Abstract: The effect of feeding substitute diet on the predation ability of Harmonia dimidiata Fabricius was investigated by feeding the predator with the eggs of Ephestia kuehniella Zeller and water or honey water until adult and measuring the predator's functional response and searching efficacy to Aphis craccivora Koch. The results showed that the predation functional response of H. dimidiata to A. craccivora in each handling conformed to Holling Ⅱ model. Under the same predation density, the theoretical maximum daily predation amount, pest control efficiency (a/T_h value), and searching efficiency ranked from high to low were control treatment (A. craccivora), EH treatment (eggs of E. kuehniella with honey), EW treatment (eggs of E. kuehniella with water). However, there was no significant difference in the actual daily predation amount of H. dimidiata of the same sex. According to the analyses, feeding on the eggs of E. kuehniella neither affected the type of predation functional response of H. dimidiata or the predation of A. craccivora. The appropriate addition of honey can improve the predation ability of H. dimidiata to A. craccivora. At the same time, the eggs of E. kuehniella and appropriate amount of honey can be used in mass production of H. dimidiata. Under the condition of no competition, to the prey A. craccivora, the optimal search densities of the female and male adults of H. dimidiata fed E. kuehniella eggs and honey were 101.78 and 90.2, respectively. Under these densities of A. craccivora, H. dimidiata predation can reach the maximum efficiency, which can be used as a reference for the ratio of benefit to harm in field application.

Key words: Harmonia dimidiata, alternative feed, Ephestia kuehniella, Aphis craccivora, predation