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Different brood interruption methods combined with chemical treatment may successfully remove most V. destructor from the honey bee colonies. Further, the timely brood reduction or break may positively impact nectar intake and is occasionally used by beekeepers during the main spring flow to increase honey production. However, the experience and data on the effect of brood break on honey production during the main summer flow are scarce or contradictory. To try to find an answer, several Varroa Task Force members started an experiment in 2021. The study takes place at 10 apiaries in 7 countries (Algeria, Croatia, Greece, Israel, Italy, Spain and Turkey). At each location, three different groups with at least 5 colonies per group were established. In two groups, queens were confined for 28 days in a small cage 28 (QC1) or 14 (QC2) days before the expected main summer honey harvest. The third group (C) of colonies had free laying queens to serve as a control group. In total 207 colonies are included in this year study. All colonies were evaluated for strength (number of frames with bees and brood) every 14 days after the experiment started. The net weight of extracted honey for each colony was measured. Adult bee infestation was measured at the beginning of the experiment and 42 days after the treatment of the control group. Queen caging groups were treated by OA trickling 28 days from the day of queens’ caging. The C group was treated by each partner using usual practices. At the beginning of experiment, there was no difference in colony strength between groups (ANOVA, F (2, 206) = 0.030, p = 0.971). A number of frames occupied with bees was significantly lower in QC groups comparing to C group 42 days after the caging but not 56 days after caging. Briefly, they started and finished with equal strength. Further, there was no significant difference in adult bee infestation at the beginning of the trial. However, at the last measurement (42 days after the treatment of QC1 and C group and 28 days after the treatment of QC2 group) significant differences are found (H = 12.825, p = 0.002). Namely, QC1 group had lower infestation comparing to C group. In the analysis of honey production, apiary and group as fixed factors were used in the model. Apiary as a factor had significant effect (GLM, F (9, 206) = 64.921, p < 0.001) with wide distribution of extracted honey between apiaries (average from 1.45 kg to 29.50 kg/apiary). Significant differences between groups are found (F (2, 206) = 4, 556, p=0.012), with group QC1 having lower amount of extracted honey comparing to QC2 and C groups. No significant differences were found between QC2 and C group. Preliminary results showed that QC1 group had a significantly lower final infestation, as well as honey production. On the other hand, QC2 group had the same amount of produced honey and final infestation as a control group. Measurements of colony strength before and after wintering period are planned.

Honey has remarkable therapeutic potential and it has been used as a remedy for thousands of years. Recently, apitherapy came in the focus of attention as an alternative medicine for treating certain conditions and diseases, especially infections. Antimicrobial activity of honey seems promising, although depending on its origin (content of phenolic compounds, polyphenols, e.g. flavonoids and phenolic acid, proteins). To address this we exposed several bacteria (E. coli, H. pylori, Mycobacterium fortuitum, Staph. aureus) and one yeast (C. albicans) to honey samples from different floral sources and geographical locations in Croatia in order to evaluate the ability of honey to inhibit their the growth. The bioassay applied was the serial twofold microdilution method with TTC/formazan endpoint) to determine minimum inhibitory concentrations (MIC). The total phenolic content was screened by the modified Folin-Ciocalteu method and the antioxidant activity by the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system and ferric reducing antioxidant power assay (FRAP). In addition, the colour and pH of honey samples were analyzed. In general Gram-negative bacteria were found to be more susceptible in comparison to Gram-positive bacteria, while most of the honey samples had no significant effects on C. albicans. The antimicrobial activity of samples depends mostly upon floral source but there were large differences among samples of the same origin. Most tested microbial species have MIC values in the range of 0.1-0.25 mg of honey per ml. Phenolic content ranged from 34.2 to 261.4 mg GAE/kg and were highly correlated to honey antioxidant capacity. This study gives an overview of specific honeys having good antibacterial activity against microorganisms easily accessible and therefore can provide a complementary and/or alternative therapy in certain conditions. Moreover, we characterized the antioxidant potential and phenolic content of honey samples with regard to its potential therapeutic efficacy. Namely, antioxidant potential correlated to phenolic and flavonoids content of honey samples and it is hypothesized that antioxidant capacity is responsible, at least in part, for deterimed biological activity honey samples.

Because of the remarkable therapeutic potential, honey has been used as a remedy for thousands of years. Consequently, the apitherapy has recently entered into the focus of attention as an unconven-tional method for treating certain conditions and diseases, especially infections as well as promotion of the health and human well-being. Antimicrobial activity of honey has been attributed to hydrogen-peroxide, which is produced by glucose-oxidase and phenolic compounds. The total polyphenol con-tent in honey partially reflect their antioxidant capacity. The presence and concentration of phyto-chemicals, especially flavonoids as well as phenolic acid, can vary and depend significantly upon ho-ney origin. In order to assess the antimicrobial activity of various honeys, total of 23 samples repre-senting fewer honey types deriving from different floral sources and geographical locations in Croatia were evaluated for their ability to inhibit the growth of nine gram (+) and gram (-) bacteria and two moulds. The bioassay applied for determination of the antimicrobial effects took up the well-agar dif-fusion method (preliminary screening method). The micro-dilution method with TTC (2, 3, 5-triphenyl tetrazolium chloride) indicated the viability of bacteria and resulted with the Minimum inhibitory con-centration (MIC) values. The total phenolic content was screened by the modified Folin-Ciocalteu method and the antioxidant activity was assessed by means of the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging system. In addition, the color and pH of honey samples were analyzed. All honey samples showed antimicrobial activity at variable levels, depending upon the floral source and the geographical origin. A well-agar diffusion assay revealed the development of inhibition zones de-pending on the type and concentration of honey involved as well as the test pathogen. Gram (-) bacte-ria were found to be more susceptible as compared to gram (+). The majority of tested pathogens showed MIC values in the range of 12-20% of honey. Generally, dark colored honeys showed more inhibitory properties than light colored. Phenolic content, expressed as gallic acid equivalent, ranged from 34.2 to 261.4 mg/kg and was highly correlated to the values of honey antioxidant capacity. Higher antioxidative and scavenging activity was observed for dark honey samples, too. This study showed that honey samples possess certain antibacterial activity against test microorganisms that can be of certain use when considering an alternative therapy in some conditions. Moreover, it gave the characterization of the antioxidant potential as well as of the phenolic content of honey samples with some regard to the therapeutic efficacy and sanitary benefits for different purposes. Moreover, the re-sults of the study imply that specific honeys tend to have certain capacity for the food spoilage preven-tion as the result of the growth inhibition of food-borne microorganisms. It suggests that they could be potentially considered for the use as food preservatives for some foods and under appropriate condi-tions what should be further proved by additional research.