1. Graduate School of Science; Osaka City University; 3-3-138, Sugimoto, Sumiyoshi Osaka 558-8585 Japan
2. Organization for Research Promotion; Iwate University; 3-18-8 Ueda, Morioka Iwate 020-8550 Japan
3. Institute of Stingless Honeybees Science; 1-7 Wakaba, Tsukuba Ibaraki 300-1249 Japan
4. Graduate School of Engineering; Osaka City University; 3-3-138, Sugimoto, Sumiyoshi Osaka 558-8585 Japan