Many factors, such as larval diet, developmental space and rearing management result huge differentiation in queen development (Wei et al.,2019; Yi et al.,2020; He et al.,2021). Researchers explored methods in high-quality queen rearing (Woyle.,1971; Gabka et al.,2011; Rangel.,2012; Wei et al.,2019). Previous study found that the size of eggs laid in queen cells was larger than in worker cells, and the weight of newly emerged and the number of ovarioles of queens rearing with eggs in queen cells was larger than in worker cells and 2-day old larvae (Wei et al.,2019). Furthermore, the larger the eggs used, the larger the reared queen. Hence, the quality of queens in QE was better than WE. In addition, nurse bees feed larvae in worker cells with less worker jelly and provide larvae in queen cells with abundant royal jelly. The difference in food nutrition provides to QE and L larvae developing, which resulting huge differences in the quality of queens (Wang et al.,2016).
The growth, productivity, and survival of a colony depends in large part on the health and reproductive capacity of its queen (Tarpy et al.,2013; Rangel et al.,2012; Nelson et al.,1983;). The quantitative reproductive potential of a queen represents her “quality” (Amiri et al.,2017). Moreover, beekeepers prefer larger size with higher weight queens in commercial queen-rearing. Many pieces of evidences confirmed that the newly born weight, thorax size was strongly correlated with queen ovariole number which influences queen fecundity and quality (Nelson et al.,1983; Dodologlu et al.,2003; Amiri et al.,2017; Wei et al.,2019; He et al.,2021).
In fact, these results from the present study are consistent with our previous study (Wei et al., 2019) where QE showed significantly higher weight, ovariole number and thorax size than both WE and L. Our results agreed with the previous results (Wei et al., 2019; He et al.,2021), revealing that queens reared from eggs lied in queen cells was a practicable way for high-quality queens.
The production of honey and bee bread in colonies is extremely related to the collection capacity of forager bees. Moreover, the collection capacity of forager bees is strongly related to the area of wings which reflects in flight capacity (Zeng.,1992). In our study, the collected pollen cluster in legs of QE forager bees was much heavier than WE and L. Moreover, the wings length and width of QE forager bees were significantly higher than WE and L, suggesting that colonies with queens were reared from eggs in queen cells were more productive (Zeng.,1992; Blanken et al.,2015).
It is supposed that honey bee maternal effects had profound impacts on offspring phenotype (Wolf et al.,2009; Wei et al., 2019). However, it is unclear whether the quality difference in queens’ development caused by maternal effects can be transmitted to their offspring and eugenics exists in honey bee colony. Therefore, we further explored the quality difference of worker and queen offspring among the three groups. We found that eggs laid by reared queens of QE were much bigger, and the quality of offspring worker bees and queens of QE were much better. Results of the present study showed that maternal effect had profound influences on queen development, and these influences will carry over their offspring, causing huge differences in the quality of their offspring.
Nevertheless, our results indicate difference in queen quality caused by maternal effects will accumulative in their later generations, we will compare the quality differences in the queen offspring from queens of QE group laid eggs in queen cells, grafted eggs laid by queens of WE group and grafted larvae developed from eggs laid by queens of L group in the following study. In a word, rearing queens from eggs laid in queen cells is a practicable method for high-quality queens, which is important for promoting the development of beekeeping and agriculture. We also need to further explore the optimal conditions for queens laying eggs in queen cells to expand the scale of commercial queen-rearing from eggs lied in queen cells and gradually apply it to beekeeping practice.