Abstract:Using the bioassay and biochemical methods, the insecticides susceptibility and detoxification enzymes of different Aphis citricola von der Goot populations were investigated to study the influence of host on A.citricola. The relative toxicity of imidacloprid, malathion, deltamethrin, methomyl to A.citricola population live on almond, plum, pear, apple were 3.53, 3.12, 2.55, 1.00; 2.42, 2.06, 1.69, 1.00; 2.96, 1.66, 1.43, 1.00; 2.11, 1.65, 1.37, 1.00, respectively. The susceptibility of aphis to pesticides was highest in population on almond, flowed by those on plum, pear and apple. Activities of glutathion-S-transferase (GST), acetylcholinesterase (AChE), carboxyl esterase (CarE) and mixed function oxidase (MFO) were highest in apple population, followed by pear, plum and almond populations of aphids. The GST, AChE, CarE and MFO activities of A.citricola population live on apple, pear, plum and almond was 2.32, 1.73, 1.35, 1.00; 2.48, 1.73, 1.66, 1.00; 1.60, 1.27, 1.23, 1.00; 2.02, 1.31, 1.13, 1.00, respectively. The differences of each enzyme activity of different aphid populations reach significant levels. All results indicated the host can influence the pesticide susceptibility and detoxification enzymes activity of A.citricola.