Recommended methods for the detection and measurement of resistance of agricultural pests to pesticides; tentative method for nymphs of cocoa mirids (Distantiella theobroma Dist. and Sahlbergella singularis Hagl.)
Nymphal mirids at fourth and fifth instars of the cocoa capsids are collected in the field and taken to a simply equipped laboratory for testing. The mirids are confined in groups of ten onto filter papers which have been impregnated with the appropriate insecticide. They are inspected at intervals for knockdown and the responding percentages plotted against time on logarithmic probability paper, so that LT 50 and LT 90 values, etc., can be estimated. Baseline data for various insecticides are thus established for susceptible strains. It is then possible to select discriminating exposure periods which can be used to screen samples of mirids for resistance. Failure of some individuals to respond at the end of such tests is a danger signal calling for more extensive testing to define the degree of resistance present.
| Format: | biblioteca |
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| Published: |
1971
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| Subjects: | THEOBROMA CACAO, DISTANTIELLA THEOBROMAE, SAHLBERGELLA SINGULARIS, MIRIDAE, INSECTICIDAS, PLAGUICIDAS, RESISTENCIA QUIMICA, |
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| Summary: | Nymphal mirids at fourth and fifth instars of the cocoa capsids are collected in the field and taken to a simply equipped laboratory for testing. The mirids are confined in groups of ten onto filter papers which have been impregnated with the appropriate insecticide. They are inspected at intervals for knockdown and the responding percentages plotted against time on logarithmic probability paper, so that LT 50 and LT 90 values, etc., can be estimated. Baseline data for various insecticides are thus established for susceptible strains. It is then possible to select discriminating exposure periods which can be used to screen samples of mirids for resistance. Failure of some individuals to respond at the end of such tests is a danger signal calling for more extensive testing to define the degree of resistance present. |
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