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The decline in the bee colony strength due to high levels of  infestations necessitates the development of new control methods. This study evaluates the effectiveness of glycerin-oxalic acid strips and essential oils in managing . The experiment was conducted in 2022 at the experimental apiary in Debelec, part of the Institute of Animal Husbandry in Kostinbrod. Six experimental groups, each treated with a different preparation, were compared to a control group of untreated colonies. Treatments included Beevital Hiveclean (20 ml per colony), Varro Red (2 ml per frame), ammonium nitrate strips (1.3 mm), glycerin-oxalic acid strips (1.3 mm), and glycerin-oxalic acid strips of paper-cellulose (2.3 mm) or cellulose-cotton (2.3 mm). The control group remained untreated. The glycerin-oxalic acid strips made of cellulose and cotton (2.3 mm) showed the highest efficacy, reducing the mite infestation by 17.79% compared to the control. The glycerin-oxalic acid strips of paper-cellulose (2.3 mm) were also effective, achieving a 17.05% reduction in mite levels. These results provide valuable insights for beekeepers seeking alternative and sustainable methods for controlling infestations.

Honey bee (Apis mellifera) colony development and honey productivity depend on both nutritional resources and the availability of bioactive compounds that support brood rearing and physiological regulation. While supplemental feeding with sugar syrup provides carbohydrates, it does not supply essential phytoactive substances. Tribulus terrestris L., a medicinal plant rich in furostanol saponins such as protodioscin, flavonoids, and glycosides, has demonstrated hormone-like and adaptogenic properties in various organisms, yet its potential as a natural stimulant in apiculture remains largely unexplored. This study evaluated the effect of T. terrestris extract on honey productivity of bee colonies over two consecutive seasons (2024–2025) in northeastern Bulgaria. Experimental groups received inverted sugar syrup supplemented with either T. terrestris extract or the Startovit mineral-vitamin stimulant, while a control group received syrup only. Results indicated that colonies receiving T. terrestris extract achieved significantly higher honey yields - up to 35% more than controls in 2024 and 43% in 2025. The findings demonstrate that T. terrestris extract can safely and effectively enhance colony performance and honey production, offering a cost-efficient, natural alternative to synthetic stimulants in apiculture.

Honey bee (Apis mellifera L.) colony productivity and foraging activity are influenced by both external factors, such as climatic conditions and nectar availability, and internal factors, including colony strength and queen fertility. While plant-based supplements have been studied for their effects on colony health and productivity, the impact of Tribulus terrestris L. on summer flight activity remains unknown. This study evaluated the effect of T. terrestris extract on honey bee foraging behavior over two consecutive seasons (2024–2025) in three Bulgarian apiaries. Three groups were established: a control fed with inverted sugar syrup, an experimental group supplemented with T. terrestris extract, and a second experimental group receiving the Startovit mineral-vitamin stimulant. Flight activity was measured by counting bees departing each hive during three-minute intervals. Results showed that T. terrestris supplementation significantly increased summer flight activity compared to the control and “Startovit” groups, with the highest increases observed in 2024. These findings provide the first experimental evidence that T. terrestris extract can enhance honey bee foraging behavior, suggesting its potential as a natural, non-hormonal stimulant to improve colony performance and resource utilization.

The aim of this study was to determine the heavy metals concentrations in soil, inflorescences of Brassica napus and rapeseed honey sampled from some regions of north-eastern Bulgaria. Thirteen locations were selected for experimental studies. The soils, plants and honeys samples were taken from conventional beekeeping areas away from major industrial pollutants. The median amounts of elements in the soil samples (mg/kg DW) are 1.1246 for Fe(s), 0.7048 for Al(s), 0.5636 for Pb(s), 0.1658 for Cu(s) and 0.0148 for Zn(s). The median amounts of heavy metals measured in the inflorescences of Brassica napus (mg/ kg DW) are 5.5430 for Fe(p), 2.9095 for Zn(p), 1.3225 for Pb(p), 0.2593 for Cu(p) and 0.2105 for Al(p). The median heavy metals concentrations in tested honey (mg/kg DW) are 1.0026 for Fe(h), 0.1849 for Al(h), 0.1832 for Pb(h), 0.1250 for Zn(h), 0.0702 for. Cu(h). The relationship between the heavy metal in soil, plants and honey was investigated using the Spearman’s rank correlation coefficient. Significant differences in the concentrations of Fe(s), Al(s) and Pb(s) in soils, Fe(p) and Zn(p) in the plant samples, Fe(h) in honey samples from the different locations were found. The heavy metal content tested in honey did not pose a risk to human health.

The supplementary feeding of bee colonies under conditions of limited natural food sources is essential for maintaining their health and productivity. Pollen is a major source of protein for bees, collected during plant flowering. Its absence negatively affects the secretory activity of the hypopharyngeal glands (HPGs) in young nurse bees. This study aimed to assess the effect of different protein sources provided during the spring period on the development of HPGs in worker bees. An experiment was conducted with 28 bee colonies divided into seven groups of four colonies each—one control and six experimental. The colonies were fed soy isolate (Glycine max), brewer’s yeast (Saccharomyces cerevisiae), spirulina (Arthrospira platensis), pea protein (Pisum sativum), and bee pollen (a mixture of pollens from various plant species). The results confirmed the critical role of pollen, as 40% of bees in the pollen-fed group exhibited HPGs at grade 4. The group supplemented with spirulina showed similar results (35.8%), indicating its potential as an alternative protein source. These findings highlight the importance of proper protein supplementation and suggest that spirulina could serve as a promising substitute for pollen in early spring feeding to support colony development.

Environmental pollution with pesticides as a result of intensive agriculture harms the development of bee colonies. Bees are one of the most important pollinating insects on our planet. One of the ways to protect them is to relocate and build apiaries in populated areas. An important condition for the development of bee colonies is the rich species diversity of flowering plants and the size of the areas occupied by them. In this study, a methodology for detecting and distinguishing white flowering nectar source trees and counting bee colonies is developed and demonstrated, applicable in populated environments. It is based on UAV-obtained RGB imagery and two convolutional neural networks—a pixel-based one for identification of flowering areas and an object-based one for beehive identification, which achieved accuracies of 93.4% and 95.2%, respectively. Based on an experimental study near the village of Yuper (Bulgaria), the productive potential of black locust (Robinia pseudoacacia) areas in rural and suburban environments was determined. The obtained results showed that the identified blooming area corresponds to 3.654 m2, out of 89.725 m2 that were scanned with the drone, and the number of identified beehives was 149. The proposed methodology will facilitate beekeepers in choosing places for the placement of new apiaries and planning activities of an organizational nature.

Global climate change, intensive agriculture, and anthropogenic pollution adversely affect flowering plants and the vitality of bee colonies. In nutritional stress conditions, bees deplete the food reserves of their fat body to sustain colony life. Beekeepers play a critical role by providing supplemental nutrient solutions. This study examines the effects of various sugar syrups on the fat body development of worker bees (Apis mellifera macedonica). The colonies were divided into one control group and five experimental groups: one fed with 1:1 sugar/water syrup, one with 2:1 sugar/water syrup, one with inverted syrup (Apiinvert), one with HFCS (high-fructose corn syrup) (Isosweet), and one with 1:1 honey/water syrup. Fat body development was assessed through meticulous dissection, and the degrees of development were documented using a USB digital microscope (Bresser). The results indicate significant seasonal variations in fat body development, with winter depletion and recovery influenced by supplemental feeding. Apiinvert and honey/water syrup promoted higher fat body stages, while Isosweet led to elevated fifth degrees of development but raised concerns about potential toxicity due to the hydroxymethylfurfural (HMF) formation of improperly stored syrups. This study concludes that adequate supplemental feeding with easily digestible sugars is critical for promoting fat body development, enhancing winter survival, and ensuring overall colony health. These findings provide practical guidance for beekeepers to optimize feeding strategies and support resilient bee colonies.

The paper reviews the existing state of fishing worldwide and in Bulgaria. Then the scheme is determined, according to which the live fish moves from the water basins in which it is raised and lives until it is sent to the store network and the end customers. As a result of the studies conducted, two-week points in the transitional warehouses have been identified. They are characterized by four main indexes: oxygen, temperature, Ph acidity and water level in the container. It these four are not within the determined allowances, it is possible the quality of the environment for storing the live fish to be deteriorated, which can lead to premature death of the fish. In this respect, a regression model with the four main indexes that are to be monitored and maintained within the allowance values has been created for achieving high quality of the storage environment. For the regression model has been determined a coefficient of determination R = 0.9131, and a Fisher’s criterion, which is 5.0143 compared to the one in the Table - 2.5802, which shows that the model is adequate and can be used for further calculations. For the practical solution of the problem, it has been proposed to introduce an intelligent information system in the transitional warehouses for storing live fish before the end processing. The system proposed will be used to monitor and control the four main indexes and to improve the conditions for storing live fish when it is moved along the chain of fish farms to the warehouses for end processing.