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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Predátorské chování v dopravním sektoru - případ "České Dráhy v. Leo Express" / Predatory Behaviour in Transportation Sector - "Czech Railways v. Leo Express" case

Slámová, Iva January 2018 (has links)
It is important to control whether dominant companies in particular market sectors follow laws and rules and do not abuse their dominance at the expense of weaker companies. This behaviour is likely to damage current or avoid the entry of new competitors, shrink the competition and set the environment for price changes the consumer is exposed to. The thesis clarifies the theoretical aspect of this issue and tries to apply it on the real case from the railway transport sector in order to describe the procedure of defining relevant market and market share and investigating the abusive behaviour. A questionnaire survey among railway passeners is an integral part of the thesis. JEL Classification D21, D22, K21, L11, L12, L40 Keywords Predatory prices, relevant market, SSNIP test, railway transport, Czech Railways Author's e-mail Iva-Slamova@seznam.cz Supervisor's e-mail vacek@fsv.cuni.cz
102

Influência da vegetação nativa de Mata Atlântica sobre a ocorrência e distribuição de ácaros (Acari) da seringueira (Hevea brasiliensis Muell Arg.) no estado da Bahia

Nuvoloni, Felipe Micali [UNESP] 18 February 2011 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:22:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-18Bitstream added on 2014-06-13T20:29:29Z : No. of bitstreams: 1 nuvoloni_fm_me_sjrp.pdf: 1127819 bytes, checksum: eaf97a3b38a45d5649983644c5c97660 (MD5) / Plantas nativas podem servir como reservatório para ácaros predadores que também são encontrados em plantas cultivadas. Fragmentos florestais presentes na borda de seringais podem influenciar positivamente a ocorrência de ácaros predadores no seringal, pois esses podem se deslocar da vegetação nativa para as seringueiras e vice-versa. O objetivo desse estudo foi conhecer as espécies de ácaros associadas às plantas nativas de Mata Atlântica, que ocorrem próximas a seringais na região sul da Bahia, com ênfase nas espécies predadoras. As coletas foram qualitativas em três áreas: uma que faz limite com a borda do seringal, e duas em que as plantas nativas adentram o interior do seringal. Foram registradas 164 espécies representando 24 famílias, sendo as famílias Phytoseiidae e Tarsonemidae aquelas com o maior número de espécies registradas. Schefflera sp. (Araliaceae) foi a planta que abrigou a maior riqueza de ácaros predadores (19) e também o maior número de fitoseídeos (8). Essa elevada riqueza de predadores pode ser um indicativo de sua importância em servir como reservatório para esses ácaros. O grande número de espécies acarinas registradas nesse estudo ressalta a importância deste bioma como um dos centros mundiais de biodiversidade / Native trees can be used as reservoir by predators mites that live in crops. Forest fragments located in the edge of rubber tree crops can influence helpfully the occurrence of predators mites in the rubber tree crops, because they can move from native vegetation to the rubber trees. In this study we assessed the mites species that live associated with native plants of the Atlantic Rainforest, neighboring to rubber tree crops from southern of the Bahia State, with emphasis in the predators species. The samples were qualitative and taken monthly from May 2008 to April 2009 in three areas: one these is located on the border of rubber tree crop and two whose native plants had within the rubber tree crop. We registered 164 mite species belonging to 24 families. Phytoseiidae and Tarsonemidae were the families with the higher number of species. Schefflera sp. (Araliaceae) was the native tree with the richest fauna of predators (19) and phytoseiid mites (8). This high richness can indicates its importance like a reservoir of these species of mites.. The high number of mites species found in this study highlights the great importance of this biome as a worldwide hotspot
103

Aspectos biológicos e taxa de consumo de Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae) predando Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) /

Brito, Juliana Pires. January 2009 (has links)
Orientador: Sergio Antonio De Bortoli / Banca: Robson Thomaz Thuler / Banca: Rogéria Inês Rosa Lara / Resumo: O trabalho foi desenvolvido no Laboratório de Biologia e Criação de Insetos (LBCI) da FCAV - UNESP - Jaboticabal, para avaliar os aspectos biológicos e a taxa de consumo do predador Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae), alimentando-se de ovos e lagartas de segundo ínstar de Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) e em ovos de Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) (considerado tratamento testemunha). Para as espécies estudadas, O. insidiosus apresentou um período ninfal maior quando alimentado com lagartas de P. xylostella. O consumo total, durante a fase ninfal, foi maior quando alimentados com ovos de A. kuehniella, ovos e lagartas de P. xylostella, respectivamente. Na fase adulta, o período de pré-oviposição foi menor para os insetos alimentados com lagartas de P. xylostella, o que resultou em um encurtamento nessa fase biológica do predador. Os ovos de P. xylostella foram nutricionalmente mais adequados ao desenvolvimento de O. insidiosus. Para os ovos de P. xylostella, O. insidiosus apresentou curva de resposta funcional tipo II e mostrou uma tendência de estabilização nas densidades mais altas. A taxa de ataque (a) foi de 0,0127 ovos/hora e 0,00233 lagartas/hora e o tempo de manipulação (Th) foi de 1,4037 horas e de 2,7903 horas, para ovos e lagartas de P. xylostella, respectivamente. / Abstract: This study was done at the Laboratório de Biologia e Criação de Insetos (LBCI) at FCAV - UNESP - Jaboticabal, to assess the biological aspects and the rate of consumption of the predator Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae), feeding on eggs and second instar larvae of Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae) and on eggs of Anagasta kuehniella (Zeller, 1879) (Lepidoptera: Pyralidae) (considered to be check treatment). For the species studied, O. insidiosus presented a longer nymph period when fed with P. xylostella caterpillars. Total consumption, during the nymph stage, was greater for A. kuehniella eggs, P. xylostella eggs and caterpillars, respectively. In the adult phase, the preoviposition period was shorter for the insects fed on P. xylostella caterpillars, demonstrating a shortening of this biological phase in the predator. The eggs of P. xylostella were nutritionally better suited to the development of O. insidiosus. For the eggs of P. xylostella, O. insidiosus presented a type II functional response curve, showing a tendency to stabilize in higher densities. The searching rate (a) was 0.0127 eggs/hour and 0.00233 caterpillars/hour and the handling time (Ht) was 1.4037 hours and 2.7903 hours, for P. xylostella eggs and caterpillars, respectively. / Mestre
104

Exploration of potential agents for the biological control of the red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), on coconut palms in Brazil / Exploração de agentes potenciais para o controle biológico do ácaro-vermelho-das-palmeiras, Raoiella indica Hirst (Acari: Tenuipalpidae), em coqueiros no Brasil

Daniel Chiaradia Oliveira 17 March 2015 (has links)
The red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), has been considered an important pest on coconut palm (Cocos nucifera L.) in the New World. Several studies have been conducted to understand the ecology of this mite, aiming at its control. The search for effective natural enemies to control R. indica has been considered a priority to reduce its importance in areas where it has been newly reported, with special attention to predatory mites of the family Phytoseiidae. Little has been published about the phytoseiid fauna of Thailand, where R. indica has been found at low population levels, perhaps due to the action of natural enemies. The general objective of this thesis was to select promising predatory mites in Thailand (Bangkok and Kamphaeng Saen) to control R. indica on coconut palms in Brazil, to introduce them and to conduct an initial evaluation of their efficiency. Initially, a list of the phytoseiid mites until then reported from Thailand and a taxonomic key to help in their separation were prepared. Thirty two phytoseiid species were known from Thailand before this study; seven new records were presented. The predatory mite fauna associated with R. indica in the central region of Thailand and their population dynamics were assessed. Phytoseiidae was the predatory family most frequently found on coconut and lady palm, Rhapis excelsa (Thunb.) A. Henry, although at low levels (maximum of 0.003 specimens/ cm2 on coconut and 0.008 specimens/ cm2 on lady palm). Amblyseius largoensis (Muma) was the most abundant predator in both sites and on both hosts, except on coconut in Bangkok, which the most abundant was Euseius nicholsi (Ehara & Lee). The levels of R. indica were very low (maximum of 0.03 specimens/ cm2 on coconut and 0.48 specimens/ cm2 on lady palm), compared to what have been reported in other parts of the world. The direct effect of rainfall on the population of R. indica on coconut seedlings in Thailand was evaluated. The results suggested that rainfall reduces considerably the population of R. indica, mainly when the accumulated precipitation in 15 days was over 100 mm. A new mite genus and species of Blattisociidae collected on coconut flowers in Thailand were described. The performances of two predatory mite populations introduced from Thailand, a population previously introduced from La Reunion and a population native from Roraima, Brazil, were compared in relation to their effect on the population of R. indica. The efficiency of the predators could not be demonstrated on coconut seedlings, contrasting with what would be expected from their observed behavior in the laboratory. This result could be due to the overexposure of the predators to sunlight on the leaf surface because of the architecture of the seedlings, probably stimulating them to move to more protected microhabitats. On adult coconut plants, in which the abaxial leaf surface is less exposed, the evaluated predators could have a better performance. Further efforts should be dedicated to evaluate this hypothesis. / O ácaro-vermelho-das-palmeiras, Raoiella indica Hirst (Acari: Tenuipalpidae), tem sido considerado uma importante praga em coqueiro (Cocos nucifera L.) no Novo Mundo. Vários estudos têm sido conduzidos para entender a ecologia deste ácaro, visando ao seu controle. A busca de inimigos naturais eficazes para controlar R. indica tem sido considerada uma prioridade para reduzir a sua importância em áreas em áreas em que tem sido recentemente encontrado, com atenção especial aos ácaros predadores da família Phytoseiidae. Pouco tem sido publicado sobre a fauna de fitoseídeos da Tailândia, onde R. indica tem sido encontrado em baixos níveis populacionais, talvez devido à ação de inimigos naturais. O objetivo geral desta tese foi selecionar ácaros predadores promissores na Tailândia (Bangkok e Kamphaeng Saen) para o controle de R. indica em coqueiros no Brasil, introduzi-los e realizar uma avaliação inicial de sua eficiência. Inicialmente, uma lista dos fitoseídeos até então relatados da Tailândia e uma chave taxonômica para ajudar na sua separação foram elaboradas. Trinta e duas espécies de fitoseídeos eram conhecidas da Tailândia antes deste estudo; sete novos registros foram apresentados. Os ácaros predadores associados a R. indica na região central da Tailândia e sua dinâmica populacional foram avaliadas. Phytoseiidae foi a família de predadores mais freqüentemente encontrada em coqueiro e palmeira ráfia [Rhapis excelsa (Thunb.) A. Henry], embora os seus níveis sejam baixos (máximo de 0.003 espécimes/ cm2 em coqueiro e 0.008 espécimes/ cm2 em palmeira ráfia). Amblyseius largoensis (Muma) foi o predador mais abundante em ambos os locais e em ambos hospedeiros, exceto no coqueiro em Bangkok, em que o mais abundante foi Euseius nicholsi (Ehara & Lee). Os níveis de R. indica foram muito baixos (máximo de 0.03 espécimes/ cm2 em coqueiro e 0.48espécimes/ cm2 em palmeira ráfia), em comparação com o que tem sido relatado para outras partes do mundo. O efeito direto da chuva sobre a população de R. indica foi avaliado em mudas de coqueiro na Tailândia. Os resultados sugeriram que a chuva reduz consideravelmente a população de R. indica, principalmente quando a precipitação acumulada em 15 dias foi superior a 100 mm. Um novo gênero e espécie de ácaro da família Blattisociidae coletada em flores de coqueiro na Tailândia foram descritos. Os desempenhos de duas populações de ácaros predadores introduzidos da Tailândia, uma população previamente introduzida de La Reunion e uma população nativa de Roraima, Brasil, foram comparados em relação a seus efeitos sobre a população de R.indica. Não foi demonstrada a eficiência dos predadores em mudas de coqueiro, contrastando com o que era esperado a partir dos comportamentos observados no laboratório. Este resultado poderia ser devido à exposição excessiva dos predadores à luz do sol na superfície das folhas, por causa da arquitetura das mudas, provavelmente estimulando-os a se locomover para microambientes mais protegidos. Em coqueiros adultos, em que a superfície abaxial da folha é menos exposta, os predadores avaliados poderiam ter melhor desempenho. Esforços adicionais deveriam ser dedicados para avaliar esta hipótese.
105

Papel dos receptores opióides m e k da substância cinzenta periaquedutal (PAG) na seleção comportamental durante a lactação. / Role of periaqueductal gray m and k opioid receptors in behavioral selection during lactation.

Marianne Orlandini Klein 20 April 2012 (has links)
Após o parto, a mãe deve optar por buscar por comida ou cuidar da prole sendo que a substância cinzenta periaquedutal (PAG) é uma área central importante de regulação, seleção e um sítio de ação de opióides. Ainda não se sabe a importância funcional de cada um dos receptores opióides na PAG sobre a expressão dos comportamentos materno e predatório. Foram utilizadas ratas com cânula unilateral implantada na PAG e divididas em dois experimentos: Experimento 1, onde as ratas receberam injeções de agonista m, ou o agonista k, ou sulfato de morfina, ou veículo; Experimento 2, onde receberam antagonista m seguido de sulfato de morfina, ou antagonista k seguido de sulfato de morfina, ou sulfato de morfina, ou veículo. Os animais foram avaliados no teste de comportamento materno versus predatório. Os resultados sugerem que o tônus opióide endógeno é importante para a expressão do comportamento predatório e há possibilidade da morfina agir em mais de um tipo de receptor opióide simultaneamente para promover a inibição do comportamento materno nesse contexto. / After giving birth, a mother must both provide subsistence and care for her young. Periaqueductal gray (PAG) is an important area for behavioral selection and a site of opioid action. The functional role of PAG opioid receptors in the expression of maternal and predatory behaviors is not clear. Rats with unilateral guide cannulae implanted in the PAG were separated into two experiments: Experiment 1 where the animals received injectios of m receptor agonist, or k receptor agonist, or morphine sulfate, or vehicle; Experiment 2, where they received m receptor antagonist followed by morphine sulfate, or k receptor antagonist before morphine sulfate, or morphine sulfate, or vehicle. The animals were then tested for maternal behavior vs. predatory hunting. The results suggest that endogenous opioid tone is important for the expression of predatory behavior. The results further raise the possibility that morphine acts at more than one type of opioid receptor simultaneously to inhibit maternal behavior in this context.
106

Diversidade e dinâmica populacional de ácaros em frutos de coqueiro e descrição de nova espécie de Proctolaelaps / Diversity and population dynamics of mites in coconut fruits and description of new species of Proctolaelaps

REIS, Aleuny Coutinho 20 June 2006 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-11-22T16:17:56Z No. of bitstreams: 1 Aleuny Coutinho Reis.pdf: 1114699 bytes, checksum: c08877da9bd2f13a4cce3c479b18f69f (MD5) / Made available in DSpace on 2016-11-22T16:17:56Z (GMT). No. of bitstreams: 1 Aleuny Coutinho Reis.pdf: 1114699 bytes, checksum: c08877da9bd2f13a4cce3c479b18f69f (MD5) Previous issue date: 2006-06-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Aceria guerreronis Keifer, 1965 (Actinedida: Eriophyidae) is considered an important pest of coconut palm worldwide. Although being an important pest, lack information about the population dynamics of A. guerreronis and natural enemies associated with this pest in Brazil. Thus, this work investigated the population dynamics of A. guerreronis and their predatory mites on coconuts in the coastal counties of Maragogi (States of Alagoas), Itamaracá (State of Pernambuco), and Pitimbu (State of Paraíba). In addition, present the description of a new species, Proctolaelaps (Ascidae) found associated with the pest. The survey was conducted once a month from January to December 2005 collecting 30 coconuts from three different plants on each of these locales. In the laboratory, the coconut’s bracts were taken off and observed under stereomicrocopic, and all mites found were collected, mounted in slides and identified. Based on the data obtained were determined the dynamics of identified species and ecological indices for the species making up the communities. A. guerreronis exhibited greater abundance during December, June and May in Maragogi, Itamaracá and Pitimbu counties, respectively. Among the families of predatory mites, the phytoseiids were the most abundant accounting for 97%, 95% and 82% of individuals collected in Itamaracá, Maragogi and Pitimbu, respectively. And, among phytoseiids, Neoseiulus baraki (Athias-Henriot) was the most abundant, dominant, frequent and regularly collected in all surveyed fields. The new species of Proctolaelaps was characterized based on the absence of the seta z3 and R3, a dilated seta Z5 in the apex, and a spermatodactyl longer than usual in other species. / Aceria guerreronis Keifer (Prostigmata: Eriophyidae) é considerada uma das principais pragas do coqueiro no mundo. Embora sendo importante, pouco se sabe sobre os inimigos naturais de A. guerreronis no Brasil, assim como a sua dinâmica populacional. O objetivo desse trabalho foi identificar os inimigos naturais de A. guerreronis e estudar a dinâmica populacional desse eriofídeo e de seus predadores nos municípios litorâneos de Maragogi-Alagoas, Itamaracá-Pernambuco e Pitimbu-Paraíba, além de descrever uma nova espécie de Proctolaelaps (Ascidae) encontrada associada a esta praga. Durante o ano de 2005, amostraram-se mensalmente 30 frutos de coqueiro em cada um dos três campos localizado nos municípios de Maragogi, Itamaracá e Pitimbu. No laboratório, as brácteas foram separadas dos frutos e examinadas sob estereomicroscópio. Os ácaros foram coletados, montados em lâminas, identificados e quantificados. Determinou-se a abundância, freqüência, constância e dominância das espécies. Os maiores níveis populacionais de A. guerreronis foram verificados nos meses de dezembro em Maragogi, junho em Itamaracá e maio em Pitimbu. Dentre as famílias de ácaros predadores, os fitoseídeos foram os mais abundantes, representando 97; 95 e 82% dos ácaros coletados em Itamaracá, Maragogi e Pitimbu, respectivamente. Dentre esses, Neoseiulus baraki (Athias-Henriot) foi dominante, muito abundante, muito freqüente e constante em todos os campos. A espécie nova de Proctolaelaps se caracteriza pela ausência das setas z3 e R3, Z5 dilatada no ápice, além do espermadáctilo bastante longo.
107

Evolução da memória em aranhas do grupo Orbiculariae / Evolution of memory in Orbiculariae spiders

Vanessa Penna-Gonçalves 01 April 2011 (has links)
A memória é considerada por muitos pesquisadores como um dos produtos mais fascinantes da evolução biológica, justamente por proporcionar aos animais a vantagem adaptativa de se utilizar de uma experiência prévia para a solução de problemas necessários para a sobrevivência. Os animais se utilizam de processos mnemônicos durante o forrageamento, a seleção de parceiros sexuais, seleção de habitat e a preferência alimentar. As aranhas são um modelo interessante em estudos de memória e há evidências do uso de experiências passadas na otimização do forrageio: a teia permite que as aranhas capturem e armazenem mais de um item alimentar. Há carência na literatura de estudos comparativos evolutivos da memória, o que dificulta identificar as possíveis pressões seletivas. O primeiro objetivo deste trabalho foi fazer um estudo comparativo de aspectos da memória predatória em aranhas do grupo Orbiculariae. Este grupo é monofilético e tem como principal sinapomorfia a construção de teia orbicular. Porém, ao longo da evolução, o padrão de teia foi se modificando desde uma estrutura plana até uma tridimensional. Tais modificações podem ter gerado diferenças comportamentais e no sistema de memória dessas aranhas. Por este motivo, o outro objetivo, foi traçar a evolução da memória dentro do grupo. Delinearam-se três grupos de estudo com sete espécies. Na condição natural, observou-se a captura de duas presas sucessivas. Na condição experimental I, ofereceu-se uma primeira presa (p1) à aranha e, em seguida, ofereceu-se uma segunda (p2); durante o deslocamento da aranha até p2, retirou-se p1 da teia. Na condição II, ao invés de se oferecer p2, a aranha foi atraída à periferia (simulando a queda de p2). No deslocamento da aranha até a fonte de vibração removeu-se p1. O indício de memória é observado quando, na supressão da presa, a aranha executa um comportamento denominado Busca. Neste, a aranha executa sacudidas/detecções dos fios no centro/refúgio da teia. A busca por p1 roubada foi observada em todas as espécies estudadas, exceto em Z. geniculata no grupo I. A presença de p2 parece interferir na expressão da memória de p1; deixar p2 na teia enquanto busca por p1, aumenta as chances de p2 também ser roubada por ação dos cleptoparasitas. Zosis apresenta algumas peculiaridades, entre elas a ausência de veneno. Dessa forma, o tempo gasto durante a imobilização de p2 parece ser suficiente para causar o esquecimento de p1. Todas as espécies buscaram por p1 quando não houve oferta de p2, inclusive Zosis. O tempo de busca, na condição I, diminui da base de Araneoidea até as famílias mais derivadas. No grupo II, há uma aparente inversão do sinal filogenético e o tempo de busca aumenta na família mais derivada. A estrutura da teia tridimensional parece ser mais complexa e, por este motivo, exigiria um sistema de navegação espacial também mais complexo quando comparado às aranhas orbitelas. A construção da teia parece ter sido crucial para a captura e armazenamento de presas excedentes, e tal comportamento, juntamente com a diversificação das teias, favoreceu a variação e evolução da memória na Ordem Araneae / Memory is one of the most fascinating products of biological evolution, because it endows animals with the adaptive use a prior experiences to solve survival problems. Animals use mnemonic processes during foraging, selection of sexual partners, habitat selection, and feeding preference. Spiders are an interesting model for studies of memory, and there is evidence of their using of past experiences in optimizing foraging: the web allows the spiders to capture and store more than one food item. In literature, there are few comparative studies, and no one about the evolution of memory, making it difficult to identify the possible selective pressures on memory. The first objective here was to make a comparative study on the aspects of predatory memory in spiders of the group Orbiculariae. This group is monophyletic and its main synapomorphy is building an orbicular web. However, during evolution, the web pattern changed from a flat to a three-dimensional structure. Such changes may have caused differences in behavior and memory. For that reason, another goal was to trace the evolution of memory within the group. We used three experimental groups with seven species each. In natural conditions, there was an observation of the capture of two successive preys. In the experimental condition I, a first prey (p1) was offered to the spider and, subsequently, another prey (p2) was offered; during the locomotion of the spider towards p2, p1 was removed from the web. In condition II, instead of offering p2, the spider was attracted to the periphery (simulating the fall of p2). As the spider moved towards the source of vibration, p1 was removed. The evidence of memory is observed when, in the suppression of the prey, the spider performs a behavior called search behavior: the spider runs plucking on threads in the web hub/retreat. The search for stolen p1 was observed in all species studied, except for Zosis geniculata in group I. The presence of p2 appears to interfere with the expression of p1 memory, and also leaving p2 on the web while searching for p1, increases the chances of having p2 stolen by the action of kleptoparasites. Zosis presents some peculiarities, including the absence of poison glands, leading to a prolonged immobilization of p2, in a time lag that could then be sufficient forget p1. All species sought by p1 when there was no offer of p2, including Zosis. The search time, in condition I, decreases from the base of Araneoidea until the most derived families. In group II, there is an apparent reversal of the phylogenetic signal and the search time increases in the most derived family. The three-dimensional structure of the derived webs seems to be more complex and, therefore, it would require a spatial navigation system also more complex if compared to the flat orbweb. The construction of the web seems to have been crucial for prey capture and storage of surpluses, and such behavior, along with the diversification of the webs, favored the variation and evolution of memory in the Order Araneae
108

Impact of cover cropping on arthropods in corn on the western high plains

Davis, Holly N. January 1900 (has links)
Master of Science / Department of Entomology / Larry L. Buschman, Lawrent Buschman / This study evaluated whether using a cover crop with corn would increase the threat from spider mites in western Kansas because cover crops may serve as a winter host. This study also evaluated whether a cover crop could affect corn rootworm and other ground dwelling arthropods in the cornfield. In the first study, downy brome, Bromus tectorum L., was used as the winter cover crop. There were two trials repeated for three years each. Each trial included: two amounts of irrigation, downy brome, and herbicide to control weeds. In the first trial there were no significant differences in corn rootworm, Diabrotica virgifera LeConte, damage across treatments, because there were no differences in brome residue across the treatments. In the second trial, corn rootworm damage was significantly more in plots with higher amounts of downy brome residue. There were no differences in numbers of spider mites: Banks grass mites, Oligonychus pratensis (Banks) or twospotted spider mites, Tetranychus urticae Koch, across treatments. Spider mite populations appeared to be suppressed by the predatory mite Neoseiulus spp., which also overwintered in the cover crop. Corn rootworm samples taken from a no-till irrigation experiment were variable among irrigation treatments but indicated a trend for rootworm damage to increase with increasing irrigation. In the second study, winter wheat, Triticum aestivum L., was used as the winter cover crop. There were three trials repeated for three years each. Each trial included two amounts of irrigation and winter wheat and three amounts of herbicide to control weeds. Upon completion of the agronomy trials, the plots were split into two subplots and one was tilled. Pitfall traps were installed to capture ground dwelling arthropods: (Coleoptera: Carabidae), wolf spiders (Araneae: Lycosidae) and crickets (Orthoptera: Gryllidae). Four carabid genera were more common under no-till conditions. One was more common in tilled plots. Five carabid genera were more common in plots with a history of high weed densities. Two carabid genera were more numerous in plots with the history of a cover crop. Crickets were more common under no-till conditions. Wolf spiders were more common in no tillage with a history of a cover crop.
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An investigation of plant-derived cardiac glycosides as a possible basis for aposematism in the aphidophagous hoverfly Ischiodon aegryptius (Wiedemann) (Diptera: Syrphidae)

Malcolm, Stephen Baillie January 1977 (has links)
The chemical defences of insects against predators are either passive or aggressive. Passive defence is achieved through crypsis, and aggressive defence is maintained by a conspicuous or 'aposematic' (Poulton, 1890) appearance that advertises some noxious quality of the insect harmful to a predator. Aposematism is mutually beneficial to both the bearer and its predator, whereas crypsis only benefits the prey species. It is therefore not surprising that the fascinating array of chemical defences in insects is both diverse and widespread (Roth and Eisner, 1962). Intro. p. 1.
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An assessment of human carnivore conflict in the Kalahari region of Botswana

Klein, Rebecca Ann January 2014 (has links)
Human wildlife conflict is a considerable conservation challenge that threatens many carnivore species worldwide and is a result of complex socio-economic and ecological processes. An understanding of the drivers of conflict is essential for any efforts to achieve coexistence. This study investigated the levels of conflict, livestock management and tolerance amongst the farming communities of the Southern and Western Kalahari in Botswana. A questionnaire survey was completed with 310 farmers throughout the region. The majority of respondents regarded coexisting with carnivores as a challenge, with losses due to depredation perceived as the greatest problem facing farmers. Conflict was widespread throughout the study area, with some spatial variations for certain species. Cattle management levels were low and while smallstock management was better, the use of improved levels of management could reduce current levels of conflict. Tolerance levels were generally low with few respondents seeing the benefits of coexistence with carnivore species. The results indicated that farm type, gender, education level, source of income, livestock numbers, location and land use all have an effect on perceived conflict and tolerance levels and strongly interact with each other. In general cattleposts were characterised by higher proportions of females, lower education levels, more benefits derived from wildlife and veld products and fewer livestock than fenced ranches. They also experienced more conflict, carried out more management and had better tolerance levels. It could be that closer connections to the land and deriving benefits from natural resources resulted in more tolerance and this is certainly worth further investigation. An improvement in the use of effective methods of livestock management, targeted environmental education programs to develop a greater awareness for the conservation value of carnivores and a diversification of livelihoods to include benefits from natural resources have the potential to reduce conflict and improve tolerance in the Kalahari region.

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