• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 83
  • 57
  • 16
  • 9
  • 1
  • 1
  • Tagged with
  • 188
  • 62
  • 53
  • 45
  • 36
  • 34
  • 27
  • 23
  • 20
  • 18
  • 17
  • 15
  • 13
  • 13
  • 12
  • 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.
41

Impact of harvest operations on parasitism of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae)

Meers, Scott Byron. January 2005 (has links) (PDF)
Thesis (M.S.)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: Wendell L. Morrill. Includes bibliographical references (leaves 119-126).
42

Aspectos biológicos e reprodutivos de Selitrichodes neseri (Hymenoptera : Eulophidae) Kelly & La Salle e estabelecimento do parasitoide em plantios florestais de eucalipto no Brasil /

Puretz, Barbara Oliveira de, 1991. January 2017 (has links)
Orientador: Carlos Frederico Wilcken / Banca: Pedro José Ferreira Filho / Banca: Michele Potrich / Resumo: Árvores do gênero Eucalyptus apresentam alto potencial econômico no setor florestal brasileiro, estão adaptadas às condições edafoclimáticas no Brasil proporcionando crescimento rápido, madeira de qualidade e usos múltiplos. No entanto, esta produção é comprometida por alguns fatores, destacando-se os insetos-praga. Uma das principais pragas exóticas do eucalipto no Brasil é Leptocybe invasa (Hymenoptera: Eulophidae). A fêmea realiza sua oviposição nas nervuras centrais das folhas, pecíolos e ramos, formando galhas, causando redução no crescimento, desfolha e morte da planta. Uma das principais medidas de controle deste inseto é o controle biológico, com o parasitoide exótico Selitrichodes neseri (Hymenoptera: Eulophidae). Neste trabalho foram avaliados a longevidade de adultos de S. neseri em diferentes concentrações de mel e diferentes temperaturas em laboratório, bem como foi realizado a descrição de ovários e sistema reprodutor masculino, e a recuperação de S. neseri em campo. Estes estudos básicos são importantes para analisar o potencial de S. neseri para controle de L. invasa em laboratório e em campo. Para a avaliação da longevidade de S. neseri, fêmeas e machos foram individualizados em tubos de vidro, esses insetos foram coletados recém emergidos, sexados, identificados e colocados nos tubos. Nesse experimento foram oferecidas as seguintes concentrações de mel: mel puro (100%), soluções de mel a 50% e 10% e testemunha (sem alimento). As temperaturas testadas foram 1... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Trees of the genus Eucalyptus are economically important to the Brazilian forestry, they have a good adaptation to the edaphoclimatic conditions in Brazil, providing fast growth, quality wood and multiple uses. However, this production is compromised by some factors, especially insect pests. One of the main exotic pest of eucalyptus in Brazil is Leptocybe invasa (Hymenoptera: Eulophidae). The female postures the eggs in the central ridge of the leaves, petioles and branches forming galls, causing growth reduction, defoliation and even plant death. One of the main control measures of this pest is the biological control, with the exotic parasitoid Selitrichodes neseri (Hymenoptera: Eulophidae). In this work the longevity of S. neseri adults in different concentrations of honey and different temperatures in the laboratory, description of ovaries and male reproductive system, and the recovery of S. neseri in the field were evaluated. These basic studies are important to analyze the potential of S. neseri for control of L. invasa in the laboratory and in the field. For the evaluation of the longevity of S. neseri, females and males were individualized in glass tubes, these insects were collected freshly emerged, sexed and identified to this experiment the following concentrations were used: pure honey (100%), 50% honey and 10% honey and control (without food). The temperatures tested were 18, 22, 25, 30 and 34 °C. All treatments were carried out in conditioned chambers with RH 60 ± 10% and of photoperiod 12 h, and evaluated from the first day of emergence until the death of each parasitoid. The Tukey-Kramer test adjusted by Sidak was used. For the description of the ovaries and the male reproductive system, three samples were analyzed, females of S. neseri mates, females of S. neseri virgins and males of S. neseri, these samples were placed in historesin and submitted to 2 μm histological cuts, these cuts ... / Mestre
43

Parasitóides, bruquídeos e plantas hospedeiras : riqueza de espécies e dinâmica espacial em escala local /

Rodrigues, Ligia Maria da Silva. January 2008 (has links)
Orientador: Marcelo Nogueira Rossi / Banca: Valmir Antonio Costa / Banca: Wesley Augusto Conde de Godoy / Resumo: O presente estudo foi dividido em duas partes. A primeira parte (capítulo 1) teve como objetivo avaliar se as características nutricionais dos frutos de Mimosa bimucronata influenciam a formação dos padrões de distribuição espacial de Acanthoscelides schrankie e seus parasitóides, os quais por sua vez podem determinar os padrões de dependência de densidade espacial na interação hospedeiro-parasitóide. Ramos em frutificação foram marcados e coletas quinzenais de frutos foram feitas em 2006 e 2007. Após a emergência dos insetos, análises nutricionais dos frutos de cada ano foram feitas (teor de água, nitrogênio e fenóis). Tanto A. schrankiae como seus parasitóides apresentaram estrutura espacial bem definida apenas durante o ano de 2007. Foram observados padrões independentes, inversamente dependentes e diretamente dependentes da densidade espacial, dependendo do momento de observação. Associações espaço-temporal significativas com e sem atraso de tempo entre bruquídeos e parasitóides, e entre bruquídeos e a porcentagem de parasitismo foram observadas. Associações espaciais mais intensas foram observadas sem atraso de tempo. Portanto, as populações de bruquídeos e parasitóides foram dinamicamente acopladas, mas tal padrão foi dependente do ano de observação. Constatou-se uma dissociação espacial significativa das populações de bruquídeos e parasitóides com os conteúdos de fenóis dos frutos, ou seja, a forte associação entre bruquídeos e parasitóides ocorreu em ramos com menor concentração de compostos fenólicos, o que pode ter contribuído para a formação dos padrões espaciais observados. Associações espaciais significativas não foram observadas entre as populações de bruquídeos e parasitóides com os respectivos teores de água e nitrogênio. Na segunda parte (capítulo 2) investigou-se... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study was divided into two parts. The objective of the first part (chapter 1) was to investigate whether fruit quality of Mimosa bimucronata plants influenced the spatial distribution patterns of Acanthoscelides schrankie and its parasitoids, which in turn would determine spatial density dependent patterns of host-parasitoid interactions. Branches were previously selected and fruits were collected at each fifteen days in years 2006 and 2007. After emergence of all insects, nutritional analyses of fruits were carried out for each year (water, nitrogen and phenolic contents). A. schrankiae and its parasitoids presented well defined spatial structure only in 2007. Independent, inversely density dependent and directly density dependent spatial patterns were verified; however, such patterns depended of the moment of observation. Significant spatio-temporal associations with and without time lags were observed between bruchids and its parasitoids and also between bruchids and the percentage of parasitism. The most significant spatial associations were verified without time lags. Therefore, bruchid and parasitoid populations were dynamically coupled, but these patterns were dependent of the year of observation. Significant spatial dissociations were verified between phenolic contents of M. bimucronata fruits and bruchid and parasitoid populations; therefore, significant spatial associations between bruchids and their parasitoids occurred on branches with lower concentrations of phenolic compounds, which may have determined the observed spatial patterns in the field. Significant spatial associations were not observed between bruchid and parasitoid populations and the water and nitrogen contents. In the second part (chapter 2), the species richness of bruchids and their host plants was investigated in a semi-deciduous forest fragment named as "Mata da Bica" (Botucatu-SP)... (Complete abstract click electronic access below) / Mestre
44

The Effects of Insecticides on Squash Bug, its Egg Parasitoids and Pollinators in Virginia Cucurbit Production

Wilson, James M. 02 February 2017 (has links)
My dissertation and research focused on the effects of insecticides on squash bugs, its egg parasitoid, and pollinators in the production of cucurbits in Virginia. Plants in the cucumber family are dependent on insect pollination for successful fruit set, and are also susceptible to plant eating insects. Squash bugs are capable of transmitting cucurbit yellow vine decline, and their feeding can cause significant wilt and death in many varieties. To control for squash bug and other pests, growers commonly combine the application of broad-spectrum insecticides with the frequently applied prophylactic fungicides. Broad-spectrum insecticide applications are known to have negative effects on natural enemy populations, are capable of promoting insecticide resistance, and can have negative effects on pollinators if care in their use is not taken. Squash bugs have several natural enemies, but their predominant egg parasitoid is most effective at reducing damaging populations. The scelionid wasp Gryon pennsylvanicum Ashmead, is a prevalent egg parasitoid in Virginia and can be negatively affected by the application of broad-spectrum insecticides. Through survey efforts I found that G. pennsylvanicum is widely distributed throughout Virginia and is capable of high rates of egg parasitism (>90%). This is contrary to the 20% level previously assumed for the East Coast. I explored the effects of narrow-spectrum insecticides on the fate of the egg parasitoids, those developing in the host egg and emerged adults of G. pennsylvanicum. Contact assays showed that the insecticides λ-cyhalothrin and sulfoxaflor had caused high adult parasitoid mortality. As new insecticides get registered for use there is often concern about their effect on pollinators, specifically the European honey bee Apis mellifera L. I evaluated the use of large flight cages as a method to measure the sub-lethal effects of narrow-spectrum insecticides to honey bees, as a means to qualify risk. The method utilizes small colonies of honey bees (with stores of nectar and pollen) and their feeding at a treated sucrose solution after being trained to a feeder in an enclosed arena. This choice-test style behavioral experiment shows promise in qualifying the risks associated with insecticide exposure in the field. In the case of pyrifluquinazon, colonies repeatedly choose to avoid feeding at tainted feeders even after training with no other outside sources of food present. Further researching the sub-lethal behavioral effects that insecticides have on bees in a colony can help us better qualify their risk. / Ph. D. / My dissertation and research focused on the effects of insecticides on squash bugs, its egg parasitoid, and pollinators in the production of cucurbits in Virginia. Plants in the cucumber family are dependent on insect pollination for successful fruit set, and are also susceptible to plant eating insects. Squash bugs are capable of transmitting cucurbit yellow vine decline, and their feeding can cause significant wilt and death in many varieties. To control for squash bug and other pests, growers commonly combine the application of broad-spectrum insecticides with the frequently applied prophylactic fungicides. Broad-spectrum insecticide applications are known to have negative effects on natural enemy populations, are capable of promoting insecticide resistance, and can have negative effects on pollinators if care in their use is not taken. Squash bugs have several natural enemies, but their predominant egg parasitoid is most effective at reducing damaging populations. The scelionid wasp <i>Gryon pennsylvanicum</i> Ashmead, is a prevalent egg parasitoid in Virginia and can be negatively affected by the application of broad-spectrum insecticides. Through survey efforts I found that <i>G. pennsylvanicum</i> is widely distributed throughout Virginia and is capable of high rates of egg parasitism (>90%). This is contrary to the 20% level previously assumed for the East Coast. I explored the effects of narrow-spectrum insecticides on the fate of the egg parasitoids, those developing in the host egg and emerged adults of <i>G. pennsylvanicum</i>. Contact assays showed that the insecticides λ-cyhalothrin and sulfoxaflor had caused high adult parasitoid mortality. As new insecticides get registered for use there is often concern about their effect on pollinators, specifically the European honey bee <i>Apis mellifera</i> L. I evaluated the use of large flight cages as a method to measure the sub-lethal effects of narrow-spectrum insecticides to honey bees, as a means to qualify risk. The method utilizes small colonies of honey bees (with stores of nectar and pollen) and their feeding at a treated sucrose solution after being trained to a feeder in an enclosed arena. This choice-test style behavioral experiment shows promise in qualifying the risks associated with insecticide exposure in the field. In the case of pyrifluquinazon, colonies repeatedly choose to avoid feeding at tainted feeders even after training with no other outside sources of food present. Further researching the sub-lethal behavioral effects that insecticides have on bees in a colony can help us better qualify their risk.
45

Análise cladística das moscas parasitoides de formigas dos gêneros Neodohrniphora Malloch 1914, Cremersia Schmitz 1924 e Eibesfeldtphora Disney 2009 (Diptera, Phoridae, Metopininae) / Cladistics analysis of the ant-parasitoid flies of the genera Neodohrniphora Malloch 1914, Cremersia Schmitz 1924 and Eibesfeldtphora Disney 2009 (Diptera, Phoridae, Metopininae)

Pereira, Thalles Platiny Lavinscky 27 February 2019 (has links)
Os dípteros da família Phoridae possuem grande diversidade, bem como apresentam entre seus gêneros e espécies uma das maiores plasticidades de papeis no ecossistema, atuando como herbívoros, decompositores, polinizadores, parasitoides etc.. Alguns grupos são conhecidos como parasitoides de formigas como os gêneros Cremersia Schmitz 1924, Eibesfeldtphora Disney 2009 e Neodohrniphora Malloch 1914. Em termos filogenéticos, a primeira hipótese cladistica proposta recuperou Cremersia Schmitz e Neodohrniphora Malloch como gêneros irmãos. Posteriormente, Neodohrniphora foi classificado em três subgêneros: N. (Eibesfeldtphora Disney), N. (Neodohrniphora Malloch) e N. (Wallerphora Disney). Mais recentemente, o subgênero Eibesfeldtphora foi elevado ao nível de gênero e os gêneros Cremersia e Neodohrniphora foram sinonimizados como único grupo, baseado em análises morfológicas. Tais mudanças foram justificadas com base nas características do ovipositor. Portanto, os objetivos do presente trabalho foram no capítulo 1, reconstruir as relações filogenéticas entre os gêneros Cremersia, Eibesfeldtphora e Neodohrniphora revisando amplamente os caracteres morfológicos de genitália e estudar as relações coevolutivas com seus hospedeiros, e no capítulo 2 revisar taxonomicamente o gênero Neodohrniphora. A maior parte do material estudado e analisado morfologicamente foi proveniente principalmente das coleções LACM (Los Angeles - EUA) e MZSP (São Paulo - Brasil). O resultado da análise filogenética recuperou os gêneros como monofiléticos e a presença de traços coevolutivos entre os parasitoides e os hospedeiros. No segundo capítulo sete novas espécies foram descritas para o gênero Neodohrniphora. Esse estudo confirma a importância de estudos de genitália feminina para os grupos de parasitóides, tanto para informações taxonômicas como para filogenéticas. Trabalhos futuros serão importantes para elucidar melhor esses mecanismos de oviposição dos forídeos, como o estudo da musculatura do abdômen e a observação em campo do ataque dos parasitóides às formigas / The Phoridae have a great diversity, as well as presenting one of the largest plasticides of roles in the ecosystem, acting as herbivores, decomposers, pollinators, parasitoids, etc. Some groups are known as ant parasitoids like the genera Neodohrniphora Malloch 1914,. Cremersia Schmitz 1924 and Eibesfeldtphora Disney 2009. In phylogenetic studies, the first proposed cladistic hypothesis recovered Cremersia Schmitz and Neodohrniphora Malloch as sister genera. Subsequently, Neodohrniphora was classified into three subgenus: Eibesfeldtphora, Neodohrniphora and Wallerphora. More recently, the subgenus Eibesfeldtphora was raised to the genus level and the genera Cremersia and Neodohrniphora were synonymized, based on morphological analyzes. The synonym was justified based on the characteristics of the ovipositor. The objective of the present work was to reconstruct the phylogenetic relationships between the genera Cremersia, Eibesfeldtphora and Neodohrniphora, revising extensively the morphological characters of genitalia and to study the coevolutionary relations with their hosts, and in chapter 2 make a revision of the genus Neodohrniphora. Most of the material studied and analyzed morphologically came from the LACM (Los Angeles - USA) and MZSP (São Paulo - Brazil) collections. The result of the phylogenetic analysis recovered the genera as monophyletic and the presence of coevolutionary traits between the parasitoids and the hosts. This study confirms the importance of studies of female genitalia for groups of parasitoids, both for taxonomic and phylogenetic information. Future works will be important to elucidate better the oviposition mechanisms of parasitoids, as the study of the musculature of the abdomen and the field observation of the attack of the parasitoids to the ants
46

Biology of the rice leafroller Cnaphalocrocis (Marasmia) exigua (Butler) (Lepidoptera: Pyralidae: Pauristinae) in Fiji

Singh, Satya Ram, University of Western Sydney, Faculty of Science, Technology and Agriculture, School of Horticulture January 1997 (has links)
The rice leafroller Cnaphalocrocis exigua (Butler) in the only species of the rice leaf folder/roller complex in Fiji. It is one of the major rice pests in the country, its pest status being exacerbrated by the cultivation of high-yielding varieties with minimal pest resistance. Detailed studies on the biology of the moth, in particular on the development, emergence, mating and flight behaviour, effect of adult nutrition on fecundity, egg hatchability and longevity, effect of larval nutrition on larval survival, pupation, pupal weight, pupal eclosion, and fecundity, egg hatchability and longevity of resultant adults, parasitism, and population ecology of C. exigua were carried out in Fiji from 1985 to 1987, and from June to August 1990. This study showed that there are several parasitoids of C. exigua in Fiji, and of those the egg and larval parasitoids Trichogramma sp. and Trathala flavo-orbitalis (Cameron) respectively are significant biotic mortality factors. Their impact as natural suppressors of C. exigua in fields of high yielding rice varieties was, however, inadequate to prevent C. exigua reaching damaging levels. Since C. exigua responds strongly to rice varietal differences, plant nitrogen status, and seasonal factors, is suspected to utilise pheromones during mating, and has numerous biocontrol agents in South East Asia and the Philippines, it appears to be an excellent candidate for an integrated pest management (IPM) program in Fiji. Before IPM strategies can be formulated, however, further investigations on rice varietal resistance, exploitation of exotic parasitoids and pathogens, and detailed studies on the possible presence of sex pheromones need to be conducted. / Doctor of Philosophy (PhD)
47

The molecular mechanism of immune evasion by the eggs and larvae of the Endoparasitoid Venturia canescens in its host, Ephestia kühniella /

Kinuthia, Wanja. January 1996 (has links) (PDF)
Thesis (Ph. D.)--University of Adelaide, Dept. of Crop Protection, 1997. / Includes bibliographical references (leaves 82-111).
48

Patch exploitation by the parasitoids of Plutella xylostella (L.): from individual behaviour to population dynamics /

Wang, Xin-geng. January 2001 (has links) (PDF)
Thesis (Ph.D.)--University of Adelaide, Dept. of Applied and Molecular Ecology, 2001. / Includes bibliographical references (leaves 204-230).
49

Phylogeny and founding stage of Lasius (Acanthomyops) (Hymenoptera: Formicidae)

Raczkowski, Joseph Martin. January 2008 (has links)
Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 161-172).
50

Hymenopteran parasitoid diversity & tri-trophic interactions : the effects of habitat fragmentation in Wellington, New Zealand : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology and Biodiversity /

Schnitzler, Franz-Rudolf. January 2008 (has links)
Thesis (Ph.D.)--Victoria University of Wellington, 2008. / Includes bibliographical references.

Page generated in 0.0357 seconds