Yali Du

Overwintering performance in the Apis mellifera directly affects colony survival, spring buildup, and pollination services. Although honeybees with different genetic backgrounds have evolved distinct overwintering strategies, the genetic basis and molecular regulation of these strategies remain poorly understood. We investigated the Hunchun bee, a black landrace of Apis mellifera distributed in Jilin Province, using four Apis mellifera subspecies as comparison populations. Whole-genome resequencing and genome-wide scans identified 209, 122, 305, and 388 genes under selection in the four pairwise comparison groups between the Hunchun bee and Apis mellifera ligustica, Apis mellifera carnica, Apis mellifera caucasica, and Apis mellifera mellifera, respectively. Transcriptomic sequencing identified differentially expressed genes (DEGs) in thoracic tissues at distinct stages of overwintering. The largest set of common DEGs was detected during mid-overwintering (617 genes), which was enriched in oxidative phosphorylation, tricarboxylic acid cycle, and ribosome-related pathways. Expression of genes that encode β-octopamine receptors was higher during early overwintering but was lower during the middle and late stages. Twelve annotated genes were consistently differentially expressed across all three overwintering stages and were common to all four pairwise comparisons. Of these, 11 showed higher expression in the Hunchun bee and were associated with flight muscle contraction, structural support, RNA processing, or post-transcriptional regulation. Separately, integrative analysis of mid-overwintering DEGs and signatures of selection identified two candidate genes, LOC408595 (locomotion-related protein Hikaru Genki) and LOC413025 (peroxidasin). These two genes contained 26 coding-sequence SNPs, including two missense variants in LOC413025 (p.D947N and p.Y1275N). Taken together, these results identify putative candidate genes and variants for overwintering adaptation in the Hunchun bee, which establishes a theoretical foundation for investigating its molecular regulatory mechanisms.

The collection of honey and propolis is crucial for the nutrition and health of honey bee colonies. In this study, Apis mellifera with high productivity for both honey and propolis (MJ) was developed through long-term selective breeding using Apis mellifera caucasica and Apis mellifera carnica as breeding materials, resulting in substantial improvements in both honey yield and propolis production. To elucidate the genetic basis and molecular mechanisms underlying efficient foraging behavior for nectar and resins in honey bees, whole-genome resequencing was performed on MJ, the C-lineage, and the O-lineage of Apis mellifera. In addition, transcriptome sequencing was conducted using MJ and Apis mellifera ligustrica, which exhibited the highest honey and propolis production traits. MJ had a composite genetic background dominated by O-lineage ancestry. Compared with C-lineage honey bees, MJ exhibited 234 candidate genes under selection, mainly related to chitin and amino sugar metabolism. Transcriptome analysis identified 504 and 2676 differentially expressed genes between MJ and Italian honey bees in the nectar-forager and resin-forager comparisons, respectively, involving chemosensory gene families. Genes upregulated in MJ nectar and resin foragers were mainly associated with redox regulation and energy metabolism, respectively. Integrated analyses identified 7 candidate genes associated with nectar foraging and 41 candidate genes associated with resin foraging; these genes were involved in chemosensory responsiveness, flight-related structural traits, energy metabolism, and redox regulation in MJ. These findings provide genetic and transcriptomic resources for further studies on the division of labor in foraging and molecular breeding in honey bees.

Safe overwintering is a challenging issue in rearing management that is inevitably faced by beekeepers in high-latitude regions. Under the combined influence of multiple factors, the overwintering loss rate of Western honey bees has risen continuously, and investigating the molecular mechanisms related to safe overwintering has become key. The Hunchun bee, an Apis mellifera ecotype in Jilin Province, China, exhibits strong overwintering ability during an overwintering period of more than five months. To investigate the molecular mechanisms of its cold resistance, we conducted a comparative transcriptomic analysis between the summer breeding period (July) and different overwintering intervals (November, December, January, and February), and then systematically identified key genes and signaling pathways related to cold resistance. The results showed that the highest number of differentially expressed genes (DEGs) was found between December and July. Compared with July, the upregulated genes in Hunchun bee in December were significantly enriched in several pathways, such as ion transport and neuroactive ligand–receptor interactions, and the downregulated genes were significantly enriched in pathways related to fatty acid metabolism, glutathione metabolism, and the peroxisome. Notably, a total of 378 shared DEGs were obtained from the four comparison groups, and several candidate cold-resistant gene families, such as AFPs, HSPs, C₂H₂-ZFPs, STKs, and LRRCs, were identified among the shared DEGs of the winter season. Additionally, 749 shared DEGs related to protein modification and metabolic process regulation were identified between the four successive overwintering intervals. Four shared genes, including sensory neuron membrane protein 1 (SNMP1), were revealed by pairwise comparison of the four intervals. The above results collectively indicate that the Hunchun bee attenuates winter-induced stress responses during the overwintering process by maintaining osmotic pressure balance, reducing fatty acid metabolism, increasing antioxidant capacity, and synthesizing cold-resistant macromolecular proteins. It was also found that chemical signal perception may serve a role in maintaining the stability of the overwintering bee colony. The key genes and pathways related to cold resistance identified in this study not only provide a basis for explaining the overwintering molecular mechanism for Apis mellifera of Hunchun bee but also offer key data to improve overwintering management strategies for Western honey bees.

The conservation and breeding of the western honey bee (Apis mellifera) is central dependent on accurate subspecies assignment, but the most commonly used methods are labor-intensive classical morphometrics and costly molecular assays. We developed an XGBoost-based classification framework using a compact set of routinely measurable characters. A curated dataset of labeled workers was measured under harmonized protocols; features were screened according to embedded importance, and model performance was assessed using five-fold cross-validation, outperforming standard machine learning baselines. The resulting model using only the top 10 characters—primarily forewing venation angles and abdominal plate metrics—achieved high performance (accuracy = 0.98; F1 = 0.99) and an area under the receiver operating characteristic curve (AUC) of 0.99 (95% CI = 0.995–0.999). SHAP analyses confirmed the discriminatory contributions of these features, while error inspection suggested that misclassifications were concentrated in morphologically overlapping lineages. The model’s performance supports its use as a rapid triage tool alongside genetic testing, providing a scalable and interpretable tool for researchers to create and deploy custom morphometric models, demonstrated here for A. mellifera but portable to other insect taxa.

Honeybees are prone to poisoning, also known as jujube flower disease, after collecting nectar from jujube flowers, resulting in the tumultuous demise of foragers. The prevalence of jujube flower disease has become one of the main factors affecting the development of the jujube and beekeeping industries in Northern China. However, the pathogenic mechanisms underlying jujube flower disease in honeybees are poorly understood. Herein, we first conducted morphological observations of the midgut using HE-staining and found that jujube flower disease-affected honeybees displayed midgut damage with peritrophic membrane detachment. Jujube flower disease was found to increase the activity of chitinase and carboxylesterase (CarE) and decrease the activity of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and the content of CYP450 in the honeybee midgut. Transcriptomic data identified 119 differentially expressed genes in the midgut of diseased and healthy honeybees, including CYP6a13, CYP6a17, CYP304a1, CYP6a14, AADC, and AGXT2, which are associated with oxidoreductase activity and vitamin binding. In summary, collecting jujube flower nectar could reduce antioxidant and detoxification capacities of the honeybee midgut and, in more severe cases, damage the intestinal structure, suggesting that intestinal damage might be the main cause of honeybee death due to jujube nectar. This study provides new insights into the pathogenesis of jujube flower disease in honeybees.

The decreasing number of bees is a global ecological problem. With the advancement of agricultural modernisation, the large-scale use of neonicotinoid insecticides is one of the main factors leading to the decline of bees. The aim of the present study was to investigate the effect and the mechanisms underlying bees impaired by dinotefuran. Acute (48 h) oral toxicity tests showed that a 5% lethal concentration (LC₅) was 0.220 mg/L, and a 20% lethal concentration (LC₂₀) was 0.458 mg/L. The gene expression profile shows that when compared with the control group, the LC₅ group induced 206 significantly upregulated, differentially expressed genes (DEGs) and 363 significantly downregulated DEGs, while the LC₂₀ group induced 180 significantly upregulated DEGs and 419 significantly downregulated DEGs. Significantly, transcriptomic analysis revealed DEGs involved in immunity, detoxification, and the nervous system, such as antimicrobial peptides, vitellogenin, synaptotagmin-10, AChE-2, and nAChRa9. Furthermore, Gene Ontology (GO) annotation and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis revealed that DEGs were enriched in amino acid and fatty acid biosynthesis and metabolism pathways. Collectively, our findings will help clarify the deleterious physiological and behavioural impacts of dinotefuran on bees and provide a basis for future research on the mechanisms underlying bees impaired by dinotefuran.

Correct gustatory recognition and selection of foods both within and outside the hive by honey bee workers are fundamental to the maintenance of colonies. The tarsal chemosensilla located on the legs of workers are sensitive to nonvolatile compounds and proposed to be involved in gustatory detection. However, little is known about the molecular mechanisms underlying the gustatory recognition of foods in honey bees. In the present study, RNA-seq was performed with RNA samples extracted from the legs of 1-, 10-, and 20-d-old workers of Apis cerana cerana Fabricius, a dominant indigenous crop pollinator with a keen perception ability for phytochemicals. A total of 124 candidate chemosensory proteins (CSPs), including 15 odorant-binding proteins (OBPs), 5 CSPs, 7 gustatory receptors (GRs), 2 sensory neuron membrane proteins (SNMPs), and 95 odorant receptors (ORs), were identified from the assembled leg transcriptome. In silico analysis of expression showed that 36 of them were differentially expressed among the three different ages of A. c. cerana workers. Overall, the genes encoding OBPs and CSPs had great but extremely variable FPKM values and thus were highly expressed in the legs of workers, whereas the genes encoding ORs, GRs, and SNMPs (except SNMP2) were expressed at low levels. Tissue-specific expression patterns indicated that two upregulated genes, AcerOBP15 and AcerCSP3, were predominately expressed in the legs of 20-d-old foragers, suggesting they may play an essential role in gustatory recognition and selection of plant nectars and pollens. This study lays a foundation for further research on the feeding preferences of honey bees.