Study of the stimulating effect of <i>Tribulus terrestris</i> L. on honey productivity of bee colonies

Abstract 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.