Honey bee (Apis mellifera) health is crucial for honey bee products, and effective pollination and is closely associated with gut bacteria. Various factors such as reduced habitat, temperature, disease, and diet affect the health of honey bees, by disturbing the homeostasis of the gut microbiota. In this study, high-throughput 16S rRNA gene sequencing was used to analyze the gut microbiota of Apis mellifera subjected to seven different diets. The identified microbiota in the Apis mellifera gut from all the diets consisted of Lactobacillus (62%), followed by Rhizobiaceae (21%), Snodgrassella (4%), and Erwiniaceae (4%) among other 33 genera. Based on diet types, Lactobacillus a lactic acid bacteria (LAB), dominates the microbiota with the highest relative abundance in AIGT+SAC (91%), AIGT+Soytide (88%), and AIGT+Apple juice (69%) diet groups. Bifidobacterium and Commensalibacter appeared as the second most abundant genera in AIGT+SAC and AIGT+Soytide diet groups, respectively. These bacteria are important markers for honey bee health. Considering the importance of these diets in shaping their host microbiome into a healthy status. Individual honey bee health (IHH) was observed to validate the quality and correlation between the microbiota and honey bee health. The results were consistent, indicating that Apis mellifera fed on AIGT+Soytide and AIGT+SAC diet showed the highest health expression level of vitellogenin. The group with 60%Syrup possessing Rhizobiaceae as the dominant taxa showed poor health status. This finding paved the way for establishing a link between gut microbiota and IHH under different diets.

Apis cerana and Apis mellifera, are very important honey species for agriculture in Asian countries. In recent decades, A. cerana populations have sharply declined in all Asian countries as a result of Sacbrood Virus infection and have now recovered to their original size. It can change the genetic structure of local populations of A. cerana. We used the nuclear gene Vitellogenin VG to assess the genetic structure of local populations of A. cerana and the signature of adaptive selection. We performed a population genetic analysis of the honey bees A. cerana from South Korea in comparison with A. cerana samples from Russia, Japan, Nepal, and China. The sequences of the gene VG of a closely related honey bee species, A. mellifera, from India and Poland were used as outgroup samples. A comparative analysis of northern and southern A. cerana populations was performed. The signatures of positive adaptive selection were found in the local population of A. cerana. We performed the Tajima's neutrality D test for A. cerana populations from different local populations based on the gene VG exon sequences. All A. cerana populations showed signs of population size expansion following the possible recent decline in population sizes. The local populations of A. c. koreana were subdivided according to their geographical distribution into southern, northern, and central Korean clusters. The gene VG exon sequences can be used as informative markers for monitoring the changes in genetic structure and adaptation to the environment processes in A. cerana populations.