Abstract: A dual-choice experiment was conducted to observe the host selection and offspring developmental performances of koinobiontic parasitoid Meteorus pulchricornis on Spodoptera litura larval instars (except the first and last instars). The parasitoid showed no preference for L₄ and L₅, but exhibited preference to lower instar larvae in L₂ vs. L₃ and L₃ vs. L₄ . No significant difference was observed in the cocoon formation rate among the offspring parasitoids from different host instars at oviposition. The emergence rate decreased with the increase of host instars, and was higher from attacking L₂ and L₃ than that from attacking L₅. The mortality rate of the offspring developed from attacking L₅ was 2.5 times higher than that from attacking L₂ 2, and 5.4 times higher than that from attacking L₃. The offspring developed from attacking L₃ had the shortest development time (11.9 days), being 6.8 days shorter than that from attacking  L₄ and 4.7 days shorter than that from attacking L₂. There were no significant differences in the body size of progeny parasitoids on host instars at oviposition, as measured by hind tibia length. This study suggested that M. pulchricornis based its host selection more on host body size or its related characters than on host development stage per se.

Key words: Winter-time flooded paddy field, CH₄ and N₂O, Emission rate