Abstract
A. glomeratus usually parasitizes on larvae of Pieris rapae crucivora in Kyoto, but in Sapporo it parasitizes not only on P. rapae, but also on P.napi nesis and Aporia crataegi adherbal. The frequency of parasitism on P. napi and A. crataegi was no lower than on P. rapae. The oviposition preference tests proved that the parasitoid of Sapporo population can attack both P. rapae and P. napi larvae indiscriminately. The potentiality of successful parasitization of different Pieris larvae and oviposition tendencies with parasitoids from different origins were examined by artificial parasitization. The parasitoids of Sapporo population were different from those of Kyoto population. The former can develop in P. melete larvae in which the latter can not because of a hemocytic reaction of the host. Among the Sapporo population, the parasitoids grown in A. crataegi in the field were different from those grown in Pieris larvae in their oviposition tendencies. This difference suggested that Sapporo population has some strains associated with a limited host species.
