Made available in DSpace on 2014-06-11T19:30:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-12-17Bitstream added on 2014-06-13T18:41:12Z : No. of bitstreams: 1 ambrosio_jb_dr_rcla.pdf: 849914 bytes, checksum: 8eebea30948cfc32353c99fa5c95f4e0 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O Brasil é o maior produtor de cana-de-açúcar no mundo. Dentre os Estados brasileiros, São Paulo representa 60% de todo o açúcar produzido e 70% das exportações. Pela alta produção de cana-de-açúcar no Estado de São Paulo e o consequente consumo elevado de agrotóxicos, este trabalho teve como objetivo investigar os efeitos citotóxicos, genotóxicos e mutagênicos de baixas concentrações de dois agrotóxicos utilizados nesta cultura, o herbicida sulfentrazona e o inseticida imidaclopride, tanto em testes individuais quanto associados entre si. As avaliações foram feitas pelos testes de aberrações cromossômicas (AC) e de micronúcleos (MN) em Allium cepa; teste do MN e ensaio do cometa em células HepG2; e teste de Ames com Salmonella typhimurium. Para melhor avaliar o modo de ação dos agrotóxicos, a técnica de hibridização in situ fluorescente (FISH) com sonda pan-centromérica foi associada ao teste do MN realizado com células HepG2. Os testes com A. cepa indicaram genotoxicidade para todas as concentrações de imidaclopride, após um período de recuperação de 48 horas. A maior indução de pontes e aderências cromossômicas sugeriu uma ação clastogênica para o inseticida. Esta hipótese foi confirmada nos testes com HepG2, pela técnica de FISH, uma vez que a maioria dos MN (76,6%) não apresentou sinal fluorescente, indicando presença de fragmentos cromossômicos. Para o herbicida sulfentrazona, foram observadas AC para todas as concentrações, considerando os diferentes tempos de tratamento. A indução de MN foi observada para a menor concentração, para todos os tempos de tratamento, sugerindo que os danos induzidos por essa concentração persistem ao longo do ciclo celular. A maior concentração testada do herbicida causou uma diminuição no índice mitótico... / Brazil is the largest producer of sugarcane in the world. Among the Brazilian states, São Paulo represents 60% of all sugar produced and 70% of exports. Due to the high production of sugarcane in São Paulo state and the great pesticide consumption, this work investigated the cytotoxic, genotoxic and mutagenic effects of low concentrations of two pesticides utilized in sugarcane culture: the herbicide sulfentrazone and the insecticide imidacloprid, both individually and combined. The evaluations were made by chromosome aberrations (CA) and micronucleus (MN) tests in Allium cepa, MN and comet assay in HepG2 cells and Ames test with Salmonella typhimurium. Associated to the MN test in HepG2 cells, the fluorescent in situ hybridization (FISH) technique with pan-centromeric probe was applied in order to better evaluate the mode of action of the agrochemicals. The tests with A. cepa indicated genotoxicity for all concentrations of imidacloprid, after a recovery period of 48 hours. The higher induction of bridges and chromosome stickiness suggests a clastogenic action for the insecticide. This hypothesis was confirmed in the tests with HepG2, by FISH, since most of the MN (76.6%) did not present fluorescent signal, indicating presence of chromosomal fragments. For the herbicide sulfentrazone, CA were observed in all concentrations, in the different treatment times. The induction of MN was observed for the lowest concentration for all the treatment times, suggesting that the damages induced by this concentration persist throughout the cell cycles. The highest concentration tested of the herbicide caused a decrease in the mitotic index of the cells after 72 hours recovery period. This effect may be associated with the high amount of induced chromosome stickiness. The mixture of pesticides induced cytotoxicity, genotoxicity... (Complete abstract click electronic access below)

Neste trabalho foram desenvolvidas metodologias para a determinação de substâncias de interesse, como metais pesados (micronutrientes e contaminantes), macronutrientes e pesticidas em solo e águas naturais com ultramicroeletrodo de irídio recoberto com filme de Hg eletrodepositado (UME Ir-Hg) e técnicas voltamétricas, utilizando uma cápsula porosa de cerâmica como cela eletroquímica. As metodologias de medidas com os ultramicroeletrodos foram desenvolvidas inicialmente em condições controladas e posteriormente aplicadas a medidas in-situ, com experimentos com águas naturais e solos, conduzidos em laboratório e também com posteriores medidas em amostras reais. Segundo os resultados obtidos foi possível explorar as metodologias voltamétricas, principalmente as de pulso e redissolução anódica, como ferramentas para estudos in-situ dos metais Cd(II), Pb(II) e Cu(II) e do inseticida organofosforado paration metílico, substâncias de grande interesse, obtendo-se um bom nível de repetibilidade e sensibilidade, com limites de detecção em amostras reais de centenas de ppb\'s. / In this work a methodology for determination of metallic ions (micronutrients and contaminants), macronutrients and pesticides in soil and natural waters was developed using an Hg plated iridium based ultramicroelectrode and voltammetric techniques, using a ceramic capsule as an electrochemical cell. The measurement procedures were developed initially in controlled conditions and therefore applied to in-situ measurements, in soil and natural waters, performed in lab and with real field samples. Regarding the obtained results it was possible do explore the voltammetric techniques, mainly the pulsed and stripping ones, as tools for in-situ determination of Cd(II), Pb(II), Cu(II) and the insecticide methyl parathion, with good reproducibility and sensibility, with detection limits in the order of hundreds of parts per billion.

Made available in DSpace on 2016-04-28T14:57:34Z (GMT). No. of bitstreams: 1 2008 - Marcus Nascimento Santos.pdf: 462545 bytes, checksum: 46bb8f8940f38566f10544863c83cbb2 (MD5) Previous issue date: 2008-07-25 / This work was made in the Research Institute Botanic Garden of Rio de Janeiro (JBRJ) where two experiments were carried out in two steps. The first step had the following objectives: to study the attack behavior of subterranean termites over stakes of pinus trap in three areas of different compositions floristic seed source in the JBRJ, appointed by cerrado-JB, lawn - JB and forest-JB over one year. To study the environmental influences on the pinus baits attack by subterranean termites monthly over year of observation. The subterranean termites belonged to the species, Coptotermes gestroi (Wasmann) (areas cerrado-JB and lawn-JB) and Heterotermes longiceps (Snyder) (area forest-JB), (Isoptera: Rhinotermitidae). The second step aimed to study botanical extracts with bioinseticida action for the control of subterranean termite, C. gestroi. In each area 6 blocks with three plot were buried stakes and collected and replaced monthly over 12 months. The stakes of Pinus sp were previously immersed in distilled water for three periods (0, 24 or 48 hours). The environmental variables were evaluated: luminosity (morning and afternoon), soil temperature (morning and afternoon), air temperature (maximum and minimum), rainfall, soil moisture, humidity, pH and carbon (C) organic soil. The results showed that the attack on baits of Pinus sp occurred all the year without a preference for different periods of immersion in distilled water. The peak of the attack on stakes occurred in months march and september. The environmental variables: humidity, soil moisture and rainfall had significant correlation with the attack on the stakes of Pinus sp by subterranean termites. C. gestroi attack had negative correlation with environmental variables. H. longiceps attack had negative correlation with humidity and positive correlation with soil moisture. The acid pH soil areas studied appeared to be helpful to the activities of the foraging termites. The amount of organic C available in the soil seems don t have influence on foraging activities of the two species of termites. The attack on baits of Pinus sp by the species C. gestroi was more severe that the attack by H. longiceps. In the second step the termites were exposed to seven treatments with five replications each for 20 days. The aqueous extract of the leaves of Melia azedarach, Tectona grandis, Carapa guianensis, Aspidosperma polyneuron, Myracrodruon urundeuva and Leucaena leucocephala, the concentration of 10%, were impregnated with pieces of corrugated cardboard. With the exception of L. leucocephala, which was lower consumption of cardboard, the other plant extracts and control (paper and distilled water) were also consumed. The insecticidal activity of the extracts of M. azedarach, M. urundeuva and T. grandis was responsible for 100, 100 and 95.38% mortality of termites, respectively. The extracts of L. leucocephala, A. polyneuron and C. guianensis showed no activity insecticide for the control of C. gestroi. / Este trabalho foi realizado no Instituto de Pesquisas Jardim Bot?nico do Rio de Janeiro (JBRJ) onde foram desenvolvidos dois experimentos descritos em duas etapas. A primeira etapa teve como objetivos: avaliar mensalmente ao longo de 12 meses estacas de Pinus sp como isca-armadilha para cupins subterr?neos em tr?s ?reas de composi??es flor?sticas distintas no arboreto do JBRJ, nomeadas de cerrado-JB, gramado-JB e mata-JB, e verificar a influ?ncia dos fatores ou vari?veis ambientais sobre o ataque as iscas de Pinus sp pelos cupins subterr?neos das esp?cies, Coptotermes gestroi (Wasmann) (?reas cerrado-JB e gramado-JB) e Heterotermes longiceps (Snyder) (?rea mata- JB), (Isoptera: Rhinotermitidae). A segunda etapa teve como objetivo avaliar extratos bot?nicos com a??o bioinseticida para o controle do cupim subterr?neo, C. gestroi. As estacas foram enterradas em cada ?rea em 6 blocos com tr?s parcelas cada e mensalmente coletadas e substitu?das ao longo de 12 meses. As estacas de Pinus sp foram previamente imersas em ?gua destilada por tr?s per?odos (0, 24 ou 48 horas). Foram avaliadas as seguintes vari?veis ambientais: luminosidade (manh? e tarde), temperatura do solo (manh? e tarde), temperatura relativa do ar (m?xima e m?nima), precipita??o pluviom?trica, umidade do solo, umidade relativa do ar, pH e Carbono (C) org?nico do solo. O ataque ?s iscas de Pinus sp pelos cupins subterr?neos ocorreram durante todo o ano e sem uma prefer?ncia do pinus sob diferentes per?odos de imers?o em ?gua destilada. O pico do ataque ?s estacas ocorreu nos meses de mar?o e setembro. Umidade relativa do ar, umidade do solo e precipita??o pluviom?trica tiveram correla??o significativa com o ataque ?s estacas de Pinus sp pelos cupins subterr?neos. Entretanto, para C. gestroi essas vari?veis ambientais tiveram correla??o negativa com o ataque as estacas. Para H. longiceps a umidade relativa do ar teve correla??o negativa e a umidade do solo positiva. O pH ?cido dos solos das ?reas estudadas pareceu ser prop?cio ?s atividades de forrageamento dos cupins. A quantidade de C org?nico dispon?vel no solo pareceu n?o ter influenciado a atividade de forrageamento das duas esp?cies de cupins. O ataque ?s iscas de Pinus sp pela esp?cie C. gestroi foi mais severo que o ataque por H. longiceps. Na segunda etapa do trabalho os cupins foram expostos a sete tratamentos com cinco repeti??es cada durante 20 dias. Os extratos aquosos das folhas de Melia azedarach, Tectona grandis, Carapa guianensis, Aspidosperma polyneuron, Myracrodruon urundeuva e Leucaena leucocephala, na concentra??o de 10%, foram impregnados em peda?os de papel?o corrugado. Com exce??o de L. leucocephala, cujo consumo do papel?o foi menor, os demais extratos vegetais e a testemunha (papel?o e ?gua destilada) foram consumidos igualmente. A atividade inseticida dos extratos de M. azedarach, M. urundeuva e T. grandis foi respons?vel por 100, 100 e 95,38% de mortalidade de cupins, respectivamente. Os extratos de L. leucocephala, A. polyneuron e C. guianensis n?o apresentaram atividade inseticida para o controle de C. gestroi.

Public awareness of declining pollinator populations has increased interest in creating “bee–friendly” urban landscapes. I quantified bee visitation and assemblages of 72 species of flowering woody plants common in urban landscapes. I found strong plant species effects and variation in seasonal activity of particular bee taxa but no overall differences in bee visitation or genus diversity between native versus nonnative species or trees versus shrubs. Analysis of pollen from a subset of these plants revealed small but statistically significant differences in total and essential amino acids between native and nonnative species and trees and shrubs, although each group had species with high quality pollen. Uptake and dissipation of soil–applied imidacloprid and dinotefuran was measured in nectar and leaves of two woody plant species, Ilex × attenuata and Clethra alnifolia to assess concentrations to which pollinators might be exposed in landscape settings. Three application timings were evaluated. Residues in nectar and tissue were analyzed by HPLC–MS/MS in two successive years. Residues in nectar following autumn or spring applications exceed concentrations shown to adversely affect individual and colony–level traits of bees. Summer application mitigated concentrations of imidacloprid (8–31 ng/g), but not dinotefuran (235–1191 ng/g), in nectar.

Community assembly following disturbance is a key process in determining the composition and function of the future community. However, replicated studies of community assembly at whole ecosystem scales are rare. Here is described a series of whole-lake experiments in which the recovery of zooplankton communities is tracked following an ecosystem-scale disturbance. Fourteen lakes in eastern Washington were chosen: seven lakes were treated with rotenone, while the remaining seven were reference. Each lake was monitored up to six months before and one to two years after the rotenone treatments. Zooplankton tows were taken monthly, at a shallow, intermediate, and deep site in each lake, and were later enumerated and identified. A depth profile of environmental variables was taken at the deepest site. Community responses following disturbance were assessed using coarse metrics of abundance and diversity, community composition measures, and the relative importance of species traits was assessed by grouping taxa into functional groups. Communities were considered recovered if there was no significant difference between treatment and reference in zooplankton community metrics of abundance, diversity, and composition. There was a steep decline in the abundance and diversity of the zooplankton community post-treatment. In many of the lakes, cyclopoid copepods, the group with a unique dormancy strategy, were the first group to recover, remained dominant for a few months, and may have exhibited priority effects advantages. Calanoid copepods were the slowest group to recover, perhaps due to their slow rate of development. There were varying recovery times and patterns between lakes, potentially based upon geographic location and severity of the winter season. These findings suggest that dormancy strategies, rate of development, and abiotic conditions following disturbance may be important in helping to understand recovery processes. Results of this study may give insight to disturbance ecology and the relative importance abiotic versus biotic characteristics that structure post-impacted communities.

Thesis (M.Sc. (Agric.)) --University of Limpopo, 2010 / The objectives of the study were to estimate genetic parameters for tick resistance and to evaluate the effect of the level of tick infestation on the estimates of genetic parameters in South African Bonsmara cattle. Field data of repeated tick count records (n = 11 280) on 1 176 animals were collected between 1993 and 2005 by ten breeders participating in the National Beef Recording and Improvement Scheme. The distribution of tick count records were normalized using a Box-Cox transformation. Data were divided into 7 sub-data sets based on the mean tick count per contemporary group, to facilitate the investigation of the effect of level of tick infestation on the derived genetic parameters. A repeatability animal model including the fixed effects of contemporary group and age of animal at tick counting and random effects of the direct additive genetic, permanent environmental and residual effects was used to estimate genetic parameters using REML procedures. The additive genetic variances for tick count ranged from 0.01 to 0.08. Variances for the permanent environment ranged from 0.00 to 0.03. Phenotypic variance decreased with increasing mean tick count level while additive genetic variance increased with increasing mean tick count level. The heritability also increased with mean tick count level until a mean tick count level of ≥30. The highest heritability estimate obtained in the current study was 0.17 for data with mean tick count level ≥25. These results suggest that sufficient genetic variation for tick count exists in the Bonsmara cattle. Therefore genetic selection for tick resistance is feasible even though genetic progress may be slow. / the Limpopo Department of Agriculture (LDA) and the Department of Science and Technology (DST)

L'utilisation de pesticides conventionnels, en particulier les pesticides chimiques de synthèse, a considérablement réduit les pertes de récoltes et a connu un succès commercial. Cependant, l'utilisation excessive de pesticides chimiques qui manquent de toxicité spécifique a provoqué une série de problèmes environnementaux et de santé publique. L'intérêt de la recherche vers de nouveaux biopesticides naturels avec de nouveaux modes d'actions vise à un meilleur équilibre entre l'efficacité des pesticides et la réduction des méfaits possibles pour l'environnement et les humains. Les plantes sont une source importante de biopesticides. Les acides chlorogéniques (CQA), isolés à partir de diverses plantes et présentent in vivo et in vitro un large spectre d'activités biologiques, ont attiré l'attention avec un potentiel comme biopesticides basé sur la toxicité brevetée de l'acide 3,5-di-O-caféoylquinique contre les larves de Myzus persicae. L'étude des propriété insecticides notamment la mode d'action et l'étude de certaines relations structure-activité pourrait bénéficier de la synthèse de différents dérivés et analogues de CQA. Des analogues des acides 4-désoxy-3,5-dicinnamoy quiniques et 3,4- et 4,5-dicinnamoylquiniques naturels ont été synthétisés. Sept analogues dans la série 4-désoxy ont été soumis à des essais insecticides et deux composés présentent une activité insecticide plus élevée que l'acide 3,5-dicaféoylquinique naturel. Comme perspectives à ce travail, confirmer l'activité des composés synthétisés sur d'autres espèces de pucerons d'importance agronomique pourrait être réalisé. De plus, d’autres collaborations avec des biologistes pourraient être établies afin d’évaluer d'autres activités des composés synthétisés ou les utiliser comme outils pour étudier des mécanismes de biosynthése. / The use of conventional pesticides, especially the synthetic chemical pesticides, has greatly reduced the crop losses and gained a commercial success. However, the excessive use of pesticides lacking toxic specificity has caused a series of environmental and public health problems. The research interest toward new naturally-occurring biopesticides with novel modes of actions aims at a better balance between the efficiency of pesticide and reducing possible harms to environment and humans. Botanicals are an important source of biopesticides. Cinnamoyl quinic acids (CQA), isolated from various plants and shown to exhibit in vivo and in vitro a wide spectrum of biological activities, have attracted the attention with potential as biopesticides based on the patented toxicity of 3,5-di-O-caffeoylquinic acid against the larvae of Myzus persicae. The investigation of the insecticidal activity of CQA including their mode of action and the study of some structure-activity relationships could benefit from the synthesis of different CQA derivatives and analogs. A series of natural CQA derivatives natural 3,4- and 4,5-dicinnmamoylquinic acid derivatives but also analogs like 4-deoxy-3,5-dicinnamoylquinic acids were so synthesized. Seven targeted 4-deoxy CQA analogs were subjected to insecticidal assays, and two compounds were found to exhibit higher insecticidal activities than natural 3,5-dicaffeoylquinic acid. As perspectives to this work, confirming the activity of the synthesized compounds on other aphid species of agronomic importance could be performed. Furthermore, other collaborations could be established with biologists dedicated to measure other bioactivities of the synthesized compounds or use them as tools to investigate various biological pathways.

L'utilisation des produits phytosanitaires est indispensable pour augmenter la qualité des productions agricoles. Cependant les directives européennes et nationales préconisent une réduction de 50 % de leur utilisation pour préserver l'environnement et limiter les effets secondaires sur les organismes non-cibles. Dans cette optique, et pour optimiser l'efficacité de ces produits tout en diminuant leur dose d'utilisation, il est nécessaire de caractériser les facteurs cellulaires et moléculaires impliqués dans la modulation de l'effet insecticide de ces composés sur leurs cibles membranaires. Parmi les insecticides les plus utilisés en agriculture, les néonicotinoïdes occupent une place importante sur le marché. Ils ont pour cible les récepteurs à l'acétylcholine de type nicotinique (nAChRs) du système nerveux central des insectes. Chez la blatte Periplaneta americana, des cellules neurosecrétrices identifiées, les neurones DUM, expriment deux sous-types de nAChRs, (nAChR1 et nAChR2). Alors que nAChR1 est sensible à l'imidaclopride (IMI), néonicotinoïde de première génération, cet insecticide ne présente aucun effet sur nAChR2. Afin d'obtenir une meilleure compréhension du mode d'action de ces insecticides sur des nAChRs insensibles, l'objectif de ce travail de recherche a été de caractériser du point de vue électro-pharmacologique les facteurs cellulaires et moléculaires qui influencent l'efficacité d'un insecticide néonicotinoïde de seconde génération, l'acétamipride (ACT) qui présente des caractéristiques chimiques différentes de l'IMI. Grâce à la technique électrophysiologique du patch-clamp, dans des conditions de potentiel imposé, il a été possible de démontrer que l'effet de l'ACT sur nAChR2 dépend du potentiel de membrane. Une dépolarisation de la membrane augmente légèrement la sensibilité de nAChR2 pour l'ACT alors qu'une hyperpolarisation produit un effet inverse significatif. Dans les deux cas, l'implication du calcium intracellulaire a été démontrée. Pour des potentiels plus positifs que le potentiel de membrane (i.e., -50 mV), l'inhibition de l'influx calcique via l'activation des canaux calciques à haut seuil d'activation (High Voltage- Activated) par le chlorure de cadmium et l'ω-conotoxine GVIA augmente la sensibilité de nAChR2 pour l'ACT. Des effets similaires sont obtenus pour des potentiels de membrane plus hyperpolarisés lorsque la perméabilité calcique est inhibée par le LOE 908, un inhibiteur des canaux TRPγ. Dans ce dernier cas, l'utilisation d'outils pharmacologiques spécifiques (e.g., forskoline, W7) a permis de révéler que la voie de signalisation intracellulaire AMPcyclique/adenylate cyclase est impliquée dans la modulation de l'efficacité de l'ACT sur nAChR2. Enfin, des mesures de la résistance membranaire, réalisées en parallèle dans des conditions de courant imposé, indiquent que l'état conformationnel des nAChR2 joue également un rôle important dans la modulation de l'efficacité de l'ACT. L'ensemble de ces résultats qui ont permis d'identifier de nouveaux facteurs cellulaires et moléculaires impliqués dans la modulation de l'efficacité d'un néonicotinoide, l'ACT ouvrent des perspectives très intéressantes pour optimiser l'efficacité d'un traitement insecticide.

La résistance aux insecticides chez les moustiques pose des problèmes de santé publique car ils sont vecteurs de nombreuses maladies. Une alternative aux insecticides chimiques est l'utilisation du bactério-insecticide Bacillus thuringiensis subsp israelensis (Bti) qui a l'avantage de produire un mélange de six toxines spécifiques des Diptères. Cependant le Bti commercial peut proliférer et s'accumuler, entrainant une forte toxicité dans les litières végétales de certains gîtes à moustiques. Afin d'étudier l'évolution de la résistance au Bti chez les moustiques, j'ai sélectionné en laboratoire une souche d'Aedes aegypti avec des litières végétales contenant des toxines de Bti. Une résistance multigénique aux toxines Cry du Bti est apparue en seulement quelques générations chez la souche sélectionnée. Plusieurs approches ont été utilisées pour rechercher les bases génétiques de la résistance au Bti chez la souche d'Ae. aegypti résistante. Deux "scans génomiques" ont permis de déterminer plusieurs régions du génome présentant des signatures de sélection. Ensuite, les niveaux de transcription de plus de 6000 gènes ont été étudiés par séquençage haut débit. La combinaison de ces résultats avec une approche "gènes candidats" a permis d'obtenir une liste de gènes potentiellement liés à la résistance au Bti. Parmi les gènes identifiés, un gène codant pour une cadhérine présente des signatures de sélection chez la souche résistante et semble donc impliqué dans la résistance au Bti. De plus, une étude de génomique des populations de l'espèce de terrain Aedes rusticus traitée depuis 20 ans au Bti a mis en évidence des signatures de sélection liées au traitement et des flux de gènes importants chez cette espèce dans la région Rhône-Alpes. La caractérisation de facteurs génétiques liés à la résistance et de facteurs biologiques liés aux espèces traitées peut aider à la mise en place de stratégies de gestion limitant l'évolution de la résistance au Bti dans ces populations.

Chemische Pflanzenschutzmittel (PSM) bekämpfen nicht nur Schadorganismen, sondern haben aufgrund ihrer hohen Toxizität auch negative Auswirkungen auf Nicht-Ziel-Organismen. Die Fragestellung der Arbeit war es, ob mit reduzierten Anwendungen von PSM ihr Gefährdungspotenzial für Prädatoren von Schädlingen verringert und dadurch das Potenzial der natürlichen Schädlingsregulation erhöht wird. In dreijährigen Freilanduntersuchungen wurden die Effekte einer dauerhaft reduzierten Dosis von chemischen PSM auf die ökologische Situation im Ackerbau anhand von drei Fallbeispielen in einem konventionell bewirtschafteten Betrieb in der Magdeburger Börde untersucht. Drei über 15 ha große Felder wurden dauerhaft in zwei Teilflächen geteilt, wobei eine Teilfläche mit der vom Landwirt gewünschten Dosis (100 %-Variante) und die andere mit jeweils genau der halben Dosis (50 %-Variante) behandelt wurde. Mittels dieser Halbfelder-Vergleiche wurden die ökologischen Situationen bezüglich des Auftretens von Blattläusen und ihren Prädatoren sowie Unkräutern vor und nach der jeweiligen PSM-Behandlung aufgenommen und ökonomische Parameter ermittelt. Ergänzend wurden im Labor Modellgefäßversuche mit abgestuften Dosierungen von Insektiziden und Herbiziden durchgeführt. Die Insektizidbehandlung übte einen großen Einfluss auf die Blattläuse und ihre Prädatoren aus, während alle vorherigen Herbizid- und Fungizidbehandlungen zu keinen Unterschieden in der Abundanz der Blattläuse und ihrer Prädatoren zwischen beiden Varianten hervorriefen. Die reduzierte Insektiziddosis führte zu keiner guten Blattlauskontrolle, während die Abundanz der blattlausspezifischen Prädatoren positiv beeinflusst wurde. Die Araneae reagierten auf die reduzierte Dosis mit einer teilweise erhöhten Aktivitätsdichte und Artendiversität. Dagegen waren diesbezüglich keine eindeutigen Effekte auf die Carabidae festzustellen. Es traten keine strukturellen Veränderungen in Form einer erhöhten Unkrautdichte durch die reduzierte Herbiziddosis auf. Erste Hinweise auf mögliche langfristige Auswirkungen einer dauerhaft reduzierten PSM-Anwendung konnten nur bei der Verunkrautung und der Aktivitätsdichte der Araneae beobachtet werden. Blattläuse profitierten demnach mehr von der reduzierten Anwendung der PSM als ihre Prädatoren, so dass zwar das Potenzial der natürlichen Blattlausregulation erhöht, die Selbstregulation aber nicht verbessert wurde. Die geschonten Prädatoren schafften es nicht, die vorhandene Restpopulation der Blattläuse zu reduzieren. Dagegen konnte in den Laborversuchen gezeigt werden, das schon bei deutlich reduzierten Insektiziddosen eine ausreichende Blattlausbekämpfung möglich ist und eine weitere Einsparung durch Ausnutzung der natürlichen Regulation durch Prädatoren erreicht werden kann. Allerdings ist eine Übertragung der Ergebnisse von Laboruntersuchungen auf Freilandbedingungen schwierig. Es kann zu einer Überschätzung der Prädatorleistung führen. / Pesticide application in order to control pest populations can also affects non-target organisms such as beneficials. Thus, effects of low-input pesticide use on the tritrophic system crop – aphid – predator were investigated in field and laboratory studies. The hypothesis was: 50% doses of pesticides, particularly insecticides, permanently conserves beneficials, improves natural control and enhances biodiversity in fields. The field study was carried out in a conventional farm in an intensive cropping region of Central Germany (Magdeburger Boerde) from 2004-2006 using half-field comparisons. Three fields (≥15 ha) were divided into two halves during the whole period of investigation representing low- and high-input variants. One half was treated by permanently 50% reduced pesticide doses, whereas the other one was characterised by good plant protection practise (100%). To determine ecological effects of a low-input plant protection strategy, abundances of aphids and their predators as well as of weeds were investigated before and after pesticide applications.In adddition, economic parameters were determined. Insecticide treatment caused greatest effect on aphids and their predators, whereas fungicide and herbicide applications did not affect their abundances. The reduced insecticide dose did not lead to a good aphid control, but the abundance of aphid specific predators was positive affected and Araneae showed enhanced activity density and diversity by the low-input insecticide use. No clear effect of reduced insecticides use on abundance, structure of dominance, and diversity of carabids could be observed. No structural changes in terms of an increased density of weeds were found. Accumulative effects of reduced pesticide use could only be observed concerning weed density and activity density of Araneae after three years. It is concluded, that aphids profit more from reduced pesticide dose than their predators. The increased predator potential did not lead to a better natural control because of higher relative survival rate of aphids in the 50%-variant. In contrast to the field study, in laboratory aphids could be sufficiently reduced by low-input insecticide doses. In some cases the dose of insecticide could be reduced even more by utilisation of the predator potential to receive a good pest control. But it is difficult to transfer the results of laboratory studies to field conditions. It could result in an overestimation of the potential of natural regulation by a predator.