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1.
PLoS Negl Trop Dis ; 14(3): e0007719, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32126087

RESUMO

The putative vector of trachoma, Musca sorbens, prefers to lay its eggs on human faeces on the ground. This study sought to determine whether M. sorbens females were attracted to volatile odours from human faeces in preference to odours from the faeces of other animals, and to determine whether specific volatile semiochemicals mediate selection of the faeces. Traps baited with the faeces of humans and local domestic animals were used to catch flies at two trachoma-endemic locations in The Gambia and one in Ethiopia. At all locations, traps baited with faeces caught more female M. sorbens than control traps baited with soil, and human faeces was the most successful bait compared with soil (mean rate ratios 44.40, 61.40, 10.50 [P<0.001]; 8.17 for child faeces [P = 0.004]). Odours from human faeces were sampled by air entrainment, then extracts of the volatiles were tested by coupled gas chromatography-electroantennography with laboratory-reared female M. sorbens. Twelve compounds were electrophysiologically active and tentatively identified by coupled mass spectrometry-gas chromatography, these included cresol, indole, 2-methylpropanoic acid, butanoic acid, pentanoic acid and hexanoic acid. It is possible that some of these volatiles govern the strong attraction of M. sorbens flies to human faeces. If so, a synthetic blend of these chemicals, at the correct ratios, may prove to be a highly attractive lure. This could be used in odour-baited traps for monitoring or control of this species in trachoma-endemic regions.


Assuntos
Fezes/química , Insetos Vetores/efeitos dos fármacos , Muscidae/efeitos dos fármacos , Feromônios/farmacologia , Compostos Orgânicos Voláteis/farmacologia , Adolescente , Adulto , Animais , Criança , Cromatografia Gasosa , Fenômenos Eletrofisiológicos , Etiópia , Feminino , Gâmbia , Humanos , Insetos Vetores/fisiologia , Masculino , Muscidae/fisiologia , Feromônios/isolamento & purificação , Compostos Orgânicos Voláteis/isolamento & purificação , Adulto Jovem
2.
PLoS Negl Trop Dis ; 14(2): e0007855, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32092056

RESUMO

Glossina pallidipes is the main vector of animal African trypanosomiasis and a potential vector of human African trypanosomiasis in eastern Africa where it poses a large economic burden and public health threat. Vector control efforts have succeeded in reducing infection rates, but recent resurgence in tsetse fly population density raises concerns that vector control programs require improved strategic planning over larger geographic and temporal scales. Detailed knowledge of population structure and dispersal patterns can provide the required information to improve planning. To this end, we investigated the phylogeography and population structure of G. pallidipes over a large spatial scale in Kenya and northern Tanzania using 11 microsatellite loci genotyped in 600 individuals. Our results indicate distinct genetic clusters east and west of the Great Rift Valley, and less distinct clustering of the northwest separate from the southwest (Serengeti ecosystem). Estimates of genetic differentiation and first-generation migration indicated high genetic connectivity within genetic clusters even across large geographic distances of more than 300 km in the east, but only occasional migration among clusters. Patterns of connectivity suggest isolation by distance across genetic breaks but not within genetic clusters, and imply a major role for river basins in facilitating gene flow in G. pallidipes. Effective population size (Ne) estimates and results from Approximate Bayesian Computation further support that there has been recent G. pallidipes population size fluctuations in the Serengeti ecosystem and the northwest during the last century, but also suggest that the full extent of differences in genetic diversity and population dynamics between the east and the west was established over evolutionary time periods (tentatively on the order of millions of years). Findings provide further support that the Serengeti ecosystem and northwestern Kenya represent independent tsetse populations. Additionally, we present evidence that three previously recognized populations (the Mbeere-Meru, Central Kenya and Coastal "fly belts") act as a single population and should be considered as a single unit in vector control.


Assuntos
Insetos Vetores/genética , Moscas Tsé-Tsé/genética , Animais , Ecossistema , Fluxo Gênico , Variação Genética , Genótipo , Insetos Vetores/classificação , Insetos Vetores/fisiologia , Quênia , Repetições de Microssatélites , Filogeografia , Densidade Demográfica , Dinâmica Populacional , Tanzânia , Moscas Tsé-Tsé/classificação , Moscas Tsé-Tsé/fisiologia
3.
Arch Virol ; 165(1): 169-178, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31773326

RESUMO

Plant viruses can alter the behavior or performance of their arthropod vectors, either indirectly (through effects of virus infection on the host plant) or directly (from virus acquisition by the vector). Given the diversity of plant viruses and their arthropod vectors, the effects for any specific system are not possible to predict. Here, we present experimental evidence that acquisition of maize Iranian mosaic virus (MIMV, genus Nucleorhabdovirus, family Rhabdoviridae) modifies the biological traits of its insect vector, the small brown planthopper (SBPH) Laodelphax striatellus. MIMV is an economically important virus of maize and several other grass species. It is transmitted by SBPHs in a persistent-propagative manner. We evaluated the effects of MIMV acquisition by SBPH on its life history when reared on healthy barley plants (Hordeum vulgare). We conclude that 1) MIMV acquisition by SBPHs increases female fecundity, duration of the nymph stage, adult longevity, and survival of SBPHs, (2) the mortality rate and female-to-male sex ratio are reduced in MIMV-infected planthoppers, and (3) MIMV infection increases the concentration of some biochemical components of the infected plants, including carbohydrates, some amino acids, and total protein, which might influence the life traits of its insect vector. The results indicate the potential of MIMV to improve the ecological fitness of its vector, SBPH, through direct or indirect effects, with the potential to increase the spread of the virus.


Assuntos
Hemípteros/fisiologia , Rhabdoviridae/fisiologia , Zea mays/metabolismo , Zea mays/virologia , Aminoácidos/metabolismo , Animais , Metabolismo dos Carboidratos , Feminino , Fertilidade , Hemípteros/virologia , Insetos Vetores/fisiologia , Insetos Vetores/virologia , Longevidade , Masculino , Proteínas de Plantas/metabolismo , Vírus de Plantas/fisiologia
4.
Phytopathology ; 110(1): 174-186, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31502517

RESUMO

Mixed viral infections in plants are common, and can result in synergistic or antagonistic interactions. Except in complex diseases with severe symptoms, mixed infections frequently remain unnoticed, and their impact on insect vector transmission is largely unknown. In this study, we considered mixed infections of two unrelated viruses commonly found in melon plants, the crinivirus cucurbit yellow stunting disorder virus (CYSDV) and the potyvirus watermelon mosaic virus (WMV), and evaluated their vector transmission by whiteflies and aphids, respectively. Their dynamics of accumulation was analyzed until 60 days postinoculation (dpi) in mixed-infected plants, documenting reduced titers of WMV and much higher titers of CYSDV compared with single infections. At 24 dpi, corresponding to the peak of CYSDV accumulation, similar whitefly transmission rates were obtained when comparing either individual or mixed-infected plants as CYSDV sources, although its secondary dissemination was slightly biased toward plants previously infected with WMV, regardless of the source plant. However, at later time points, mixed-infected plants partially recovered from the initially severe symptoms, and CYSDV transmission became significantly higher. Interestingly, aphid transmission rates both at early and late time points were unaltered when WMV was acquired from mixed-infected plants despite its reduced accumulation. This lack of correlation between WMV accumulation and transmission could result from compensatory effects observed in the analysis of the aphid feeding behavior by electrical penetration graphs. Thus, our results showed that mixed-infected plants could provide advantages for both viruses, directly favoring CYSDV dissemination while maintaining WMV transmission.


Assuntos
Afídeos , Comportamento Animal , Coinfecção , Cucurbitaceae , Insetos Vetores , Animais , Afídeos/fisiologia , Afídeos/virologia , Cucurbitaceae/virologia , Insetos Vetores/fisiologia , Insetos Vetores/virologia , Doenças das Plantas/virologia
5.
PLoS Negl Trop Dis ; 13(12): e0007905, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31830039

RESUMO

The savannah tsetse flies, Glossina morsitans morsitans and G. pallidipes, are important vectors of Rhodesian human African trypanosomiasis and animal African trypanosomiasis in East and southern Africa. We tested in Zimbabwe whether robust, synthetic fabrics, and innovative fly's-eye-view approaches to optimise fabric colour, can improve insecticide-treated targets employed for tsetse control. Flies were caught by electrocution at a standard target comprising a 1m x 1m black cotton cloth panel with 1m x 0.5m black polyester net panels on each side. Catches were subdivided by species and sex. Tsetse catches were unaffected by substitution of the black cotton with a blue polyester produced for riverine tsetse targets. Exchanging the net panels for phthalogen blue cotton to simulate the target routinely used in Zimbabwe significantly reduced catches of female G. m. morsitans (mean catch 0.7 times that at standard), with no effect on other tsetse catches. However, significantly greater proportions of the catch were intercepted at the central panel of the Zimbabwe (means 0.47-0.79) versus standard designs (0.11-0.29). We also engineered a new violet polyester cloth using models of tsetse attraction based upon fly photoreceptor responses. With and without odour lure, catches of females of both species at the violet target were significantly greater than those at standard (means 1.5-1.6 times those at standard), and typical blue polyester targets (means 0.9-1.3 times those at standard). Similar effects were observed for males under some combinations of species and odour treatment. The proportions of catch intercepted at the central panel of the violet target (means 0.08-0.18) were intermediate between those at standard and typical blue polyester. Further, the reflectance spectrum of violet polyester was more stable under field conditions than that of black cotton. Our results demonstrate the effectiveness of photoreceptor-based models as a novel means of improving targets to control tsetse and trypanosomiases.


Assuntos
Comportamento Animal , Controle de Insetos/métodos , Insetos Vetores/fisiologia , Feromônios , Coloração e Rotulagem/métodos , Têxteis , Moscas Tsé-Tsé/fisiologia , Animais , Cor , Feminino , Masculino , Odorantes , Zimbábue
6.
Parasit Vectors ; 12(1): 585, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31842951

RESUMO

BACKGROUND: Triatoma rubrofasciata is the only kissing bug species distributed globally. In the Americas, this species transmits the parasite Trypanosoma cruzi, responsible for Chagas disease. The presence of T. rubrofasciata in several Asian countries has greatly increased recently. In Vietnam, it is found in large numbers, closely associated with human environments. Although T. rubrofasciata from Asia is not infected with Tryp. cruzi, it carries other parasites such as Trypanosoma lewisi and Trypanosoma conorhini. Reports of bites by T. rubrofasciata have increased significantly in several places of Vietnam, becoming a public health problem as it produces severe anaphylactic reactions. METHODS: Specimens of T. rubrofasciata were collected from seven provinces in central Vietnam. We analyzed different biological attributes (life-cycle, starvation resistance, feeding and reproductive capacities) and genetic characteristics (chromosomes and DNA sequences) of T. rubrofasciata from Vietnam and compared them with Brazilian specimens. Natural infection with Tryp. conorhini and Tryp. lewisi were analyzed in a sample of 100 collected insects. RESULTS: Species identification of T. rubrofasciata from central Vietnam was corroborated by genetic markers. Cytogenetic analyses showed that T. rubrofasciata from central Vietnam share the same chromosomal characteristics with individuals from Brazil and Hanoi. DNA sequence analyses of a mitochondrial cytochrome b gene fragment showed little variation between Old and New World specimens. Our study sample, compared with Brazilian individuals, showed a higher survival capacity revealed by a higher hatching rate (98% compared with 80.5%), a larger amount of blood taken in single meal and long-term starvation resistance. Furthermore, this species had a high natural rate of infection with Tryp. conorhini (46%) and Tryp. lewisi (27%). CONCLUSIONS: For T. rubrofasciata of Vietnam, a high rate of fecundity throughout the year, a high capacity for starvation, and its occurrence in synanthropic environments of urban areas with a high availability of food sources are risk factors to be taken into account by vector control campaigns. The several allergic reactions caused by their bites and their high infection with Tryp. lewisi highlight the need to implement specific control programmes for T. rubrofasciata in Vietnam.


Assuntos
Comportamento Alimentar , Insetos Vetores/fisiologia , Estágios do Ciclo de Vida , Reprodução , Triatoma/fisiologia , Animais , Brasil , Citocromos b/genética , Citogenética , Variação Genética , Genótipo , Insetos Vetores/classificação , Insetos Vetores/genética , Insetos Vetores/parasitologia , Cariótipo , Análise de Sequência de DNA , Triatoma/classificação , Triatoma/genética , Triatoma/parasitologia , Trypanosoma/isolamento & purificação , Vietnã
7.
Parasit Vectors ; 12(1): 602, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31870457

RESUMO

BACKGROUND: In Brazil, Triatoma maculata is only found in the State of Roraima and is a vector of Trypanosoma cruzi, the etiological agent of Chagas disease. It occurs in wild, peridomestic and domestic habitats, with an urban infestation in Boa Vista, the capital of this Brazilian state. The aim of this study was to assess the morphological variability of the T. maculata antennal phenotype in three populations of Roraima State, using the antennal sensilla pattern analyzed under optical microscopy. METHODS: The number and distribution of four antennal sensilla types (bristles, thin and thick walled trichoidea, and basiconic) of three Brazilian populations of T. maculata from Roraima State were compared. Univariate and multivariate analyses were performed. RESULTS: The antenna of T. maculata presented the four types of sensilla. According to the density and distribution of the antennal sensilla characteristics, the multivariate analyses showed that the laboratory population is morphologically structured. Urban specimens showed a pronounced phenotypic variability. The main differences were observed in the pedicel segment, and between males and females. CONCLUSIONS: We determined the antennal phenotype in three Roraima populations of T. maculata. These results support the idea that the patterns of antennal sensilla are sensitive markers for distinct populations in the Triatominae. The infestations of T. maculata in different habitats reinforces the ability of this vector to become adapted to a variety of environments, which, could have eco-epidemiological implications for the T. cruzi transmission that are still not well understood.


Assuntos
Variação Biológica da População , Insetos Vetores/anatomia & histologia , Triatoma/anatomia & histologia , Distribuição Animal , Animais , Feminino , Insetos Vetores/fisiologia , Masculino , Densidade Demográfica , Sensilas/anatomia & histologia , Triatoma/fisiologia
8.
Rev Soc Bras Med Trop ; 52: e20190020, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31778398

RESUMO

INTRODUCTION: Different blood meal sources can affect biology of triatomines. METHODS: We studied the influence of two different blood meal sources (rabbits and hens) on five biological parameters in Meccus phyllosomus pallidipennis and collected biological parameters. RESULTS: The cohort fed on rabbits had a shorter median life-cycle and lower mortality rate than that fed on hens. Both cohorts required a similar number of blood meals to reach adulthood. Median longevity and number of blood meals for adults were similar between both cohorts. CONCLUSIONS: The studied parameters reflect the high grade of adaptation of M. p. pallidipennis feeding on different hosts.


Assuntos
Comportamento Alimentar/fisiologia , Insetos Vetores/fisiologia , Estágios do Ciclo de Vida/fisiologia , Triatominae/fisiologia , Animais , Doença de Chagas/transmissão , Galinhas , Coelhos
9.
PLoS Negl Trop Dis ; 13(11): e0007832, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31751334

RESUMO

BACKGROUND: Canine leishmaniasis (CanL) is a severe chronic disease caused by Leishmania infantum and transmitted by sand flies of which the main vector in the Western part of the Mediterranean basin is Phlebotomus perniciosus. Previously, an immunochromatographic test (ICT) was proposed to allow rapid evaluation of dog exposure to P. perniciosus. In the present study, we optimized the prototype and evaluated the detection accuracy of the ICT in field conditions. Possible cross-reactions with other hematophagous arthropods were also assessed. METHODOLOGY/PRINCIPAL FINDINGS: The ICT was optimized by expressing the rSP03B protein in a HEK293 cell line, which delivered an increased specificity (94.92%). The ICT showed an excellent reproducibility and inter-person reliability, and was optimized for use with whole canine blood which rendered an excellent degree of agreement with the use of serum. Field detectability of the ICT was assessed by screening 186 dogs from different CanL endemic areas with both the SGH-ELISA and the ICT, and 154 longitudinally sampled dogs only with the ICT. The ICT results corresponded to the SGH-ELISA for most areas, depending on the statistical measure used. Furthermore, the ICT was able to show a clear seasonal fluctuation in the proportion of bitten dogs. Finally, we excluded cross-reactions between non-vector species and confirmed favorable cross-reactions with other L. infantum vectors belonging to the subgenus Larroussius. CONCLUSIONS/SIGNIFICANCE: We have successfully optimized the ICT, now also suitable to be used with whole canine blood. The test is able to reflect the seasonal fluctuation in dog exposure and showed a good detectability in a field population of naturally exposed dogs, particularly in areas with a high seroprevalence of bitten dogs. Furthermore, our study showed the existence of favorable cross-reactions with other sand fly vectors thereby expanding its use in the field.


Assuntos
Doenças do Cão/diagnóstico , Imunoensaio/métodos , Insetos Vetores/fisiologia , Leishmaniose/veterinária , Phlebotomus/fisiologia , Animais , Doenças do Cão/sangue , Doenças do Cão/parasitologia , Cães , Feminino , Insetos Vetores/parasitologia , Leishmania infantum/fisiologia , Leishmaniose/sangue , Leishmaniose/diagnóstico , Leishmaniose/parasitologia , Camundongos Endogâmicos BALB C , Phlebotomus/parasitologia
10.
Parasit Vectors ; 12(1): 478, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31610815

RESUMO

BACKGROUND: Mepraia gajardoi and Mepraia spinolai are endemic triatomine vector species of Trypanosoma cruzi, a parasite that causes Chagas disease. These vectors inhabit arid, semiarid and Mediterranean areas of Chile. Mepraia gajardoi occurs from 18° to 25°S, and M. spinolai from 26° to 34°S. Even though both species are involved in T. cruzi transmission in the Pacific side of the Southern Cone of South America, no study has modelled their distributions at a regional scale. Therefore, the aim of this study is to estimate the potential geographical distribution of M. spinolai and M. gajardoi under current and future climate scenarios. METHODS: We used the Maxent algorithm to model the ecological niche of M. spinolai and M. gajardoi, estimating their potential distributions from current climate information and projecting their distributions to future climatic conditions under representative concentration pathways (RCP) 2.6, 4.5, 6.0 and 8.5 scenarios. Future predictions of suitability were constructed considering both higher and lower public health risk situations. RESULTS: The current potential distributions of both species were broader than their known ranges. For both species, climate change projections for 2070 in RCP 2.6, 4.5, 6.0 and 8.5 scenarios showed different results depending on the methodology used. The higher risk situation showed new suitable areas, but the lower risk situation modelled a net reduction in the future potential distribution areas of M. spinolai and M. gajardoi. CONCLUSIONS: The suitable areas for both species may be greater than currently known, generating new challenges in terms of vector control and prevention. Under future climate conditions, these species could modify their potential geographical range. Preventive measures to avoid accidental human vectorial transmission by wild vectors of T. cruzi become critical considering the uncertainty of future suitable areas projected in this study.


Assuntos
Doença de Chagas/transmissão , Mudança Climática , Insetos Vetores/fisiologia , Triatominae/fisiologia , Trypanosoma cruzi/fisiologia , Animais , Área Sob a Curva , Doença de Chagas/epidemiologia , Chile/epidemiologia , Humanos , Umidade , Insetos Vetores/parasitologia , Modelos Biológicos , Filogeografia , Curva ROC , Chuva , Medição de Risco , Temperatura , Triatominae/parasitologia
11.
Parasit Vectors ; 12(1): 504, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31665056

RESUMO

BACKGROUND: Triatomine bugs are vectors of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Rhodnius pallescens is a major vector of Chagas disease in Panama. Understanding the microbial ecology of disease vectors is important in the development of vector management strategies that target vector survival and fitness. In this study we examined the whole-body microbial composition of R. pallescens from three locations in Panama. METHODS: We collected 89 R. pallescens specimens using Noireau traps in Attalea butyracea palms. We then extracted total DNA from whole-bodies of specimens and amplified bacterial microbiota using 16S rRNA metabarcoding PCR. The 16S libraries were sequenced on an Illumina MiSeq and analyzed using QIIME2 software. RESULTS: We found Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes to be the most abundant bacterial phyla across all samples. Geographical location showed the largest difference in microbial composition with northern Veraguas Province having the most diversity and Panama Oeste Province localities being most similar to each other. Wolbachia was detected in high abundance (48-72%) at Panama Oeste area localities with a complete absence of detection in Veraguas Province. No significant differences in microbial composition were detected between triatomine age class, primary blood meal source, or T. cruzi infection status. CONCLUSIONS: We found biogeographical regions differ in microbial composition among R. pallescens populations in Panama. While overall the microbiota has bacterial taxa consistent with previous studies in triatomine microbial ecology, locality differences are an important observation for future studies. Geographical heterogeneity in microbiomes of vectors is an important consideration for future developments that leverage microbiomes for disease control.


Assuntos
Bactérias/classificação , Doença de Chagas/transmissão , Insetos Vetores/microbiologia , Microbiota , Rhodnius/microbiologia , Actinobacteria/classificação , Actinobacteria/genética , Análise de Variância , Animais , Bactérias/genética , Bacteroidetes/classificação , Bacteroidetes/genética , Biodiversidade , Código de Barras de DNA Taxonômico , Ecossistema , Firmicutes/classificação , Firmicutes/genética , Biblioteca Gênica , Humanos , Insetos Vetores/fisiologia , Panamá , Filogeografia , Reação em Cadeia da Polimerase , Proteobactérias/classificação , Proteobactérias/genética , RNA Ribossômico 16S/química , Rhodnius/fisiologia
12.
Virol J ; 16(1): 106, 2019 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-31438971

RESUMO

BACKGROUND: Plant viruses can affect vector's behaviors in order to enhance viral transmission. Cucurbit chlorotic yellows virus (CCYV) (genus Crinivirus) is an emergent RNA plant virus and is transmitted specifically by biotypes B and Q of tobacco whitefly, Bemisia tabaci (Gennadius), in a semipersistent manner. METHODS: We used the electrical penetration graph (EPG) to investigate the effect of CCYV on the feeding behaviors of B. tabaci biotypes B and Q. RESULTS: CCYV could affect, both directly and indirectly, the feeding behaviors of B. tabaci to various degrees, depending on biotypes and sexes of the insect. CCYV showed stronger direct effects on biotype Q than on biotype B in terms of increased non-phloem probing and phloem salivation. CCYV increased non-phloem probing and phloem salivation more on females than on males of biotype Q, and increased phloem salivation more on females than on males of biotype B. CCYV had stronger indirect effects, via virus-infested plants, on biotype B than on biotype Q by enhancing phloem sap ingestion and feeding bouts. CCYV increased non-phloem probing and feeding bouts more on males than on females of biotype B, and decreased phloem sap ingestion more on males than on females on biotype Q indirectly. CONCLUSIONS: The results clearly indicated that CCYV affects the feeding behaviors of B. tabaci, which may lead to increased ability of the B. tabaci for CCYV transmission.


Assuntos
Crinivirus , Comportamento Alimentar , Hemípteros/fisiologia , Hemípteros/virologia , Doenças das Plantas/virologia , Animais , Feminino , Insetos Vetores/fisiologia , Insetos Vetores/virologia , Masculino , Floema , Fatores Sexuais
13.
Parasit Vectors ; 12(1): 411, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31439006

RESUMO

BACKGROUND: Stable isotope labeling is a promising method for use in insect mark-capture and dispersal studies. Culicoides biting midges, which transmit several important animal pathogens, including bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV), are small flies that develop in various semi-aquatic habitats. Previous Culicoides dispersal studies have suffered from the limitations of other labeling techniques, and an inability to definitively connect collected adult midges to specific immature development sites. RESULTS: Adult C. sonorensis were successfully labeled with 13C and 15N stable isotopes as larvae developing in a semi-aquatic mud substrate in the laboratory. High and low-dose isotope treatments for both elements significantly enriched midges above the background isotope levels of unenriched controls. Enrichment had no effect on C. sonorensis survival, though a slight (~ 5 day) delay in emergence was observed, and there was no significant effect of pool size on 13C or 15N enrichment levels. CONCLUSIONS: Stable isotope labeling is life-long, and does not interfere with natural insect behaviors. Stable isotope enrichment using 13C or 15N shows promise for Culicoides dispersal studies in the field. This method can be used to identify adult dispersal from larval source habitat where a midge developed. It may be possible to detect a single enriched midge in a pool of unenriched individuals, though further testing is needed to confirm the sensitivity of this method.


Assuntos
Distribuição Animal , Ceratopogonidae/fisiologia , Insetos Vetores/fisiologia , Marcação por Isótopo , Animais , Isótopos de Carbono , Ecossistema , Larva , Isótopos de Nitrogênio
14.
Mem Inst Oswaldo Cruz ; 114: e190170, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31365633

RESUMO

BACKGROUND: The state of Rondônia (RO) is a hot spot for human cases of cutaneous leishmaniasis. Many sandfly species in RO are putative vectors of leishmaniasis. OBJECTIVES: This study examines the diversity patterns and the presence of Leishmania DNA and blood meal sources of sandflies in RO. METHODS: A sandfly survey was performed between 2016 and 2018 in 10 municipalities categorised into three different environment types: (i) Conservation Unit (CUN) - comprised of preserved ombrophilous forests; (ii) Forest Edge (FE) - small forest fragments; and (iii) Peridomicile (PE) - areas around dwellings. FINDINGS: A total of 73 species were identified from 9,535 sandflies. The most abundant species were Psychodopygus davisi (1,741 individuals), Nyssomyia antunesi (1,397), Trichophoromyia auraensis (1,295) and Trichophoromyia ubiquitalis (1,043). Diversity was the highest in CUN, followed by the FE and PE environments. One pool of Ps. davisi tested positive for Leishmania braziliensis, reinforcing the possibility that Ps. davisi acts as a vector. The cytochrome b (cytb) sequences were used to identify three blood meal sources: Bos taurus, Homo sapiens and Tamandua tetradactyla. MAIN CONCLUSIONS: Our results demonstrated that sandflies can switch between blood meal sources in differing environments. This study enhances the knowledge of the vector life cycle in RO and provides information relevant to leishmaniasis surveillance.


Assuntos
Reservatórios de Doenças/parasitologia , Insetos Vetores/fisiologia , Leishmaniose Cutânea/transmissão , Psychodidae/parasitologia , Animais , Animais Domésticos/parasitologia , Brasil/epidemiologia , Feminino , Florestas , Humanos , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/veterinária , Masculino , Densidade Demográfica , População Urbana
15.
PLoS Negl Trop Dis ; 13(7): e0007558, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31310607

RESUMO

BACKGROUND: Onchocerciasis, or river blindness, has historically been an important cause of blindness, skin disease and economic disruption in Africa and the Americas. It is caused by the filarial parasite Onchocerca volvulus, which is transmitted by black flies in the genus Simulium. Over the past decade, several international programs have been formed to control, or more recently eliminate onchocerciasis, using mass drug administration (MDA) of ivermectin. However, in many areas of Africa (particularly those which are endemic for the eyeworm, Loa loa, or where vector densities are very high) ivermectin MDA alone will not be sufficient to achieve elimination. In these situations, additional interventions may be necessary. METHODOLOGY/PRINCIPAL FINDINGS: The Esperanza Window trap (EWT), a simple trap originally developed to replace human landing collections for entomological surveillance of O. volvulus transmission was optimized, resulting in a 17-fold improvement in trap performance. The optimized trap was tested in trials in schools and in agricultural fields to determine if it could reduce vector biting locally. The traps resulted in a 90% reduction in biting in the school setting. In the field setting, results varied. In one location, the traps reduced biting by roughly 50%, while in a separate trial, the traps did not significantly reduce the biting rate. Examination of the two settings suggested that trap placement may be critical to their success. CONCLUSIONS/SIGNIFICANCE: These results suggest that the optimized EWT might be capable of reducing local vector black fly biting in areas commonly frequented by residents. Together with other recently developed methods of community directed vector control, the traps may augment ivermectin MDA, bringing the goal of onchocerciasis elimination within reach in much of Africa.


Assuntos
Mordeduras e Picadas de Insetos/prevenção & controle , Controle de Insetos/instrumentação , Insetos Vetores/fisiologia , Oncocercose/prevenção & controle , Simuliidae/fisiologia , Animais , Feminino , Humanos , Controle de Insetos/métodos , Insetos Vetores/parasitologia , Loa/fisiologia , Onchocerca volvulus/fisiologia , Oncocercose/transmissão , Oncocercose Ocular/prevenção & controle , Oncocercose Ocular/transmissão , Instituições Acadêmicas , Simuliidae/parasitologia , Uganda
16.
Enzyme Microb Technol ; 129: 109358, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31307582

RESUMO

Many bacterial and viral plant pathogens are transmitted by insect vectors, and pathogen-mediated alterations of plant physiology often influence insect vector behavior and fitness. It remains largely unknown for most plant pathogens whether, and how, they might directly alter the physiology of their insect vectors in ways that promote pathogen transmission. Here we examined whether the presence of "Candidatus Liberibacter solanacearum" ("Ca. L. solanacearum"), an obligate bacterial pathogen of plants and of its psyllid vector alters the physiochemical environment within its insect vector, the potato psyllid (Bactericera cockerelli). Microelectrodes were used to measure the local pH and oxygen tension within the abdomen of "Ca. L. solanacearum"-free psyllids and those infected with "Ca. L. solanacearum". The hemolymph of infected psyllids had higher pH at 9.09 ± 0.12, compared to "Ca. L. solanacearum"-free psyllids (8.32 ± 0.11) and a lower oxygen tension of 33.99% vs. 67.83%, respectively. The physicochemical conditions inside "Ca. L. solanacearum"-free and -infected psyllids body differed significantly with the infected psyllids having a higher hemolymph pH and lower oxygen tension than "Ca. L. solanacearum"-free psyllids. Notably, the bacterial titer increased under conditions of higher pH and lower oxygen tension values. This suggests that the vector's physiology is altered by the presence of the pathogen, potentially, resulting in a more conducive environment for "Ca. L. solanacearum" survival and subsequent transmission.


Assuntos
Hemípteros/microbiologia , Insetos Vetores/microbiologia , Rhizobiaceae/fisiologia , Animais , Hemípteros/fisiologia , Concentração de Íons de Hidrogênio , Insetos Vetores/fisiologia , Doenças das Plantas/microbiologia
17.
Plant Dis ; 103(9): 2184-2190, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31287372

RESUMO

Little cherry disease (LCD) threatens the long-term economic sustainability of the Pacific Northwest sweet cherry (Prunus avium) industry. Results from a series of partial budget analyses indicate that additional investments in monitoring, testing, spraying to control for insect vectors, and removing infected trees are lower than the reduced profit losses compared with the do-nothing scenario. Also, management can prevent or lessen the negative impacts of higher little cherry virus (Velarivirus little cherry virus 1, Ampelovirus little cherry virus 2) spread rates. Our findings illustrate the importance of prevention, correct identification, and controlling for insect vectors in preventing the dissemination of LCD, for which the only known treatment is tree removal.


Assuntos
Agricultura , Closteroviridae , Doenças das Plantas , Prunus avium , Agricultura/métodos , Animais , Closteroviridae/fisiologia , Frutas , Controle de Insetos , Insetos Vetores/fisiologia , Doenças das Plantas/prevenção & controle , Prunus avium/virologia , Washington
18.
Parasit Vectors ; 12(1): 367, 2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31349854

RESUMO

BACKGROUND: Biting midges in the genus Culicoides (Diptera: Ceratopogonidae) transmit bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) to ruminants, thus exerting a significant economic impact on animal agriculture worldwide. However, very little is known about the larval habitat characteristics of Culicoides species associated with BTV/EHDV transmission, particularly in southeastern USA, limiting the establishment of effective midge control strategies. In this study, we examined the habitat associations of Culicoides species abundant on a commercial cervid farm in Florida, USA and quantified several environmental variables of their habitat to identify the key variables associated with midge abundance. METHODS: Mud/substrate samples from three potential larval habitats on the farm (edges of streams, puddles and seepages) were brought to the laboratory and incubated for adult emergence, and the percentage organic matter, macronutrients, micronutrients, pH, electrical conductivity, moisture and microbial concentrations of the substrate were quantified. RESULTS: Strong habitat associations were observed for Culicoides haematopotus (Malloch) (stream edge), Culicoides stellifer (Coquillett) (puddles) and Culicoides loisae (Jamnback) (stream edge), the most commonly emerging midge species from the samples. Suspected vector species of BTV/EHDV on the property, C. stellifer and Culicoides venustus (Hoffman), emerged mainly from habitats with moderate-high levels of pollution (edges of puddles and seepages) as indicated by the relatively higher concentrations/levels of organic matter, nutrients and other environmental variables in these samples. The emergence of C. insignis was too low to form any meaningful conclusions. For each Culicoides species, only weak positive or negative associations were detected between midge abundance and the various environmental variables quantified. CONCLUSIONS: Habitat associations of Culicoides species abundant on a local cervid/animal farm vary, most likely as a function of certain biotic/abiotic characteristics of the habitat. Further studies across a larger spatial and temporal scale will be needed to experimentally evaluate/identify the key factors more strongly associated with the abundance of target Culicoides species. This information, in the long term, can be potentially exploited to render local habitats unsuitable for midge oviposition/larval development.


Assuntos
Ceratopogonidae/fisiologia , Cervos/parasitologia , Ecossistema , Fazendas , Insetos Vetores/fisiologia , Agricultura , Animais , Ceratopogonidae/genética , Meio Ambiente , Feminino , Larva/fisiologia , Masculino , Sudeste dos Estados Unidos
19.
Arch Virol ; 164(9): 2333-2338, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31187278

RESUMO

Grapevine leafroll-associated virus 3 (GLRaV-3) is an economically significant virus of grapevines, with secondary spread mediated by several species of mealybug and soft scale insects. To better understand virus-vector interactions, sensitive virus detection in these insects is a key tool. In this research, two new hydrolysis-probe-based real-time assays for GLRaV-3 detection were developed and compared to three existing assays. Of the five assays compared, the one-step RT-qPCR probe-based assay was the most sensitive and reliable, with as few as 10 virus RNA copies detected. This is the first description of a real-time molecular assay for virus detection in mealybugs with such sensitivity.


Assuntos
Closteroviridae/isolamento & purificação , Hemípteros/virologia , Insetos Vetores/virologia , Doenças das Plantas/virologia , Vitis/virologia , Animais , Closteroviridae/classificação , Closteroviridae/genética , Closteroviridae/fisiologia , Hemípteros/fisiologia , Insetos Vetores/fisiologia
20.
Environ Monit Assess ; 191(Suppl 2): 331, 2019 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-31254126

RESUMO

Visceral leishmaniasis is a public health problem in Brazil. This disease is endemic in most of Bahia state, with increasing reports of cases in new areas. Ecological niche models (ENM) can be used as a tool for predicting potential distribution for disease, vectors, and to identify risk factors associated with their distribution. In this study, ecological niche models (ENMs) were developed for visceral leishmaniasis (VL) cases and 12 sand fly species captured in Bahia state. Sand fly data was collected monthly by CDC light traps from July 2009 to December 2012. MODIS satellite imagery was used to calculate NDVI, NDMI, and NDWI vegetation indices, MODIS day and night land surface temperature (LST), enhanced vegetation index (EVI), and 19 Bioclim variables were used to develop the ENM using the maximum entropy approach (Maxent). Mean diurnal range was the variable that most contributed to all the models for sand flies, followed by precipitation in wettest month. For Lutzomyia longipalpis (L. longipalpis), annual precipitation, precipitation in wettest quarter, precipitation in wettest month, and NDVI were the most contributing variables. For the VL model, the variables that contributed most were precipitation in wettest month, annual precipitation, LST day, and temperature seasonality. L. longipalpis was the species with the widest potential distribution in the state. The identification of risk areas and factors associated with this distribution is fundamental to prioritize resource allocation and to improve the efficacy of the state's program for surveillance and control of VL.


Assuntos
Ecossistema , Insetos Vetores/fisiologia , Leishmaniose Visceral/transmissão , Psychodidae/fisiologia , Animais , Brasil/epidemiologia , Monitoramento Ambiental/estatística & dados numéricos , Geografia Médica , Insetos Vetores/classificação , Leishmaniose Visceral/epidemiologia , Psychodidae/classificação , Chuva , Temperatura
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