Insecticide Susceptibility And Resistance Mechanisms In Body Lice In Russia

Abstract:
The majority of body lice colonies examined in Moscow were permethrin resistant and susceptible to organophosphorus (fenthion, malathion) and neonicotinoid insecticides. Metabolic resistance of body lice to permethrin was investigated using synergists piperonyl butoxide (PBO), S,S,S-tributylphosphorotrithioate (DEF) and diethylmaleate (DEM). Synergism with enzyme inhibitors in permethrin-resistant body lice demonstrated that in some cases enhanced metabolism was involved in pyrethroid resistance. Resistance to permethrin was partially suppressed by` PBO, DEM and DEF, which suggests possible involvement of monooxygenases, esterases and glutathion-S-transferases in the resistance mechanism. Since the use of synergists did not lead to full suppression of resistance, it appears that lice also posses knockdown resistance (kdr). Body lice were studied by real-time PCR to detect kdr mutations (T917I and L920F) in the para-orthologous voltage-sensitive sodium channel gene, which are associated with permethrin resistance. The frequency of occurrence of the pyrethroids resistance gene was measured in 153 lice. Of these, 101 (66.0%) turned out to be homozygous resistant, 18 (11.8%) homozygous susceptible, and 34 (22.2%) heterozygous.