Toxicity of commonly used insecticides and their influences on protective enzyme activity of multicolored Asian lady beetle Harmonia axyridis (Pallas) Study on predation preference of Harmonia axyridis (Pallas) and Adonia variegata (Goeze) on red and green color morph pea aphids Evaluation of the effect of nitenpyram on Harmonia axyridis (Pallas) using life table technique