A Recessive Factor for Organophosphate-Resistance in Populations of the Two-Spotted Spider Mite, Tetranychus telarius1

Abstract

The significance of a recessive r-factor for organophosphate resistance for a population of Tetranychus telarius (L.) was investigated. By inbreeding all other factors contributing to resistance were removed from the population. It was found that the r-factor depresses vitality in its carrier in homozygous condition. In a given population mites heterozygous for the gene are equal competitors for the normal homozygous type or even show slight superiority to the latter.