State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, China. Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing 100700, China. Molecular and Computational Biology Program, Departments of Biological Sciences, Chemistry, Physics, and Computer Science, University of Southern California, Los Angeles, California 90089, USA. Institute of Apicultural Research, Key Laboratory of Pollinating Insect Biology, Chinese Academy of Agricultural Science, Beijing 100093, China.