1. Department of Plant Breeding and Genetics, Cornell University, Ithaca, NewYork 14853‐1901 USA
2. International Rice Research Institute, DAPO Box 7777, Metro Manila 1301, Philippines
3. Kunming Institute of Zoology, the Chinese Academy of Sciences, No. 32 Jiaochang Donglu Kunming, Yunnan 650223 P.R. China