Characteristics Of Gnawing And Rebuilding Combs Of Apis Cerana Cerana And The Effect Of Old Combs On The Development Of Workers

Apis cerana cerana,a native Chinese honey bee species,has the biological characteristic of gnawing off the combs.In this study,Apis cerana cerana was used as the research object,based on the characteristics of Apis cerana cerana gnawing off the combs to analyze the patterns of gnawing and rebuilding combs,to investigate the effects of old combs on the development of workers.This study aimed to reveal the significance of Apis cerana cerana gnawing off the combs and to provide a theoretical research basis for the development of rearing and management measures of Apis cerana cerana.Firstly,the old combs of Apis cerana cerana used for 1 year were collected in different seasons,investigated the state of gnawed combs,recorded the patterns of gnawing and rebuilding brood cells,and measured the effects of two factors,old combs and old combs infected with larvae of the wax moth,on the weight of wax residue and combs area gnawed by Apis cerana cerana;Secondly,the structure of three types of brood cells was measured and revealed by using epoxy resin to make brood cell molds and comparing the birth weight and external morphological characteristics of newly emerged workers cultivated by the three types of brood cells;Finally,the contents of 10 heavy metals in 6-day-old larvae and newly emerged workers cultivated in newly built and old brood cells and the cocoon left in the brood cells were examined.In addition,the expression levels of four detoxification genes of Acc CYP4AV1,Acc CYP314A1,Acc CYP4 AZ,and Acc CYP6AS5 in 6-day-old larvae and newly emerged workers cultivated in newly built and old brood cells were analyzed.The research results were as follows:(1)Apis cerana cerana mainly gnawed off the combs which used for more than half a year,and the gnawed sites were concentrated in the brood-rearing area.Apis cerana cerana can gnaw off old combs in two patterns.The first pattern was to completely gnaw off the brood cells on the old combs;The second pattern was to only gnaw off the walls of the brood cells.Workers can build new walls based on the cell base containing a small amount of cocoon to form a semi-rebuilt brood cell.In addition,Apis cerana cerana mainly gnawed off the combs infected with larvae of the wax moth by completing the removal of the infected area and leaving comb holes,and then secreted wax to rebuild new cells to fill the gap.The old combs and combs infected with larvae of the wax moth were the main factors inducing Apis cerana cerana to gnaw off the combs,and the phenomenon of gnawing off the combs will intensify in winter.(2)The cocoon remaining in the cell after the completion of the development of the brood resulted in changes in the brood cell structure.The weight and base thickness of the cocoon was significantly greater in the old brood cells than those in the semi-rebuilt brood cells.The main shapes of the newly built,old,and semi-rebuilt brood cells were hexagonal prism,frustum of a pyramid shape,and hexagonal prism having three rhombuses,hemisphere,and hemisphere-shaped bases,respectively.The diameter and volume of the semi-rebuilt brood cell and the morphological size of the cultivated workers were almost the same as those of the newly built brood cell but significantly larger than the old brood cell.(3)Heavy metals such as chromium,copper,zinc,selenium,cadmium,lead,manganese,nickel,and arsenic were detected in the cocoon,6-day-old larvae,and newly emerged workers,while no mercury was detected in all samples.The development of Apis cerana cerana has suffered from heavy metal stress in the old brood cell.Compared with the newly built brood cell,the content of heavy metals in 6-day-old larvae and newly emerged workers from newly built and old brood cells and the cocoon left in the brood cells increased significantly,which led to an increase in the expression of four detoxification genes,namely,Acc CYP4AV1,Acc CYP314A1,Acc CYP4 AZ,and Acc CYP6AS5.This study revealed the characteristics of gnawing and rebuilding combs of Apis cerana cerana,and the influence of newly built,old,and semi-rebuilt brood cell structure on the birth weight and the development of external morphological characteristics of workers.It was clear that the accumulation of cocoon in the brood cell was the reason for the change of brood cell structure,the increase of heavy metal content.In this study,the behavior characteristics of gnawing off the comb cell of Apis cerana cerana were further explored and excavated,which laid a foundation for the biological theory research of Apis cerana cerana,and provided a basis for the feeding management and reasonable comb replacement.