M.Sc. / The possible resistance of the red spider mite, Tetranychus cinnabarinus, on cotton to the acaricides triazophos and profenofos was studied in the Groblersdal/Marble Hall area. During the 1980 and 1981 seasons T. cinnabarinus was collected from cotton in four districts where mite infestations had been controlled the preceeding two seasons with up to three triazophos sprays per year. A laboratory culture of T. cinnabarinus served as the control and the response of these mites to different concentrations of acaricides were compared with those of the four field cultures. The toxicity of triazophos and profenofos was evaluated by using the slide-dip technique and mortality readings were taken 24 hours after exposure to the acaricide solutions. The data were subjected to a pro bit analysis. Where pro bit lines could not be fitted second degree polinomial regressions were fitted through the log dose and empirical probits. During 1980 there was little difference between the susceptibility of the four field cultures to triazophos. However, the regression lines of all four cultures when compared with those of the control culture indicated resistance to triazophos. After these field cultures had been reared under controlled conditions and not exposed to pesticides for a year all signs of triazophos resistance disappeared. The four field cultures collected in 1981 showed great variability in their response to triazophos but no indication of resistance was observed. This may be because the recommended cotton pest control programme was more closely followed by the cotton producers in 1981 and fewer acaricide sprays were applied. The accuracy of the mortality readings made 24 hours after exposure to triazophos was investigated by taking readings at intervals of 8 hours. An analysis of the results indicated that the mortality curves calculated from all readings were not significantly different and consequently mortality readings were made every 24 hours after exposure to the acaricide solution. A second laboratory strain of T. cinnabarinus, obtained from the Fruit and Fruit Technology Research Institute in Stellenbosch, and regarded as susceptible to organo phosphates was also tested for resistance to triazophos. The regression lines obtained for this culture was similar to that obtained from the 1980 field cultures. This was taken as an indication of possible resistance and this culture was therefore not used as a con trol in this study. The control culture and the Groblersdal/Marble Hall field cultures did not differ significantly in their susceptibility to profenofos. However, profenofos is not widely used for the control of T. cinnabarinus on cotton and these results indicate that it can still be used effectively for the control of T. cinnabarinus. A third acaricide, amitraz, was also examined to determine its effect on T. cinnabarinus. The slide-dip technique was found to be unsuitable for the determination of mite resistance to amitraz. This acaricide is slow acting and an observation interval longer than 24 hours is required to obtain the necessary mortality data. It is difficult to exclude the effects of starvation when the slide-dip technique is used for prolonged periods and consequently amitraz was not tested further. An alternative method for the effective evaluation of this acaricide must be developed. From this study no definite evidence of resistance of T. cinnabarinus in the Grtoblersdal/Marble Hall cotton growing area to triazophos or profenofos was found. It was concluded that both can still be used effectively in the control programme for mites on cotton.

Thesis (PhD (Paraclinical Sciences, Veterinary Science))--University of Pretoria, 2009. / Includes bibliographical references. Also available in print format.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第23618号 / 農博第2481号 / 新制||農||1088(附属図書館) / 学位論文||R4||N5366(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 日本 典秀, 教授 田中 千尋, 准教授 刑部 正博 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

La gale humaine, récemment reconnue comme maladie tropicale négligée par l’OMS est due à l'acarien Sarcoptes scabiei variété hominis. La gale est un problème majeur de santé publique avec une prévalence mondiale estimée à 200 millions de cas/an. La morbidité est surtout liée aux surinfections bactériennes par Streptococcus pyogenes et Staphylococcus aureus. L’arsenal thérapeutique demeure limité. Plusieurs molécules sont disponibles, surtout des traitements topiques (dont la perméthrine). L’ivermectine de la famille des lactones macrocycliques est la seule molécule orale disponible. Elle a une efficacité prouvée mais pas absolue. La plupart des molécules ne sont pas ovicides et leurs demi-vies, plus courtes que le cycle du parasite, impliquent de proposer systématiquement une deuxième application/prise à une semaine d’intervalle. Des inquiétudes concernant l'apparition de sarcoptes résistants à la perméthrine et à l’ivermectine apparaissent. Des alternatives sont donc nécessaires à courte échéance. Le traitement de la gale comprend toujours un traitement médical pour le patient et ses contacts mais également une désinfection de son environnement mais aucune mesure de décontamination n’a pu réellement faire la preuve de son efficacité.L’objectif de cette thèse a été de proposer et d’évaluer des alternatives thérapeutiques pour la prise en charge de la gale en utilisant de nouveaux modèles expérimentaux, in vitro et in vivo, notamment dans un modèle animal porcin. Dans la première partie de la thèse, deux spécialités vétérinaires de la famille des lactones macrocycliques (moxidectine) ou des isoxazolines (afoxolaner) ont été évaluées dans deux essais thérapeutiques. L’efficacité d’une administration orale unique de moxidectine et d’afoxolaner a été évaluée sur des porcs expérimentalement infestés. Une évaluation pharmacologique plasmatique et cutanée a aussi pu être réalisée. La deuxième partie de la thèse a porté sur une meilleure connaissance des molécules déjà disponibles et sur leur amélioration. L’activité ovicide de différentes molécules a été évaluée. La possibilité d’utiliser une dose plus importante d’ivermectine a pu elle aussi être étudiée. Dans la troisième partie de la thèse, nous avons travaillé sur la prise en charge de l’environnement. Nous avons évalué in vitro l’efficacité́ de différentes procédures de lavage en machine pour l’éradication d’une population de Sarcoptes scabiei ainsi que l’effet de la congélation, du séchage en lave-linge et de l’utilité de sacs en plastique occlus. Nous avons aussi étudier l’activité de molécules répulsives ou de produits acaricides pour la prise en charge des sarcoptes dans l’environnement.L’ensemble des résultats de ces différentes études va nous permettre de proposer de nouvelles alternatives pour la prise en charge thérapeutique de la gale. Certaines nouvelles alternatives vont pourvoir être évaluées chez l’homme prochainement. Pour l’environnement, des recommandations précises et universelles à l’échelle individuelle mais aussi collective pourront être proposées dans les pays développés mais aussi dans les pays en voie de développement. / Human scabies is caused by the mite Sarcoptes scabiei variety hominis. Scabies was recently recognized as a neglected tropical disease, due to its high global prevalence estimated to be around 200 million cases/year and its high morbidity mainly related to bacterial superinfection by Streptococcus pyogenes and Staphylococcus aureus. The therapeutic arsenal remains limited. Several molecules are available, including topical treatments. Ivermectin, a member of the macrocyclic lactone family is the only oral drug available. It has proven efficacy but not absolute. Most molecules are not ovicidal and their half-lives are too short to cover the entire parasite cycle. Indeed, a second application/intake at one week interval is mandatory. Furthermore, resistance to the main acaricides has been reported. Thus, alternatives need to be found in the short term. Treatment of scabies always includes medical treatment for the patient and his contacts, but also a disinfection of his environment. However, the efficacy of decontamination procedures, especially those possible in resource poor settings, has not been determined with a good level of evidence.The aim of this thesis was to propose and evaluate therapeutic alternatives for the management of scabies by using new experimental models, in vitro and, in vivo in an experimental porcine animal model.In the first part of the thesis, two veterinary molecules from the macrocyclic lactones family (moxidectin) or the isoxazolines (afoxolaner) were evaluated in two therapeutic trials. Efficacy of a single oral administration of moxidectin and afoxolaner was evaluated in experimentally infested pigs. A plasma and cutaneous pharmacological evaluation was also possible.The second part of the thesis focused on increasing our knowledge on molecules already available and on their improvement. We studied the ovicidal activities of currently available molecules for human scabies treatment and molecules use in the veterinary clinic. Furthermore, we studied the potential of a higher dose of ivermectin for scabies treatment.In the third part of the thesis, we worked on the management of the environment. We evaluated in vitro the effectiveness of different machine washing procedures for the eradication of a population of Sarcoptes scabiei as well as the effect of freezing, drying and the usefulness of closed plastic bags. We also studied the activity of repellent molecules or acaricide products for the management of Sarcoptes mites in the environment.Using the results of these different studies it will be possible to propose new alternatives for the therapeutic management of human scabies. New alternatives will be evaluated in humans in the next future. For the environment, specific and universal recommendations at individual and collective level will be proposed.

Sarcoptes scabiei est un acarien ectoparasite obligatoire. Sa présence dans la couche cornée de l’épiderme est à l’origine d’une gale dite sarcoptique. Cette ectoparasitose a été décrite chez 104 espèces de mammifères représentant 27 familles distinctes. Les traitements actuels de la gale sarcoptique ne sont pas toujours satisfaisants et il n’existe pas de produits qui permettent d’éliminer S. scabiei dans l’environnement. Par ailleurs, la diversité génétique de S. scabiei n’est pas clairement définie et l’unicité de l’espèce fait toujours l’objet de controverses.L’objectif de cette thèse a été d’évaluer l’efficacité d’acaricides vis-à-vis de S. scabiei en utilisant un modèle animal ou par le biais de tests in vitro. La diversité génétique d’isolats d’origine animale a également été étudiée. La première partie du travail de thèse a concerné un essai thérapeutique L’efficacité d’une administration orale unique d’afoxolaner, une molécule du groupe des isoaxazolines, a été évaluée sur des porcs expérimentalement infestés. Le critère principal d’évaluation a été la réduction du nombre de sarcoptes mis en évidence dans les raclages cutanés. Huit jours après le traitement, aucun sarcopte n’a été détecté sur les 4 porcs ayant reçu l’afoxolaner alors que des sarcoptes étaient toujours présents sur les 3 porcs ayant reçu de l’ivermectine. Tous les porcs traités étaient guéris à la fin de l’essai (J35) alors que les animaux non traités sont demeurés infestés. Les autres critères d’évaluation étaient l’évolution du score clinique et de prurit. Les lésions cutanées ont rapidement régressé dans le groupe traité par l’afoxolaner alors qu’elles étaient encore présentes à J14 dans le groupe traité avec l’ivermectine. La deuxième partie du travail de thèse a porté sur l’évaluation in vitro de différentes molécules ou produits acaricides. Plusieurs concentrations d’une solution d’ivermectin ou de moxidectine ainsi 11 huiles essentielles ont été testées. Après 24h de contact avec l’ivermectine et la moxidectine, la dose létale 50% étaient de 150,2±31,4 µg/mL et 608,3±88,0 µg/mL, respectivement. Une concentration inférieure à 1 ng/mL (pour l’ivermectine) ou à 10 ng/mL (pour la moxidectine) n’a aucune activité acaricide. Pour les huiles essentielles, des tests par fumigation et par immersion ont été réalisés. Parmi Lavandula augustifolia, Melaleuca altenifolia, Pelargonium asperum, Eucalyptus radiate, Leptospermum scoparium, Cryptomeria japonica, Citrus aurantium ssp amara et 3 l’huile essentielle identifiée (BOB4, BOB5, BOB9) testés par immersion, l’huile essentielle identifiée BOB4 s’est révélée la plus efficace (une solution à 1% tue tous les acariens en 20 min). Parmi les 10 huiles essentielles énumérées avant, plus Juniperus oxycedrus testés par immersion, l’huile essentielle de Melaleuca altenifolia s’est révélée la plus efficace (tous les acariens sont morts en 4 min). Pour le contrôle de S. scabiei dans l’environnement, différents biocides ou répulsifs ont été examinés. La durée moyenne de survie a été calculée pour les produits comportant de la perméthrine, de l’esdépallethrine et de la bioresmethrine, de la bifenthrine, de la cyperméthrine et de l’imiprothrine, de la cyfluthrine, de la tétramethrine et de la sumithrine, du DEET, de l’icaridine et le produit IR3535. La deuxième partie du travail de thèse a porté sur la diversité génétique d’isolats de S. scabiei provenant d’animaux. Une partie du gène cox1 a été amplifiée. L’analyse des séquences ainsi obtenues semble montrer que les sarcoptes circulant chez le Chien sont issus de population de sarcoptes d’origine humaine. / Sarcoptes scabiei is an ectoparasite responsible for the emerging/re-emerging disease called scabies in humans or mange in animals. It was reported in 104 species across 27 families of domestic and wild animals. Current treatments for scabies/mange are limited and there are no efficient products for the environment control of S. scabiei. Moreover, the taxonomic status of S. scabiei is still under controversy and the question remains that whether it represents a single species or several taxa.The objectives of the thesis were to assess the susceptibility to acaricides and analyse the genetic diversity of S. scabiei from animals. In the first part of the thesis, an animal model was used to evaluate the efficacy of afoxolaner, a new acaricide from the isoaxazoline family. The primary outcome of efficacy was based on the reduction in the number of live mites counted in skin scrapings following treatment. At day 8, four afoxolaner-treated pigs (out of four) were mite-free, while mites were still found in three (out of three) ivermectin-treated pigs. All treated pigs were cured at the end of the study (day 35) and all pigs in the control group remained infected. Secondary outcomes included measures on the reduction of skin lesions and pruritus. The clinical lesions of scabies infection were allowed to disappear completely for all the pigs in the afoxolaner group but not in the ivermectin group at 14 days after the treatment. An increase of the pruritus was observed right after treatment, followed by a decrease of the pruritus score in both treated groups. The second part of the thesis was to evaluate the scabicidal effect of molecules or products using an in vitro test. A gradient of concentrations of ivermectin and moxidectin as well as 11 essential oils have been evaluated in vitro against S. scabiei. After 24h of exposure to ivermectin and moxidectin, the median lethal concentrations were 150.2±31.4 µg/mL and 608.3±88.0 µg/mL, respectively. Doses of ivermectin under 1 ng/mL and moxidectin under 10 ng/mL showed no scabicidal effect. Fumigation and contact bioassays were used for the assessment of essential oils efficacy. Among Lavandula augustifolia, Melaleuca altenifolia, Pelargonium asperum, Eucalyptus radiate, Leptospermum scoparium, Cryptomeria japonica, Citrus aurantium ssp amara and 3 other unknown oils (BOB4, BOB5, BOB9) tested with the contact bioassay, the essential oil identified as BOB4 demonstrated the best scabicidal effect (1% solution killed all the mites in 20 min). Among the 10 essential oils listed before plus Juniperus oxycedrus with the fumigation bioassay, the oil Melaleuca altenifolia demonstrated the best scabicidal effect (all the mites died in only 4 min). For environmental control of S. scabiei, the efficacy of biocides or repellents was assessed. The median survival time was calculated for permethrin (4% and 0.6%), esdepallethrin and bioresmethrin, bifenthrin, cypermethrin and imiprothrin, cyfluthrin, tetramethrin and sumithrin, DEET (25% and 50%), icaridin and IR3535. The third part of the thesis included the study of the genetic diversity of populations of S. scabiei from animals. A part of cox1 was used for phylogenetic analyses. The results showed that Sarcoptes mites from dogs seem to derive from humans.

Rhipicephalus microplus belongs to the Ixodidae, the largest family of ticks, which are of great economic importance due to their negative socio-economic impact on agriculture (BROUQUI 2011; PORTO NETOA et al. 2011; SONENSHINE 1991). Acaricides have been the first choice in tick control for cattle farmers, but R. microplus rapidly acquires resistance to these chemicals. Replication slippage and recombination drive genetic diversity in tick populations (BAFFI et al. 2007; GUERRERO et al. 2007; LI et al. 2007); generating point mutations and frame shifts within the genes targeted by acaricides, resulting in resistance (BAFFI et al. 2007; HERNANDEZ et al. 2002; HERNANDEZ et al. 2000; JONSSON et al. 2010; MORGAN et al. 2009). In addition, resistance can quickly accumulate in a population due to the pangamy mating structure of ticks (CHEVILLON et al. 2007b; CUTULLÉ et al. 2010) and their ability to produce multiple generations within one season (BUDELI et al. 2009; LI et al. 2007). Vaccines have become increasingly important to control ticks, as acaricide resistance can be acquired by field tick populations within two years (RODRIGUEZ-VIVAS et al. 2011). Although Bm86 has been successful against multiple-acaricide resistant ticks, recent reports indicate that the Bm86 vaccine has become ineffective, possibly due to resistance (PARIZI et al. 2009). Also, Bm86 vaccines display great variability in terms of their efficacy against ticks isolated across Argentina (GARCIA-GARCIA et al. 2000; PARIZI et al. 2009). This is hypothesised to be due to the genetic variability between R. micoplus populations. The majority of phylogenetic studies on ticks have been based on slow evolving sequences, such as 18S or 28S rRNA, which provide genus-level resolution. The COI, D3, ANT and ITS2 genes have the potential to resolve intra-specific and interspecies variation, and may assist with the identification of cryptic speciation within R. microplus of South Africa (ANSTEAD et al. 2011; BARKER 1998; CAREW et al. 2009; MURRELL et al. 2000; SONGA et al. 2011). Phylogeography is a multidisciplinary field that utilises phylogenetic (molecular evidence of speciation) and population genetic principles (coalescence theory), in combination with additional data (such as geography and population history), to determine the genetic relationships of populations within a species (AVISE 2009) and was one of the main aspects of this study. The phylogenetic and population genetic structure of R. microplus will provide valuable information to geneticists, farmers and acaricide/vaccine suppliers about the different R. microplus tick populations of South Africa. The information will facilitate more efficient and targeted tick control whether acaricide or vaccine based as opposed to the inefficient approaches generally adopted to tick control. / Dissertation (MSc)--University of Pretoria, 2014. / lk2014 / Genetics / MSc / Unrestricted

Les maladies impliquant des micro-organismes représentent un problème majeur de santé publique en raison du fort taux de mortalité provoqué par l'accroissement et l'émergence de souches résistantes. De même, les régions tropicales du Monde et La Réunion doivent faire face depuis plusieurs années à la pression accrue d'arthropodes ravageurs de cultures et vecteurs de maladies. Pour lutter contre ces arthropodes, les pesticides synthétiques aux conséquences désastreuses sur l'Homme et l'environnement sont principalement utilisés. Depuis quelques années, on observe un phénomène grandissant de résistance aux molécules conventionnelles à la fois chez les micro-organismes et les arthropodes. Face à ce constat, il est primordial de proposer de nouvelles molécules bioactives capables de lutter efficacement contre les ravageurs et les micro-organismes. Dans ce cadre, un criblage préliminaire réalisé sur vingt plantes endémiques et indigènes de La Réunion a permis de mettre en évidence l'activité antibactérienne et acaricide des extraits acétate d'éthyle de plusieurs espèces végétales. En raison de son large spectre d'activités biologiques, Peperomia borbonensis Miq. (Piperaceae), a été sélectionnée pour une investigation chimique et biologique approfondie. La suite de nos travaux a été consacrée à l'isolement et la caractérisation des métabolites secondaires de l'extrait apolaire de cette espèce. Les fractionnements bio-guidés réalisés ont conduit à l'isolement de quatorze molécules dont un amide à la structure nouvelle. Par ailleurs, l'étude de la fraction volatile de cette espèce a montré le potentiel insecticide de l'huile essentielle des feuilles pour lutter contre la mouche du melon B. cucurbitae. / The emergence of resistant strains in infectious diseases is a major public health issue. Similarly, arthropods which caused important economic damages in tropical and subtropical areas are continuously developing resistance to chemicals. To counteract this situation, it is essential to find new bioactive molecules able to fight pests and micro-organisms. In this context a preliminary screening was performed on twenty endemic plants and native of Reunion. Twenty-six ethyl acetate extracts were tested for their antibacterial and acaricidal activities. Considering its broad spectrum of activity, Peperomia borbonensis Miq. (Piperaceae), was selected for further chemical and biological investigations. Two bio-guided fractionations were performed on its apolar extract and let to the isolation of fourteen molecules. Moreover, the study of the volatile fraction has shown the insecticidal potential of the leaf essential oil of P. borbonensis against the melon fly B. cucurbitae.

O objetivo desse trabalho foi o de coletar informações básicas para a implementação de um programa de manejo da resistência de Brevipalpus phoenicis (Geijskes, 1939) ao acaricida hexitiazox na cultura de citros. A suscetibilidade de ovos de B. phoenicis a hexitiazox foi avaliada através de um bioensaio de contato direto. Foi verificado que há efeito da idade de ovos de B. phoenicis na suscetibilidade, sendo que ovos no início do desenvolvimento embrionário (1 a 3 dias) foram menos tolerantes a hexitiazox do que ovos de 4 a 9 dias de idade. A CL50 estimada para a população suscetível de referência (linhagem S) foi de 0,89 mg de hexitiazox/L de água (IC 95% 0,75-1,03). Para o isolamento da resistência de B. phoenicis a hexitiazox (linhagem R), um trabalho de seleção em condições laboratoriais foi realizado a partir de uma população coletada em um pomar de citros da região de Barretos-SP, onde o uso de hexitiazox tinha sido intenso e falhas no controle do ácaro haviam sido reportadas com esse acaricida. A intensidade da resistência de B. phoenicis a hexitiazox foi maior que 10.000 vezes. Concentrações discriminatórias entre 10 e 320 mg de hexitiazox/L de água foram definidas para um programa de monitoramento da resistência de B. phoenicis ao hexitiazox. Resultados do levantamento da suscetibilidade a hexitiazox em populações de B. phoenicis provenientes de diferentes pomares dos Estados de São Paulo e Minas Gerais revelaram uma grande variabilidade na freqüência de resistência. Não foi observada relação entre o regime de uso do hexitiazox e a freqüência de resistência. Estudos da dinâmica da resistência em laboratório revelaram que a resistência de B. phoenicis a hexitiazox é estável, isto é, a freqüência de resistência não diminui significativamente na ausência de pressão de seleção. Portanto, os resultados obtidos no presente trabalho indicam a necessidade de implementação imediata de estratégias de manejo da resistência de B. phoenicis a hexitiazox para a prolongar a vida útil desse acaricida. / The objective of this study was to collect baseline information for implementing an acaricide resistance management program of Brevipalpus phoenicis (Geijskes, 1939) to hexythiazox in citrus. The egg susceptibility of B. phoenicis to hexythiazox was measured by a direct contact bioassay. It was observed a significant effect of the egg developmental stage on susceptibility; that is, 1 to 3-day old eggs were less tolerant to hexythiazox than 4 to 9-day old eggs. The estimated LC50 for the S strain was 0.89 mg of hexythiazox/L of water (95% CI 0.75-1.03). To isolate hexythiazox-resistant B. phoenicis, a laboratory selection was conducted with a field population collected in a citrus grove located in Barretos-SP, where the intensity of hexythiazox use was high and field failures in the control of B. phoenicis were reported with the use of this acaricide. The intensity of resistance was greater than 10,000- fold. Discriminating concentrations between 10 and 320 mg of hexythiazox/L of water were defined for monitoring the resistance of B. phoenicis to hexythiazox. Results from a survey of susceptibility of B. phoenicis populations collected from citrus groves located in the State of São Paulo and Minas Gerais revealed a great variability in the frequency of resistance. No correlation was observed between the intensity of hexythiazox use and the frequency of resistance. Studies on dynamics of resistance showed that the resistance of B. phoenicis to hexythiazox is stable under laboratory conditions; that is the frequency of resistance did not decline significantly in the absence of selection pressure. Therefore, results obtained herein indicate the urgent need to implement resistance management strategies of B. phoenicis to hexythiazox in order to prolong the lifetime of this acaricide.

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-05-12T20:06:08Z No. of bitstreams: 1 TatianePenha.pdf: 1070731 bytes, checksum: 317d377ddfce7d741b49eecde3cf7ec4 (MD5) / Made available in DSpace on 2017-05-12T20:06:08Z (GMT). No. of bitstreams: 1 TatianePenha.pdf: 1070731 bytes, checksum: 317d377ddfce7d741b49eecde3cf7ec4 (MD5) Previous issue date: 2016-10-31 / Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA) / The tick Rhipicephalus microplus, found in tropical and subtropical regions, has caused great harm to the Brazilian livestock. The damage caused by this tick the Brazilian livestock exceeds three billion dollars. Verbenaceae Lippia genus, especially the species L. sidoides and L. gracilis, have been reported with potential activity in larvae and R. microplus females. Therefore, the aim of this study was to evaluate the acaricide activity of L. sidoides and L. gracilis essential oils and its major compounds thymol and carvacrol and characterize morphological changes in ovaries of R. microplus females from lethal concentrations 50 (LC50) and 75% (LC75) of the study population. After selection of the genotypes (LGRA-106, LGRA-201, LSDI-102 and LSDI-103), groups of 10 engorged females were subjected to the immersion test in essential oils at different concentrations and DMSO 3% was used for the control. After seven days, the ticks were dissected in phosphate buffer solution and the ovaries were fixed in 2.5% glutaraldehyde for a period of 24 hours. The tissues were dehydrated and embedded in plastic molds Leica resin for histological analysis. The results visualization and characterization of the ovary and the different stages of development of oocytes. In the control group, treated with 3% DMSO, changes in the tissues have not been verified. In groups treated with the L. gracillis oils and L. sidoides oils, vacuolization was observed in oocytes II, III, IV and V, cell membrane disintegration in oocytes II, III, IV and V, with complete morphological deformation of oocytes IV and V. The major compounds, thymol and carvacrol seem to be actively working on these changes. The results showed activity of the different genotypes of the essential oils and their major compounds in larvae and females of R. microplus and allowed to elucidate the mechanism of action of the same in the oogenesis of the females, leading to believe that the compounds tested are promising for the development of acaricide products. / O carrapato Rhipicephalus microplus, encontrado em regiões tropicais e subtropicais, ocasionam mais de três bilhões de dólares à pecuária brasileira. Óleos essenciais de Verbenáceas do gênero Lippia, especialmente Lippia sidoides e Lippia gracilis, têm sido descritos com potencial atividade carrapaticida e interferindo na reprodução de diferentes espécies de carrapatos. O objetivo desse trabalho foi avaliar a atividade carrapaticida dos óleos essenciais de L. sidoides e L. gracilis e seus compostos majoritários timol e carvacrol, selecionando os genótipos que apresentam maiores atividades contra o carrapato bovino e caracterizar as alterações morfológicas dos ovários de fêmeas de R. microplus a partir das concentrações letais para 50 (CL50) e 75% (CL 75) da população estudada. Após a seleção dos genótipos (LGRA-106, LGRA-201, LSDI-102 e LSDI-103, grupos de 10 fêmeas ingurgitadas foram submetidas ao teste de imersão em óleos essenciais em diferentes concentrações e para o controle foi utilizado DMSO 3%. Após sete dias, as fêmeas foram dissecadas em solução tampão fosfato e os ovários foram fixados em glutaraldeído 2,5% por um período de 24 horas. Os tecidos foram desidratados e incluídos em moldes plásticos de resina Leica para análise histológica. Os resultados permitiram a visualização e caracterização do ovário e dos diferentes estágios de desenvolvimento dos ovócitos. No grupo controle (DMSO 3%), não foram verificadas alterações nos tecidos. Nos grupos tratados com os óleos de L. gracillis e L. sidoides foram observadas vacuolizações de ovócitos II, III, IV e V, desintegração de membrana plasmática em ovócitos II, III, IV e V, com completa deformidade morfológica de ovócitos IV e V. Os compostos majoritários, timol e carvacrol parecem estar atuando ativamente nessas alterações. Os resultados obtidos mostraram atividade dos diferentes genótipos dos óleos essenciais e seus compostos majoritários em larvas e fêmeas de R. microplus e permitiu elucidar o mecanismo de ação dos mesmos na oogêse das fêmeas, levando a crer que os compostos testados são promissores para o desenvolvimento de produtos carrapaticidas.

Cattle ticks and tick-borne infections (TBIs) undermine cattle health and productivity in the whole of sub-Saharan Africa (SSA) including Nigeria. In this West African country, two thirds of the cattle population are reared in the central-northern regions, kept under the traditional pastoral husbandry of Fulani herders. Under the Fulanis’ management, cattle are grazed extensively, being exposed to infestation by several tick genera (i.e. Amblyomma, Hyalomma, and Rhipicephalus spp., sub-genus Boophilus spp. included), vectors of the causative agents of the most important bovine TBIs in West Africa: anaplasmosis, babesiosis and ehrlichiosis (cowdriosis). Nevertheless, the Fulani pastoralists do not usually employ chemicals to control ticks in their cattle, merely relying on traditional methods (i.e. manual removal of the most conspicuous specimens). This approach, however, does not prevent cattle from being re-infested, leaving the animals challenged by a broad variety of other tick species, most of which are vectors of economically relevant TBIs. Knowledge of tick and TBIs occurrence is an essential pre-requisite to assist field diagnosis and devising effective control strategies for a given area. Existing information on tick infestation of cattle in Nigeria is rather out-dated, mostly derived from studies carried out in the south of the country. Similarly, all studies published to date on cattle TBIs in the country do not include any molecular analysis, being based instead on cytological and/or serological diagnostics. Therefore, the aim of the present thesis was to assess the presence of cattle ticks and TBIs occurring in an area of Central Nigeria (i.e. Plateau State). This is a densely populated area with traditionally managed cattle, where no acarides have historically been employed on livestock. The work undertaken herein firstly reviews the information available to date on ticks and TBIs known to be endemic in Nigerian cattle, identifying gaps present in the existing knowledge, leading to the rationale of this study. An initial survey was conducted documenting the tick species infesting cattle in Central Nigeria, in order to assess the infestation rate of surveyed animals at the time of the year when the tick load on the host is known to be most abundant (i.e. the wet season). The survey provided novel information on tick populations in cattle in Nigeria disclosing the presence of a broad variety of species, most of which are vectors of hazardous TBIs. In order to conduct a molecular diagnosis of the TBIs within the study area, a novel methodology was developed (i.e. reverse line blotting, RLB). The application of this approach was based on a thorough review of its application to the diagnosis of TBIs worldwide as well as in SSA. The optimisation of the RLB at the University of Edinburgh to enable the detection of a broad-spectrum of TBIs in Nigeria, caused by an array of five genera of microorganisms (i.e. Ehrlichia and Anaplasma, Theileria and Babesia, Rickettsia spp.) is presented. The assessment of the analytical sensitivity of this technique for the detection of Anaplasma marginale, a highly endemic tick-borne pathogen in SSA, demonstrated a detection threshold of ≥ 7 infected cells (keeping the limit of a natural infection). The occurrence of TBIs in cattle in the study area was assessed during a large-scale epidemiological survey through the application of the validated RLB. This study disclosed the occurrence of a high prevalence of several bovine TBIs in Central Nigeria, some of which are of great veterinary and zoonotic concern. The RLB enabled the detection of carrier status as well as of numerous multiple infections (69.5%, 95% CI: 65.5–73.6%). Based on the findings presented, endemic stability for highly prevalent haemoparasites (i.e. Theileria mutans, Theileria velifera, Theileria taurotragi, Anaplasma marginale, Ehrlichia species Omatjenne) is postulated, whereas a more instable epidemiological scenario is hypothesized for other microorganisms (i.e. Anaplasma centrale and Babesia bovis), which might be connected with outbreaks of clinically apparent disease, sporadically seen in the study area. The effect of a monthly tsetse-borne trypanosomiasis-focused control programme (based on the application 0.005% deltamethrin spray formulation, applied only to the lower quarters of cattle) on the kinetics of bovine TBIs was assessed at the village level. Longitudinal monitoring of control and treated cattle was conducted over the period of eleven months. Results generated provide input to the improvement of future control strategies to be rolled out across SSA, aiming to achieve an integrated control of both trypanosomiasis and TBIs. The present thesis contributes to a better understanding of the epidemiology of bovine TBIs in Nigeria as well as in the rest of West Africa, using a highly sensitive tool of wide applicability. These findings will be shared with the local pastoralist communities to further promote effective yet sustainable, vector control, in tune with the traditional long-established practices.