Abstract: 【Aim】 Experiments were conducted to evaluate the effects of ultraviolet treatment of Grapholita molesta (Busck) eggs on parasitization and emergence of Trichogramma pintoi Voegele. The optimal ultraviolet intensity and irradiation time to treat G. molesta eggs were determined in order to provide the treatment and storage means of host eggs in mass rearing of T. pintoi. 【Methods】 T. pintoi adults within 12 h after emergence were supplied to parasitize G. molesta eggs which were irradiated by various ultraviolet intensities for different time, the parasitization performance was observed, and the parasitization rate and emergence rate were calculated and compared with that of T. pintoi parasitized G. molesta eggs not irradiated by ultraviolet. 【Results】 The results showed that the parasitization rate of T. pintoi significantly decreased when T. pintoi parasitized the G. molesta eggs which were irradiated by ultraviolet. With the enhancement of ultraviolet intensity and irradiation time, the parasitization rate significantly decreased, while the emergence rate had little change. When the G. molesta eggs were irradiated for 1-2 h by 15 W ultraviolet light or irradiated for 1 h by 30 W ultraviolet light, the emergence rate increased over 80% when compared to the control. But when G. molesta eggs were irradiated by ultraviolet for 3 h, the emergence rate decreased obviously.【Conclusion】 Parasitism and development of T. pintoi could be affected by ultraviolet intensity and treatment time. Therefore, irradiation with ultraviolet light of 15 W for 1 h is suggested in mass rearing of Trichogramma by small eggs in the laboratory.

Key words: Trichogramma pintoi, Grapholita molesta, eggs, ultraviolet intensity, ultraviolet irradiation time, parasitism