Abstract: 【Aim】 Rearing host and wasp age affect the egg load of Trichogramma wasps. In this study, in order to understand the relationship between rearing host and egg load or between the female size and egg load of Trichogramma wasps, we studied the effects of rearing hosts on the female size and egg load of wasps of three Trichogramma species (Trichogramma dendrolimi, Trichogramma ostriniae and Trichogramma japonicum) using Corcyra cephalonica eggs and Ostrinia furnacalis eggs as hosts.【Methods】 The three Trichogramma species were reared in climatic cabinet (25±1℃, photoperiod 14L:10D). Female egg load was observed at different ages (0-72 h-old) by dissecting the wasps under microscopy. Female hind tibia length was measured, and the relationship between female egg load and female age as well as between body size and rearing hosts was analyzed. 【Results】 The egg load of wasps of three Trichogramma species increased as female age increased within 48 h after wasp emergence. The egg load of 72 h-old wasps was lower than that of 48 h-old wasps of the corresponding species except for T. ostriniae wasps emerged from C. cephalonica eggs and T. dendrolomi  wasps emerged from O. furnacalis eggs. The egg load of T. ostriniae wasps emerged from O. furnacalis eggs was significantly higher than that of the wasps emerged from C. cephalonica eggs, whereas the result was opposite for T. dendrolimi (except 12 and 24 h-old) and T. japonicum. The egg load of T. dendrolimi wasps was the highest and T. japonicum held the least eggs among three Trichogramma species of the same age when C. cephalonica eggs were used as the rearing host. When the wasps emerged from O. furnacalis eggs, egg load of T. ostriniae was the highest and T. japonicum held the least eggs among the three Trichogramma species. There was a significant positive liner relationship between egg load and female size for the three Trichogramma species, and the relevance degree increased with female age. 【Conclusion】 Hind tibia length can be used as an index to evaluate the quality of T. dendrolimi,T. ostriniae and T. japonicumwasps. Rearing host, Trichogramma species and female adult age significantly affect the egg load of Trichogramma wasps. Host suitability also affects the size of Trichogramma wasps, and suitable rearing host helps to improve the quality of Trichogramma wasps.

Key words: Trichogramma dendrolimi, Trichogramma ostriniae, Trichogramma japonicum, fecundity, host suitability