Abstract For the last thirty years, Bulgaria has been gripped by a demographic crisis, which has led to a rapid decrease in the number of the population. This is due to the demographic transformation and the country entering the fourth stage of the demographic transition. To it we can add the large migration flows, characteristic of the economic crisis during the transition. The aim is to analyze the deteriorating demographic indicators, which are closely related to the socio-economic problems in Bulgaria. The methods used allow population projections to be made, which are also unfavourable. The deepening of the negative demographic processes, which leads to an acute labour shortage, difficult functioning of the social systems, ethnic change of the population and depopulation of significant territories of the country, has been traced. The need for a more effective demographic policy and adequate intervention by the state is shown.
The Brown Marmorated Stink Bug (BMSB), Halyomorpha halys (Stål, 1855) (Hemiptera: Pentatomidae), is one of the most dangerous, invasive agricultural pests globally, causing significant economic losses. This review synthesizes current scientific research on its taxonomy, morphology, biology, ecology, and management, with a focus on the invasion in Europe and the status in Bulgaria. The analysis confirms that H. halis, an invasive pest native to East Asia and established in our country since 2016, is already causing damage to agricultural crops. Key factors for its spread are extreme polyphagy (over 300 host species), its overwintering behavior (entering buildings and vehicles, facilitating anthropochory), and high reproductive potential. Temperature requirements (lower developmental threshold ≈14.2°C and ≈538 DD for a full cycle) and data from the region strongly indicate that species is univoltine or has one and a partial second generation in the main agricultural regions of Bulgaria. Climate change is expected to expand the areas supporting bivoltinism and increase population pressure. Effective management is impossible without implementing an integrated approach (IPM), focusing on behavioral tactics (monitoring at crop borders with pheromone attractants) and urgently researching the potential for biological control with the egg parasitoid Trissolcus japonicus, which is already established adventively in other parts of Europe.
It is hypothesised that wild plants have the potential to be used as ornamentals. The term ‘wild’ as applied to plant species refers to those that grow spontaneously in self-sustaining populations. The ornamentals encompass a diverse array of herbaceous seasonal flowers, shrubs, semi-shrubs, and woody species. A significant attribute of ornamentals is their aesthetic appeal. The cultivation of plants is driven by a variety of factors, including the presence of specific characteristics such as: flowers, leaves, fragrance, fruit, stem, bark, or due to the presence of particular physiological and morphological characteristics. There is an emerging trend of incorporating novel wild native plants that possess ornamental value with the objective of reducing the financial burden associated with garden maintenance, enhancing the survival rates of plants in unfavourable conditions, and curtailing the propagation of alien floral species to regulate their dispersal. The present study constitutes an inventory of the floristic diversity of native wild ornamental plants of the priority 62CO* Ponto-Sarmatic steppes natural habitat, that have decorative qualities. In the course of the field surveys conducted as part of the 62C0* habitat restoration project, 60 species from 22 families were identified as having the potential to be used as ornamental plants. The majority of these species are classified as perennial herbaceous.
Abstract This study presents the first detailed in situ assessment of natural background radiation in the tourist-accessible portion of Biserna Cave, Bulgaria. Using portable gamma-ray dosimeter and radon detectors, we measured ambient gamma-ray dose rates and radon concentrations along the cave route. Radon was measured at eleven depth-profile points, and a time-weighted average inhalation dose was calculated using a 40% – 20% – 40% time-distribution model (entry – final – travel). The resulting 1-hour inhalation dose (radon) is ~ (3.81 – 10.695) µSv, including a mean gamma-ray component (0.177 µSv/h), the max total is ≈ 10.872 µSv. For a seasonal visitor population of 2,000 – 2,500, the max collective dose is 21.7 – 27.2 mSv. Tour guides, with ~ 115 h exposure annually, receive ~ (0.42 – 1.22 mSv) ± (0.126 – 0.450) mSv. These values lie well below regulatory limits for public exposure, but the elevated radon concentration levels in deeper zones merit attentive occupational monitoring. The study underscores the importance of depth-resolved profiling and site-specific dose modelling in cave ecotourism settings.
