n omethoate-resistant strain of carmine spider mite(Tetranvchus cinnabarinus Boisdu-val)was obtained by laboratory selection of a colony collected from Henan cotton field after16 selections with omethoate in a concentration ranging from 66.67 to 133.33(μl/L)during16 generations and got a resistance to this insecticide increased from 8. 33 folds(before selec-tion)to about 36.93 folds。This was compared with a susceptible population collected fromGushi county in Henan province to ensure a homogeneous colony fo...