Browsing by Subject "Pesticides"
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Item A Comparison of Phytotoxic and Other Non-Insecticidal Effects of Several Systemic Pesticides Applied to Four Solanaceous Vegetable Crops(Texas Tech University, 1972-08) Kiser, Daniel WesleyNot Available.Item Ecotoxicological simulation modeling: effects of agricultural chemical exposure on wintering burrowing owls(Texas A&M University, 2008-10-10) Engelman, Catherine AllegraThe 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.Item Pesticide risk mitigation of avian wildlife in Iowa agroecosystems(Texas Tech University, 1999-05) Sauls, Benjamin TillmanModem agricultural practices have had a significant impact on the structure and suitability of agricultural landscapes as habitat for both plant and animal species. Many species of farmland wildlife have demonstrated population declines, which parallel increased herbicide use and altered land management. Habitat loss may often be greater threat to wildlife than pesticide use in agricultural landscapes. Mitigation may not focus on a particular pesticide product but more on the effect of an agricultural practice. The objective of this research project was to quantify the response of avian species to habitat enhancement and to provide forms of compensatory mitigation for pesticide effects on wildlife. During the first phase of habitat enhancement, unsprayed field borders were established along hedgerows on 4 sites and 4 other sites were conventionally farmed and used as reference sites. Northern bobwhite (Colinus virginianus) survival and nesting success were monitored and compared between unsprayed and reference sites. Results indicated that less than 20% of bird locations were on or adjacent to hedgerows on either reference or unsprayed sites. Bobwhite dispersed from hedgerows on reference and unsprayed sites before the borders were established. The next phase of this habitat enhancement research project involved planting a 10 m grass/forb border adjacent to the hedgerow on 3 sites. Three similar sites were conventionally farmed and referred to as reference sites. Bobwhite health indices and the nutritional value of crop contents for bobwhite and ring-necked pheasant(Phasianus colchicus) were measured on all sites. Results indicated that grassy field borders were not effective in increasing body condition indices of northern bobwhite and crop content results were heavily biased by specimens that contained soybean contents. During the spring, grassy border and reference sites were monitored for songbird activity. Avian abundance, species richness and nesting success of songbird species were compared between grassy border and reference sites. Overall, songbird populations were positively correlated with the increased grass/forb composition of the grassy borders. However, the extent of important differences in songbird populations was difficult to determine due to small sample size and limited seasonal data.Item Propazine residue as influenced by rate, date, and method of application(Texas Tech University, 1969-05) Leonard, Wesley LeeNot available