La classification actuelle de la famille des Phytoseiidae n'est pas basée sur de réelles études phylogénétiques et par conséquent, de nombreuses questions se posent sur la validité des taxa supra-spécifiques mais également vis-à-vis des taxa spécifiques. Ce travail de thèse avait donc pour objectif de répondre à de telles questions pour deux genres : Phytoseiulus et Neoseiulella, en utilisant pour la première fois des approches phylogénétiques moléculaires et morphologiques. Ces études phylogénétiques ont été également associées à des études biogéographiques. Les résultats obtenus par ces deux approches sont congruents et semblent montrer que ces deux genres ne sont pas monophylétiques : le genre Phytoseiulus semble au mieux paraphylétique, tandis que le genre Neoseiulella serait polyphylétique. Ces résultats sont différents de ceux développés dans les diverses révisions successives de ces deux taxa. Ce travail de thèse a permis de répondre également à des questionnements sur cinq synonymies au sein du genre Neoseiulella. L'étude de pratiquement tous les types des espèces du genre Neoseiulella nous a permis de redéfinir le genre, en excluant trois espèces et en discutant certaines synonymies. Une clé d'identification des adultes femelles des espèces valides a également été proposée. Des études complémentaires, notamment des analyses moléculaires, seront nécessaires afin de conclure plus définitivement sur les relations évolutives entre les taxa étudiés / The present classification of the family Phytoseiidae is not based on solid phylogenetic studies and therefore, many taxonomic questions still arise, concerning the validity of supra-specific and specific taxa identified to-date. This thesis thus aimed to answer such questions for two genera, Phytoseiulus and Neoseiulella, using for the first time molecular and morphological phylogenetic analyses. Biogeographic analyses have been also carried out. Results obtained by both morphological and molecular approaches are congruent and seem to show that both genera are not monophyletic: Phytoseiulus seems paraphyletic whereas Neoseiulella seems polyphyletic. These results are different from those obtained with previous revisions of these two taxa. Furthermore, this study allowed to conclude on five synonymies within the genus Neoseiulella. The observation of nearly the totality of the species belonging to the genus Neoseiulella permitted to redefine this genus, excluding three species and discussing some synonymies. Lastly, an identification key of the adult females was proposed for the valid species of the genus Neoseiulella. Further experiments, including molecular investigations, are however still required in order to obtain more reliable conclusions on the evolutionary relationships of the studied taxa.

No description available.

L'acarien rouge de la tomate Tetranychus evansi Baker & Pritchard est un ravageur important des Solanaceae dans divers pays. Il a été introduit accidentellement en Afrique sans ses ennemis naturels. Actuellement, on le trouve dans beaucoup de pays africains et il est considéré comme un ravageur clef dans quelques-uns d'entre eux. L'origine supposée de cet acarien est l'Amérique du Sud. Quelques espèces de prédateurs ont été rapportées en association avec T. evansi. Cependant, différents tests réalisés en laboratoire ont pu démontrer l'inefficacité de ces espèces contre ce ravageur. L'objectif de la présente étude est de continuer la recherche d'agents de contrôle efficaces pour lutter contre T. evansi en Afrique. Pour ceci, la présence de ce ravageur et de ses prédateurs a été étudiée au Brésil et en Argentine, principalement sur les solanacées, d'octobre 2002 à décembre 2004. Dans l'ensemble des prospections, ils ont été trouvé environ 28 000 spécimens de T. evansi au Brésil et 35 000 en Argentine. Dans ces deux pays, un total de 15 espèces de prédateurs de la famille des Phytoseiidae ont été trouvés en association avec ce ravageur. Parmi ces derniers, Phytoseiulus longipes Evans a été l'espèce la plus prometteuse comme agent de contrôle de T. evansi. Ce prédateur a été trouvé à Uruguaiana-RS, Brésil et ceci constitue la première observation de cette espèce dans ce pays. L'acceptation de T. evansi comme proie pour cette population de P. longipes a été évaluée au laboratoire par deux essais. Dans le premier test, le taux moyen journalier d'oviposition du prédateur a été evalué sur T. evansi et sur 3 autres sources de nourriture: Tetranychus urticae Koch, pollen de Ricinus communis L. ou pollen de Typha sp. Dans le deuxième test, la préférence du prédateur pour T. evansi ou T. urticae a été étudiée. Le taux moyen journalier d'oviposition de P. longipes a été approximativement identique pour une alimentation vis-à-vis de T. evansi et T. urticae (respectivement 3,4 et 3,5 oeufs). Le prédateur n'a pas pondu lorsqu'il était alimenté avec les deux types de pollen. Les études suivantes concernant les tests de choix au laboratoire ont toujours démontré des proportions significativement plus grandes de P. longipes sur les folioles avec T. evansi que sur les folioles avec T. urticae. Ensuite, la biologie détaillée de P. longipes a été étudiée, en utilisant les nourritures précédemment citées. La survie des différents stades immatures de P. longipes a été approximativement de 94 % et de 80 % quand ils étaient alimentés avec T. evansi et T. urticae, respectivement. Cette survie a été nulle sur les deux types de pollen. La durée des stades immatures du prédateur alimenté avec ces proies ont été identiques (4,7 et 4,8 jours). Les augmentations des effectifs de P. longipes ont été élevées tant sur T. evansi que sur T. urticae. Le prédateur a présenté un taux intrinsèque d'accroissément naturel ( rm) de 0,363 et un taux fini d'accoissement ( γ ) de 1, 44 avec T. evansi. Il a présenté un rm de 0, 320 et un γ de 1, 38 avec T. urticae. Les résultats obtenus dans ce travail indiquent que P. longipes est un prédateur prometteur pour la lutte biologique contre T. evansi. Ils suggèrent également l'utilité de l'introduction de ce prédateur dans le continent africain pour être utilisé dans un programme de lutte biologique classique. / O ácaro vermelho do tomateiro, Tetranychus evansi Baker & Pritchard, é uma praga importante de Solanaceae em diversos países. Introduzido acidentalmente na África, livre de seus inimigos naturais, atualmente encontra-se em muitos países do continente africano, sendo em alguns deles considerado uma praga-chave. Suspeita-se que este ácaro seja originário da América do Sul. Algumas espécies de predadores têm sido reportadas em associação com T. evansi. Testes conduzidos em laboratório por diferentes pesquisadores não têm podido demonstrar a eficiência daquelas como agente de controle daquela praga. O objetivo do presente estudo foi dar continuidade à busca de agentes de controle eficientes, para o controle de T. evansi na África. Para tanto, investigou-se no Brasil e na Argentina a ocorrência desta praga e de seus predadores, principalmente em solanáceas, de outubro de 2002 a dezembro 2004. No total, foram encontrados cerca de 28 000 espécimes de T. evansi no Brasil e 35 000 na Argentina. Naqueles dois países, encontrou-se um total de 15 espécies de predadores da família Phytoseiidae associados a esta praga. Dentre estas, Phytoseiulus longipes Evans foi a que se mostrou mais promissora como agente de controle de T. evansi. Este predador foi encontrado em Uruguaiana-RS, Brasil, sendo esta a primeira constatação desta espécie naquele país. A aceitação de T. evansi como presa para aquela população de P. longipes foi avaliada em laboratório através de dois testes. No primeiro, comparou-se a oviposição média diária do predador quando alimentado com T. evansi e com 3 outras fontes de alimento: Tetranychus urticae Koch, pólen de Ricinus communis L. ou de Typha sp. No segundo, avaliou-se a preferência do predador por T. evansi ou T. urticae. A oviposição média diária de P. longipes foi aproximadamente a mesma (3,4 e 3,5 ovos) quando alimentado com T. evansi ou T. urticae. Não houve oviposição quando o predador foi alimentado com os dois tipos de pólen. Avaliações sucessivas em testes de livre escolha conduzidos no laboratório demonstraram proporções sempre significativamente maiores de P. longipes em folíolos com T. evansi que em folíolos com T. urticae. Posteriormente, a biologia detalhada de P. longipes foi estudada, utilizando-se os alimentos anteriormente citados. A sobrevivência dos diferentes estágios imaturos de P. longipes foi de aproximadamente 94 % e 80 % quando alimentado com T. evansi e T. urticae, respectivamente, e nula quando em presença de ambos os tipos de pólen. A duração da fase imatura do predador alimentado com aquelas presas foi praticamente a mesma (4,7 e 4,8 dias). Phytoseiulus longipes demonstrou alta capacidade de aumento populacional quando alimentado com T. evansi ou com T. urticae. Apresentou uma capacidade inata de aumento em número (rm) de 0,363 e razão finita de aumento em número (γ) de 1,44 quando alimentado com T. evansi; apresentou rm de 0,320 e γ de 1,38 quando alimentado com T. urticae. Os resultados obtidos neste trabalho indicam que P. longipes é um predador promissor para ser utilizado no controle biológico de T. evansi. Sugerem também a conveniência de introduzi-lo no continente africano para o uso em um programa de controle biológico clássico.

L'acarien rouge de la tomate Tetranychus evansi Baker & Pritchard est un ravageur important des Solanaceae dans divers pays. Il a été introduit accidentellement en Afrique sans ses ennemis naturels. Actuellement, on le trouve dans beaucoup de pays africains et il est considéré comme un ravageur clef dans quelques-uns d'entre eux. L'origine supposée de cet acarien est l'Amérique du Sud. Quelques espèces de prédateurs ont été rapportées en association avec T. evansi. Cependant, différents tests réalisés en laboratoire ont pu démontrer l'inefficacité de ces espèces contre ce ravageur. L'objectif de la présente étude est de continuer la recherche d'agents de contrôle efficaces pour lutter contre T. evansi en Afrique. Pour ceci, la présence de ce ravageur et de ses prédateurs a été étudiée au Brésil et en Argentine, principalement sur les solanacées, d'octobre 2002 à décembre 2004. Dans l'ensemble des prospections, ils ont été trouvé environ 28 000 spécimens de T. evansi au Brésil et 35 000 en Argentine. Dans ces deux pays, un total de 15 espèces de prédateurs de la famille des Phytoseiidae ont été trouvés en association avec ce ravageur. Parmi ces derniers, Phytoseiulus longipes Evans a été l'espèce la plus prometteuse comme agent de contrôle de T. evansi. Ce prédateur a été trouvé à Uruguaiana-RS, Brésil et ceci constitue la première observation de cette espèce dans ce pays. L'acceptation de T. evansi comme proie pour cette population de P. longipes a été évaluée au laboratoire par deux essais. Dans le premier test, le taux moyen journalier d'oviposition du prédateur a été evalué sur T. evansi et sur 3 autres sources de nourriture: Tetranychus urticae Koch, pollen de Ricinus communis L. ou pollen de Typha sp. Dans le deuxième test, la préférence du prédateur pour T. evansi ou T. urticae a été étudiée. Le taux moyen journalier d'oviposition de P. longipes a été approximativement identique pour une alimentation vis-à-vis de T. evansi et T. urticae (respectivement 3,4 et 3,5 oeufs). Le prédateur n'a pas pondu lorsqu'il était alimenté avec les deux types de pollen. Les études suivantes concernant les tests de choix au laboratoire ont toujours démontré des proportions significativement plus grandes de P. longipes sur les folioles avec T. evansi que sur les folioles avec T. urticae. Ensuite, la biologie détaillée de P. longipes a été étudiée, en utilisant les nourritures précédemment citées. La survie des différents stades immatures de P. longipes a été approximativement de 94 % et de 80 % quand ils étaient alimentés avec T. evansi et T. urticae, respectivement. Cette survie a été nulle sur les deux types de pollen. La durée des stades immatures du prédateur alimenté avec ces proies ont été identiques (4,7 et 4,8 jours). Les augmentations des effectifs de P. longipes ont été élevées tant sur T. evansi que sur T. urticae. Le prédateur a présenté un taux intrinsèque d'accroissément naturel ( rm) de 0,363 et un taux fini d'accoissement ( γ ) de 1, 44 avec T. evansi. Il a présenté un rm de 0, 320 et un γ de 1, 38 avec T. urticae. Les résultats obtenus dans ce travail indiquent que P. longipes est un prédateur prometteur pour la lutte biologique contre T. evansi. Ils suggèrent également l'utilité de l'introduction de ce prédateur dans le continent africain pour être utilisé dans un programme de lutte biologique classique. / O ácaro vermelho do tomateiro, Tetranychus evansi Baker & Pritchard, é uma praga importante de Solanaceae em diversos países. Introduzido acidentalmente na África, livre de seus inimigos naturais, atualmente encontra-se em muitos países do continente africano, sendo em alguns deles considerado uma praga-chave. Suspeita-se que este ácaro seja originário da América do Sul. Algumas espécies de predadores têm sido reportadas em associação com T. evansi. Testes conduzidos em laboratório por diferentes pesquisadores não têm podido demonstrar a eficiência daquelas como agente de controle daquela praga. O objetivo do presente estudo foi dar continuidade à busca de agentes de controle eficientes, para o controle de T. evansi na África. Para tanto, investigou-se no Brasil e na Argentina a ocorrência desta praga e de seus predadores, principalmente em solanáceas, de outubro de 2002 a dezembro 2004. No total, foram encontrados cerca de 28 000 espécimes de T. evansi no Brasil e 35 000 na Argentina. Naqueles dois países, encontrou-se um total de 15 espécies de predadores da família Phytoseiidae associados a esta praga. Dentre estas, Phytoseiulus longipes Evans foi a que se mostrou mais promissora como agente de controle de T. evansi. Este predador foi encontrado em Uruguaiana-RS, Brasil, sendo esta a primeira constatação desta espécie naquele país. A aceitação de T. evansi como presa para aquela população de P. longipes foi avaliada em laboratório através de dois testes. No primeiro, comparou-se a oviposição média diária do predador quando alimentado com T. evansi e com 3 outras fontes de alimento: Tetranychus urticae Koch, pólen de Ricinus communis L. ou de Typha sp. No segundo, avaliou-se a preferência do predador por T. evansi ou T. urticae. A oviposição média diária de P. longipes foi aproximadamente a mesma (3,4 e 3,5 ovos) quando alimentado com T. evansi ou T. urticae. Não houve oviposição quando o predador foi alimentado com os dois tipos de pólen. Avaliações sucessivas em testes de livre escolha conduzidos no laboratório demonstraram proporções sempre significativamente maiores de P. longipes em folíolos com T. evansi que em folíolos com T. urticae. Posteriormente, a biologia detalhada de P. longipes foi estudada, utilizando-se os alimentos anteriormente citados. A sobrevivência dos diferentes estágios imaturos de P. longipes foi de aproximadamente 94 % e 80 % quando alimentado com T. evansi e T. urticae, respectivamente, e nula quando em presença de ambos os tipos de pólen. A duração da fase imatura do predador alimentado com aquelas presas foi praticamente a mesma (4,7 e 4,8 dias). Phytoseiulus longipes demonstrou alta capacidade de aumento populacional quando alimentado com T. evansi ou com T. urticae. Apresentou uma capacidade inata de aumento em número (rm) de 0,363 e razão finita de aumento em número (γ) de 1,44 quando alimentado com T. evansi; apresentou rm de 0,320 e γ de 1,38 quando alimentado com T. urticae. Os resultados obtidos neste trabalho indicam que P. longipes é um predador promissor para ser utilizado no controle biológico de T. evansi. Sugerem também a conveniência de introduzi-lo no continente africano para o uso em um programa de controle biológico clássico.

Made available in DSpace on 2015-03-26T13:30:42Z (GMT). No. of bitstreams: 1 texto completo.pdf: 484977 bytes, checksum: 368d0f7fd7c2f8a96df8c45cef7c69bf (MD5) Previous issue date: 2011-02-22 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Em todo o mundo lavouras de tomate sofrem o ataque de pragas. Uma das principais pragas do tomate é o ácaro vermelho Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae). Uma característica marcante de T. evansi é a sua alta produção de teia sobre suas plantas hospedeiras. Essa teia pode afetar diretamente os inimigos naturais, reduzindo a sua eficiência de predação ou indiretamente alterando seu comportamento de busca. No entanto, alguns ácaros predadores da família Phytoseiidae podem ser bem adaptados para lidar com a teia dos ácaros fitófagos. Para selecionar agentes de controle biológico eficientes é importante compreender as interações diretas e indiretas entre os organismos envolvidos no agroecossistema em questão. Nesta dissertação, foi investigado o papel da teia produzida por T. evansi como mediadora de interações diretas e indiretas com seus inimigos naturais. No Capítulo 1 foram investigados os efeitos da teia produzida por T. evansi em suas interações com o ácaro predador Phytoseiulus longipes Evans (Acari: Phytoseiidae). Foi avaliado se fêmeas de T. evansi reconhecem sinais químicos do predador e se estes sinais podem induzir os ácaros a produzirem mais teia. Os resultados mostram que a presa não produz mais teia em resposta a estímulos de risco de predação, no entanto, passa a depositar uma maior parcela de seus ovos suspensos na teia, longe da superfície da folha. Esses ovos suspensos sofreram uma menor predação por P. longipes do que os ovos que se encontravam na superfície da folha. Entretanto a taxa de predação de P. longipes sobre ovos de T. evansi em discos com e sem teia não diferiram, indicando que esse predador não é afetado negativamente pela teia de sua presa. No segundo capítulo foi estudado se a teia produzida por T. evansi pode afetar o comportamento de forragemamento de P. longipes modulando a sua preferência entre ambientes e presas. Estudou-se também se ocorre predação intraguilda entre P. longipes e outro ácaro predador Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae), que podem coocorrerem sobre as mesmas plantas. Observou-se que P. longipes prefere as metades de discos de folhas que apresentavam uma estrutura mais complexa (mesmo quando eles não tinham alimento) em relação às metades dos discos com ovos e sem teia de T. evansi. Esta preferência por ambientes de estrutura complexa pode ser explicada pela menor taxa de predação intraguilda de P. macropilis observada em discos de tomate com teia de ácaros. A presença da teia reduziu a capacidade predatória de P. macropilis. A diferença entre ambos os predadores para lidar com a teia de ácaros fitófagos pode ser explicado em parte pelas diferenças no comprimento das setas dorsais j3, z2 e z4, que são mais longas em P. longipes. Com relação à preferência de P. longipes por espécies de presas, observou-se que os ácaros predadores escolheram T. evansi a T. urticae, tanto em presença quanto ausência de teia. Esses resultados indicam que a teia de T. evansi pode mediar o comportamento de forrageamento de ácaros da família Phytoseiidae de acordo com seus níveis de adaptações morfológicas e comportamentais. Em linhas gerais, pode-se concluir que os ácaros predadores P. longipes são bem adaptados para lidar com a grande quantidade de teia produzida por T. evansi. Além de não evitar plantas com elevada quantidade de teia, esse ácaro predador pode se beneficiar desse ambiente complexo, reduzindo a competição com outros predadores. No entanto, a presença do predador estimula T. evansi a mudar seu comportamento de oviposição, reduzindo a eficiência predatória de P. longipes. Assim, ao alterar o seu comportamento de oviposição em resposta aos sinais dos predadores, as fêmeas de T. evansi utilizam mais eficientemente sua teia para protegerem sua prole. / Worldwide, tomato suffers from herbivory. One of the most important tomato pests is the red spider mite Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae). A striking characteristic of T. evansi is its high production of web over its host plants. The web can directly affect natural enemies by reducing its predation efficiency or indirectly by changing its foraging behaviour. However some Phytoseiidae can be well adapted to cope with spider mite webbing. To select efficient biologicol control agents, it is important to understand the direct and indirect interactions between the organims involved in the agroecosystem. In this dissertation, I investigated how the web produced by T. evansi mediates direct and indirect interactions with its natural enemies. In Chapter 1 I investigate the effects of the web produced by T. evansi on its interactions with the predatory mite Phytoseiulus longipes Evans. We tested whether spider mite females recognize predator cues and whether these can induce the spider mites to produce denser web. We found that the prey did not produce denser web in response to such cues, but laid more eggs suspended in the web, away from the leaf surface. These suspended eggs suffered less predation by P. longipes than eggs that were laid on the leaf surface, under the web. However the predation rate of P. longipes on eggs of T. evansi on discs with and without web was not different, indicating that this predatory mite is not negatively affected by the spider mite web. In the second Chapter I studied whether the complex web produced by spider mites could affect the foraging behaviour of P. longipes modulating its preference between patches and prey. Was also studied if there is intraguild predation between the predatory mites P. longipes and Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae), which can co-occur on the same plants. We observed that P. longipes always preferred the leaf discs halves with more complex environmental structure (even when there was no food on it) to discs half with eggs and no web of T. evansi. The strong preference for patches with complex structure could be explained by the reduced rate of intraguild predation by P. macropilis observed on tomato discs with spider mite web. As observed, the presence of spider mite web reduced the predatory efficiency of P. macropilis in intraguild predation experiment. The difference between both predatory mites to cope with the web of spider mites could be explained in part by the differences in length of the setae j3, z2 and z4 that are longer in P. longipesi, but is needed manipulation of these traits. With respect to the preference of P. longipes by prey species, we observed that the predator chose T. evansi to T. urticae, both in the presence and absence of web. These results indicate that spider mite web can mediate the foraging behaviour of phytoseiid mites according to their level of morphological and behavioral adaptation to webbing. In general, we conclude that the predatory mite P. longipes is well adapted to cope with the higher web densities produced by T. evansi. Besides not avoid thus plants with high amounts of web, P. longipes can benefit from this complex environment by reducing competition with others predators. However the presence of the predatory mite stimulates T. evansi to change its oviposition behaviour, reducing the predation efficiency of P. longipes. Thus, by altering their oviposition behaviour in response to predator cues, females of T. evansi make better use of their web to protect their offspring.

Afin de limiter l’impact négatif des ravageurs sur les plantes cultivées, des agents de lutte biologique sont souvent introduits sous abris. Or, des interactions peuvent apparaître entre eux, comme la prédation intraguilde, et modifier l’efficacité de la lutte biologique. De plus, les défenses directes des plantes hôtes peuvent perturber l’efficacité des ennemis naturels. La question se pose donc de savoir s’il est possible de limiter les interactions négatives entre ennemis naturels et l’impact de la plante hôte sur leur développement. Pour répondre à cet objectif, afin d’optimiser la lutte biologique contre l’acarien Tetranychus urticae, ravageur très problématique, nous avons considéré deux cultivars de tomates caractérisés par des densités en trichomes et des concentrations en composés secondaires contrastéesl’acarien prédateur Phytoseiulus macropilis et Macrolophus pygmaeus, punaise prédatrice souvent employée pour lutter contre les aleurodes. Au cours d’essais conduits en serre, P. macropilis a permis de réguler T. urticae sans différence entre les deux cultivars, alors qu’en microcosmes le taux d’oviposition de P. macropilis a été supérieur sur le cultivar ayant la densité en trichomes non glandulaires la plus élevée. La consommation d’œufs de P. macropilis par M. pygmaeus en microcosmes n’a pas été observée en serre. Les interactions entre arthropodes se sont également traduites par une agrégation supérieure des T. urticae en présence des deux prédateurs et de P. macropilis en présence de M. pygmaeus. Avant de proposer P. macropilis comme nouvel agent de lutte bio / To suppress pest populations to such levels that damage to thecrop is minimized, multiple biological control agents are oftenintroduced in greenhouses. However, negative interactionsamong them, such as intraguild predation, might appear thatcan decrease the effi ciency of the plant protection strategy.Furthermore, plant direct (physical or chemical) defenseshave a negative impact on the pests but might also have animpact on the natural enemies. Therefore, the question iswhether it is possible to limit the negative interactions amongbiological control agents and the infl uence of the crop on thebehavior and development of the natural enemies. To optimizebiological control of Tetranychus urticae, a very problematicpest in tomato greenhouses, the effi ciency of the predatorymite Phytoseiulus macropilis was tested on two cultivars withdifferent trichome densities and concentrations of secondarycompounds, in presence or absence of Macrolophus pygmaeus,a mirid often used to regulate whitefl y populations.During two years, under greenhouse conditions, P. macropiliswell-controlled the population of T. urticae. There was no evidenceof intraguild predation between the two predators, butin the presence of M. pygmaeus, P. macropilis tended to havea more clumped spatial distribution. However, in microcosms,M. pygmaeus fed on P. macropilis eggs. Moreover, P. macropilislaid signifi cantly more eggs on the tomato cultivar with thehighest density of non-glandular trichomes, but this resultwas only observed in microcosms. The different dynami

Doctor of Philosophy / Department of Entomology / David C. Margolies / Yoonseong Park / The predatory mite Phytoseiulus persimilis (Acari, Phytoseiidae) is one of the most frequently released natural enemies for biological control of spider mites in greenhouse and outdoors crops. In this research, I utilized Expresses Sequence Tags (ESTs), the most cost effective approach for transcriptome exploration, to study three different aspects of this arachnid species for which there is little genomic information. I combined two EST datasets from different whole body cDNA libraries and analyzed by bioinformatics means. Approximately 54% of 10,256 uniESTs were annotated based on the homology to sequences in the National Center for Biotechnological Information (NCBI) database. A list of these uniESTs, sorted from most to least likelihood based on the expected value from the blast search in public databases, was used to create tools for each of the three studies. First, I described sixty-one genes encoding products known to be important in pesticide metabolism and in endocrinology, including cytochrome P450s, glutathione-S-transferases, acetylcholinesterase homologs, neuropetides and neurohormones. Findings on arachnid specific esterases and neuropetides, and possible benefits to pest management programs, were discussed. Next, I inferred divergence time for Acari and the point of divergence of two lineages within anactinotrichid mites, Ixodes scapularis and Phytoseiulus persimilis. I used expresses sequence tags from the predatory mite P. persimilis to pull out 74 orthologous amino acid sequences of invertebrates species: nine insect species, Daphnia pulex, Ixodes scapularis, and Caenorhabditis elegans. I estimated a similar origin for Chelicerata (578.1 ± 38.2 - 482.2 ± 7.2 Mya) as in other recent studies. However, divergence dating using amino acid sequences suggested a Devonian origin of anactinotrichid mites (487.6 ± 32.2 - 410.1 ± 6.1 Mya) based on four reference dates (two fossil records and two molecular clocks) and four amino acid substitution methods; this estimate is much earlier that those in the current literature. This discrepancy of divergence times may be due to the use of a global clock. Finally, I developed molecular markers from the EST dataset to examine inheritance in the haplodiploid system in P. persimilis. Biparental contribution of chromosomes is required among the predatory mites but the paternal chromosome set seems to be eliminated or loss (Paternal genome loss, PGL) in male offspring. However, genetic studies in other two phytoseiid species were suggested diploid males with PGL only in the germ cells. In the present study, haploid adult males of P. persimilis have been observed using five independent EST-derived markers. Single mites derived from inter-population crosses were genotyped after whole genome amplification. The parahaploid genetic system in P. persimilis is supported by this study, in which both sexes arise from fertilized eggs but the paternal chromosome set is subsequently lost in males.

Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-10-02T13:10:51Z No. of bitstreams: 1 texto completo.pdf: 635809 bytes, checksum: e37d831054d0f79444a7bba9655025d9 (MD5) / Made available in DSpace on 2017-10-02T13:10:51Z (GMT). No. of bitstreams: 1 texto completo.pdf: 635809 bytes, checksum: e37d831054d0f79444a7bba9655025d9 (MD5) Previous issue date: 2017-08-08 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Os ácaros predadores são comumente usados como agentes de controle biológico e as espécies Phytoseiulus macropilis e Neoseiulus californicus têm sido consideradas para serem liberadas em conjunto para controlar uma importante praga, o ácaro rajado Tetranychus urticae. Porque predadores que interagem podem interferir uns com os outros, um passo importante para a liberação bem-sucedida de múltiplos predadores em programas de controle biológico requer determinar como os predadores respondem à presença uns dos outros e se eles estão envolvidos em interações intraguilda. Diante disso, inicialmente, foi investigado se esses dois ácaros predadores evitam a presença um do outro. Sabe-se que predadores e parasitoides podem usar voláteis associados à presença de espécies competidoras quando forrageiam por áreas com presas ou hospedeiros. Portanto, foi analisado se as duas espécies de predadores usam substâncias voláteis que emanam de plantas com presas e heteroespecíficos para evitar locais de presa com a outra espécie de predador. Além disso, foi avaliado se esses predadores interagem através da predação intraguilda, em que predadores competidores matam e comem-se uns aos outros. No entanto, como não há consenso em relação aos critérios para avaliar a ocorrência de tal interação, primeiro foi explorado os critérios existentes e então foi sugerido diretrizes para o desenho de experimentos. Com base nessas diretrizes, foi investigado tanto a capacidade de P. macropilis e N. californicus para matar os estágios da outra espécie como a capacidade de se beneficiar alimentando-se destes estágios, ambos pré-requisitos para a ocorrência de predação intraguilda. As descobertas mais importantes sobre as possíveis interações entre esses predadores são que nenhum dos predadores usou voláteis para evitar locais de presas ocupadas pelos heterospecíficos. No entanto, eles se envolveram em predação intraguilda recíproca. Além disso, foi mostrado que a ontogenia claramente desempenhou um papel crítico na determinação da ocorrência de predação intraguilda dentro deste sistema de predadores. Foi discutido as possíveis explicações para não se evitar os odores produzidos e a interação entre estágios ontogênicos e interações intraguilda. / Predatory mites are commonly used as biological control agents and the species Phytoseiulus macropilis and Neoseiulus californicus have been considered to be released together to control an important pest, the two-spotted spider mite Tetranychus urticae. Because interacting predators may interfere with each other, an important step towards the implementation of successful release of multiple predators in biological control programs requires to resolve how predators respond to the presence of each other and whether they are involved in intraguild interactions. Given this, initially, I investigated whether these two predatory mites avoid the presence of each other. It is known that predators and parasitoids can use volatiles associated with the presence of competing species when foraging for patches with prey or hosts. I therefore investigated whether the two predator species use volatiles emanating from plants with prey and heterospecifics to avoid prey patches with the other predator species. Furthermore, I assessed whether these predators interact trough intraguild predation, in which competing predators also kill and eat each other. However, because there is no consensus regarding criteria to evaluate the occurrence of such interaction, I first explored existing criteria and suggested guidelines for the design of experiments. Based on these guidelines, I subsequently evaluated both the capacity of P. macropilis and N. californicus to kill stages of the other species and the capacity to benefit from feeding on these stages, both prerequisites for the occurrence of intraguild predation. The most important findings regarding the possible interactions among these predators are that neither of the predators used volatiles to avoid prey patches occupied by the heterospecific predators. However, they did engage in reciprocal intraguild predation. Moreover, I show that ontogeny clearly played a critical role in determining the occurrence of intraguild predation within this predator system. I discuss the possible explanations for the lack of odour-mediated avoidance and the interplay between ontogenetic stages and intraguild interactions.

The spider mite predator Phytoseiulus persimilis Athias-Henriot and the thrips predator Amblyseius cucumeris (Oudemans) are both commercially mass-reared for use as biological control agents for greenhouse pests. The ability to stockpile these mites in cold storage would greatly facilitate economical mass-production and distribution. In addition, these two species provide an opportunity for comparative studies of cold hardiness because P. persimilis originated in subtropical Mediterranean type climates and is thought to be incapable of entering diapause whereas A. cucumeris is widespread in temperate zones where adult females enter a reproductive diapause for overwintering. Temperature/mortality curves confirmed that both species are freezing intolerant in the traditional sense that supercooling points (SCPs), at which freezing of body fluids occurs, represent absolute lower lethal temperatures. Both species were capable of moderate supercooling, into the range of-20°C to -30°C, and both showed a trend of increasing SCP temperatures during development from egg to adult that suggested an inverse relationship between supercooling capacity and body size within species. The only exception to this trend was adult female A. cucumeris, which may be significant because this is the only life stage that is capable of diapause or survival of temperate winters. On the other hand, diapause induction and low temperature acclimation had little or no effect on supercooling capacity, and survival of nonacclimated mites at subzero temperatures above their SCPs was limited to very short periods of exposure, suggesting that the SCP represents a physical property of the mites rather than an adaptation for survival of exposure to subzero temperatures. Cold-storage survival of both species was optimum at 7.5°C, was greatly enhanced when a source of moisture was provided, and was enhanced even further when food was provided even though the mites were held at temperatures below their theoretical temperature threshold for development. Under these conditions, survival of P. persimilis was 80% after six weeks whereas that of A. cucumeris was only 35% after the same period of time. Furthermore, longevity and fecundity of P. persimilis after eight weeks of cold storage were comparable to mites taken directly from rearing cultures whereas oviposition by A. cucumeris after six weeks of cold storage was low and irregular compared to previously reported values. Temperature data from areas where P. persimilis survives outdoors indicate that this species is capable of surviving prolonged exposure to temperatures below 10°C and occasional exposure to subzero temperatures, and apparently does so without diapausing. On the other hand, A. cucumeris may be capable of surviving prolonged exposures to subzero temperatures, but only as diapausing adult females. The results of the current studies are consistent with these ideas and further suggest that nondiapausing A. cucumeris are less cold hardy than P. persimilis. / Graduate

The twospotted spider mite, Tetranychus urticae Koch, is a serious pest of many ornamental plants (Johnson and Lyon, 1991). Pesticide resistance, the high cost of pesticides and loss of production time have raised interest by growers to introduce predatory phytoseiid mites to manage twospotted spider mites and reduce their need for acaricide applications (Sabelis, 1981). The predatory mite Phytoseiulus persimilis Athias-Henriot has been used successfully in integrated pest management programs for T. urticae suppression. Despite the success of P. persimilis in reducing populations of T. urticae, acaricide applications may still necessary due to limitations associated with the effectiveness of P. persimilis introductions. The objectives of this study were to; 1. Measure the effects of acaricides on the density and age structure of T. urticae populations. 2. Determine the compatibility of acaricides in an IPM program by measuring the toxicity of residues to P. persimilis and T. urticae adults. 3. Study the feeding behavior of P. persimilis on T. urticae. 4. Measure the effects of combinations of acaricides followed by release of P. persimilis on T. urticae populations using greenhouse trials. The effects of ten acaricides on T. urticae populations were measured on infested Buddleia x davidii 'White Profusion' cuttings. Acaricides did not alter age structure in predictable manner. Initial analysis of results demonstrates that cuttings treated with acaricides had age structures that were different from control treatments. However, these differences were not distinguishable from natural fluctuations in the age structure. Chlorfenapyr may have changed the age structure of T. urticae. Azadirachtin, pyridaben and spinosad did not suppress T. urticae populations at the rates and formulations tested in this trial. Abamectin, bifenthrin, chlorfenapyr, Gowan 1725,oil and neem oil suppressed T. urticae populations. Hexythiazox suppressed T. urticae populations but these results were not seen until two weeks after application. The effects of acaricide residues were tested on adult P. persimilis and T. urticae 1, 3, 7, and 14 days after application using a leaf disk system. Abamectin, Gowan 1725, hexythiazox, horticultural oil, neem oil, pyridaben and spionsad were not toxic to P. persimilis adults while bifenthrin and chlorfenapyr residues were toxic to P. persimilis. Tetranychus urticae mortality from chlorfenapyr residues was significantly greater than the control 1,3,7 and 14 days after application. Tetranychus urticae mortality from bifenthrin and abamectin residues was significantly greater than the control 3, 7, and 14 days after application. Tetranychus urticae mortality caused by Gowan 1725, horticultural oil, and neem oil residues was significantly greater than the control 1 day after application, while mortality from hexythiazox and spinosad residues was not significantly greater than the control at any of the times tested in this study. Phytoseiulus persimilis feeding behavior studies examining life stage preference tests and functional response studies were conducted on bean leaf disks. We found P. persimilis functional response to be a type II response for both eggs and adults with handling times of 0.079 hours for eggs and 3.399 hours for adults. The effects of a combination of acaricides followed by release of P. persimilis on T. urticae populations was tested using greenhouse studies conducted on infested Buddleia plants. In the first trial, severe plant damage occurred despite a reduction in the mean number of mites per leaf in treatments with oil+ predator treatments 7 days after release. Results from the second greenhouse trial produced plants with less visual damage compared to those in the first greenhouse trial. Treatments with predators alone and predators + acaricides produced similar results. However, treatments with predators had a mean numbers of mites per leaf that were significantly less than treatments with acaricides alone. The results demonstrate that the acaricides tested in the second greenhouse trial allowed the predators to provide suppression of T. urticae populations. A high release rate was used in the second greenhouse trial and lower release rates as well as different acaricide predator combinations need be tested to explore the possibility of new management techniques. Our results suggest that the number of pest mites present in the crop may be the most important factor affecting the success of biological control with predators. Combinations of oil applications followed by introduction of P. persimlis 3 days after release provided suppression of T. urticae populations in a meaningful time frame. I was not able to shape the age structure of T. urticae populations in a predictable manner with acaricide applications. Phytoseiulus persimilis does not have a prey-stage preference when feeding on T.urticae, but the shorter handling time for eggs may indicate that they are better able to suppress populations with higher proportions of eggs. However, we cannot determine if P. persimilis can keep T. urticae populations composed of predominately of eggs below threshold levels because our greenhouse trials did not test this hypothesis. Phytoseiulus persimilis feeding on adult T. urticae may suppress T. urticae populations below threshold levels because a reduction in the number of adults will lead to a reduction in the number of T. urticae eggs deposited on a plant. Our research suggests that abamectin and oil are two acaricides that would be less detrimental to the survival of P. persimilis. Additional greenhouse trials with compatible acaricides should be conducted as well as research on the threshold density of T. urticae that will allow P. persimilis to provide adequate control. / Master of Science