Advances and knowledge gaps on climate change impacts on honey bees and beekeeping: A systematic review

The Western honey bee Apis mellifera is a managed species that provides diverse hive products and contributing to wild plant pollination, as well as being a critical component of crop pollination systems worldwide. High mortality rates have been reported in different continents attributed to different factors, including pesticides, pests, diseases, and lack of floral resources. Furthermore, climate change has been identified as a potential driver negatively impacting pollinators, but it is still unclear how it could affect honey bee populations. In this context, we carried out a systematic review to synthesize the effects of climate change on honey bees and beekeeping activities. A total of 90 articles were identified, providing insight into potential impacts (negative, neutral, and positive) on honey bees and beekeeping. Interest in climate change's impact on honey bees has increased in the last decade, with studies mainly focusing on honey bee individuals, using empirical and experimental approaches, and performed at short-spatial (<10 km) and temporal (<5 years) scales. Moreover, environmental analyses were mainly based on short-term data (weather) and concentrated on only a few countries. Environmental variables such as temperature, precipitation, and wind were widely studied and had generalized negative effects on different biological and ecological aspects of honey bees. Food reserves, plant-pollinator networks, mortality, gene expression, and metabolism were negatively impacted. Knowledge gaps included a lack of studies at the apiary and beekeeper level, a limited number of predictive and perception studies, poor representation of large-spatial and mid-term scales, a lack of climate analysis, and a poor understanding of the potential impacts of pests and diseases. Finally, climate change's impacts on global beekeeping are still an emergent issue. This is mainly due to their diverse effects on honey bees and the potential necessity of implementing adaptation measures to sustain this activity under complex environmental scenarios.

Nectar Characteristics and Honey Production Potential of Five Rapeseed Cultivars and Two Wildflower Species in South Korea

The growing beekeeping industry in South Korea has led to the establishment of new honey plant complexes. However, studies on honey production from each species are limited. This study aimed to assess the honey production potential of various Brassica napus cultivars and two wildflower species. The nectar characteristics of B. napus varied significantly among the cultivars. Absolute sugar concentrations differed among the cultivars, but sugar composition ratios were similar. In contrast, the amino acid content remained relatively uniform regarding percentage values, irrespective of the absolute concentrations. Estimations of honey potential production per hectare (kg/ha) resulted in the following ranking among cultivars: 'JM7003' (107.1) > 'YS' (73.0) > 'JM7001' (63.7) > 'TL' (52.7) > 'TM' (42.4). The nectar volume of Pseudolysimachion rotundum var. subintegrum and Leonurus japonicus increased during the flowering stage. P. rotundum var. subintegrum was sucrose-rich and L. japonicus was sucrose-dominant. Both species predominantly contained phenylalanine, P. rotundum var. subintegrum had glutamine as the second most abundant amino acid, and L. japonicus had tyrosine. The honey production potential was 152.4 kg/ha for P. rotundum var. subintegrum and 151.3 kg/ha for L. japonicus. These findings provide a basis for identifying food resources for pollinators and selecting plant species to establish honey plant complexes.

Plant Species as Potential Forage for Honey Bees in the Al-Baha Mountain Region in Southwestern Saudi Arabia

The contribution of bee forages in the form of nectar, pollen, and propolis to beekeeping development depends on plant species diversity. The data concerning the increase in honey production in southwestern Saudi Arabia, which was unexpected with the deterioration of the vegetation cover, becomes a concrete background for this study, which planned to list the bee plant species contributing as sources of nectar, pollen, and propolis. The sampling method followed a purposive random sampling approach, and 20 × 20 m plots were considered with a total of 450 sample plots. Bee forage plants were identified based on flower morphology and honey bees' actions during floral visits at active foraging hours. A checklist of bee forages containing 268 plants species belonging to 62 families was documented. The number of pollen source plants (122) was more than nectar (92) and propolis (10) source plants. Regarding seasonal distribution, spring and winter were relatively good seasons for honey bees in terms of pollen, nectar, and propolis availability. Generally, this study is an essential step towards understanding, conserving, and rehabilitating plant species providing nectar, forage, and propolis to honey bees in Al-Baha Region of Saudi Arabia.

Observation of Genetic Gain with Instrumental Insemination of Honeybee Queens

Controlling mating in the honeybee (Apis mellifera) is part of one of the greatest challenges for the beekeeping industry's genetic selection programs due to specific characteristics of their reproduction. Several techniques for supervising honeybee mating with relative effective control have been developed over the years to allow honeybee selection. As part of this project, we compared the genetic gains for several colony performance traits, obtained using the BLUP-animal method, according to the selection pressure applied in controlled reproduction (directed fertilization versus instrumental insemination). Our results show similar genetic gains for hygienic behavior and honey production between colonies whether queens were fertilized naturally or via instrumental insemination, as well as similar or lower genetic gains for colonies with queens inseminated for spring development. In addition, we noticed greater fragility in queens following insemination. These findings show that instrumental insemination is an effective tool for reproductive control in genetic selection and for estimating breeding values more precisely. However, this technique does not result in queens of superior genetic quality for commercial purposes.

Greenhouse Gas (GHG) Emissions from Honey Production: Two-Year Survey in Italian Beekeeping Farms

The objective of this study was to quantify the climate change (CC) impact of the honey supply chain in different beekeeping systems and farms, over two consecutive years. The CC impact category is quantified as kg CO₂ equivalent and it evaluates the GHG emissions, mainly CO₂, N₂O, and CH₄. The results ranged from 0.44 to 3.18 (p = 0.039) kg CO₂e/kg honey with higher values in 2021 than 2020. The main contributors to climate change of the honey supply chain are represented by transport and supplemental feeding inputs. The beekeeping system (migratory or stationary) influenced CC: the contribution to CC for stationary farms was estimated at 0.58 kg CO₂e/kg honey and 2.48 for migratory ones (p < 0.001). Given the close connection between honey yield and LCA results due to the unit of measurement of impact, i.e., kg of honey produced, an index was developed (wildflower honey climate index) as a simple benchmark tool for prediction of honey yield in the survey context. Using the data from the present study, we found that the index is positively related to honey yield (r = 0.504; p < 0.05) but negatively related to supplemental feeding (r = -0.918; p < 0.01) and overall carbon footprint (r = -0.657; p < 0.05). Further studies are needed to better explain the effects of weather on honey production, as well as environmental impact.

Nosema ceranae Infections in Honey Bees (Apis mellifera) Treated with Pre/Probiotics and Impacts on Colonies in the Field

Alternatives to the antibiotic fumagillin for the control of Nosema ceranae, a gut parasite of the honey bee, are needed. The prebiotics eugenol, chitosan, and naringenin and the probiotic Protexin^® (Enterococcus faecium) provided in sugar syrup or protein patty either in spring or fall were evaluated for their effects on N. ceranae infection, colony population, honey yield and winter survivorship using field colonies. In the first year, spring treatments with eugenol, naringenin, and Protexin^® significantly reduced N. ceranae infection and increased honey production, while Protexin^® also increased adult bee populations and chitosan was ineffective. Fall treatments increased survivorship and decreased N. ceranae infection the following spring. In the second year, selected compounds were further tested with a larger number of colonies per treatment and only protein patty used in the spring and sugar syrup in the fall. Protexin^® and naringenin significantly decreased N. ceranae infections and increased the population of adult bees after spring treatment, but did not affect honey yields. There were no differences between treatments for colony winter mortality, but surviving colonies that had been treated with Protexin^® and naringenin were significantly more populated and had lower N. ceranae spore counts than control, non-treated colonies. Protexin^® and naringenin were the most promising candidates for controlling N. ceranae and promoting honey bee populations, warranting further investigation. Future research should investigate the optimal colony dose and treatment frequency to maximize colony health.

The Effect of Diet on the Composition and Stability of Proteins Secreted by Honey Bees in Honey

Honey proteins are essential bee nutrients and antimicrobials that protect honey from microbial spoilage. The majority of the honey proteome includes bee-secreted peptides and proteins, produced in specialised glands; however, bees need to forage actively for nitrogen sources and other basic elements of protein synthesis. Nectar and pollen of different origins can vary significantly in their nutritional composition and other compounds such as plant secondary metabolites. Worker bees producing and ripening honey from nectar might therefore need to adjust protein secretions depending on the quality and specific contents of the starting material. Here, we assessed the impact of different food sources (sugar solutions with different additives) on honey proteome composition and stability, using controlled cage experiments. Honey-like products generated from sugar solution with or without additional protein, or plant secondary metabolites, differed neither in protein quality nor in protein quantity among samples. Storage for 4 weeks prevented protein degradation in most cases, without differences between food sources. The honey-like product proteome included several major royal jelly proteins, alpha-glucosidase and glucose oxidase. As none of the feeding regimes resulted in different protein profiles, we can conclude that worker bees may secrete a constant amount of each bee-specific protein into honey to preserve this highly valuable hive product.

Pollen Collection, Honey Production, and Pollination Services: Managing Honey Bees in an Agricultural Setting

Hybrid canola seed production is an important pollination market in Canada; typically both honey bees (Apis mellifera L. (Hymenoptera: Apidae)) and Alfalfa Leafcutting bees (Megachile rotundata Fab. (Hymenoptera: Megachilidae)) are concurrently managed to ensure pollination in this high-value crop. Beekeepers are paid to provide pollination services, and the colonies also produce a honey crop from the canola. Pollen availability from male-fertile plants is carefully managed in this crop to provide an abundance of pollen to fertilize male-sterile ('female') plants. This abundance of pollen represents an underutilized resource for beekeepers, and an opportunity to diversify the hive-products produced for market in this management system. We used a commercial-style pollen trap to collect pollen from colonies twice weekly for the duration of canola pollination, and compared the honey production and amount of sealed brood in colonies with pollen traps to those without pollen traps. We found that while pollen trapping reduced honey production, there was no negative impact on brood production, and at current market prices, the per-hive revenue was higher in colonies from which pollen was trapped. Pollen trapping honey bee colonies in the context of hybrid canola pollination, therefore, offers beekeepers an opportunity to diversify their products and increase their revenue.

Assessment of bacterial quality of honey produced in Tamale metropolis (Ghana)

The bacterial quality of honey from different production sites within Tamale metropolis, Ghana, was estimated using standard microbiological methods. Honey samples were bought from six different production sites within Tamale metropolis and labeled. Samples that were taken from location B recorded the least mean bacterial count of 6.0 × 10⁴ colony forming units/mL with samples taken from location D showing the highest, 1.1 × 10⁵ colony forming units/mL. However, samples from production sites E and F recorded no bacteria growth. Bacteria isolated included Escherichia coli, Staphylococcus spp., Shigella spp., Streptococcus spp., and Bacillus spp. The pH values of honey samples from the various locations were found to be directly correlated to the average bacteria load. The variation in bacteria load and species at the various production sites and the absence of bacteria growth in two production sites is an indication of the differences in production practices, as well as hygienic conditions at these sites. The presence of these isolates is a cause for concern as pathogenic strains of these bacteria can cause serious health related problems.

Temporal Variation in Honey Production by the Stingless Bee Melipona subnitida (Hymenoptera: Apidae): Long-Term Management Reveals its Potential as a Commercial Species in Northeastern Brazil

Even though stingless beekeeping has a great potential as a sustainable development tool, the activity remains essentially informal, technical knowledge is scarce, and management practices lack the sophistication and standardization found in apiculture. Here, we contributed to the further development of stingless beekeeping by investigating the long-term impact of management and climate on honey production and colony survival in the stingless bee Melipona subnitida Ducke (1910). We analyzed a 10-yr record of 155 M. subnitida colonies kept by a commercial honey producer of northeastern Brazil. This constitutes the longest and most accurate record available for a stingless bee. We modeled honey production in relation to time (years), age, management practices (colony division and food supplementation), and climatic factors (temperature and precipitation), and used a model selection approach to identify which factors best explained honey production. We also modeled colony mortality in relation to climatic factors. Although the amount of honey produced by each colony decreased over time, we found that the probability of producing honey increased over the years. Colony divisions decreased honey production, but did not affect honey presence, while supplementary feeding positively affected honey production. In warmer years, the probability of producing honey decreased and the amount of honey produced was lower. In years with lower precipitation, fewer colonies produced honey. In contrast, colony mortality was not affected by climatic factors, and some colonies lived up to nine years, enduring extreme climatic conditions. Our findings provide useful guidelines to improve management and honey production in stingless bees.

Geographic variation in the growth of domesticated honey bee stocks: disease or economics?

Declines in the stocks of domesticated honey bees in some countries have been attributed to disease, which is at odds with an increasing global trend in the total number of hives. Based on data on annual growth rates in hive numbers and honey production for 87 countries, we tested the hypothesis that geographic heterogeneity in the growth of the domesticated honey bee population can be attributed to disease. In contrast to predictions of this hypothesis, changes in honey production varied in proportion to changes in hive number. Also, growth in honey production was not more spatially heterogeneous than growth in hive numbers, as expected under a scenario of contagious pests. We argue that although disease aggravates production costs, it has less effect on changes in national hive numbers than labor costs, so that geographic variation in the growth of the global honey bee stock reflects the global division of human labor that is a hallmark of economic globalization, rather than persistent and pervasive biological causes.