Genetics of Permethrin Resistance in the Horn Fly (Diptera: Muscidae)1

In horn fly, Haematobia irritans (L.), inheritance of permethrin resistance was determined using a strain that had been selected to be 100-fold more resistant at the LC50 than the susceptible strain. Resistance is determined by a single, incompletely recessive, sex-linked gene. Resistance was not significantly altered by addition of metabolic detoxification synergists S, S, S-tributyl phosphorotrithioate and piperonyl butoxide, indicating that the resistance mechanism was knockdown resistance target-site insensitivity.