Insects
Two laboratory strains and five field populations of house flies
were used in this study. TJS, an insecticide-susceptible strain was
collected from a dairy farm in Beijing of China, and reared without
exposure to insecticide since 1982; BJD, a strain derived from a collection
in 1983 from a poultry farm in Beijing and selected with
deltamethrin and maintained in the laboratory. Five field populations
were collected in 2009 from five different locations (Guangdong,
Shanghai, Shandong, Beijing and Jilin) across China. F20 to
F23 adults were used for toxicity bioassay and expression profiling
determination in this study. The details about these strains were
described in Qiu et al. [21] and Wang et al. [22].