test interventions against vector-borne diseases such as malaria and dengue. For the same reason, however, the independence of clusters may be compromised if the distances between clusters is too small to ensure independence. In other words they may be subject to spillover effects. METHODS: We distinguish two types of spatial spillover effect: between-cluster dependence in outcomes, or spillover dependence; and modification of the intervention effect according to distance to the intervention arm, or spillover indirect effect. We estimate these effects in trial of insecticide-treated materials against the dengue mosquito vector, Aedes aegypti, in Venezuela, the endpoint being the Breteau index. We use a novel random effects Poisson spatial regression model. Spillover dependence is incorporated via an orthogonalized intrinsic conditional autoregression (ICAR) model. Spillover indirect effects are incorporated via the number of locations within a certain radius, set at 200m, that are in the intervention arm. RESULTS: From the model with ICAR spatial dependence, and the degree of surroundedness, the intervention effect is estimated as 0.74-favouring the intervention-with a 95% credible interval of 0.34 to 1.69. The point estimates are stronger with increasing surroundedness within intervention locations. CONCLUSION: In this trial there is some evidence of a spillover indirect effect of the intervention, with the Breteau index tending to be lower in locations which are more surrounded by locations in the intervention arm.


Assuntos
Aedes/efeitos dos fármacos , Inseticidas/farmacologia , Controle de Mosquitos/métodos , Mosquitos Vetores/efeitos dos fármacos , Aedes/fisiologia , Animais , Dengue/transmissão , Humanos , Mosquitos Vetores/fisiologia , Análise Espacial , Venezuela
19.
PLoS Negl Trop Dis ; 14(9): e0008561, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32881871

RESUMO

Combined incompatible and sterile insect technique (IIT-SIT) has been considered to be an effective and safe approach to control mosquito populations. Immobilization of male adults by chilling is a crucial process required for the packing, transportation and release of the mosquitoes during the implementation of IIT-SIT for mosquito control. In this study, effects of chilling on the Aedes albopictus males with triple Wolbachia infections (HC line), a powerful weapon to fight against the wild type Ae. albopictus population via IIT-SIT, were evaluated under both laboratory and field conditions. Irradiated HC (IHC) males were exposed to 1, 5 and 10°C for 1, 2, 3, 6 and 24 h. The survival rate of the post-chilled IHC males was then monitored. Longevity of post-chilled IHC males was compared to non-chilled males under laboratory and semi-field conditions. Mating competitiveness of IHC/HC males after exposure to 5 or 10°C for 0, 3 and 24 h was then evaluated. Effects of compaction and transportation under chilled conditions on the survival rate of IHC males were also monitored. The optimal chilling conditions for handling IHC males were temperatures between 5 and 10°C for a duration of less than 3 h with no negative impacts on survival rate, longevity and mating competitiveness when compared to non-chilled males. However, the overall quality of post-chilled IHC/HC males decreased when exposed to low temperatures for 24 h. Reduced survival was observed when IHC males were stored at 5°C under a compaction height of 8 cm. Transportation with chilling temperatures fluctuating from 8 to 12°C has no negative impact on the survival of IHC males. This study identified the optimal chilling temperature and duration for the handling and transportation of Ae. albopictus IHC male adults without any detrimental effect on their survival, longevity and mating competitiveness. Further studies are required to develop drone release systems specific for chilled mosquitoes to improve release efficiency, as well as to compare the population suppression efficiency between release of post-chilled and non-chilled males in the field.


Assuntos
Aedes/microbiologia , Aedes/fisiologia , Controle de Mosquitos/métodos , Wolbachia/fisiologia , Animais , Temperatura Baixa , Feminino , Masculino , Reprodução
20.
PLoS Negl Trop Dis ; 14(9): e0008365, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32898130

RESUMO

Insecticide resistance poses a significant threat to the control of arthropods that transmit disease agents. Nanoparticle carriers offer exciting opportunities to expand the armamentarium of insecticides available for public health and other pests. Most chemical insecticides are delivered by contact or feeding, and from there must penetrate various biological membranes to reach target organs and kill the pest organism. Nanoparticles have been shown to improve bioactive compound navigation of such barriers in vertebrates, but have not been well-explored in arthropods. In this study, we explored the potential of polyanhydride micro- and nanoparticles (250 nm- 3 µm), labeled with rhodamine B to associate with and/or transit across insect biological barriers, including the cuticle, epithelium, midgut and ovaries, in female Ae. aeygpti mosquitoes. Mosquitoes were exposed using conditions to mimic surface contact with a residual spray or paint, topical exposure to mimic contact with aerosolized insecticide, or per os in a sugar meal. In surface contact experiments, microparticles were sometimes observed in association with the exterior of the insect cuticle. Nanoparticles were more uniformly distributed across exterior tissues and present at higher concentrations. Furthermore, by surface contact, topical exposure, or per os, particles were detected in internal organs. In every experiment, amphiphilic polyanhydride nanoparticles associated with internal tissues to a higher degree than hydrophobic nanoparticles. In vitro, nanoparticles associated with Aedes aegypti Aag2 cells within two hours of exposure, and particles were evident in the cytoplasm. Further studies demonstrated that particle uptake is dependent on caveolae-mediated endocytosis. The propensity of these nanoparticles to cross biological barriers including the cuticle, to localize in target tissue sites of interest, and to reach the cytoplasm of cells, provides great promise for targeted delivery of insecticidal candidates that cannot otherwise reach these cellular and subcellular locations.


Assuntos
Aedes/fisiologia , Nanopartículas , Polianidridos , Aedes/citologia , Animais , Linhagem Celular , Endocitose , Feminino , Controle de Mosquitos/métodos , Rodaminas/química , Distribuição Tecidual
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