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.

Dominance hierarchies are ubiquitous in invertebrates and vertebrates, but little is known on how genes influence dominance rank. Our gaps in knowledge are specifically significant concerning female hierarchies and in insects. To start filling these gaps we studied the social bumble bee Bombus terrestris, in which social hierarchies among females are common and functionally significant. Dominance rank in this bee is influenced by multiple factors, including juvenile hormone (JH) that is a major gonadotropin in this species. We tested the hypothesis that the JH responsive transcription factor Krüppel homologue 1 (Kr-h1) mediates hormonal influence on dominance behavior in the bumble bee. We first developed and validated a perfluorocarbon nanoparticles-based RNA interference protocol for knocking down Kr-h1 expression. We then used this procedure to show that Kr-h1 mediates the influence of JH not only on oogenesis and wax production, but also on aggression and dominance rank. To the best of our knowledge, this is the first study causally linking a gene to dominance rank in social insects, and one of only a few such studies in insects or in female hierarchies. These findings are important for determining whether there are general molecular principles governing dominance rank across gender and taxa.

Citrus greening disease or huanglongbing (HLB) caused by Candidatus Liberibacter asiaticus (CLas) limits the citrus production worldwide. CLas is transmitted by the Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Psyllidae) in a persistent-propagative manner. Application of insecticides to manage the psyllid vectors and disease is the most common practice. Understanding the molecular interaction between CLas and ACP and interrupting the interrelationship can provide an alternative to insecticides for managing citrus greening disease. Transcriptome analysis of ACP in response to CLas showed differential expression of 3911 genes (2196 up-regulated, and 1715 down-regulated) including the key genes of ACP involved in cytoskeleton synthesis and nutrition-related proteins. Majority of the differentially expressed genes were categorized under molecular function followed by cellular components and biological processes. KEGG pathway analysis showed differential regulation of carbohydrate, nucleotide and energy metabolic pathways, the endocytotic pathway and the defense-related pathways. Differential regulation of genes associated with the key pathways might favors CLas to become systemic and propagate in its insect vector. The study provides an understanding of genes involved in circulation of CLas in ACP. The candidate genes involved in key physiological processes and CLas transmission by ACP would be potential targets for sustainable management of ACP and CLas.