Objective  Tests to screen and determine sensitivities of insecticides for controlling Paracoccus marginatus Williams and Granara DE Willink, an important new invasive pest on papaya plants in China, were conducted.

  Method  The sensitivities of 2^nd nymphs and female adults of P. marginatus to 15 insecticides were determined by means of leaf immersion for pesticide selection.

  Result  Five applications of pesticides including 25 g·L⁻¹L lambda-cyhalothrin SC, 10% chlorfenapyr SC, 4.5% beta-cypermethrin EC, 15% pyridaben EW, and 15% tolfenpyrad SC with high toxicity to P. marginatus were selected for further evaluation. Among them, the lethal medium concentration (LC₅₀) of 25 g·L⁻¹ lambda-cyhalothrin SC was the lowest with LC₅₀ on the 2^nd nymphs and female adults being 0.243 0 mg·L⁻¹ and 0.782 1 mg·L⁻¹, respectively. It was followed by 10% chlorfenapyr SC, 4.5% beta-cypermethrin EC, 15% pyridaben EW and 15% tolfenpyrad SC in that order. The 2^nd nymphs were significantly more sensitive to the insecticides than the female adults.

  Conclusion  It appeared that 25 g·L⁻¹ lambda-cyhalothrin SC, 10% chlorfenapyr SC, 4.5% beta-cypermethrin EC, 15% pyridaben EW or 15% tolfenpyrad SC could be used to control or prevent a P. marginatus outbreak.