Mortality in Apis mellifera L. colonies in China from 2009 to 2013 Morphological characteristics and microsatellite DNA genetic diversity of Nigeria African honey bee, Anhui Apis mellifera and theirs hybrid generationⅡ Comparative study on the niches of Apis mellifera ligustica and Apis cerana cerana Effects of pollination by different bees on peach fruit development and quality under greenhouse conditions