Honey bee (Apis cerana) queen rearing methods influence queen morphological characteristics and reproductive related gene expression

Abstract

The quality of the queen is crucial for the survival and growth of honey bee colonies. There have been studies related to raising queens with excellent performance since the invention of artificial queen rearing technologies. However, relatively few studies have been undertaken that evaluate the relationship between queen quality and queen morphology and the expression level of reproduction-related genes using different-aged brood in artificial queen rearing practices of Eastern honey bees (Apis cerana). Therefore, we transferred eggs, 1-day-old larvae, 2-day-old larvae, and 3-day-old larvae to queen cells to rear queens until the queen emerged. We measured 12 indicators (the acceptance rate, birth weight, length, caliber and maximum diameter of queen cells, thorax length, width and weight, head width, wing length and width, and number of ovarian tubes). Moreover, the relative expression levels of Hexamerin, Vitellogenin, and Transferrin were measured using fat bodies and ovaries dissected from the newly emerged virgin queens. The results showed that queens reared from eggs exhibited the best morphological indexes and occupied the most abundant reproductive related gene expression level. Parameter values for queen from 1-day-old larvae were significantly higher than those for queens from 2-day-old larvae and 3-day-old larvae, and there was no significant difference between values for queens from 2-day-old larvae and 3-day-old larvae in most data, except for the relative gene expression. In conclusion, as the age of the brood increased, the quality of the queen bees declined. Rearing queens from fertilized eggs are far more likely to yield a better outcome for queen performance and colony function. This study provides data support for raising high-quality queens of Apis cerana, which would be benefit for the protection and better utilization of our native honey bee species.