Abstract: Aimed to examine the prediction from the optimal diet model of classical foraging theory, i.e., female wasps prefer to lay eggs on most suitable hosts for the development of their offspring, a test experiment was conducted, taking Meteorus pulchricornisand its natural hosts Spodoptera litura and Mythimna separata larvae as test objects. To control the confounding effects of host body size and age, female M. pulchricornis was exposed to the larvae of the two host species with similar body size and same age, each at three levels. The results showed that M. pulchricornis preferred M. separate to S. litura in terms of the number of ovipositor-drilling and parasitization rate as measured by pupation rate. However, the offspring from S. litura was larger than that from M. separata as measured by the weight of cocoons and the hind tibia length of emerged adults. No significant difference was observed in the longevity of the M. pulchricornis adults from the two host species. A discussion was made on the mismatch between M. pulchricornis oviposition preference and its offspring developmental performances.

Key words: Chorthippus dubius, Biology, Spatial pattern, Population dynamics