Genetical aspects of insecticide resistance.

Studies on the mode of inheritance of insecticide resistance have been making rapid progress over the last few years and now cover some twenty-two species and about seventy different strains. These studies include not only the inheritance of particular forms of resistance but also the genetical aspects of cross-resistance and biochemical properties causing or related to resistance. The author reviews 27 instances of resistance recently subjected to genetic analysis; all but four were considered to be examples of monofactorial inheritance. The use of genetic markers has made it possible in some instances to map the genes responsible for resistance and has proved useful in the study of the genetic mechanisms involved in cross-resistance and multiple resistance. Correlations have been established between resistance, genetic constitution, and the activity of certain enzymes. Experiments are described illustrating the technique of crossing genetically marked resistant strains with susceptible strains in the study of the mode of inheritance of resistance to DDT and dieldrin.