Browsing by Subject "Insecticide"

Now showing 1 - 3 of 3
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    The effect of relative humidity on acaricide efficacy against and dispersal characteristics of the mold mite Tyrophagus putrescentiae
    (2013-06) Freitag, Jessica Anne
    This study determined the effects of relative humidity on mold mites (Tyrophagus putrescentiae) with regard to acaricide efficacy and dispersal characteristics. The mold mite is a stored product pest that can infest retail habitats. Mold mite survival depends on relative humidity (RH), and RH levels may affect efficacy of residual acaricides. In a simulated retail habitat, increasing humidity levels generally decreased acaricide efficacy. Results indicated that some acaricides may create a barrier against this mite. A second study analyzed mold mite dispersal characteristics. Mite infestations may remain undetected until mites leave the food package. Arenas provided an enclosed food reservoir incubated at high RH, and an open space incubated at one of three RH levels. Mite activity was monitored daily until dispersal characteristics were determined. Explosive dispersal, a mass-migration within 24 h, was observed. Therefore, direct sampling of habitat may be necessary to detect infestations before explosive dispersal has occurred.
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    Evaluation of Endophytic Beauvaria bassiana as a Targeted Insecticide in Tomato
    (2015-09) Pai, Shantal; Bushley, Kathryn
    A targeted insecticide treatment has great value in agriculture because it would mitigate insect damage while causing no harm to non-harmful insects, especially pollinators. Beauvaria bassiana is an endophyte which has been shown to improve plant growth and is a known insect pathogen. It was hypothesized that the combination of these two traits would make B. bassiana a potential targeted insecticide. Two tomato (Solanum lycoperscicum) varieties, Early Girl and Heinz 1706-BG, were inoculated with Beauvaria bassiana. The Early Girl variety was tracked to assess plant-fungal interactions, while the Heinz variety was inoculated with beet armyworm larvae (Spodoptera exigua) to examine effects of Beauveria on herbivory. Our results show that B. bassiana was transferred from the leaf tissue to the beet armyworm larvae, infecting and killing some insects, and slowing insect damage. Our results also show some indication that B. bassiana of pathogenic, rather than mutualistic, interaction with the Early Girl variety of tomato.
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    The Nature of Defense: Coevolutionary studies, ecological interaction, and the evolution of 'natural insecticides,' 1959-1983
    (2009-11) Mason Dentinger, Rachel Natalie
    The field of "coevolutionary studies" became a vigorous domain of discovery in the 1960s, and its practitioners were direct inheritors of the modern evolutionary synthesis of the 1940s. They were also direct inheritors of a natural environment that seemed increasingly on the decline, thanks primarily to the destructive actions of humans. Thus, in my account, knowing--the pursuit of knowledge about the natural world--is inextricably interwoven with doing--the practical business of interacting with and altering the natural world, for better or worse. In the case of coevolutionary studies, the act of changing nature through technological intervention with chemical insecticides profoundly changed the way that biologists understood the natural world and the way that humans understood our own place in the natural world. In building this argument, I draw from the work of a variety of science studies scholars, especially environmental historians and historians of science who have examined the boundary between nature and technology, and so-called "basic" and "applied" sciences. I find that the values of control and intervention that are implicit in the applied sciences can have a direct, substantive effect on shaping the direction and form that basic science assumes. As a result, coevolutionary theory was, to a large extent, predicated on the role of humans as participants--interactors--in the very natural systems that coevolutionists strove to understand. To understand this dynamic, I analyze how methods, metaphors, and materials derived from the applied sciences of economic entomology and agronomy formed a foundation for coevolutionary studies. It is no coincidence that most of the scientists in this narrative were disciplinarily rooted in entomology or insect physiology, two fields where potent toxins aimed at destroying insects were of significant importance. These insect scientists were intimately familiar with the methods, metaphors, and materials used to intervene technologically in the operation of nature. Moreover, the model of chemical activity, of the causal agency of potent molecular tools, which dominated both insect physiology and economic entomology, shaped the model of biochemical interaction that drove early coevolutionary studies.