The mite Varroa destructor is widely acknowledged as the most destructive threat to honey bee (Apis mellifera) colonies on a global scale. Varroa mite infestations in bee colonies are intricately linked with viral infections, collaboratively leading to diminished bee populations and accelerated colony losses. Extensive research has firmly established the correlation between varroa mites and viruses, underscoring the mite’s efficiency in spreading viruses among bees and colonies. The effective control of varroa mites is expected to result in a decrease in viral infections within bee colonies. Research suggests that thermal treatments (hyperthermia) present a viable approach to combat varroa mites, with studies demonstrating the role of heat stress in reducing viral infections in affected bees. This article examines the extant literature surrounding the utilization of hyperthermia as a potential method to ameliorate the adverse impacts of varroa mites and their associated viral infections on honey bee colonies. It also outlines the thermal characteristics of these stressors. Diverse devices can be used for subjecting colonies to hyperthermia treatment, targeting mites both within and outside of brood cells. The application of thermal treatments, typically ranging between 40 and 42 °C for 1.5–3 h, as a method to reduce varroa mites and viral infections, has shown promise. Notably, the precise effectiveness of hyperthermia treatment in comparison with alternative varroa mite control measures remains uncertain within the available literature. The potential deleterious repercussions of this control mechanism on immature and mature honey bees are evaluated. Concurrently, the detrimental implications of prolonged treatment durations on colonies are discussed. Regarding viral infections, hyperthermia treatment can impact them negatively by either reducing varroa mite infestations or by inducing the production of heat shock proteins that possess potential antiviral properties. Various factors are identified as influential on hyperthermia treatment efficacy within bee colonies, including the device type and treatment duration, necessitating further empirical investigations. Additionally, this article highlights the existing gaps in the knowledge and provides insights into the prospective directions of research concerning this control method.

Varroa destructor is by far the most serious threat to the western honey bee, Apis mellifera. A screen bottom board, a cultural method for mite control, is a modified bottom board with a screen that allows mites to fall onto a sticky board, or the grass or soil below the screen. Whether or not a screen bottom board can reduce varroa significantly has been controversial. Most studies show a trend of lower varroa populations in colonies with these boards, but the results are usually not statistically significant. To understand whether the negative results have been due to small sample sizes, or because the board is actually ineffective, we conducted a meta-analysis with seven published studies with a total of 145 colonies. Meta-analysis showed that the confidence intervals of the combined effect sizes were negative with a Hedges’ g of −1.09 (SE 0.39, 95% CI −2.0 to −0.19, p < 0.01), which suggests that the varroa population in colonies with screen bottom boards is significantly lower compared to those with traditional wooden floors. We thus conclude that the screen bottom board does have a significantly negative impact on the varroa population and can be part of tool kits for mite control.

Exposure to low temperatures during honeybee development has been shown to impede brain development and affect cognitive function in adult bees. On the other hand, neuronal damage due to oxidative stress has been reported in many cases. Hence, biochemical parameters related to oxidative stress in honeybee pupae brain were determined. The levels of GSH in the pupal brain decreased after 24 h and 48 h of exposure to low temperatures; there were also reduced activities of SOD and CAT enzymes following 48 h of low-temperature treatment compared to the control group. Furthermore, analysis of transcriptome data post-24 h and -48 h low-temperature stress revealed the suppression of the glutathione metabolism and peroxisome pathways in pupal brains. Additionally, expression pattern clustering analysis and KEGG enrichment showed that 10 differentially expressed genes with down-regulated expression trends post-low-temperature treatment were significantly enriched in the peroxisome pathway, including PEX10, highlighting their connection to peroxisome function. RT-qPCR validation was conducted on 11 core enriched genes in pathways identified via GSEA, and all these genes exhibited a downregulated expression pattern, confirming the inhibition of glutathione metabolism and peroxisome function under low-temperature stress. The present study showed that exposing honeybee pupae to low temperatures suppressed both the glutathione metabolism and peroxisome pathways, resulting in increased oxidative stress. This research enhances our understanding of how the pupal brain reacts to cold stress and illuminates the neural damage associated with low temperatures during honeybee capped brood development.

Thermal condition affects the development and growth of ectotherms. The stenothermic honeybee brood, particularly the prepupae, are sensitive to low rearing temperature. The fat body plays important roles in energy reserve and metabolism during the honeybee brood development. To date, the fat body metabolic changes in prepupae responding to cold stress have not been completely understood. In this study, the ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS)-based non-target metabolome was analyzed between the cold-treated (CT, 20 °C, 36 h) and control (CK, 35 °C) fat body in prepupal honeybees. The fat body metabolomic data showed that the levels of 1860 and 254 metabolites were significantly increased and decreased, respectively, in cold-stressed prepupae. These altered metabolites, glutamine, glutamic acid, pyroglutamic acid, and oxidized glutathione, were significantly enriched into glutamine metabolism and glutathione metabolism pathways. Furthermore, the expression levels of glutamine metabolism-related genes, glutaminase (GLS), glutamate dehydrogenase (GDH), and gamma-glutamyl transferase (GGT-1 and GGT-7), were significantly decreased in cold-exposed prepupae compared with the control groups. Meanwhile, the oxidized glutathione (GSSG), but not the reduced glutathione (GSH) content, was increased in the cold-exposed group compared with controls. Collectively, our data revealed the fat body metabolomic changes in larva-to-pupa transition when exposed to cold stress. Our data provided new insights into stenothermic honeybee sensitivity to cold, characterized by perturbation of glutamine metabolism and oxidative stress.

Honey is a sweet substance laboriously collected and crafted from nectar by bees, and since ancient times, it has been deeply cherished by humans for its unique flavor and nutritional value. Litchi honey stands out among various types of honey with its unique flavor and sweet taste, and it is particularly favored by consumers. In accordance with the testing methodologies specified in relevant Chinese national standards, we conducted an exhaustive analysis of the physicochemical properties of six litchi honey samples in Southern China. The results showed that the moisture content fell within a range of 17.18% to 22.7%, while the electrical conductivity remained below 0.28 mS/cm, and amylase activity surpassed 7.7 mL/(g·h). The fructose content varied from 36.5% to 39.6%, with glucose content ranging between 30.57% and 37.63%. The combined total of these two monosaccharides was found to be within the spectrum of 69.63% to 77.23%, and sucrose content was recorded between 0.59% and 1.15%. The F/G was between 1.05 and 1.28, the proportion of fructose in reducing sugars ranged from 51.28% to 56.22%, and the maltose content was between 1.09% and 1.51%. The HMF content was measured between 1.04 and 3.49 mg/kg. Moreover, the presence of C-4 plant sugars was absent in all tested honey samples. These results definitively demonstrate that the physicochemical attributes of all litchi honey samples align with the standards set forth by Chinese national regulations and international authorities such as CODEX. During our in-depth examination of volatile constituents, we identified 26 common compounds, with trans-linalool oxide, linalool, lilac aldehyde B, lilac aldehyde D, α-terpineol, and cedrol emerging as pivotal in crafting the unique flavor and aroma profile of litchi honey. Additionally, the detection of methyl cyclosiloxane in litchi honey has garnered our attention, necessitating a comprehensive investigation into the honey production process. In conclusion, this study not only establishes a robust scientific basis for the quality assurance and product development of litchi honey but also provides valuable reference information for consumers in their selection of honey products.

Cuticular proteins (CPs)—key components of the insect exoskeleton—not only regulate development but also serve as structural barriers that enhance resistance against environmental stressors. This study identified CP gene families in Apis mellifera and analyzed their expression patterns during the worker capped brood development stages from mature larva to pre-eclosion. Using a comprehensive genome-wide bioinformatic approach, we identified 85 CP genes in A. mellifera which comprise six families: CPR (n = 43), CPAPs (n = 27), CPF (n = 2), Tweedle (n = 2), CPLCP (n = 8) and Apidermin (n = 3). Analysis of CP gene evolutionary relationship revealed that each CP family forms a distinct, relatively independent clade. Domain and motif analyses confirmed that all CPR members harbor a conserved Chitin_Bind_4 domain, consistent with CPR family structures in other taxa. Additionally, CPAP members possess one or three Chitin-binding Peritrophin-A domain (CBM_14), CPF members possess a conserved Pupal cuticle protein C1 domain (Cuticle_3), and Tweedle members contain a conserved domain of unknown function (DUF243). In addition, the analysis found no conserved domain within the CPLCP and Apidermin families. RNA-seq data revealed dynamic expression patterns of AmCPs during pupal development, with each gene family displaying a relatively characteristic temporal profile. Quantitative PCR validation of eight highly expressed CPR genes at 9 days post-capping confirmed the RNA-seq results. This work provides a comprehensive bioinformatic characterization and transcriptional analysis of CP genes in A. mellifera, offering a foundation for future functional studies on cuticle formation and identifying candidate genes potentially involved in cuticle development in honeybees. This work relies on transcriptomic data and in silico analyses. All proposed biological roles are hypothetical and require experimental validation.