Biological efficacy of fumigants: time/dose response phenomena
1986
Winks, R.G.
The biological efficacy of fumigants is discussed in terms of the relationship between concentration (C) and time (t) in the toxicity of these materials. It takes the form Cnt=k, where k is the dosage required for a specified level of Kill and n is the toxicity index. The toxicity index varies with poison, species, developmental stage, and strain. Knowledge of the toxicity index or indices, and the range over which they apply, will help to optimize dosages. In the laboratory, an understanding of the toxicity index is essential in any meaningful comparison of strains, particularly when some measure of resistance is required. When measuring the toxicity of a fumigant in the laboratory, including comparisons of strains such as in resistance testing, it is essential that the time to respond to the dosage applied is properly considered. In a batch of insects, the time to death stabilizes when all insects that have received a dose in excess of their tolerance have responded. The point at which mortality stabilizes is described as the mortality end-point. This end-point varies with dosage, concentration, and the species or strain. Measurements of toxicity that are not based on end-point mortalities are of little or no value
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