The influence of various diets on the quality of Apis mellifera queens was assessed. Colonies intended for queen cell production were assigned to four groups fed on (1) sugar-only, (2) mix of sugar, honey and fresh pollen, (3) sugar and pollen substitute (FeedBee®), and (4) natural sources. In addition, a fifth group had queen cells obtained naturally, by swarming. Sugar-only diet exerted a significant (p < 0.05) stimulating effect on the acceptance of queen cells and the weight of newly emerged queens, not affecting mated queens. Among mated queens those raised by bees fed on the mix of sugar, honey and fresh pollen had significantly (p < 0.05) larger numbers of ovarioles in comparison with all the others. Their weight was significantly higher than that of the queens from groups given FeedBee^® and swarming queens. Compared to the latter, they had significantly wider spermatheca. Given the parameters monitored, FeedBee^® proved not to be advantageous for queens.

Commercially and traditionally managed bees were compared for oxidative stress (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and malondialdehyde (MDA)), the prevalence of parasites (Lotmaria passim, Crithidia mellificae and Nosema ceranae/apis) and social immunity (glucose oxidase gene expression). The research was conducted on Pester plateau (Serbia—the Balkan Peninsula), on seemingly healthy colonies. Significant differences in CAT, GST and SOD activities (p < 0.01), and MDA concentrations (p < 0.002) were detected between commercial and traditional colonies. In the former, the prevalence of both L. passim and N. ceranae was significantly (p < 0.05 and p < 0.01, respectively) higher. For the first time, L. passim was detected in honey bee brood. In commercial colonies, the prevalence of L. passim was significantly (p < 0.01) lower in brood than in adult bees, whilst in traditionally kept colonies the prevalence in adult bees and brood did not differ significantly. In commercially kept colonies, the GOX gene expression level was significantly (p < 0.01) higher, which probably results from their increased need to strengthen their social immunity. Commercially kept colonies were under higher oxidative stress, had higher parasite burdens and higher GOX gene transcript levels. It may be assumed that anthropogenic influence contributed to these differences, but further investigations are necessary to confirm that.

This work was aimed at the detection of the differences in the occurrence of seven bee pathogens between bee colonies kept in commercial and traditional ways. The research was conducted on 120 apparently healthy, commercially kept colonies in DB hives and 24 traditionally kept colonies in primitive, so-called trmka hives on the Pester Plateau. Brood samples were taken from all colonies to assess the occurrence of bee brood disease agents (Paenibacillus larvae, Melissococcus plutonius, Ascosphaera apis and sacbrood virus – SBV) and adult bee pathogens (deformed wing virus – DWV, chronic bee paralysis virus – CBPV and acute bee paralysis virus – ABPV). PCR diagnostics was used in all cases, in compliance with the existing methods adopted by OIE. Concerning bee brood disease-causing agents, in commercial hives P. larvae (16.67% samples), A. apis (15.83%) and the SBV (96.67%) were confirmed, whilst in traditional hives, SBV was the only one detected (33.33%). M. plutonius was not found in any sample. As for adult bee diseases, in both commercial and traditional hives all of the three viruses were detected (DWV, ABPV, CBPV), but their occurrence in the former (100.00, 100.00 and 83.33%, respectively) was significantly (p<0.001) higher than in the latter (33.33% occurrence of each). No commercially kept colonies were free from all disease causes, while in the traditionally kept group there were 66.66% of such colonies. It can be concluded that the traditional way of beekeeping provides significantly better conditions for maintenance of bee health and their resistance to pathogens.

Apart from the efficiency of coumaphos against Varroa mites, its impact on the oxidative status and survival of the honey bee ( Apis mellifera ) was assessed. The research was conducted on hives from the same apiary, equalised regarding the number of bees, brood area and food storage. Based on Varroa infestation the hives were allotted to two groups: non-infested (N) and infested (I). Both groups were either treated (T) – NT and IT, or untreated (U) – NU and IU. The treatment of infested bees was controlled with a follow-up treatment with amitraz. The efficiency of coumaphos was 96-97%. This organophosphate had a negligible effect on bee survival, but it significantly affected their oxidative status: superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST) activities, and the concentrations of malonyl dialdehyde (MDA). Coumaphos significantly (p˂0.0001) decreased SOD activity in non-infested bees, but increased it in those infested. By contrast, both CAT and GST activities, as well as MDA concentrations significantly increased (from p˂0.05 to p˂0.0001) after treatment in all groups, with the exception of IT, where it declined. Coumaphos in non-infested hives caused oxidative stress per se , not unlike varroa in infested colonies. However, in infested colonies it decreased oxidative stress, owing to its efficacy against Varroa mites and contributed to the recovery of bee colonies. In spite of its certain downsides, coumaphos remains an effective anti-varroa substance, but should be used with precaution, not to add to the effects of environmental factors which may cause red-ox misbalance.