I want to determine the effect of pesticides on enzyme inhibition in the body of insects. How many concentrations of pesticides are needed?
If the concentrations are selected wisely then 5. If poor choices are made then it might take hundreds or thousands. I might try doing this as two experiments. Experiment 1 is a range finder. Start with field rate and divide by 100. This is the highest concentration. Then do four more rates each one 100 times less concentrated than before. Based on these results, you should be able to get a narrow enough range that 5 or 6 doses should work. You want an untreated control, 1 dose that has no effect all the way to a dose that is the smallest required for 100% kill.
There may be other important details depending on the research question. To be relevant to a grower the application method must relate to a field application methodology.
If the concentrations are selected wisely then 5. If poor choices are made then it might take hundreds or thousands. I might try doing this as two experiments. Experiment 1 is a range finder. Start with field rate and divide by 100. This is the highest concentration. Then do four more rates each one 100 times less concentrated than before. Based on these results, you should be able to get a narrow enough range that 5 or 6 doses should work. You want an untreated control, 1 dose that has no effect all the way to a dose that is the smallest required for 100% kill.
There may be other important details depending on the research question. To be relevant to a grower the application method must relate to a field application methodology.
Ideally 5 to 6 concentrations shall work. Start with 10 mg/ ml say, and keep on diluting 10 folds, determine all concentrations that give 100 percent effect, and those giving more than 50 percent and less than 50 percent effect.
As Dr. Timothy A Ebert explained, the bioassy experiment could dived to two trial. The first trial, The following concentrations are used 1, 10, 100, 1000 ( the maximum conc. depends on the field rate (1/10 of the field conc.). In this trial 4 conc. are enough . From the results obtained, the period of concentrations that cause death between 16: 84% is divided to a number of concentrations.
Provided that there is a coefficient of multiplication between the concentrations selected between 2 to 5. For example, the concentration that caused 15% death (100 ppm) while the concentration that caused 86% death was 1,600. The selected concentrations will be 100, 200, 400, 800, 1600 This is enough.
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