Cotesia kariyai was provided to the laboratory by Dr. Yooichi Kainoh at University of Tsukuba, Ibaraki, Japan. To maintain the wasp culture, 3rd to 4th instars of M. separata larvae were offered to female wasps for oviposition. Soon after emergence from their host, the wasp larvae span a cocoon. Clusters of cocoons were placed in a glass tube (w=22 mm, length=200 mm) with honey as food for wasps at 18uC in the continuous dark conditions. The wasps emerging from the cocoons were kept (or stored) under the same conditions until they were used in the experiments within 7 days after the emergence. Oviposition-inexperienced females were used.