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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.
531

Helicoverpa armigera e Spodoptera frugiperda (Lepidoptera : Noctuidae): Dieta artificial, produtos para controle e efeitos em polinizadores /

Truzi, Caio Cesar. January 2020 (has links)
Orientador: Sergio Antonio De Bortoli / Resumo: Helicoverpa armigera (Hübner, 1808) e Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) são insetos cosmopolitas, polífagos e que causam danos tanto na fase vegetativa quanto na reprodutiva de vários cultivos. Entre os métodos disponíveis para controle, os mais utilizados são o químico e a utilização de plantas Bt, porém o uso incorreto resultou em diversos relatos de resistência a esses dois métodos. Deste modo, surgiu a necessidade de novas tecnologias e produtos para o controle desses insetos-praga, sendo que o controle biológico com bactérias e vírus, e extratos de plantas podem ser ferramentas importantes frente a esses problemas. Além da resistência, outro problema que o uso incorreto dos inseticidas pode causar é a toxicidade a organismos não alvo, como as abelhas Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae), que vem sofrendo com a mortalidade causada por esses produtos. Para a realização de pesquisas que auxiliem e aprimorem os programas de Manejo Integrado de H. armigera e S. frugiperda, é essencial uma metodologia de criação que permita a obtenção de uma grande quantidade de indivíduos, sendo que dietas artificiais adequadas auxiliam a criação em grande escala. Neste sentido, o objetivo deste trabalho foi investigar o efeito de diferentes níveis proteicos na dieta artificial para criação destas espécies, o efeito agudo das concentrações letais e os efeitos subletais de inseticidas químicos, biológicos e de extrato da planta Piper cubeba Linnae... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Helicoverpa armigera (Hübner, 1808) and Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) are cosmopolitan, polyphagous insects that cause damage both in the vegetative and in the reproductive phase of several crops. Among the methods available for its control, the most used are the chemical and the use of Bt plants, however the incorrect use has resulted in several reports of resistance to both methods. Thus, there was a need to development of new technologies and products for the control of these pest insect, and biological control with bacteria and viruses, and plant extracts can be important tools in the face of these problems. In addition to resistance, another problem that the incorrect use of pesticides can cause is toxicity to non-target organisms, such as honey bees Apis mellifera Linnaeus, 1758 (Hymenoptera: Apidae), which has been suffering from the mortality caused by these products. In order to carry out research that helps and improve the Integrated Management programs of H. armigera e S. frugiperda, a rearing methodology is essential that allows the obtaining of a large number of individuals, and adequate artificial diets assist the rearing on a large scale. In this sense, the aim of this research was to investigate the effect of diferente protein levels in the artificial diet for the rearing of these species, the acute effect of lethal concentrations and the sublethal effects of chemical and biological pesticides, and plant extract from the pla... (Complete abstract click electronic access below) / Doutor
532

Étude biophysique des facteurs influençant l'activité des toxines du bacille de Thuringe

Fortier, Mélanie January 2007 (has links)
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.
533

Space matters: Quantifying ecosystem-mediated externalities

Missirian, Anouch January 2020 (has links)
Economic and ecological processes interact with one another over both spatial and temporal dimensions.This dissertation explores four socio-ecological systems where space crucially matters for both economic and ecological outcomes. In the first chapter, a windborne chemical dictates the diffusion in space of a new agricultural technology. The second chapter dissects the notion of landscape complexity to find which of its components matter for the intensity of insect pressure in agriculture, and thus the use of insecticides. In the third chapter, the location of participants in an environmental program seeking to curb deforestation points to additionality problems and anticipates the lack of measurable effects of the program. Knowing where crops are grown and temperatures less well-suited for their thriving is key to identifying in chapter four the effects of weather fluctuations on asylum applications into the European Union. The spatial dimension tends to be hard to apprehend and overlooked, but those four pieces together stress that space matters in the study of sustainable development.
534

The Effects of Neonicotinoid Exposure on Embryonic Development and Organ Mass in Northern Bobwhite Quail

Gobeli, Amanda 05 1900 (has links)
Since their emergence in the early 1990s, neonicotinoid use has increased exponentially to make them the world's most prevalent insecticides. Although there is considerable research concerning the lethality of neonicotinoids, their sub-lethal and developmental effects are still being explored, especially with regards to non-mammalian species. The goal of this research was to investigate the effects of the neonicotinoid imidacloprid on the morphological and physiological development of northern bobwhite quail (Colinus virginianus). Bobwhite eggs (n = 650) were injected with imidacloprid concentrations of 0 (sham), 10, 50, 100 and 150 grams per kilogram of egg mass, which was administered at day 0 (pre-incubation), 3, 6, 9, or 12 of growth. Embryos were dissected on day 19 when they were weighed, staged, and examined for any overt structural deformities. Embryonic heart, liver, lungs and kidneys were also weighed and preserved for future use. Treated embryos exhibited increased frequency of severely deformed beaks and legs, as well as larger hearts and smaller lungs at the higher dosing concentrations. Some impacts are more pronounced in specific dosing periods, implying that there may be critical windows of development when embryos are highly susceptible to neonicotinoid exposure. This investigation suggests that imidacloprid could play a significant role in chick survival and declining quail populations in treated regions of the country.
535

Subletální efekty insekticidů neonikotinoidů na migrační potenciál pavouků / Sublethal effects of the insecticides neonicotinoids on migration abilities of spiders

Přibáňová, Gabriela January 2021 (has links)
The purpose for using pesticides is to kill organisms that cause damage (so-called pests) on various crops and thus prevent possible crop losses. Their side effect is a negative impact on non-target organisms. The presented diploma thesis is focused on the effect of neonicotinoids on invertebrates particularly on spiders. Its main goal was to document their influence on behavioral parameters influencing dispersal abilities such as locomotion and tendency to spread by wind (so-called ballooning). The diploma thesis compares the influence of neonicotinoids on model species, Pardosa lugubris (Walckenaer, 1802) and Phylloneta impressa (L. Koch, 1881) with different modes of prey hunting and compares the influence on adult and nymphal stages. Pesticides Actara® 25 WG, Biscaya® 240 OD, Confidor® 200 OD and Mospilan® 20 SP were applied to the spiders under laboratory conditions and their effect was tested at different concentrations and different methods of application. The biggest impact on spiders had Confidor. It clearly had the most significant negative effect on mobility and a tendency to spider wind propagation. The lethal effects were caused by neonicotinoids in nymphal individuals Pardosa lugubris, especially Confidor (even 100% mortality for tarsal application). During an experiment studying the...
536

REGIONAL VARIATION IN INSECTICIDE SUSCEPTIBILITY IN ODOROUS HOUSE ANTS (TAPINOMA SESSILE)

Kaitlyn Marie Brill (11198025) 28 July 2021 (has links)
The odorous house ant (<i>Tapinoma sessile</i>) is an adaptive and widespread pest ant species found in North America. Despite the economic and ecological impact of pest ants, effective management still faces many challenges and control failures with liquid spray insecticides in urban and natural environments. In many insects such as bed bugs and cockroaches, chemical control measures have resulted in insecticide resistance. However, in contrast to non-social insects, insecticide resistance has never been documented in social insects. The current study had three main goals. The first objective was to examine regional variation in <i>T. sessile</i> insecticide susceptibility to three classes of insecticides commonly used in urban ant control. The second objective was to compare insecticide susceptibility in <i>T. sessile</i> colonies collected in natural vs. urban areas. The final objective was to determine if insecticide susceptibility varies in workers vs. queens. A total of 30 <i>T. sessile</i> colonies were collected within a 50-mile radius of Purdue University campus, Tippecanoe County, Indiana. Fifteen colonies were collected in natural areas and 15 in urban areas. Insecticide susceptibility of all 30 colonies was tested using residual exposure assays. Urban and natural colonies showed no significant differences in tests with lambda-cyhalothrin and fipronil. In tests with dinotefuran, urban colonies were significantly more tolerant relative to natural colonies. These results suggest that habitat type does not reliably predict susceptibility levels in individual populations. Queens were found to be significantly more tolerant relative to their worker counterparts across all three insecticides. Lower insecticide susceptibility in the queens may explain why <i>T. sessile</i> is such a persistent pest in urban environments. This 15 study’s results can in part provide a foundation for the development of more effective and efficient control methods for <i>T. sessile</i>.
537

Developing Integrated Pest Management Tactics for Squash Vine Borer

McFarland, Michael C. 24 May 2017 (has links)
No description available.
538

Towards the development of a mycoinsecticide to control white grubs (Coleoptera: Scarabaeidae) in South African sugarcane

Goble, Tarryn Anne January 2013 (has links)
In the KwaZulu-Natal (KZN) Midlands North region of South Africa, the importance and increased prevalence of endemic scarabaeids, particularly Hypopholis sommeri Burmeister and Schizonycha affinis Boheman (Coleoptera: Melolonthinae), as soil pests of sugarcane, and a need for their control was established. The development of a mycoinsecticide offers an environmentally friendly alternative to chemical insecticides. The identification of a diversity of white grub species, in two Scarabaeidae subfamilies, representing seven genera were collected in sugarcane as a pest complex. Hypopholis sommeri and S. affinis were the most prevalent species. The increased seasonal abundances, diversity and highly aggregated nature of these scarabaeid species in summer months, suggested that targeting and control strategies for these pests should be considered in this season. Increased rainfall, relative humidity and soil temperatures were linked to the increased occurrence of scarab adults and neonate grubs. Beauveria brongniartii (Saccardo) Petch epizootics were recorded at two sites in the KZN Midlands North on H. sommeri. Seventeen different fluorescently-labelled microsatellite PCR primers were used to target 78 isolates of Beauveria sp. DNA. Microsatellite data resolved two distinct clusters of Beauveria isolates which represented the Beauveria bassiana senso stricto (Balsamo) Vuillemin and B. brongniartii species groups. These groupings were supported by two gene regions, the nuclear ribosomal Internal Transcribed Spacer (ITS) and the nuclear B locus (Bloc) gene of which 23 exemplar Beauveria isolates were represented and sequenced. When microsatellite data were analysed, 26 haplotypes among 58 isolates of B. brongniartii were distinguished. Relatively low levels of genetic diversity were detected in B. brongniartii and isolates were shown to be closely related. There was no genetic differentiation between the two sites, Harden Heights and Canema in the KZN Midlands North. High gene flow from swarming H. sommeri beetles is the proposed mechanism for this lack of genetic differentiation between populations. Microsatellite analyses also showed that B. brongniartii conidia were being cycled from arboreal to subterranean habitats in the environment by H. sommeri beetles. This was the first record of this species of fungus causing epizootics on the larvae and adults of H. sommeri in South Africa. The virulence of 21 isolates of Beauveria brongniartii and two isolates of B. bassiana were evaluated against the adults and larvae of S. affinis and the adults of H. sommeri and Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). Despite being closely-related, B. brongniartii isolates varied significantly in their virulence towards different hosts and highlighted the host specific nature of B. brongniartii towards S. affinis when compared to B. bassiana. Adults of S. affinis were significantly more susceptible to B. brongniartii isolates than the second (L2) or third instar (L3) grubs. The median lethal time (LT₅₀) of the most virulent B. brongniartii isolate (C13) against S. affinis adults was 7.8 days and probit analysis estimated a median lethal concentration (LC₅₀) of 4.4×10⁷ conidia/ml⁻¹. When L2 grubs were treated with a concentration of 1.0×10⁸ conidia/ml⁻¹, B. brongniartii isolates HHWG1, HHB39A and C17 caused mortality in L2 grubs within 18.4-19.8 days (LT₅₀). Beauveria brongniartii isolate HHWG1 was tested against the L3 grubs of S. affinis at four different concentrations. At the lowest concentration (1×10⁶ conidia/ml⁻¹), the LT₅₀ was 25.8 days, and at the highest concentration (1×10⁹ conidia/ml⁻¹) the LT₅₀ dropped to 15.1 days. The persistence of B. bassiana isolate 4222 formulated on rice and wheat bran and buried at eight field sites in the KZN Midlands North was evaluated by plating out a suspension of treated soil onto a selective medium. All eight field sites showed a significant decline in B. bassiana CFUs per gram of soil over time, with few conidia still present in the samples after a year. Greater declines in CFUs were observed at some sites but there were no significant differences observed in the persistence of conidia formulated on rice or wheat bran as carriers. Overall, poor persistence of B. bassiana isolate 4222 was attributed to suboptimum temperatures, rainfall, which rapidly degraded the nutritive carriers, attenuated fungal genotype and the action of antagonistic soil microbes. Growers’ perceptions of white grubs as pests and the feasibility of a mycoinsecticide market were evaluated by means of a semi-structured questionnaire. The study showed that the reduced feasibility of application, general lack of potential demand for a product, high cost factors and most importantly, the lack of pest perception, were factors which would negatively affect the adoption of a granular mycoinsecticide. Growers however exhibited a positive attitude towards mycoinsecticides, and showed all the relevant attributes for successful technology adoption. It is recommended that because B. brongniartii epizootics were recorded on target pests which indicated good host specificity, dispersal ability and persistence of the fungus in the intended environment of application; that a mycoinsecticide based on this fungal species be developed. What will likely increase adoption and success of a mycoinsecticide is collaboration between various industries partners to increases market potential in other crops such as Acacia mearnsii De Wild (Fabales: Fabaceae).
539

Impacto de inseticidas neonicotinoides em abelhas africanizadas e nativas sem ferrão (Hymenoptera: Apoidea): toxicidade, alterações na atividade de locomoção e riqueza de espécies em pomares de citros / Impact of neonicotinoid insecticides on Africanized and native stingless bees (Hymenoptera: Apoidea): toxicity, changes in locomotion activity and species richness in citrus orchards

Jacob, Cynthia Renata de Oliveira 10 July 2019 (has links)
Os polinizadores são organismos fundamentais para o funcionamento de ecossistemas naturais e agrícolas, incrementando mais de 75% na produção das culturas agrícolas. Dentre os animais que participam do processo de polinização, as abelhas são consideradas as mais efetivas. Entretanto, um constante declínio na população desses polinizadores vem sendo reportado em diversos países, levando a preocupações ecológicas e econômicas, devido às perdas, tanto na produtividade agrícola como na biodiversidade. Dentre as diversas hipóteses para o declínio, o uso intensivo de agrotóxicos na agricultura tem causado preocupação, já que muitos destes compostos possuem um amplo espectro de ação, atingindo não somente os organismos alvo, mas também insetos benéficos, como as abelhas. Assim, objetivou- se com este estudo avaliar resíduos do inseticida neonicotinoide imidacloprido em amostras de flores de citros e a sua influência na riqueza de espécies de abelhas presentes nos pomares, bem como os possíveis efeitos dessas concentrações na atividade locomotora de abelhas Apis mellifera africanizada, Scaptotrigona postica e Tetragonisca angustula após exposição oral em condições de laboratório. Além disso, estimou-se a concentração letal média (CL50) dos neonicotinoides mais utilizados (acetamiprido, imidacloprido, tiacloprido e tiametoxam) para estas espécies de abelhas, e os níveis de comprometimento motor após exposição de abelhas a essas concentrações. Imidacloprido foi detectado em amostras de flores de todo os pomares, com maior concentração para área em Anhembi/SP (6,26 ng g-1 de imidacloprido) e menor concentração em Barretos/SP (3,24 ng g-1 de imidacloprido). Foram identificadas, no total, 17 espécies de abelhas visitando flores de citros, com predominância de A. mellifera em todos os pomares. No entanto, não houve relação entre a riqueza de espécies e de imidacloprido residual. Alterações significativas na atividade locomotora foram verificadas após exposição às concentrações de 0,006 e 6,26 ng &#181;L-1 de imidacloprido, com maior alteração nas variáveis de duração e frequência de repouso. Além disso, verificaram-se diferentes níveis de toxicidade entre os ingredientes ativos estudados, com menor toxicidade oral aguda para os compostos com radical ciano (acetamiprido e tiacloprido) e maior para os que apresentam radical nitro (imidacloprido e tiametoxam). A locomoção das três espécies de abelhas foi reduzida em relação ao controle após exposição a todos os neonicotinoides. Com menor nível de comprometimento quando expostas ao acetamiprido. Assim, os resultados obtidos neste estudo esclarecem os efeitos dos inseticidas neonicotinoides sobre as espécies de abelhas na região Neotropical, e contribuem para a formulação de estratégias para integrar o controle de pragas e conservação dos polinizadores. / Pollinators are fundamental organisms for the functioning of natural and agricultural ecosystems, increasing more than 75% the production of agricultural crops. Among the animals that participate in the pollination process, bees are considered the most effective. However, a steady decline in the population of these pollinators has been reported in several countries, leading to ecological and economic concerns, due to the losses in both agricultural productivity and biodiversity. Among the several hypotheses for the decline, the intensive use of pesticides in agriculture the fields has caused concern, as many of these compounds possess a broad spectrum of action, reaching not only the target organisms, but also beneficial insects, as bees. Thus, the objectives of this study were to detect and quantify the residual concentration of imidacloprid in samples of citrus flowers and if these concentrations influence the richness of bee species present in the orchards, as well as the possible effects of these concentrations on the locomotion activity of three bee species (Africanized Apis mellifera, Scaptotrigona postica and Tetragonisca angustula) after oral exposure under laboratory conditions. In addition, the median lethal concentration (LC50) the most used neonicotinoids (acetamiprid, imidacloprid, thiacloprid and thiamethoxam) to these bee species was estimated, and the levels of motor impairment after bee exposure to these concentrations. Imidacloprid was detected in flower samples in all orchards, with a higher concentration in Anhembi/SP (6.26 ng g-1 of imidacloprid) and lower concentration in Barretos/SP (3.24 ng g-1 of imidacloprid). A total of 17 species of bees were identified visiting citrus flowers, predominating A. mellifera in all orchards. However, there was no relationship between species richness and residual imidacloprid concentrations in the flowers of each evaluated region. Significant changes in the activity bee locomotion were observed after exposure to concentrations of 0.006 and 6.26 ng &#181;L-1 of imidacloprid, with a higher level of impairment for the variables duration and frequency of rests. In addition, different levels of toxicity were observed among the active ingredients studied, with lower acute oral toxicity for cyano compounds (acetamiprid and thiacloprid) and higher for those with nitro radical (imidacloprid and thiamethoxam). The locomotion of the three bee species was reduced in relation to the control after exposure to all neonicotinoids, with a lower level of impairment when exposed to acetamiprid. Thus, the results obtained in this study shed light on the effects of neonicotinoid insecticides on bee species the Neotropical region, and contribute the formulation of strategies to integrate pest control and pollinator conservation.
540

Bioativador em culturas monocotiledôneas: avaliações bioquímicas, fisiológicas e da produção / Bioactivator in monocot crops: biochemical, physiological and production analysis

Macedo, Willian Rodrigues 18 February 2013 (has links)
Estudos sobre agroquímico geralmente reportam sobre sua eficiência no controle de pragas. Como no caso do tiametoxam, um inseticida sistêmico do grupo dos neonicotinóides que atua inibindo a ação do receptor nicotínico acetilcolina (nAChR) dos insetos levando-os à morte. Porém, essa molécula apresenta ações fisiológicas nas plantas capazes de influenciar o desenvolvimento das culturas, e quando um agroquímico apresenta essa atividade é comumente chamado de bioativador, devido ao aumento do vigor e da produtividade das plantas tratadas. O objetivo deste trabalho foi avaliar os efeitos bioquímicos, fisiológicos e produtivos de doses crescentes do tiametoxam, aplicado via tratamento de sementes, nos cultivos de trigo, braquiária, arroz e milho. Experimentos com trigo, braquiária e arroz foram conduzidos em vasos, sob casade- vegetação, no Horto Experimental do Departamento de Ciências Biológicas da ESALQ/USP, Piracicaba, SP. Enquanto a condução da cultura do milho ocorreu em casa-de-vegetação, do Departamento de Agronomia no CEDETEG/UNICENTRO, e em área de plantio comercial, ambos no município de Guarapuava, PR. Durante a realização dos experimentos foram mensuradas características biométricas de: índice de emergência; altura de plantas; índice de clorofilas (SPAD); massa seca da parte aérea; comprimento, área e volume radicular. Parâmetros bioquímicos como: atividade de nitrato redutase; fenilalanina amônia-liase; conteúdo de proteína total; pigmentos fotossintéticos e conteúdo de nutrientes foliares. Parâmetros sobre a qualidade nutricional da braquiária também foram analisadas. E ao final do ciclo reprodutivo dos cereais foram determinados alguns parâmetros relacionados à produção. Foi constatado que o tiametoxam interferiu sobre diversos parâmetros bioquímicos, em todas as culturas testadas, com destaque para a potencial ação dessa molécula sobre atividades de nitrato redutase e fenilalanina amônia-liase, bem como sobre o conteúdo de proteína total em trigo e braquiária, além de alterar o teor de pigmentos fotossintéticos foliares em arroz e milho. Para as culturas do trigo e da braquiária foram notadas modificações severas sobre a fisiologia e produção. Concluiu-se que a aplicação de tiametoxam, via tratamento de sementes, foi responsável por moderar o metabolismo e o desenvolvimento vegetal, até o final do ciclo da planta, de maneira que as plantas submetidas a essa molécula expressaram maior vigor e, consequentemente, apresentaram maior aptidão para incrementar sua produção. / Studies on agrochemicals generally report on their effectiveness in pests control. As with thiamethoxam, a systemic insecticide of the neonicotinoid group that acts by inhibiting the action of acetylcholine nicotinic receptor (nAChR) of insects, leading to death. But this molecule which has physiological effect in plants, can influence crop development; and when an agrochemical presents this activity, it is commonly called bioactivator due to increased vigor and productivity of the treated plants. The aim of this study was to evaluate: biochemical, physiological and productive effects of increasing doses of thiamethoxam applied as seed treatment in wheat, Brachiaria, rice and corn crops. Experiments with wheat, rice and Brachiaria were conducted in pots under greenhouse, in the Horto Experimental of Biological Sciences Department of ESALQ/USP, Piracicaba, SP. While one corn crop was conducted in a greenhouse of the Department of Agronomy at CEDETEG / UNICENTRO, the other one was conducted in the field, both in Guarapuava, PR. We measure the biometric characteristics: emergence index, plant height, chlorophyll index (SPAD), shoot dry weight, length, root area and volume. Biochemical parameters such as: nitrate reductase activity, phenylalanine ammonia-lyase, total protein content, photosynthetic pigments and leaf nutrient content. Parameters on the nutritional quality of Brachiaria were also analyzed. And at the end of the reproductive cycle of cereals some parameters related to production were determined. It was found that thiamethoxam interfered in various biochemical parameters in all tested crops, highlighting the potential action of this molecule on activities of nitrate reductase and phenylalanine ammonia-lyase, as well as the total protein content in wheat and pasture, besides changing the content of photosynthetic pigments in rice and corn leaves. For wheat and Brachiaria crops severe changes were noted on the plant physiology and production. It is concluded that the application of thiamethoxam, via seed treatment, was responsible for moderating metabolism and plant development, until the end of the life cycle of the plant, so that the plants under this molecule expressed greater vigor and thus had higher ability to increase production.

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