Doctor of Philosophy / Division of Biology / Kristin Michel / The biting midge, Culicoides sonorensis, vectors orbiviruses of economic importance, such as epizootic hemorrhagic disease virus (EHDV). Due to the limitations in available molecular tools, critical Culicoides-orbivirus interactions underlying vector competence remain unclear. To provide a foundation for the study of midge-EHDV interactions, RNA interference (RNAi) was developed as a reverse genetic tool, and EHDV-2 infection dynamics were determined within C. sonorensis. To develop RNAi, exogenous double-stranded RNA (dsRNA) was injected into C. sonorensis adults specific to the C. sonorensis inhibitor of apoptosis protein 1 (CsIAP1) ortholog (dsCsIAP1). A significant decrease in CsIAP1 transcripts was observed in whole midges, with highest reduction in the midgut. In addition, dsCsIAP1-injected midges had increased mortality, a loss of midgut tissue integrity, and increased caspase activity. The longevity and midgut phenotypes were partially reversed by the co-injection of dsRNA specific to the C. sonorensis initiator caspase Dronc ortholog and CsIAP1. These results demonstrated that RNAi can be achieved in the midge midgut through injection of target dsRNAs into the hemolymph. Furthermore, the time course of EHDV-2 infection within C. sonorensis was characterized. EHDV-2 infection was observed in the midgut and secondary tissues, including the salivary glands, by 5 days post-feeding (dpf). These data are consistent with dissemination of EHDV-2 to secondary susceptible tissues throughout the midge via the hemolymph and indicate that virus transmission by C. sonorensis may occur as early as 5 dpf. This work provides a foundation for the future study of Culicoides-orbivirus interactions, including the antiviral role of RNAi at the midgut barrier.

This thesis deals with biting midges of the genus Culicoides, which are tiny nematoceran insects belonging to the Diptera, and their parasites. Biting midges partake in transmissions of several parasitical organisms of various groups. Most notably, they are the vectors of several pathogenic viruses which might have a serious impact on livestock. However, the thesis deals with detection of parasites belonging to Trypanosomatids and Filarioids related to two independent biting midges collections - from the Czech Republic and from the Central African region. Apart from testing biting midges, there were carried out the tests on the occurrence of the same group of parasites within ruminant hoofed games in the Czech Republic. Our goal was to find out whether the same parasites occur with biting midges and their hosts (hoofed games) and whether biting midges could play a role as vectors. Biting midges are relatively overlooked group of haematophagous insects. Until recently, they had not been paid much attention, which changed with the spread of Bluetongue virus over Europe. This stimulated a widespread monitoring of biting midges in several European countries, including the Czech Republic. This helped to gain a large amount of data about the occurrence of biting midges near livestock. Nevertheless, there is no...

No description available.

A large epizootic of the vector-borne disease bluetongue occurred in northern Europe from 2006-2009, costing the economies of the infected countries several hundreds of millions of euros. During this time, the United Kingdom (UK) was exposed to the risk of bluetongue by windborne incursions of infected Culicoides biting midges from the northern coast of mainland Europe. The first outbreaks which occurred in the UK in 2007 were attributed to this cause. Although bluetongue virus (BTV) no longer appears to be circulating in northern Europe, it is widely suggested that it and other midge-borne diseases may emerge again in the future, particularly under a changing climate. Spread of BTV is strongly influenced by the weather and climate however limited use has been made of meteorologically based models to generate predictions of its spread to the UK. The extent to which windborne BTV spread can be modelled at timescales from days to decades ahead, to inform tactical and strategic decisions taken to limit its transmission, is therefore examined here. An early warning system has been developed to predict possible incursion events on a daily timescale, based on an atmospheric dispersion model adapted to incorporate flight characteristics of the Culicoides vectors. The system’s warning of the first UK outbreak in September 2007 was found to be greatly beneficial to the UK livestock industry. The dispersion model is also shown to be a useful post-outbreak epidemiological analysis tool. A novel approach has been developed to predict BTV spread into the UK on climate-change timescales as dispersion modelling is not practical over extended periods of time. Using a combination of principal component and cluster analyses the synoptic scale atmospheric circulations which control when local weather conditions are suitable for midge incursions were determined. Changes in the frequency and timing of these large scale circulations over the period 2000 to 2050 were then examined using an ensemble of regional climate model simulations. The results suggest areas of UK under the influence of easterly winds may face a slight increase in risk and the length of the season where temperatures are suitable for BTV replication is likely to increase by around 20 days by 2050. However a high level of uncertainty is associated with these predictions so a flexible decision making approach should be adopted to accommodate better information as it becomes available in the future.

This thesis focuses on the development of protozoan parasites from Leishmania donovani complex in their insect vectors and summarizes results of five parts of the project I participated in during my Ph.D. studies. Sand flies of genera Phlebotomus and Lutzomyia are the only proven vectors of leishmaniasis, however, the role of alternative vectors, like ticks, fleas and biting midges is frequently discussed in the literature. In this work, we showed that Eurasian species of biting midge Culicoides nubeculosus does not support late stage infections of L. major and L. infantum. We also demonstrated that microscopical observation of Leishmania promastigotes in the digestive tract of bloodfeeding arthropods remains a crucial method for any conclusion about the vector competence of the suspected insect. In the second part of our study were compared the life-cycle parameters and vector competence of two Ethiopian P. orientalis colonies for L. donovani. Marked differences between colonies were found in life-cycle parametes, however, molecular analyses did not reveal any genetic differences. Experimental infections showed that both P. orientalis colonies are very susceptible to L. donovani infection and even the lowest infective dose tested (2 × 103 promastigotes/ml; corresponding to 1-2 promastigotes) was...

Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-13T19:34:20Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tiago Gallina Corrêa.pdf: 1514650 bytes, checksum: d88af72f3dfc4c6107504dc1ec16ea8a (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-04-13T19:42:38Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tiago Gallina Corrêa.pdf: 1514650 bytes, checksum: d88af72f3dfc4c6107504dc1ec16ea8a (MD5) / Made available in DSpace on 2017-04-13T19:42:38Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tiago Gallina Corrêa.pdf: 1514650 bytes, checksum: d88af72f3dfc4c6107504dc1ec16ea8a (MD5) Previous issue date: 2005-10-14 / Sem bolsa / Dermatite alérgica estacional foi estudada em um rebanho de ovinos Hampshire Down em um estabelecimento no município de Capão do Leão, Rio Grande do Sul. A epidemiologia, sinais clínicos e lesões macroscópicas foram observadas no estabelecimento verificando-se a época de ocorrência da enfermidade, a idade e sexo dos animais afetados e localização das lesões. A patologia microscópica foi estudada em biopsias de pele de ovinos afetados. Para a verificação da etiologia, insetos foram capturados com aspiradores entomológicos, semanalmente, das 16h00minh às 09h00minh, entre os meses de janeiro a abril de 2005. Os dados relativos à temperatura média, umidade relativa do ar e velocidade média dos ventos na região de ocorrência da doença foram obtidos na Estação Agro-climatológica da Universidade Federal de Pelotas. A prevalência da doença no período estudado foi de 40% e animais de qualquer idade e ambos os sexos foram afetados. A enfermidade ocorreu principalmente entre dezembro e março e alguns animais permaneceram com lesões durante todo o ano. Os sinais clínicos eram de inquietação e prurido e as lesões ocorriam principalmente nas orelhas, ao redor dos olhos e na região ventral do abdômen, caracterizando-se pela presença de eritema e pápulas, nos casos agudos, e espessamento da pele com rachaduras, exsudação, formação de crostas, e alopecia, nos casos crônicos; esses freqüentemente apresentavam infecções secundárias. As lesões histológicas eram principalmente de dermatite eosinofílica perivascular, observando-se, também, hiperqueratose, acantose e presença de pústulas sub corneais ou intra-epidérmicas nos casos crônicos. Os insetos capturados no período de estudo da doença foram identificados como Anopheles albitarsis e Culicoides insignis. Durante a captura observou-se que os animais apresentavam prurido intenso quando picados por Culicoides, mas não por Anopheles. As temperaturas média mínima e máxima no período, foram de 17ºC e 28ºC, respectivamente, e a velocidade média dos ventos foi de 12,84km/h. Ambas as espécies de insetos capturados têm hábitos noturnos aproximando-se dos animais para hematofagia em torno de 30min após o ocaso do sol.Testes intradérmicos realizados com antígenos obtidos a partir desses dípteros revelaram reação de hipersensibilidade aos antígenos de C. insignis. Os resultados obtidos indicam que a enfermidade estudada ocorre em conseqüência de hipersensibilidade imediata causada pela picada desse díptero. / A seasonal dermatitis was studied in a Hampshire Down flock in a farm at the minicipality of Capão do Leão, state of Rio Grande do Sul, southern Brazil. Frequency and seasonal distribution of the disease, breed, sex and age of affected sheep, and clinical signs, macroscopic pathology and distribution of the lesions were obtained by visiting the farm. Histological lesions were studied in skin biopsies of affected sheep. Biting insects were collected weekly between 4:00 p.m. to 9:00 a.m., from January to April of 2005 to identify the etiological agent of disease. Data about temperature, humidity and wind speed in the region where the disease occurs were obtained in the agro climatologic Station of Pelotas Federal University. The prevalence of disease during the study period was 40% and the age of affected animals was variable. The disease occurs between December and March, but some animals stayed with lesions during the whole year. Clinical signs were characterized by pruritus and skin lesions in the ears, around the eyes, and ventral abdomen. Erythema and papules were observed in acute cases. In chronic cases, the skin was thicken, exsudative, crusty and alopecic, frequently with secondary infections. Histological lesions of affected sheep were characterized by perivascular eosinofilic dermatitis. Hyperkeratosis, acanthosis and intraepidermal pustules were observed in chronic lesions. Anopheles albitarsis and Culicoides insignis were captured during the observation period. Sheep showed pruritus mainly during de Culicoides bites. The mean minimum and maximum temperature in the period were 17ºC e 28ºC, respectively, and the mean speed wind was 12,84km/h. Both insects were caught when they approached the sheep bait 30minutes after sunset. Intradermal tests performed with de antigens of the insect extracts showed hypersensitivity reaction to C.insignis antigens. Based on the results it was suggested that the disease occurs as a consequence of an immediate hypersensitivity caused by C. insignis bite.

Culicoides molestus (Skuse) is the major species of biting midge that plagues human comfort in the estuarine Gold Coast region of southeast Queensland. Local authorities have initiated a search for an effective, non-chemical means of control, that would minimize human-midge interaction. The effectiveness of a program to control an organism, such as a biting midge, is dependent upon knowledge of the biology of the particular organism of interest. This project revolved examines the lifecycle of C. molestus in detail. It addresses questions regarding the location, seasonal distribution, and dispersal of its juvenile stages in the sand of infested beaches, and their response to chemical treatment, the monthly and annual cycles of the adult midge, and the possibilities of achieving laboratory oviposition, as a first step to laboratory colonisation. The distribution of eggs, larvae and pupae of C. molestus was found to be mostly concentrated around, but below, mean tide level. They also occurred well below the mean tide level. Eggs and larvae have been recovered from as deep as 10 cm in the sand. A seasonal study of the juveniles of this species indicated that they were more strongly influenced by tides than seasons. After a routine pest-control larviciding treatment, a beach recolonisation study revealed that beaches become suitable for oviposition approximately two months after treatment. Large larvae invaded the sprayed areas within days of treatment, which suggests the existence of a refuge outside of the reach of the insecticide. Larvae found in clean (egg- and larva-free), isolated sand containers, placed on the study beach, indicated that larvae could swim in or on the water as a way of moving around the beach. Extended bite-rate studies highlighted the existence of four peaks in adult midge biting activity during the course of a year, around the mid seasons. The strongest peaks of activity were found to be in autumn and spring, but the data suggest that the species undergoes four generations in a year. Through a series of trial-and-error experiments, oviposition under laboratory conditions was achieved. Although the time from blood-feeding to egg maturation is not yet well determined, it occurs within an eight day mean survival period. Blood quality appears critical for adult blood-fed midge survival. Midges fed on the blood of a volunteer who was frequently exposed to midge bites do not live long enough to mature its eggs. The partial ovarial development of one unfed adult female, reared in the laboratory, indicates that C. molestus is facultatively anautogenous.

La découverte du rôle des insectes en tant que vecteurs de pathogènes, établi depuis plus d'un siècle, a été l'élément moteur de la discipline " entomologie médicale et vétérinaire ". Malgré le succès de nombreuses campagnes de prévention et de programmes de lutte, nous assistons depuis une trentaine d'années à l'émergence et à la recrudescence de maladies à transmission vectorielle. Le virus de la fièvre catarrhale ovine (FCO) (Reoviridae : Orbivirus) est un très bon exemple de virus émergent en Europe dont les mécanismes de transmission sont encore peu connus dans cette région. Ce virus est transmis par des moucherons hématophages du genre Culicoides (Diptera : Ceratopogonidae) aux ruminants sauvages et domestiques. En Europe, la FCO a été pendant longtemps considérée comme une maladie exotique. À partir de 1998, plusieurs incursions apparaissent dans l'ouest du bassin méditerranéen en lien avec la remontée vers le nord de populations de Culicoides imicola, le principal vecteur afrotropical. À partir d'août 2006, l'apparition et la transmission du sérotype 8 dans le nord de l'Europe, dans des zones où C. imicola est absent, révèle l'importance des espèces autochtones et la nécessité de comprendre leur rôle vecteur. Ce travail s'intéresse aux mécanismes de transmission du virus de la FCO en Europe non méditerranéenne, en i) présentant un état de l'art de la biologie et l'écologie des Culicoides adultes, ii) en évaluant les conditions possibles d'utilisation de pièges pour estimer le taux de piqûre et iii) en décrivant les comportements trophiques pour les espèces d'intérêt vétérinaire.

Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-07-31T13:08:07Z No. of bitstreams: 1 Dissertação - Emanuelle de Sousa Farias.pdf: 2780340 bytes, checksum: bac6d0e67ce460607bfe6e587aa2068a (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-03T15:22:46Z (GMT) No. of bitstreams: 1 Dissertação - Emanuelle de Sousa Farias.pdf: 2780340 bytes, checksum: bac6d0e67ce460607bfe6e587aa2068a (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-08-03T15:26:45Z (GMT) No. of bitstreams: 1 Dissertação - Emanuelle de Sousa Farias.pdf: 2780340 bytes, checksum: bac6d0e67ce460607bfe6e587aa2068a (MD5) / Made available in DSpace on 2015-08-03T15:26:45Z (GMT). No. of bitstreams: 1 Dissertação - Emanuelle de Sousa Farias.pdf: 2780340 bytes, checksum: bac6d0e67ce460607bfe6e587aa2068a (MD5) Previous issue date: 2014-02-26 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The biting midges Culicoides are vectors of some etiological agents to humans and other mammals. There are just a few studies in Amazon basin about that insects and the diversity and richness of this genus is underestimated. The aims of this study were to describe the fauna of midges in a rural settlement in Amazon and to understand how the anthropic effects may affect the richness and abundance of these putative local vectors. Collections were done by CDC light traps in some environment as primary forest, forest borders, secondary forest, fruit garden and peridomiciliary area with animal shelters. We identified 6.093 individuals, distributed in 42 species, 39 morphotypes of seven subgenera and /or species groups and five new species of Reticulatus group. We found 13 new occurrence to Amazonas State C. aldomani, C. batesi, C. brownie, C. debilipalpis, C. flavivenula , C. franklini, C. glabellus, C. guamai, C. guttatus, C. ocumarensi, C. paramaruim, C. pusilloides and C. tidwelli, and two new occourence to the country, the species C. brownie and C. tidwelli. Our results show that different anthropic levels affect the abundance and diversity of midges. The diversity was high in less anthropized environments. The peridomiciliary areas had a high richness and abundance of Culicoides. / Os Culicoides são insetos transmissores de agentes patogênicos ao homem e outros animais. Na região amazônica existem poucos estudos sobre esses insetos e o número de espécies é subestimado. Este estudo objetivou conhecer a fauna de Culicoides de um assentamento rural na Amazônia e verificar se o efeito antrópico afeta a diversidade e abundância dos mesmos. As coletas foram feitas com armadilhas luminosas do tipo CDC em ambientes de floresta, borda de floresta, capoeira e peridomicílio. Foram identificados 6.093 indivíduos, distribuídos em 42 espécies, 39 morfótipos de sete subgênero/grupo e cinco espécies novas do grupo Reticulatus. Foram encontrados 13 novos registros de espécies de Culicoides para o estado do Amazonas: C. aldomani, C. batesi, C. brownie, C. debilipalpis, C. flavivenula , C. franklini, C. glabellus, C. guamai, C. guttatus, C. ocumarensi, C. paramaruim, C. pusilloides e C. tidwelli, sendo C. brownie e C. tidwelli novos registros para o Brasil. Os resultados indicam que diferentes graus de antropização do ambiente influenciaram a abundância e diversidade dos Culicoides, cuja diversidade foi alta em ambientes menos antropizados. Ambientes totalmente antropizados, como peridomicílio, apresentaram maior abundância e riqueza.

Abstract :Bluetongue (BT) is a vector-borne infectious disease primarily transmitted to even- toed ungulates by the bite of several Culicoides species. The global distribution of BT can be attributed to the ubiquity of its vectors and its rapid spread, likely to the enhancement of human activities (intensification of animal production, trans- port, changing habitat). During the last decades, BT established in Southern Europe and more recently emerged in Northern Europe, causing the death of millions of domestic ruminants. On the same time, a Belgian research project has been set up to develop remote-sensing tools to study the EPidemiology and Space-TIme dynamicS of infectious diseases (EPISTIS). In that general framework, this thesis aimed to study the space-time distribution of the main Culicoides vectors occurring in Italy and Belgium, at two different scales. Firstly, we aimed to clarify the role of several eco-climatic factors on the regional-scale distribution of C. imicola in time, based on weekly samplings achieved throughout Italy from 2001 to 2006 and to develop an easy-to-use and reproducible tool, which could be widely validated on the basis of former vector sampling and freely accessible remote-sensing data. Secondly, we aimed to investigate how Culicoides species were distributed in the fine-scale habitat encountered throughout the agro-ecological landscapes of Belgium, while recent studies have suggested that the landscapes configuration could explain the spatial distribution of BT. In the first part, we showed that an autoregressive model where the observed monthly growth rate is predicted by monthly temperature, allowed predicting >70% of the seasonal variability in C. imicola trap catches. The model predicted the seasonality, the altitudinal gradient, and the low populations’ activity taking place during the winter. Incorporating eco-climatic indices such as the Normalized Difference Vegetation Index into the model did not enhance its predictive power. In the second part, we quantified how Culicoides populations are spatially structured in the neighbourhood of farms, and demonstrated the unexpectedly high level of population found in forest. We also showed how four classes of land use could influence the relative abundances of Culicoides species in the agro-ecological landscapes of Belgium. Although in summer, BT vectors were abundant in each of the four classes investigated, their relative abundances varied strongly as a function of sex, species and environmental conditions, and we quantified these variations. Finally, we also presented a new method to quantify the interference between Onderstepoort light traps, and used it to measure their range of attraction for several of the most common BT vectors species in Northern Europe. The model developed on C. imicola in Italy provided enthusiastic perspectives regarding the regional-scale analyses of its distribution in time, although further improvements are nevertheless required in order to assess the broad scale ecology of BT vectors throughout Europe. Mapping the abundances of C. imicola in Sardinia high- lighted an important lack of reliability attributable to the many land use classes that are currently not sampled in the vector surveillance achieved across Europe. Together with the novelties presented in the second part and the recent findings establishing that BT could circulate among wild hosts in both epidemiological systems (i.e. in Southern and Northern Europe), we call for increasing epidemiological and entomo- logical studies at the interface between farms and the surrounding natural habitats. Last, depicting in time the landscape-scale findings for Northern Europe highlighted how dramatic could be the role played by intensive farming practices to maintain BT within the agro-ecological landscapes studied and to facilitate its circulation between them. Quantifying the amplitude of the risk of disease transmission linked to these practices would require a further complex modeling approach accounting simultaneously for the diel activity of hosts, mainly resulting from the farming activities, the diel activities of different vector species and the landscapes configuration found in contrasted agro-ecological systems.<p>Résumé :La fièvre catarrhale ovine (FCO), encore appelée maladie de la langue bleue, est une maladie infectieuse des ruminants transmise par la piqûre d’un vecteur de type moucheron appartenant au genre Culicoides (Diptera :Ceratopogonidae). L’ubiquité de ses vecteurs peut expliquer son succès d’installation à l’échelle globale. Par ailleurs, sa rapide expansion a été grandement facilitée par l’importante activité anthropique (élevage, transport, modification de l’habitat) et peut-être même par les changements climatiques globaux. La FCO a été récemment qualifiée de maladie infectieuse émergente en Europe du fait de (i) son récent établissement dans la région, bien au delà de son aire de répartition traditionnelle, (ii) de sa forte capacité de dispersion affectant chaque jour un nombre plus important d’hôtes et enfin (iii) de sa forte virulence. Après avoir détaillé les caractéristiques majeures des deux principaux foyers de FCO rencontrés en Europe depuis 1998, la présente thèse s’est plus particulièrement intéressée à l’étude de la distribution spatio-temporelle de ses principaux vecteurs dans le sud (partie 1) puis dans le nord (partie 2) de l’Europe, à différentes échelles. Dans la première partie, un modèle discret, spatialement et temporellement explicite, a été développé afin de mesurer l’influence de différents facteurs éco-climatiques sur la distribution de Culicoides imicola, principal vecteur de la FCO dans le Bassin Méditerranéen. Les profils mensuels de distribution rencontrés en Sardaigne durant 6 années consécutives ont ainsi pu être reconstitués, principalement sur base de la température. Une cartographie de l’abondance de C. imicola sur le territoire a permis de mettre à jour le manque d’information sur sa distribution en dehors des exploitations agricoles. Dans la deuxième partie du travail, nous nous sommes penchés sur la distribution spatiale des Culicoides tels qu’on peut les rencontrer au sein de différents paysages agro-écologiques de Belgique. Nous avons ainsi pu décrire la structure adoptée par les populations de Culicoides au voisinage des fermes ainsi que quantifier l’importante population présente dans les forêts avoisinantes. Nous avons par ailleurs montré l’influence de différentes catégories d’utilisation du sol sur l’abondance et la composition en espèces. Enfin, nous avons présenté une méthode permettant de quantifier l’interférence entre des pièges lumineux utilisés dans un même paysage pour échantillonner les populations, et l’avons utilisé afin de mesurer leur rayon d’attractivité sur les espèces vectrices les plus communément rencontrées dans le nord de l’Europe. En guise de conclusion générale et conjointement aux récentes découvertes de cas de FCO au sein de la faune sauvage européenne, nous appelons à réaliser un plus grand nombre d’études éco-épidémiologiques à l’interface entre exploitations agricoles et zones (semi-) naturelles avoisinantes. En outres, les résultats présentés dans la seconde partie ont été mis en relation avec le mode de fonctionnement journalier de nos exploitations agricoles. Nous avons ainsi pu déduire le rôle dramatique joué par les pratiques agricoles intensives dans le maintien du virus de la FCO au sein de nos paysages agro-écologiques, ainsi que dans sa circulation d’un paysage à l’autre. Un cadre de modélisation complexe permettant une analyse simultanée de l’activité nycthémérale des hôtes de la FCO et de ses vecteurs Culicoides en fonction de la configuration des paysages agro-écologiques est néanmoins requis afin de quantifier l’amplitude du risque de transmission de la FCO lié aux pratiques agricoles intensives. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished