Effects Of Queen Cell Size,Queen Caging Time And Transplanting Larval Age On Queen Quality Of Honeybees (Apis Mellifera)

Queens are the unique female individuals that have reproductive ability in honeybee colonies. Their quality closely links to the colony population and productivity.This study used four different diameters of queen cells(9.4mm?9.6mm?9.8mm?10.0mm) to rear Apis mellifera queens and test the effect of queen cell diameters on the quality of queens. Our results showed that the birth weight, ovarioles, thorax length and width were all significantly increased with the growth of queen cell diameters. qPCR results showed a similar trend that the expression of Vitellogenin(Vg) in queen abdomen were upregulated with the queen cell size increase. These results indicate that the queen cell size can strongly affect on the queen quality and reproductive ability.For measuring the effects of egg size on queen quality, queens were caged for 0 d, 2d and 4d and then were release to lay eggs. The results showed that the egg weight, length and width raised with the queen caging time, and queens from these eggs were also increased in terms of birth weight, ovarioles, thorax length and width. Further, the expression of Vitellogenin(Vg) in queen abdomen were upregulated with the caging time.These results revealed that the queen caging time could significantly influence egg size and their relative queen quality.We examined changes in genomic methylation, gene expression and queen morphology caused by transplanting queen-laid eggs or larvae in worker cells to queen cells. Queen larvae from transplanted worker larvae had decreased queen body size and weight compared to queens from transplanted eggs. Gene expression analysis showed that queens raised from larvae differed from queens raised from eggs in the gene expression.The number of significantly differentially expressed genes grew with the larval age increase, and these genes were involved in the immune system, caste differentiation, body development and longevity. DNA methylation levels were also higher. We propose that the worldwide commercial practice of raising queen bees from transplanted larvae has weakened bee commercial stocks by causing widespread genomic and epigenomic changes in queens that have consequences for queen quality and lifespan.