To develop an assay to detect antibodies to Bacillus thuringiensis subsp. israelensis in mallard ducks, a growth curve was first established for the bacterium. The growth curve indicated that the crystal delta endotoxin would be best harvested from the rest of the cell material after 12 hours of growth. The delta endotoxin was solubilized in alkaline conditions followed by treatment with proteases or no treatment. The two differently treated delta endotoxins were purified by column chromatography. Fractions were assayed for duck erythrocyte lysis and cytotoxicity to a mosquito cell line. The proteolyzed sample gave four protein peaks with gel filtration, and the fourth peak containing biological activity was further separated into three protein fractions by anion exchange chromatography; two of the three showed biological activity. These two fractions contained 22 and 23 kD proteins species. The nonproteolyzed sample was separated into two protein fractions by gel filtration; only the first peak contained the biological activity. This fraction was further separated into two fractions by anion exchange chromatography; only the second fraction, containing a 28 kD protein, exhibited the activity. This fraction contained a 28 kD protein. However, the fractions containing 22 or 23 kD proteins originating from the proteolyzed sample showed the highest biological activity. Mallard ducks were repeatedly exposed to an aerosolized commercial preparation of the organism. Sera were collected periodically and tested for the antibody by an enzyme-linked immunosorbent assay (ELISA). Those toxic antigens containing 22 or 23 kD proteins were unsuitable for the assay. The exposed ducks were found to produce antibodies against the first fraction from anion exchange chromatography of the proteolyzed sample. The antibody titres increased as the number of exposures increased. The results suggest that ELISA is applicable for detecting antibodies against B.t.i. in wild ducks using the fraction containing a 50 kD protein. / Graduation date: 1992

In the past 10 years we have witnessed the beginnings of the study of soil ecology as a unified science, and the general realization by soil scientists, farmers, and land managers that many of the most important economic aspects of soil health are controlled by biological factors. This research focuses on alterations in a tropical soil microarthropod community under differing intensive agricultural protocols: native vegetation, pastures and cropland, during June, July and August 1998. The effect of pesticides in potato cultivation was also studied. In the Ecuadorean montane forest, 361 morphospecies of soil arthropods, were classified during the three sampling months. August was the month with highest abundance and diversity. Acari, Coleoptera, Collembola, Diptera and Homoptera were the most abundant orders present in all the three types of land management. The native vegetation had the most abundant and diverse representation of all soil arthropod taxa compared to the pastures and croplands. Coleoptera, Diptera, Diplopoda, Diplura and Hemiptera were significantly more diverse in native vegetation than in pastures and croplands. The most abundant functional groups were the fungivores, herbivores and predators. The abundance of functional groups was significantly higher in the native vegetation for predators, herbivores and detritivores. 115 morphospecies of soil arthropods were identified in the study of arthropod response to pesticides in a complete randomized potato plot. Seasonal effects were documented for Acari, Collembola, Diptera, and Homoptera. Predators were most abundant in July and fungivores decreased in September. Neither arthropod orders nor functional groups showed a significant change in abundance between different treatments. Only Homoptera showed an increase in its abundance in the third sampling date and only in the Antracol plots. The potato plants in the whole block showed poor productivity, suggesting that the whole system was stressed by the fungal pest. / Graduation date: 2000

Across Canada, and around the world, very large amounts of pesticides are produced and applied to agricultural crops each year. Although pesticide usage is declining, they are still a necessary part of industrial agriculture. Numerous pesticides have been quantified in the atmosphere, at high levels near regions of use and at lower, but still significant levels in remote regions. Some of the most persistent pesticides have been banned, but others continue to be used despite their persistence and potential for long-range transport (LRT). We have applied and refined an XAD-2 resin-based passive air sampler (PAS) to study the concentrations of pesticides in the atmosphere. A set of laboratory experiments measured the equilibria sorption coefficients for chemicals on XAD-2 resin, allowing the determination of a new predictive equation for equilibria sorption coefficients, and thus interpretation of the range of applicability of both XAD-based PAS and active air samplers (AAS). A set of field experiments were performed to compare the data obtained by both PAS and AAS, and to study the temporal trends of a wide range of pesticides in an agricultural area of southern Ontario. Because it is now apparent that XAD-PAS sampling rates can vary between compounds and with temperature, we also determined new compound-specific sampling rates for pesticides in the XAD-PAS. The XAD-PAS were deployed in two transects across Canada, one from the Great Lakes region to the Canadian Arctic, and one across southern British Columbia in four different mountain regions and at different elevations. The air concentrations of current-use pesticides were correlated with regions of their use in both transects. The variation of air concentration with elevation was correlated with local, ground-level sources in British Columbia. The LRT of pesticides was determined from the north-south transect, and correlated to their atmospheric half-lives. Historic-use pesticides such as hexachlorobenzene and hexachlorocyclohexane were found to have relatively uniform distributions in the Canadian atmosphere, while further evidence of α-hexachlorocyclohexane evaporation from oceans was observed in both transects.

Passive air samplers (PAS) using XAD-resin were deployed at a wide variety of sites around the world for four years to asses the spatial and temporal trends of legacy organochlorine pesticides (OCPs) and current use pesticides (CUPs) in the global atmosphere. Legacy OCPs are prevalent in developing countries, whereas certain CUPs dominate in North America and Europe. OCP levels are declining world wide. Concentrations from the XAD-based PAS agreed with those from polyurethane foam (PUF) disk PAS within a factor of 4 for most sites. The comparison revealed that the sampling rate of the PUF-based PAS is more dependent on wind speed, whereas that of the XAD-PAS has a higher dependence on temperature. Analysis of PAS deployed across arid, subtropical Botswana showed that recent use has more impact on present day air concentrations than historical use. Year-long measurements by high volume air sampling in Botswana yielded higher HCB levels in winter, and higher endosulfan levels in summer. Those variations are neither related to temperature fluctuation nor seasonal hydrological events, and are therefore more likely caused by pesticide usage pattern. Very low levels of OCPs were found in the warm, dry, low organic matter soils of Botswana, including in soils from historical use areas. Such soils appear to have a low long-term storage capacity for pesticides allowing for rapid volatilization. They are thus not long-term sources of pesticides to the atmosphere. Endosulfan sulfate levels were observed to increase in tropical soils with increasing elevation. Water samples from high altitude cloud forests in Costa Rica contained very low concentrations of CUPs and it is unlikely that that those levels pose a threat to amphibians in cloud forests. Laboratory experiments and literature analysis showed that the inert gas stripping method for the determination of air-water partitioning equilibria is susceptible to surface sorption artifacts for chemicals with a interface-air partition coefficient log (KIA/m) > -3. Using larger bubbles reduces the surface-to-volume ratio and produces accurate air-water partition coefficients for chemicals with log (KIA/m) < -1.2.

Across Canada, and around the world, very large amounts of pesticides are produced and applied to agricultural crops each year. Although pesticide usage is declining, they are still a necessary part of industrial agriculture. Numerous pesticides have been quantified in the atmosphere, at high levels near regions of use and at lower, but still significant levels in remote regions. Some of the most persistent pesticides have been banned, but others continue to be used despite their persistence and potential for long-range transport (LRT). We have applied and refined an XAD-2 resin-based passive air sampler (PAS) to study the concentrations of pesticides in the atmosphere. A set of laboratory experiments measured the equilibria sorption coefficients for chemicals on XAD-2 resin, allowing the determination of a new predictive equation for equilibria sorption coefficients, and thus interpretation of the range of applicability of both XAD-based PAS and active air samplers (AAS). A set of field experiments were performed to compare the data obtained by both PAS and AAS, and to study the temporal trends of a wide range of pesticides in an agricultural area of southern Ontario. Because it is now apparent that XAD-PAS sampling rates can vary between compounds and with temperature, we also determined new compound-specific sampling rates for pesticides in the XAD-PAS. The XAD-PAS were deployed in two transects across Canada, one from the Great Lakes region to the Canadian Arctic, and one across southern British Columbia in four different mountain regions and at different elevations. The air concentrations of current-use pesticides were correlated with regions of their use in both transects. The variation of air concentration with elevation was correlated with local, ground-level sources in British Columbia. The LRT of pesticides was determined from the north-south transect, and correlated to their atmospheric half-lives. Historic-use pesticides such as hexachlorobenzene and hexachlorocyclohexane were found to have relatively uniform distributions in the Canadian atmosphere, while further evidence of α-hexachlorocyclohexane evaporation from oceans was observed in both transects.

Passive air samplers (PAS) using XAD-resin were deployed at a wide variety of sites around the world for four years to asses the spatial and temporal trends of legacy organochlorine pesticides (OCPs) and current use pesticides (CUPs) in the global atmosphere. Legacy OCPs are prevalent in developing countries, whereas certain CUPs dominate in North America and Europe. OCP levels are declining world wide. Concentrations from the XAD-based PAS agreed with those from polyurethane foam (PUF) disk PAS within a factor of 4 for most sites. The comparison revealed that the sampling rate of the PUF-based PAS is more dependent on wind speed, whereas that of the XAD-PAS has a higher dependence on temperature. Analysis of PAS deployed across arid, subtropical Botswana showed that recent use has more impact on present day air concentrations than historical use. Year-long measurements by high volume air sampling in Botswana yielded higher HCB levels in winter, and higher endosulfan levels in summer. Those variations are neither related to temperature fluctuation nor seasonal hydrological events, and are therefore more likely caused by pesticide usage pattern. Very low levels of OCPs were found in the warm, dry, low organic matter soils of Botswana, including in soils from historical use areas. Such soils appear to have a low long-term storage capacity for pesticides allowing for rapid volatilization. They are thus not long-term sources of pesticides to the atmosphere. Endosulfan sulfate levels were observed to increase in tropical soils with increasing elevation. Water samples from high altitude cloud forests in Costa Rica contained very low concentrations of CUPs and it is unlikely that that those levels pose a threat to amphibians in cloud forests. Laboratory experiments and literature analysis showed that the inert gas stripping method for the determination of air-water partitioning equilibria is susceptible to surface sorption artifacts for chemicals with a interface-air partition coefficient log (KIA/m) > -3. Using larger bubbles reduces the surface-to-volume ratio and produces accurate air-water partition coefficients for chemicals with log (KIA/m) < -1.2.

El objetivo principal de esta tesis doctoral es el de contribuir al desarollo y evaluación en la aplicación y exposición de pesticidas en plantas y su impacto sobre la salud humana y los ecosistemas. Los modelos ambientales usados para la evaluación de impacto en el análisis de ciclo de vida y en analisis de riesgo ambiental relacionan las emisiones con su impacto, combinando el destino y la exposición estimada y relacionandolo con información toxicológica. Los pesticidas liberados en aire, agua y suelos llegan al cuerpo humano a través de los alimentos, principalmente por la ingestión de las partes comestibles de los vegetales. Por dicha razón, es de gran importacia el desarollo de métodos para el análisis de residuos tóxicos en productos agrícolas. De aquí emergen las siguientes preguntas:1. ¿Como puede ser modelada la cantidad residual y el lugar de destino de los pesticidas aplicados por aire en los invernaderos? ¿Cual es su compotamiento dinámico y como afecta la concentración residual en las partes comestibles de los vegetales?2. ¿Como puede medirse y modelarse la degradación de los pesticidas tanto en superficie como en el interior de vegetación?3. ¿Como puede hacerse una estimación de la vida media específica tanto en superficie como en el interior de vegetales partiendo de la información de degradación en el suelo?4. ¿Como puede desarollarse un indicador de riesgo con el cual se puedan analizar comparativamente pesticidas basado en el lugar de aplicación, tiempo de exposición y características toxicológicas?Después de una breve introdución al análisis medioambiental y los problemas específicamente relacionados con la aplicación de pesticidas y sus características en el capítulo uno, en el capítulo dos se propone un acercamiento a través del modelado de residuos de pesticidas en tomates cultivados en invernadero. Este modelo de destino y exposición tiene en consideración el tiempo transcurrido entre la aplicación, la cosecha y el consumo, la absorción del spray depositado en la superficie de las plantas, las propiedades de transporte a través de la cutícula, la degradación en el interior de la misma planta y perdidas debido al procesado del alimento. El modelo fue validado usando datos experimentales obtenidos a partir de ensayos de campo. También se presenta la fracción de pesticida ingerido por humanos debido al consumo de tomate mostrando un escenario realista de la exposición humana a estos productos.En el capítulo tercero se presentan dos algoritmos genéricos para la estimación de (i) la vida media específica de pesticidas en superficie y (ii) en el interior de las plantas, usados en el modelo de destino y exposición. También se propone una rutina de extrapolación para estimar la vida media de plaguicidas en superficie, basándose en un factor de conversión cuya base de cálculo parte de la vida media de estos en suelos. Más adelante se presenta un método de estimación tentativa para el cálculo de la vida media de pesticidas en el interior de las plantas, básandose en datos experimentales.El capítulo cuatro es una prolongación de los capítulos dos y tres. Los resultados antes obtenidos, se combinan aquí con un nuevo método de análisis experimental para medir absorción, transporte y persistencia de pesticidas en tomates tratados por (i) spray foliar estándar y (ii) aplicación en raíces por riego por goteo. Un modelo dinámico de absorción de pesticidas por raíz trata de estimar la dependencia temporal de la concentración del contaminante en los frutos. Finalmente, los resultados experimentales son comparados con el modelo en terminos de ingestión de fracción de pesticida por parte de la población humana. En esta investigación se intenta evaluar el comportamiento medioambiental de los pesticidas comparando los diferentes métodos de aplicación de un mismo ingrediente activo.El capítulo cinco ilustra el desarollo de un nuevo método llamado PestScreen, el cual calcula el nivel relativo de riesgo de pesticidas con el fin de clasificarlos ascendentemente dependiendo de su impacto. Esta aproximación es un método de estimación del nivel relativo de riesgo y permite comparar la peligrosidad tanto a nivel de salud humana como de impacto medioambiental, de diferentes tipos de pesticidas, a través de una categorización. Este método se desarolla como una herramienta para la evaluación e identificación de pesticidas con peligrosidad medioambiental usados en la agricultura. PestScreen incorpora tanto su efecto tóxico como su destino y exposición en varios compartimentos medioambientales. Esto se realiza combinando medidas de toxicidad química con la cantidad liberada, la persistencia medioambiental, el potencial de transporte en un radio amplio y la fracción ingerida por la población humana. En el capítulo seis los principales resultados son presentados y resumidos, finalmente se sugieren recomendaciones para investigaciones futuras. / The overall goal of this dissertation is to contribute to the development of best available practice in fate and the exposure assessment of pesticides for evaluating their impacts on human health and ecosystems. Environmental models used in Life Cycle Impact Assessment (LCIA) and Environmental Risk Assessment (ERA) relate emissions to impacts by combining fate and exposure estimates with toxicological assessment data. Pesticides released to air, water, soil and plants enter the human body through food commodities, particularly through the ingestion of arable parts of plants. Therefore, specific methods to assess the presence of residues in agricultural products are of importance for human exposure assessment. This raises the following questions:1. How can the fate (from air and soil) of pesticides in/on plants cultivated in greenhouses be measured and modelled? How does dynamic behaviour affect the final residues in arable parts of plants?2. How can the degradation of pesticides on plant surfaces and within plants be measured and modelled? 3. How can a substance specific half-life in/on plants be estimated from soil degradation data using extrapolation routines?4. How can a risk indicator for comparative assessment of pesticides be developed using fate, exposure, and toxicity characteristics?After a short introduction to environmental assessment approaches and the specific problems related to the application of pesticides and their characteristics in Chapter 1, Chapter 2 proposes an approach for modelling pesticide residues in greenhouse tomato plants. This fate and exposure model considers the time between pesticide application and harvest, the time between harvest and consumption, the absorption of spray deposit on plant surfaces, transfer properties through the cuticle, degradation inside the plant and loss due to food processing. The model is validated with experimental data which was obtained from field trials conducted in the Catalan Institute for Food and Agricultural Research and Technology (Institut de Recerca i Tecnologia Agroalimentàries; IRTA) in Cabrils (Barcelona). Human intake fractions of pesticides due to ingestion of tomatoes representing a realistic scenario of human exposure to pesticide residues in foods are presented.In Chapter 3, two generic estimation routines for substance specific half-lives of pesticides (i) on plant surfaces and (ii) within plants to be used in fate and exposure models are presented. First, an extrapolation routine for the estimation of pesticide half-lives on plant surfaces based on a conversion factor from half-lives of pesticides in soil is proposed. Furthermore, a tentative estimation method for the calculation of metabolism half-lives of pesticides in inner parts of plants based on experimental data is presented.Chapter 4 presents a follow-up of Chapter 2 and Chapter 3. Previous results are combined with new experimental assessment to measure the uptake, translocation and persistence behaviour of pesticides in tomato fruits treated by (i) standard foliar spray application and (ii) soil application using direct localised drip irrigation into root zone. A dynamic root uptake model for pesticides aiming at the estimation of time dependent contaminant concentrations in fruits is proposed. Finally, experimental results are compared with model estimates in terms of human population intake fractions of pesticides. These investigations aim to evaluate the environmental performance of pesticides when the same active ingredient is applied to crops by different application techniques. Chapter 5 illustrates the development of a new method entitled PestScreen, to calculate the relative risk level of pesticides with the aim of ranking them from lowest to highest degree of concern. The approach is an estimation method of relative risk levels and allows comparing environmental and human health risks of specific pesticide types through their ranking. The method is developed to serve as an analytical tool in screening and identification of pesticides of environmental concern used in agriculture. PestScreen incorporates both the toxic effects of pesticides and their fate and exposure characteristics in different compartments of the environment. This is done by combining measures of chemical toxicity pertaining to both human health and the environment with chemical release amounts and information on overall environmental persistence, long-range transport potential and human population intake fractions. In Chapter 6 the most important results are summarized and recommendations for further research are discussed.

This study aimed to examine farmers’ descriptions of their experiences of cultivating Bt cotton and to see whether or not the farmers’ descriptions of their experiences are in coherence with the purposes with Bt cotton. This was carried out through qualitative semi-structured interviews with Bt cotton farmers in Vidarbha, Maharashtra, and a qualitative content analysis of the farmers’ descriptions. Our conclusions are among other, that the experiences of the farmers are various. Some farmers have experienced what Bt cotton was aimed to lead to; higher yields and reduced use of pesticides while other farmers have experienced the opposite.

Pesticides are natural or artificial molecules aimed to kill, or mitigate any harmful organism. Although their use in agriculture provides us with an increased crop yield, remains of chemicals on the products creates health concerns in society. Organophosphates and carbamates are two groups of insecticides. Although they are far more lethal against insects and small animals, they can also cause poisoning in humans through the inhibition of acetylcholinesterase enzyme (AChE) that plays an important role in human nervous system. Therefore, the detection of these compounds is crucial. The conventional methods for the detection of these compounds are expensive, time-consuming and need expertise. In this study, a fast, disposable, cheap and accurate acetylcholinesterase biosensor was developed to detect organophosphate and carbamate-based pesticide residues. By means of adsorption method, AChE, the chromophore 5,5&#039 / -Dithio-bis(2-nitrobenzoic acid) (DTNB) and artificial substrate acetylthiocholine (ATCh) were immobilized on the supporting material. In optimization studies / from 3 to 15U/mL concentrations were experimented for AChE, 1 to 5mM DTNB and 1 to 5mM ATCh concentration gradients were used. v As a result of the optimization studies 12U/mL ACHE concentration, 5mM DTNB concentration and 5mM ATCh concentration were determined for constructing a pesticide biosensor. Detection limit of malathion, an organophosphate-based insecticide was found as 2.5ppm in 5% methanol solution. The biosensor conserved its integrity between pH 4 and 8, and gave false positive results after pH 10. Stability studies showed that, biosensor retained its activity for at least 60 days at 4&deg / C to discrimnate between positive and negative controls.

The western burrowing owl, Athene cunicularia hypugaea, is a Federal Species of Concern, whose numbers and range have been drastically reduced from historic levels in Texas. Burrowing owls roost and forage in agricultural areas, and it has been hypothesized that exposure to insecticides may be a factor in the decline of their population. Burrowing owls wintering in southern Texas use agricultural culverts in cotton fields as roost sites, which may increase their risk of exposure to agricultural chemicals, either through ingestion of contaminated prey or through dermal exposure to agricultural runoff. Simulation modeling was used to characterize the risks to individual burrowing owls wintering in agricultural landscapes in southern Texas due to effects of exposure to insecticides or other agricultural chemicals. The simulation model was created using Stella® VII software (High Performance Systems, Inc., New Hampshire, USA). The model is broken into four submodels simulating (1) foraging behavior of burrowing owls, (2) chemical applications to crops, (3) chemical transfer and fate in the crop soil and prey items, and (4) chemical exposure in the burrowing owl. This model was used to evaluate (1) which components of the model most affect the endpoints, (2) the relationship between increased concentrations of agricultural chemicals in culverts and subsequent lethal and sublethal effects from dermal exposure to agricultural runoff, and (3) which agricultural chemicals have the greatest potential to cause adverse effects in burrowing owls. Model results suggested (1) the half-lives of agricultural chemicals in birds caused the most variation in the results, and data gaps exist for several important model components (2), exposure to increased concentrations of agricultural chemicals in culverts is unlikely to result in lethal effects, but is likely to lead to sublethal effects in burrowing owls, and (3) the chemicals with the greatest potential to negatively affect burrowing owls wintering in southern Texas are the OP insecticides chlorpyrifos, dicrotophos, and disulfoton, the oxadiazine insecticide indoxacarb, the herbicide trifluralin, and the defoliants tribufos and paraquat. The results of this model demonstrate the usefulness of simulation modeling to guide future research related to the conservation of burrowing owls.