Inheritance of resistance to pyrethroid insecticides in Tribolium castaneum (Herbst)

Abstract

A strain of Tribolium castaneum, highly resistant to pyrethroids, was isolated (single-pair method) from a pyrethroid-resistant field strain and made isogenic with a susceptible laboratory strain. Insecticide assays were used to determine the mode of inheritance and linkage of pyrethroid resistance. Resistance to deltamethrin could not be measured directly but at a 2% mortality response was about 1600-fold. The responses of SR and RS hybrids to deltamethrin were intermediate between the resistant and susceptible parent strains; there was no significant difference between the SR and RS hybrids (P>0.05). Chi-square analysis of the observed responses of the F1–backcross and F2 progenies rejected the null hypothesis that a single gene was responsible for resistance. Successive backcrosses with selection indicated the involvement of more than one gene. Test crosses with visible mutant markers suggested that resistance was associated with linkage groups VIII and IX. Assays with deltamethrin applied to grain indicated that this resistance will be rapidly selected in the field resulting in control failures.