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UBC Theses and Dissertations

The establishment of the dosage-mortality curve for an aphid : a problem in methodology. Pearson, William Daniel


A reliable technique for establishing the dosage: mortality curve for an aphid is described. Standardized conditions of rearing, collecting, treating and post-treatment holding are combined with application of measured droplets of malathion in acetone solution to individual aphids. The importance of each of these factors is discussed. The LD₅₀ of malathion to the pea aphid is 23.6 nanograms per aphid. The 95% fiducial limits about this estimate are 18.4 and 31.4 nanograms per aphid. The slope (± S,E.,n = 7) of the log-dosage: probit-mortality line is 5.5 ± 0.4. The mathematical and biological criteria used to evaluate the technique, and the possible application of the technique to selection and studies of insecticide resistant clonal lines of aphids are also discussed. Exposure of aphids on treated glass surfaces, and spraying with solutions or emulsions are also investigated and are discussed. These methods are unsatisfactory for investigation of the genetics and toxicology of insecticide resistance in aphid populations.

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