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.

Determination of the volatile fraction of Polygonum bistorta L. at different growing stages and evaluation of its antimicrobial activity against two major honeybee (Apis mellifera) pathogens.

The composition of the volatile fraction of Polygonum bistorta L. (also known as bistort or snakeroot) was investigated. Fresh aerial parts of this plant species were collected in the Western Italian Alps during the summer at three different phenological stages, namely vegetative, flowering, and fruiting, and steam-distilled in a Clevenger-type apparatus. The oils accounted for 0.004 to 0.010% of the fresh plant material, and their compositions were determined by GC/FID and GC/MS. The composition of the oils during the vegetative period varied both in quantity and quality; several classes of compounds were found with a predominance of alcohols in the vegetative phase, terpenes and linear-chained saturated hydrocarbons in the flowering phase, while saturated aliphatic acids and their methyl esters were predominant in fruiting phase. The most abundant compounds were 3-methylbut-3-en-1-ol in the vegetative phase, linalool in the flowering phase, and dodecanoic acid and its methyl ester in the fruiting phase. The obtained essential oils were then tested against two major bee pathogens, i.e., Paenibacillus larvae and Melissococcus plutonius, and against a reference bacterial species, Bacillus subtilis. Data were compared to those obtained with reference standards used against those pathogens such as the essential oils obtained from leaves and bark of Cinnamomum zeylanicum (cinnamon), and the antibiotic oxytetracyclin.

Powdered Sugar Examination as a Tool for the Assessment of Paenibacillus larvae Infection Levels in Honey Bee Colonies.

American Foulbrood (AFB) is a contagious and severe brood disease of honey bees caused by the spore-forming bacterium Paenibacillus larvae. The identification of honey bee colonies infected by P. larvae is crucial for the effective control of AFB. We studied the possibility of identifying the infection levels by P. larvae in honey bee colonies through the examination of powdered sugar samples collected in the hives. The powdered sugar was dusted on the top bars of honeycombs and collected from a sheet paper placed at the bottom of the hive. Three groups of honey bee colonies were examined: Group A1- colonies with clinical symptoms of AFB (n = 11); Group A2 - asymptomatic colonies located in apiaries with colonies showing symptoms of AFB (n = 59); Group B - asymptomatic colonies located in apiaries without cases of the disease (n = 49). The results showed that there was a significant difference in spore counting between Groups and that the spore load in sugar samples was always consistent with the clinical conditions of the colonies and with their belonging to AFB-affected apiaries or not. Based on the obtained results the cultural examination of powdered sugar samples collected from hives could be an effective tool for the quantitative non-destructive assessment of P. larvae infections in honey bee colonies.

Whole-Genome Sequence Analysis of Italian Honeybees (Apis mellifera).

At the end of the last glaciation, Apis mellifera was established in northern Europe. In Italy, Apis melliferaligustica adapted to the mild climate and to the rich floristic biodiversity. Today, with the spread of Varroa destructor and with the increasing use of pesticides in agriculture, the Ligustica subspecies is increasingly dependent on human action for its survival. In addition, the effects of globalization of bee keeping favored the spread in Italy of other honeybee stocks of A. mellifera, in particular the Buckfast bee. The purpose of this study was to characterize the Italian honeybee's population by sequencing the whole genome of 124 honeybees. Whole genome sequencing was performed by Illumina technology, obtaining a total coverage of 3720.89X, with a mean sample coverage of 29.77X. A total of 4,380,004 SNP variants, mapping on Amel_HAv3.1 chromosomes, were detected. Results of the analysis of the patterns of genetic variation allowed us to identify and subgroup bees according to their type. The investigation revealed the genetic originality of the Sicula, and in A.m. ligustica limited genetic introgression from the other breeds. Morphometric analysis of 5800 worker bees was in agreement with genomic data.

Chemical Characterization of the Volatiles of Leaves and Flowers from Cultivated Malva sylvestris var. mauritiana and their Antimicrobial Activity Against the Aetiological Agents of the European and American Foulbrood of Honeybees (Apis melfifera).

The composition of the volatile fraction of Malva sylvestris var. mauritiana (L.) Boiss. (Malvaceae) was investigated. This plant species was cultivated in the southeastern Alps as an ingredient for herbal teas and infusions. Flowers and leaves were collected at the end of the summer season and separately steam- distilled to obtain two volatile oils, the yields of which were 0.019% for leaves and 0.012% for flowers. After GC-FID and GC-MS analyses, the two oils -revealed differences in the nature and especially in the proportion of their components, which were aldehydes, alcohols, phenolics, esters, hydrocarbons and acids. Eugenol was the single most abundant compound in the leaves, totalling 46.7% of the total oil, followed by phytol with 34.4%. Flowers showed a predominance of hydrocarbons, among which the anteiso branched-chain saturated hydrocarbon, 3-methyl tricosane, was the most abundant compound, accounting for 14.9% of the total volatiles. Eugenol ranked second with 10.3%, followed by the two linear-chain saturated hydrocarbons pentacosane and tricosane forming 8.2 and 7.7% of the total oil, respectively. The occurrence and the relative abundance of compounds from various chemical classes such as phenolics, hydrocarbons and aromatic aldehydes and alcohols are discussed, together with some of their ecological implications. The obtained volatile oils were than tested against two major honeybee (Apis mellifera) pathogens, namely Paenibacillus larvae and Melissococcus plutonius, the causative agents of the American and the European foulbrood, respectively.

Volatile constituents of Trifolium pratense spp. nivale quantified at different growth stages, and evaluation of their antimicrobial activity.

The composition of the volatile fraction of Trifolium pratense L. ssp. nivale (Sieber) Asch. et Gr. from the southwestern Alps was investigated. Fresh aerial parts were collected in the summer at three different growth stages, namely vegetative, flowering and fruiting. The oils obtained by steam-distillation accounted for 0.006 to 0.011% of the fresh plant material and their composition was determined by GC/FID and GC/MS. Several classes of compounds were found, with a predominance of alcohols in all phases, followed by aldehydes, hydrocarbons, terpenes, phenolics, ketones, acids and esters. The oil composition varied both in quantity and quality; the most abundant compounds were oct-1-en-3-ol and phenylacetaldehyde in the vegetative and flowering phases, and phenylacetaldehyde and 2-phenylethanol in the fruiting phase. The essential oils obtained were tested for activity against two major bee pests, i.e. Paenibacillus larvae and Melissococcus plutonius, and against a reference bacterial species, Bacillus subtilis.