The character or the variation: the genetic analysis of the insecticide-resistance phenotype

In this critique it is argued that the genetic basis of the evolution of re sistance is dependent on how the phenotypic, and underlying genotypic, vari ation is channelled during a selective response. A polygenic response is pr eferentially favoured if selection acts within the phenotypic distribution of susceptibles; a monogenic response is predicted if selection screens rar e mutations with phenotypes outside that susceptible distribution. The rele vance of this model to the method of genetic analysis, the prediction of re sistance mechanisms to novel insecticides, the generation of resistant bene ficial insects and the development of the most effective resistance and int egrated pest management programmes is discussed.