Apis cerana cerana has the biological characteristic of gnawing off the old brood cells which reared multiple generations of workers. This study investigated the internal structure of newly built, old, and semi-rebuilt brood cells and their effects on the morphological development of workers to understand the significance of Apis cerana cerana gnawing off the old brood cells. The results showed that there was no significant difference among the three diameters (at the top, middle, and bottom positions) of newly built or semi-rebuilt brood cells (P > 0.05), but these changed within the old brood cells (P < 0.05). The top, middle, or bottom diameters of the newly built and semi-rebuilt brood cells were significantly larger than those of the old brood cells (P < 0.05), but were almost the same between the newly built and the semi-rebuilt brood cells (P > 0.05). The weight and base thickness of the cocoon were significantly greater in the old brood cells than those in the semi-rebuilt brood cells (P < 0.05). Importantly, the birth weight, body length, and the tested six external morphological indices did not show a significant difference between the newly built and semi-rebuilt brood cells (P > 0.05) but were significantly larger than those of old brood cells (P < 0.05). The size of the brood cell and the external morphology of the workers showed a positive correlation. This study highlights the significance of Apis cerana cerana gnawing off the old brood cells providing a reference for its scientific rearing.

This study investigated the changes in comb cell structure and external morphological characteristics of the Chinese honey bee under ten successive generations to determine the optimal time to replace the old combs. Accordingly, ten Chinese honey bee experimental colonies were established, and natural combs were constructed for continuous rearing of workers for 1–10 generations. The brood comb thickness, brood cell structure, birth weight, and morphological characteristics of workers were determined. Pearson correlation analyses between brood comb structure and morphological characteristics of workers were carried out. The results revealed that under ten successive generations, the color of the brood comb deepens from white or light yellow to brown and finally to black. Also, concerning the brood cell shape, the cell base changes from the three-rhomboid structure to the hemisphere, and the cell body changes from the hexagonal prism structure to the cylinder. The brood cell depth increases with an increase in brood comb thickness. The cell volume reduces with the hexagonal cell’s decreasing inner circumference side length, and diameter. A smaller cell volume leads to a decrease in the birth weight and body size of the worker, in addition, the Chinese honey bee has gnawed off the comb cells that have been cultivated for eight generations. This study suggests that the combs of Chinese honey bees should be replaced after eight generations to improve colony strength and production performance.

Hexamerins are members of the hemocyanin superfamily and play essential roles in providing amino acids and energy for the nonfeeding stages of insects. In this study, we cloned and analyzed the expression patterns of four hexamerin genes ( hex 70a , hex 70b , hex 70c , and hex 110 ) at different worker development stages and queen diapause statuses in the bumble bee, Bombus terrestris . The results of this study showed that hex 110 has the longest open reading frame (ORF; 3,297 bp) compared to the ORFs of hex 70a (2,034 bp), hex 70b (2,067 bp), and hex 70c (2,055 bp). The putative translation product of Hex 70a, Hex 70b, Hex70c, and Hex 110 has 677, 688, 684, and 1,098aa with predicted molecular mass of 81.13, 79.69, 81.58, and 119 kDa. In the development stages of workers, the expression levels of hex 70a , hex 70b , and hex 70c increased gradually from the larval stage and exhibited high expression levels at the pink eyed and brown eyed pupae stage, whereas hex 110 exhibited the highest expression level at the larval period. Four hexamerin genes were highly expressed at the prediapause status of queen ( P < 0.05), and compared to the eclosion queen, the lowest upregulation was 3.7-fold, and the highest upregulation was 1,742-fold. The expression levels of hex 70b , hex 70c , and hex 110 at diapause were significantly higher than those at postdiapause ( P < 0.05). In conclusion, hexamerins may play important roles in queen diapause and metamorphosis of larval and pupal stages.