Comb Cell Structure and Morphological Characteristics of the Chinese Honey Bee, Apis cerana cerana (Hymenoptera: Apidae), Under Successive Generations

Abstract

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.

Analysis of comb-gnawing behavior in Apis cerana cerana (Hymenoptera: Apidae)

“…This leads to the gradual buildup of these substances within the brood cells, causing structural changes and a reduction in volume inside the cell in old combs ( Hepburn et al 2007 ). Old combs negatively impact the external morphological dimensions of workers ( Hu et al 2023 ), the lifespan of honey bees ( Berry and Delaplane 2001 ), colony population and productivity ( Dizaji et al 2008 , Taha and Al-Kahtani 2020 ), and, in turn, the quality of bee products ( Rocha et al 2010 ). A study examining the brood cell structure of Western honey bees ( A. mellifera ) reported that workers expand the volume of brood cells by carefully cleaning the accumulated debris within the cells and secreting wax to increase the cell wall height, which helps the normal development of broods ( Таранов 1961 ).…”

“…The reduced size of brood cells negatively impacts the morphological characteristics of workers ( Alfalah et al 2012 ). For instance, the birth weight of workers significantly reduces after 5 generations of rearing in the brood cells ( Hu et al 2023 ). It is an important indicator of development status, reflecting the size of their external morphological structures ( Sam 1991 ).…”

Impact of Brood Cell Cocoons on Metal Accumulation and CYP450 Detoxification Gene Expression in Apis cerana cerana

“…Hence, the accumulation of feces in cells from multiple generations of workers indeed leads to increased metal content in the cocoon. Furthermore, A. c. cerana has a prominent biological behavior known as comb-gnawing, which is currently believed to be primarily caused by old combs resulting from rearing multiple generations of workers, with a reduced volume of brood cells and a not-well-developed morphological character of newly emerged workers [ 39 ]. The multi-generation combs used in this study showed comb-gnawing signs in the brood-rearing area.…”

“…Initially, two types of experimental combs were collected. These included three single-generation combs that had reared one generation of workers and three multi-generation combs that had reared numerous generations of workers (approximately eight generations), with a 1-year age and with some brood cells gnawed by workers [ 11 , 39 ]. Then, a 50 cm 2 comb block was cut from each comb’s brood-rearing area using an uncapping knife.…”

“…As the same brood cell can rear numerous generations of workers, the layers, weight, and base thickness of the cocoons significantly increase in multi-generation comb cells, leading to a reduction in cell volume [11]. However, the accumulated cocoons in the cell not only limits the developmental space of the brood, affecting the external morphology of the workers and negatively impacting the colony, but it also enriches metals [10,14,39]. Borsuk et al (2021) discovered that metals can be immobilized or metabolized in the fat bodies of Western honey bees and then expelled as feces [41].…”