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Mushroom sciarid flies Lycoriella ingenua (Dufour) and Bradysia ocellaris (Comstock) are major pests of cultivated mushrooms, Agaricus bisporus (Lange) Imbach. The economic threshold of these pests is very low because they vector ...
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Mushroom sciarid flies Lycoriella ingenua (Dufour) and Bradysia ocellaris (Comstock) are major pests of cultivated mushrooms, Agaricus bisporus (Lange) Imbach. The economic threshold of these pests is very low because they vector pathogens across mushroom beds, e. g. Verticillium fungicola which causes 'dry bubble' disease. Under controlled conditions, B. ocellaris transported more V. fungicola spores than L. ingenua from infected to sterile culture plates. Similar results were obtained when L. ingenua and B. ocellaris were collected from a growing room infected with V. fungicola then introduced onto sterile culture plates for 90 min. The external morphology of B. ocellaris and L. ingenua was examined using scanning electron microscopy. The micrographs showed clusters of V. fungicola spores attached to the inner side of a comb-like row of bristles on the fore tibia of B. ocellaris whereas L. ingenua does not possess an equivalent structure on the fore tibia. These morphological differences are the most probable explanation for the greater competence of B. ocellaris as a vector of V. fungicola compared with L. ingenua.
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Mushroom sciarid flies Lycoriella ingenua (Dufour) and Bradysia ocellaris (Comstock) are major pests of cultivated mushrooms, Agaricus bisporus (Lange) Imbach. The economic threshold of these pests is very low because they vector ...
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Mushroom sciarid flies Lycoriella ingenua (Dufour) and Bradysia ocellaris (Comstock) are major pests of cultivated mushrooms, Agaricus bisporus (Lange) Imbach. The economic threshold of these pests is very low because they vector pathogens across mushroom beds, e. g. Verticillium fungicola which causes 'dry bubble' disease. Under controlled conditions, B. ocellaris transported more V. fungicola spores than L. ingenua from infected to sterile culture plates. Similar results were obtained when L. ingenua and B. ocellaris were collected from a growing room infected with V. fungicola then introduced onto sterile culture plates for 90 min. The external morphology of B. ocellaris and L. ingenua was examined using scanning electron microscopy. The micrographs showed clusters of V. fungicola spores attached to the inner side of a comb-like row of bristles on the fore tibia of B. ocellaris whereas L. ingenua does not possess an equivalent structure on the fore tibia. These morphological differences are the most probable explanation for the greater competence of B. ocellaris as a vector of V. fungicola compared with L. ingenua.
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Filth flies have been implicated in the dispersal of human disease pathogens; however, the epidemiological parameters of the transmission of human pathogens from flies to plants are largely undescribed. The capacity of the black b...
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Filth flies have been implicated in the dispersal of human disease pathogens; however, the epidemiological parameters of the transmission of human pathogens from flies to plants are largely undescribed. The capacity of the black blow fly, Phormia regina Meigen, to acquire and subsequently deposit bacteria onto baby lettuce leaves was compared with that of the house fly, Musca domestica (L.). Adult P. regina and M. domestica were exposed to green fluorescent protein-tagged Escherichia coli O157:H7-or Salmonella enterica-inoculated manure and then allowed access to the lettuce plants. Bacteria on the plants and flies were assessed by plating and polymerase chain reaction. Although blowflies acquired significantly more E. coli O157:H7 than house flies, there was no significant difference between the deposition of bacteria on lettuce by the two fly species. In contrast, there was no significant difference in the acquisition of S. enterica by the two fly species. However, blow flies deposited more S. enterica onto lettuce than house flies. To more accurately assess transmission parameters, flies were given timed exposure and inoculation periods of 10 and 30 s. Blowflies acquired more E. coli O157: H7 than S. enterica in the both time periods. Flies exposed to manure for 30 s were then tested for deposition by forcing the flies to walk on lettuce leaves. Blow flies deposited comparable amounts of E. coli O157: H7 and S. enterica. Although house flies have historically been implicated in the transmission of human pathogens to food, the data presented suggest that blow flies are more efficient vectors of E. coli O157: H7 and S. enterica to leafy greens than house flies.
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Field-collected South African Culicoides species (Diptera, Ceratopogonidae) were fed on sheep blood containing bluetongue virus (BTV) represented by 13 low-passage reference serotypes: -1, -2, -4, -6, -7, -8, -9, -10, -11, -12, -1...
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Field-collected South African Culicoides species (Diptera, Ceratopogonidae) were fed on sheep blood containing bluetongue virus (BTV) represented by 13 low-passage reference serotypes: -1, -2, -4, -6, -7, -8, -9, -10, -11, -12, -13, -16 and -19. After 10 days of extrinsic incubation at 23.5 degrees C, of the 13 serotypes used, seven were recovered from C. (Avaritia) imicola Kieffer and 11 from C. (A.) bolitinos Meiswinkel. Virus recovery rates and the mean titres for most serotypes were significantly higher in C. bolitinos than in C. imicola. In addition, BTV was recovered from three non-Avaritia Culicoides species, namely C. (Remmia) enderleini Cornet & Brunhes (BTV-9), C. (Hoffmania) milnei Austen (BTV-4) and C. (H.) zuluensis de Meillon (BTV-16). No virus could be recovered from 316 individuals representing a further 14 Culicoides species. In Culicoides species fed on blood containing similar or identical virus titres of distinct BTV serotypes, significant differences were found in virus recovery rates. The results of this study confirm the higher vector competence of C. bolitinos compared with C. imicola..
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The mosquito-borne arbovirus Zika virus (ZIKV, Flavivirus, Flaviviridae), has caused an outbreak impressive by its magnitude and rapid spread. First detected in Uganda in Africa in 1947, from where it spread to Asia in the 1960s, ...
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The mosquito-borne arbovirus Zika virus (ZIKV, Flavivirus, Flaviviridae), has caused an outbreak impressive by its magnitude and rapid spread. First detected in Uganda in Africa in 1947, from where it spread to Asia in the 1960s, it emerged in 2007 on the Yap Island in Micronesia and hit most islands in the Pacific region in 2013. Subsequently, ZIKV was detected in the Caribbean, and Central and South America in 2015, and reached North America in 2016. Although ZIKV infections are in general asymptomatic or causing mild self-limiting illness, severe symptoms have been described including neurological disorders and microcephaly in newborns. To face such an alarming health situation, WHO has declared Zika as an emerging global health threat. This review summarizes the literature on the main vectors of ZIKV (sylvatic and urban) across all the five continents with special focus on vector competence studies. (C) 2018 The Authors. Published by Elsevier Masson SAS on behalf of Institut Pasteur.
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? 2022 Elsevier LtdDisease-transmitting vectors are living organisms that pass infectious agents from one animal/human to another. The epidemiologically important vectors are usually hematophagous arthropods, including mosquitoes,...
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? 2022 Elsevier LtdDisease-transmitting vectors are living organisms that pass infectious agents from one animal/human to another. The epidemiologically important vectors are usually hematophagous arthropods, including mosquitoes, ticks, triatome bugs, sand flies, and tsetse flies. All of them harbor an endogenous microbiota that functionally complements their host's biology. Different arthropod vectors are ecologically and behaviorally distinct, and as such, their relationships with symbiotic microbes vary. In this review, we summarize the recent discoveries that reveal how bacterial metabolic activities influence development, nutrition, and pathogen defense in mosquitoes, ticks, triatome bugs, and sand flies. These studies provide a foundation for a systematic understanding of vector–microbiota interactions and for the development of integrated approaches to control vector-borne diseases.
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The relapsing fever spirochetes Borrelia hermsii and Borrelia turicatae are each maintained and transmitted in nature by their specific tick vectors, Ornithodoros hermsi Wheeler (Acari: Argasidae) and Ornithodoros turicata (Duges)...
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The relapsing fever spirochetes Borrelia hermsii and Borrelia turicatae are each maintained and transmitted in nature by their specific tick vectors, Ornithodoros hermsi Wheeler (Acari: Argasidae) and Ornithodoros turicata (Duges), respectively. The basis for this spirochete and vector specificity is not known, but persistent colonization of spirochetes in the tick's salivary glands is presumed to be essential for transmission by these long-lived ticks that feed in only minutes on their warm-blooded hosts. To examine this hypothesis further, cohorts of O. hermsi and O. turicata were infected with B. hermsii and examined 7-260 d later for infection in their midgut, salivary glands, and synganglion. While the midgut from all ticks of both species at all time points examined were infected with spirochetes, the salivary glands of only O. hermsi remained persistently infected. The salivary glands of O. turicata were susceptible to an early transient infection. However, no spirochetes were observed in these tissues beyond the first 32 d after acquisition. Ticks of both species were fed on mice 112 d after they acquired spirochetes and only those mice fed upon by O. hermsi became infected. Thus, the vector competency for B. hermsii displayed by O. hermsi but not O. turicata lies, in part, in the persistent infection of the salivary glands of the former but not the latter species of tick. The genetic and biochemical mechanisms supporting this spirochete and vector specificity remain to be identified.
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Members of the Culex pipiens complex have been implicated as vectors of a number of arboviruses including St. Louis encephalitis, West Nile, Sindbis, and Rift Valley fever viruses. For some viruses, such as West Nile virus, labora...
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Members of the Culex pipiens complex have been implicated as vectors of a number of arboviruses including St. Louis encephalitis, West Nile, Sindbis, and Rift Valley fever viruses. For some viruses, such as West Nile virus, laboratory studies have indicated that various members of this complex have a similar ability to become infected with and transmit virus, thus providing evidence for the similarity among the various members of this complex. On the other hand, although strains of Cx. pipiens from various parts of the world have all been relatively efficient vectors of Rift Valley fever virus, Cx. quinquefasciatus from Africa, Australia, and North America have been nearly refractory to this virus, thus indicating that the various members of this complex do not necessarily respond similarly to a particular arbovirus. Based on the similar response to some viruses and differing response to others, Cx. pipiens and Cx. quinquefasciatus appear to be closely related, but distinct species.
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Aedes aegypti and Aedes albopictus are the vectors of important arboviruses: dengue fever, chikungunya, Zika, and yellow fever. Female mosquitoes acquire arboviruses by feeding on the infected host blood, thus being able to transm...
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Aedes aegypti and Aedes albopictus are the vectors of important arboviruses: dengue fever, chikungunya, Zika, and yellow fever. Female mosquitoes acquire arboviruses by feeding on the infected host blood, thus being able to transmit it to their offspring. The intrinsic ability of a vector to infect itself and transmit a pathogen is known as vector competence. Several factors influence the susceptibility of these females to be infected by these arboviruses, such as the activation of the innate immune system through the Toll, immunodeficiency (Imd), JAK-STAT pathways, and the interference of specific antiviral response pathways of RNAi. It is also believed that the presence of non-pathogenic microorganisms in the microbiota of these arthropods could influence this immune response, as it provides a baseline activation of the innate immune system, which may generate resistance against arboviruses. In addition, this microbiome has direct action against arboviruses, mainly due to the ability of Wolbachia spp. to block viral genome replication, added to the competition for resources within the mosquito organism. Despite major advances in the area, studies are still needed to evaluate the microbiota profiles of Aedes spp. and their vector competence, as well as further exploration of the individual roles of microbiome components in activating the innate immune system.
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The etiological agent of plague. Yersinia pestis, is most commonly transmitted by the bite of infectious fleas. To date, at least 28 flea species occurring in North America have been experimentally confirmed as vectors of Y. pesti...
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The etiological agent of plague. Yersinia pestis, is most commonly transmitted by the bite of infectious fleas. To date, at least 28 flea species occurring in North America have been experimentally confirmed as vectors of Y. pestis. Transmission efficiency differs among species and also between different studies of a single species. These differences may, however, in large part reflect nonstandardized experimental conditions used (hiring the first half of the 20th century When such studies were conducted in response to the rapid spread of Y. pestis across the western United States after its introduction at the beginning of this century. The majority of these early transmission studies focused on the blocked flea mechanism of transmission,,xhich typically does not occur until >2-3 wk after the flea becomes infected. Recent studies have challenged the paradigm that K pestis is usually spread by blocked fleas by demonstrating that numerous flea species, including the oriental rat flea Xenopsylla cheopis, which was the focus of the early classical Studies oil blocked flea transmission, are capable of "early-phase" transmission during the first few days after becoming infected and before a complete blockage call form. The aims of this review are to 1) summarize Y. pestis vector competency and efficiency studies for fleas occurring in North America, 2) discuss the implications of the results of these studies for our understanding of the dynamics of plague epizootics, 3) demonstrate why older transmission studies need to be repeated using a standardized experimental system, and 4) Outline future directions for studies of fleas as vectors of Y. pestis.
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