THE RESISTANCE MECHANISM OF HOUSEFLY AGAINST PYRETHROIDS
SUN YUN-QIN YUAN JIA-GUI LI JING HE FENG-QIN LIU BAO-WEN WANG JING GONG KUN-YUANInstitute of Zoology, Academia Sinica, Beijing
The resistance mechanism of permethrin- and deltainethrin-selected high resistant strains (2C1-R and Dec-R) of the house fly Musca domestica vicina was investigated through bioassay, use of different synergists, in vivo test of cuticular penetration and studies on the activities of detoxification enzymes and ATPase. It was found that the cuticular penetration of permethrin was slower in the two resistant strains than in the normal susceptible strain (NP), and the lag was more conspicuous in the Dec-R strain. The activities of esterases, mixed function oxidases and cytochrome P-450 were higher in the resistant strains. It was discernible that the major resistance mechanism was the MFO-mediated detoxification in the 2C1-R strain and the esterase activity was higher in the Dec-R strain when compared with the NP strain. The Na+-K+-ATPase activity was 46% lower in the Dec-R strain when con-pared with the susceptible strain, but the difference between the 2C1-R and NP strains was not conpicuous. The activity of Mg2+-ATPase was higher in the two resistant strains than in the NP strain. It is proposed that Mg2+-ATPas may be also an important target site for pyrethroid action.