• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 37
  • 17
  • 6
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 76
  • 48
  • 24
  • 23
  • 17
  • 15
  • 14
  • 13
  • 13
  • 12
  • 11
  • 10
  • 10
  • 10
  • 10
  • 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.
71

Toxicidade, efeito residual e repelência de acaricidas sintéticos e produtos naturais sobre Tetranychus urticae koch e Phytoseiulus macropilis (Banks), em algodoeiro / Toxicity, residual effect and repellency of synthetic acaricides and natural products on Tetranychus urticae Koch e Phytoseiulus macropilis (Banks) in cotton

ESTEVES FILHO, Alberto Belo 21 February 2012 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-11-21T16:01:30Z No. of bitstreams: 1 Alberto Belo Esteves Filho.pdf: 564769 bytes, checksum: 5fa5b6739b0d8ac06a2e177101cc0daf (MD5) / Made available in DSpace on 2016-11-21T16:01:30Z (GMT). No. of bitstreams: 1 Alberto Belo Esteves Filho.pdf: 564769 bytes, checksum: 5fa5b6739b0d8ac06a2e177101cc0daf (MD5) Previous issue date: 2012-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This work studied the lethal and sublethal effects, repellency, toxicity and residual effects of natural and synthetic acaricides on the two spotted mite, Tetranychus urticae Kock (Acari: Tetranychidae), and its predator, Phytoseiulus macropilis (Acari: Phytoseiidae). The synthetic acaricides fenpropathrin, chlorfenapyr, diafenthiuron, abamectin and spiromesifen and the botanicals oils of neem, Azadirachta indica A. Juss. (Meliaceae), Azadirachtin 1% and Azadirachtin A/B, Jatropha curcas L. (Euphobiacea) and Ricinus communis L. (Euphorbiacea) were tested. Based on LC50s e LC90s, spiromesifen was the most toxic to female mites and J. curcas to T. urticae eggs. To P. macropilis, the acaricides that caused more adverse effects were spiromesifen, J. curcas and Azadirachtin 1%. Oil of J. curcas used at sublethal concentrations was the only able to extinguish the population of T. urticae. Spiromesifen, R. communis and Azadirachtin A/B affected negatively the growth population of the two spotted spider mite. Population of P. macropilis exposed to spiromesifen, oil of J. curcas, and Azadirachtin 1% trended to extinction. However, when exposed to oil of R. communis and Azadiracthin A/B continued to grow. All acaricides tested, except oil of R. communis, were repellent to T. urticae females and affected oviposition of T. urticae. The treatment with oil of R. communis, J. curcas, and Azadiracthin 1% were repellent to the predatory female mites and affected its oviposition. The residual effect of fenpropathrin, chlorfenapyr, diafenthiuron, and abamectin caused mortality to T. urticae female over 90% up to the fourth evaluation. Fenpropathrin, diafenthiuron, abamectin, and spiromesifen caused reduction on female fecundity. The natural products tested were efficacious to two spotted spider mite adults only during the first evaluation. All tested acaricides exhibited efficacious control of T. urticae, but among the tested products the Azadiracthin A/B produced promising results to mite control in cotton ecosystem and was less harmful to the predatory mite. / O objetivo deste trabalho foi estudar os efeitos letais e subletais, repelência, toxicidade e efeito residual de acaricidas sintéticos e produtos naturais sobre Tetranychus urticae Kock (Acari: Tetranychidae) e Phytoseiulus macropilis (Banks) (Acari: Phytoseiidae). Os acaricidas fenpropatrina, clorfenapir, diafentiurom, abamectina e espiromesifeno e os óleos emulsionáveis de nim, Azadirachta indica A. Juss. (Meliaceae) (Azadiractina 1% e Azadiractina A/B), Jatropha curcas L. (Euphorbiaceae) e Ricinus communis L. (Euphorbiaceae) foram estudados. De acordo com as CLs50 e CLs90, espiromesifeno foi o mais tóxico para fêmeas, e J. curcas para ovos de T. urticae. Os acaricidas que causaram maior efeito adverso para P. macropilis, foram espiromesifeno, J. curcas e Azadiractina 1%. Espiromesifeno foi o único acaricida nocivo para P. macropilis. Quando testados em concentrações subletais, J. curcas foi o único capaz de extinguir a população de T. urticae. Espiromesifeno, R. communis e Azadiractina A/B afetaram, negativamente, o crescimento populacional da praga. A população de P. macropilis, quando exposta a espiromesifeno, J. curcas e Azadiractina 1%, tendeu à extinção. Porém, quando exposta a R. communis e Azadiractina A/B continuou crescendo. Todos os acaricidas, com exceção de R. communis, repeliram fêmeas e postura de T. urticae. Para o predador, R. communis, J. curcas e Azadiractina 1% também repeliram fêmeas e postura. Espiromesifeno e Azadiractina A/B repeliram apenas postura. Em relação à eficiência residual, fenpropatrina, clorfenapir, diafetiurom e abamectina, causaram mortalidade de fêmeas adultas de T. urticae superior a 98% até a quarta avaliação. Fepropatrina, diafentiurom, abamectina e espiromesifeno foram os que mais reduziram a fecundidade. Os produtos naturais foram eficientes para adultos, apenas na primeira avaliação, enquanto a redução de postura variou. Todos os acaricidas testados foram eficientes no controle de T. urticae, entretanto, Azadiractina A/B foi o mais promissor para o seu manejo no agroecossistema algodoeiro, pois, foi o menos nocivo para o predador.
72

Efeito de extratos vegetais e óleos essenciais de espécies nativas de Pernambuco sobre o ácaro rajado Tetranychus urticae Koch (Acari : Tetranychidae) / Effect of plant extracts and essentail oils of native species of Pernambuco on the two-spotted spider mite Tetranychus urticae (Acari : Tetranychidae)

PONTES, Wendel José Teles 01 February 2006 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-12-01T12:21:44Z No. of bitstreams: 1 Wendel Jose Teles Pontes.pdf: 861006 bytes, checksum: 961fa7bfa809cad4e7404803afd41260 (MD5) / Made available in DSpace on 2016-12-01T12:21:44Z (GMT). No. of bitstreams: 1 Wendel Jose Teles Pontes.pdf: 861006 bytes, checksum: 961fa7bfa809cad4e7404803afd41260 (MD5) Previous issue date: 2006-02-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The present work has the objective to verify the chemical composition and the bio activity of essential oils form fruits and leaves of Protium heptaphyllum and of X. sericea, and the fresh and old oil resins of Protium bahianum, as well as the effect of plant extracts of Croton sellowii, C. micans, C. rhamnifolium, C. jacobinensis and Xylopia sericea, all native species of Pernambuco, on the mite T. urticae. Major constituent identified in the essential oil of fruits from P. heptaphyllum is α-terpene (47.57 %) whereas in the leaves are the sesquiterpenes 9-epi-cariofileno (21.35 %), trans-isolongyfolanone (10.70 %) and 14-hydroxy-9-epi-cariofilene (16.70 %). The fruit oil is more efficient against mites in comparison with the leaf oil. Both oils show a property of mortality and deterrence in oviposition in the highest concentration (10μL L-1 air) and only the essential oil of fruits induces repellence on T. urticae. The essentialoils of the two resins of Protium bahianum were analysed. The old resin shows a high percentage of oxygen containing sesquiterpenes (85.40 %) with high predominance of β-(Z)-santalol acetate (83.08 %). No sesquiterpene was found in the essential oil of the fresh resin, which comprises basically monoterpenes of hydrocarbons (42.37 %) and oxygenated monoterpenes (27.71 %), from which α-phellandrene (13.86 %) and 4-terpineol (7.44 %) arte the major components, respectively. The oils show toxicity against ants, but only the essentialoil of the fresh resin show repellence. Of the studied Croton extracts, the one of the leaves of C. sellowii is the most efficient, causing 69 % of mortality and only the leaf extract of C. jacobinensis is inactive. Mites’ fecundity was affected and all extract show repellence in the concentration of 1%. The major compounds in the essential oil of fruits of X. sericea are β-pinene and α-pinene. The leaf oil is comprised basically by cubenol followed by α-epi-muurolol. Hexane extracts of fruits and the essential oils of fruits and leaves show toxicity against mites. The xylopic acid even not provoking mortality reduces mites’ fecundity. / O presente trabalho tem por objetivo verificar a composição química e a bioatividade dos óleos essenciais de frutos e folhas de Protium heptaphyllum e de Xylopia sericea, e os óleos das resinas velha e fresca de Protium bahianum, bem como o efeito de extratos vegetais de Croton sellowii, C. micans, C. rhamnifolius, C. jacobinensis e X. sericea, todas estas espécies nativas de Pernambuco, sobre o ácaro rajado Tetranychus urticae. O constituinte majoritário identificado no óleo essencial dos frutos de P. heptaphyllum foi α-terpineno (47,57%), enquanto que nas folhas foram os sesquiterpenos 9-epi-cariofileno (21,35%), trans-isolongifolanona (10,70%) and 14-hidroxi-9-epi-cariofileno (16,70%). O óleo dos frutos foi mais eficiente contra o ácaro, comparado com o óleo das folhas. Ambos os óleos apresentaram mortalidade e efeitos sobre a oviposição na maior concentração (10μL / L de ar) e apenas o óleo essencial dos frutos provocou repelência à T. urticae. Os óleos essenciais dos dois exsudatos resinosos de P. bahianum foram analisados. A resina velha mostrou alta percentagem de sesquiterpenos, contendo oxigênio (85,40%) com alta predominância de β-(Z)-santalol acetato (83,08 %). Contudo, nenhum sesquiterpeno foi detectado no óleo essencial de resina fresca, sendo este constituído basicamente de monoterpenos hidrocarbonados (42,37%) e monoterpenos oxigenados (27,71%), dos quais α-phellandrene (13,86 %) e 4-terpineol (7,44 %) foram os componentes majoritários, respectivamente. Os óleos mostraram ação fumigante, mas somente o óleo essencial de resina fresca foi repelente. Dentre os extratos de Croton estudados, verificou-se que o extrato de folhas de C. sellowii apresentou melhor performance, causando 69% de mortalidade e apenas o extrato de folhas de C. jacobinensis foi inativo. A fecundidade dos ácaros também foi afetada e todos os extratos foram repelentes na concentração de 1%. Os compostos majoritários encontrados no óleo essencial dos frutos de X. sericea foram β-pineno e α-pineno. O óleo das folhas foi majoritariamente constituído por cubenol seguido por α-epi-muurolol. Os extratos hexânicos de frutos e os óleos essenciais de frutos e folhas foram tóxicos ao ácaro rajado. O ácido xylópico, apesar de não ter provocado mortalidade, reduziu a fecundidade do ácaro.
73

Atividade de óleos essenciais de plantas das famílias Burseraceae, Lamiaceae, Rutaceae e Verbenaceae em Tetranychus urticae Koch e Neoseiulus californicus (McGregor) / Activity of essential oils from plants of families Burseraceae, Lamiaceae, Rutaceae and Verbenaceae in Tetranychus urticae Koch and Neoseiulus californicus (McGregor).

BORN, Flávia de Souza 01 February 2012 (has links)
Submitted by (edna.saturno@ufrpe.br) on 2016-12-01T14:41:32Z No. of bitstreams: 1 Flavia de Souza Born.pdf: 858418 bytes, checksum: 5785147d20d21fb9c69b74322ff6448b (MD5) / Made available in DSpace on 2016-12-01T14:41:32Z (GMT). No. of bitstreams: 1 Flavia de Souza Born.pdf: 858418 bytes, checksum: 5785147d20d21fb9c69b74322ff6448b (MD5) Previous issue date: 2012-02-01 / Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), has been controlled mainly chemical synthetic acaricides. The use of essential oils can be an alternative to this method of control. The aim of this study was to determine the effect of essential oils from plants of Families Burseraceae, Lamiaceae, Rutaceae and Verbenaceae against T. urticae and the predatory mite Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). Repellent and toxic activities of the oils were determined and compared to eugenol. Toxicity was evaluated by fumigation and residual effect in the laboratory and by direct contact in a greenhouse. The results showed that the oils of Ocimum basilicum L. and Thymus vulgaris L. were the most repellent, with RC50 = 3.43 x 10-7 and 2 x 10-4 μL/mL, respectively. The toxicity against eggs of T. urticae revealed T. vulgaris, Rosmarinus officinalis L., Citrus reticulata Blanco and O. basilicum oils as more active. Estimates of mortality concentration curves for fumigation of adult females of T. urticae revealed that was more toxic eugenol, with LC50 = 4 x 10-3 μL/L air. The test results showed that residual C. reticulata, T. vulgaris and O. basilicum oils present the same toxicity observed for eugenol. The toxicity tests to N. californicus indicated that all the oils are selective fumigation and that the O. basilicum, R. officinalis and C. reticulata oils were more selective by residual effect. The relative toxicity of the individual constituents of the essential oils and their contribuition to the acaricidal activity on T. urticae are also discussed. The highest average mortality on T. urticae in the greenhouse after 72 h of exposure were 100%, 98.85% and 96.59%, promoted by Citrus sinensis Osbek x Citrus reticulata Blanco, R. officinalis and Lippia gracilis Schauer oils, respectively. / O ácaro rajado, Tetranychus urticae Koch (Acari: Tetranychidae), tem sido controlado principalmente com acaricidas químicos sintéticos. O uso de óleos essenciais pode ser uma alternativa a esse método de controle. O objetivo deste trabalho foi determinar o efeito de óleos essenciais de plantas das Famílias Burseraceae, Lamiaceae, Rutaceae e Verbenaceae sobre T. urticae e o ácaro predador Neoseiulus californicus (McGregor) (Acari: Phytoseiidae). As atividades repelente e tóxica dos óleos foram determinadas e comparadas ao eugenol. A toxicidade foi avaliada por fumigação e efeito residual, em laboratório e por contato direto em casa de vegetação. Os resultados demonstraram que os óleos de Ocimum basilicum L. e Thymus vulgaris L. foram mais repelentes, com CR50 de 3,43 x 10-7 e 2 x 10-4 μL/mL, respectivamente. A toxicidade sobre ovos de T. urticae revelou os óleos de T. vulgaris, Rosmarinus officinalis L., Citrus reticulata Blanco e O. basilicum como mais ativos. As estimativas das curvas de concentração mortalidade para fumigação sobre fêmeas adultas de T. urticae revelaram que eugenol foi mais tóxico, com CL50 de 4 x 10-3 μL/L de ar. Os resultados dos testes de efeito residual demonstraram que os óleos de C. reticulata, T. vulgaris e O. basilicum apresentaram a mesma toxicidade observada para o eugenol. Os testes de toxicidade a N. californicus indicaram que todos os óleos foram seletivos por fumigação e os óleos de O. basilicum, R. officinalis e C. reticulata foram os mais seletivos por efeito residual. A toxicidade relativa de constituintes individuais dos óleos e sua contribuição para a atividade sobre T. urticae também são discutidos. As maiores médias de mortalidade sobre T. urticae em casa de vegetação após 72 h de exposição foram de 100%, 98,85% e 96,59%, promovidas pelos óleos de Citrus sinensis Osbek x Citrus reticulata Blanco, R. officinalis e Lippia gracilis Schauer, respectivamente.
74

Influence of the Allee effect and collective behaviour on population dynamics: the case of the two-spotted spider mite / Influence de l'effet Allee et du comportement collectif sur la dynamique des populations: le cas de l'acarien tisserand

Astudillo Fernandez, Aina 05 September 2011 (has links)
The Allee effect corresponds to a positive relationship between population size and individual fitness. This positive relationship can cause thresholds, that is, critical population sizes below which the population becomes extinct. For species submitted to the Allee effect, the formation and cohesion of groups is therefore crucial to survival. Animals can achieve this collective behaviour through local interactions. Each individual interacts locally with conspecifics and, at the scale of the group, a unity of behaviour emerges: the animals move together, rest in the same place, or choose the same habitat patch to settle on. <p><p>We use a combination of mathematical modelling and experimental work to study certain mechanisms of collective behaviour. In particular we assess the extent to which different individual interactions can induce collective patterns and thereby influence the dynamics of dispersal and settlement of populations. First, we study the collective settlement induced by the arresting effect of a marker secreted by conspecifics. Then, two potential mechanisms for collective movement are examined: following the conspecifics and following a trail laid by conspecifics. Finally, we integrate explicit mechanisms of dispersal behaviour in a dynamic model involving a set of interconnected populations. This allows the study of the interplay between collective movements and Allee effects at the scale of the metapopulation.<p><p>Our work is inspired by the lifestyle of the two-spotted spider mite, Tetranychus urticae, a phytophagous pest of recognised agricultural importance. These subsocial mites live in aggregates on the leaf surface, protected by a collectively spun silk web. Experimental evidence suggests that its population dynamics are subject to the Allee effect. Moreover, these mites show a tendency to migrate collectively, which makes them an appropriate biological model. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
75

Evaluation of image analysis for studing mite behaviour

Bowie, Mike H. January 1996 (has links)
The aim of this study was to investigate the usefulness of image analysis for studying mite behaviour. Image analysis was used to convert video recordings of mites' locomotory behaviour into a series of x,y coordinates that, when joined, closely resemble the paths of mites. The coordinates were also used to calculate walking speed, direction of travel, turning frequency, turn bias and tortuosity. Two experimental arenas were developed and used to study the movement of three mite species: 1) a leaf disc arena for two-spotted spider mite, Tetranychus urticae Koch and European red mite, Panonychus ulmi (Koch); and 2), a cover-slip/tack-trap arena for Typhlodromus pyri Scheuten. Two-spotted spider mite exhibited a change in locomotory behaviour through a 48 minute period. Mites exhibited a significant decline in distance travelled, whereas the mean stationary time (per four minute interval) more than doubled, and the duration of stationary events increased steadily over the same period. A reduction in sampling frequency of mite coordinates from one per second to one every two seconds and every four seconds produced a 5% and 12% 'loss' in path length respectively. Sample period length was shown to greatly influence the results produced for some of the mean parameters calculated, however, a reduction in sample length from 3000 to 1500 coordinates was not considered to cause a major loss in information. The influence of the inherent mite movement could not be ignored and made it difficult to make decisions on the 'best' sample length to use. Some strong correlations were found between parameters used to analyse mite locomotory behaviour. In particular, arithmetic mean vector length, speed, total stationary time and total distance travelled were significantly correlated with each other. Mean angular deviation and weighted mean vector length, which both measure the degree of clustering around the mean heading angle, were strongly negatively correlated. Parameters which differentiated between 'straight' and 'tortuous' mite movement were found to be mean meander, absolute mean turn and fractal dimensions. Mean meander was thought to be the most 'powerful', while coefficient of a straight line, a commonly used parameter for measuring tortuosity, did not significantly differentiate between the two different behaviours. Frequency distributions of turns and standard deviations of the three mite species were very similar. All three species had a slight bias to turning right (clockwise) rather than to the left (counter-clockwise) and for each species certain angles occurred more often than would be expected in a 'perfect' normal distribution. A similar pattern also occurred with the frequency distribution of two-spotted spider mite heading angles, in that angles which were expected to occur more often, did not, and vice versa. The potential to use saturated salt solutions to control relative humidity on the arena was` demonstrated and indicated that relative humidity is likely to have an important influence on mite behaviour. Two-spotted spider mites appeared to move more quickly in an attempt to escape the unfavourable, extreme (10% and 95% R.H. at 25°C) moisture conditions. All three mite species displayed a characteristic edge-walking behaviour around the arenas. However, when 'edge' and 'non-edge' behaviours were compared, mean meander was the only parameter (of the parameters tested) which gave a significant difference. Behavioural responses of European red mite and T. pyri to sub-lethal (field rate) esfenvalerate were investigated and the results indicated that these mites did not seek the unsprayed halves of the arenas during the first 48 minutes. However, significant differences in most behavioural parameters to esfenvalerate residues were found with European red mite when whole arenas were compared. Image analysis is an extremely useful research tool for studying mite behaviour because of its ability to measure many parameters quickly. Careful choice of the environmental conditions, the sampling framework, and interpretation of data is essential for meaningful results.
76

Evaluation of image analysis for studing mite behaviour

Bowie, Mike H. January 1996 (has links)
The aim of this study was to investigate the usefulness of image analysis for studying mite behaviour. Image analysis was used to convert video recordings of mites' locomotory behaviour into a series of x,y coordinates that, when joined, closely resemble the paths of mites. The coordinates were also used to calculate walking speed, direction of travel, turning frequency, turn bias and tortuosity. Two experimental arenas were developed and used to study the movement of three mite species: 1) a leaf disc arena for two-spotted spider mite, Tetranychus urticae Koch and European red mite, Panonychus ulmi (Koch); and 2), a cover-slip/tack-trap arena for Typhlodromus pyri Scheuten. Two-spotted spider mite exhibited a change in locomotory behaviour through a 48 minute period. Mites exhibited a significant decline in distance travelled, whereas the mean stationary time (per four minute interval) more than doubled, and the duration of stationary events increased steadily over the same period. A reduction in sampling frequency of mite coordinates from one per second to one every two seconds and every four seconds produced a 5% and 12% 'loss' in path length respectively. Sample period length was shown to greatly influence the results produced for some of the mean parameters calculated, however, a reduction in sample length from 3000 to 1500 coordinates was not considered to cause a major loss in information. The influence of the inherent mite movement could not be ignored and made it difficult to make decisions on the 'best' sample length to use. Some strong correlations were found between parameters used to analyse mite locomotory behaviour. In particular, arithmetic mean vector length, speed, total stationary time and total distance travelled were significantly correlated with each other. Mean angular deviation and weighted mean vector length, which both measure the degree of clustering around the mean heading angle, were strongly negatively correlated. Parameters which differentiated between 'straight' and 'tortuous' mite movement were found to be mean meander, absolute mean turn and fractal dimensions. Mean meander was thought to be the most 'powerful', while coefficient of a straight line, a commonly used parameter for measuring tortuosity, did not significantly differentiate between the two different behaviours. Frequency distributions of turns and standard deviations of the three mite species were very similar. All three species had a slight bias to turning right (clockwise) rather than to the left (counter-clockwise) and for each species certain angles occurred more often than would be expected in a 'perfect' normal distribution. A similar pattern also occurred with the frequency distribution of two-spotted spider mite heading angles, in that angles which were expected to occur more often, did not, and vice versa. The potential to use saturated salt solutions to control relative humidity on the arena was` demonstrated and indicated that relative humidity is likely to have an important influence on mite behaviour. Two-spotted spider mites appeared to move more quickly in an attempt to escape the unfavourable, extreme (10% and 95% R.H. at 25°C) moisture conditions. All three mite species displayed a characteristic edge-walking behaviour around the arenas. However, when 'edge' and 'non-edge' behaviours were compared, mean meander was the only parameter (of the parameters tested) which gave a significant difference. Behavioural responses of European red mite and T. pyri to sub-lethal (field rate) esfenvalerate were investigated and the results indicated that these mites did not seek the unsprayed halves of the arenas during the first 48 minutes. However, significant differences in most behavioural parameters to esfenvalerate residues were found with European red mite when whole arenas were compared. Image analysis is an extremely useful research tool for studying mite behaviour because of its ability to measure many parameters quickly. Careful choice of the environmental conditions, the sampling framework, and interpretation of data is essential for meaningful results.

Page generated in 0.0587 seconds