Influence of different stages of Diaeretiella rapae on development of Pachyneuron aphidis

Five species of hyperparasitoids of Diaeretiella rapae M'Intosh on aphids in vegetables field in Guangzhou, China, were found, and they are: Pachyneuron aphidis (Bouche), Syrphophagus aphidivorus (Mayr), Alloxysta fuscicornis Hartig, Dendrocerus aphidum(Kieffer) and Dendrocerus sp.; P. aphidis is an important hyperparasitoid suppressing the natural population of D. rapae. However, the growth stages of D. rapae affected the development of P. aphidis. The results from experiment showed that the development duration of P. aphidis was 15.22 d in the stage of D. rapae in pre-pupa in 1-24 h significantly longer than in pre-pupa in 48-72 h (12.21 d), while the hyperparasitism of P. aphidis was 15% in pre-pupae of D. rapae in 1-24 h significantly higher than in pre-pupa in 48-72 h(3%). The development phases of P. aphidis including egg, 1~(st) instar larva, 2~(nd) instar larva, 3~(rd) instar larva, pre-pupa and pupa, were described and their photos were given.