The Western honey bee (Apis mellifera L., Hymenoptera: Apidae) is a species of crucial economic, agricultural and environmental importance. In the last ten years, some regions of the world have suffered from a significant reduction of honey bee colonies. In fact, honey bee losses are not an unusual phenomenon, but in many countries worldwide there has been a notable decrease in honey bee colonies. The cases in the USA, in many European countries, and in the Middle East have received considerable attention, mostly due to the absence of an easily identifiable cause. It has been difficult to determine the main factors leading to colony losses because of honey bees’ diverse social behavior. Moreover, in their daily routine, they make contact with many agents of the environment and are exposed to a plethora of human activities and their consequences. Nevertheless, various factors have been considered to be contributing to honey bee losses, and recent investigations have established some of the most important ones, in particular, pests and diseases, bee management, including bee keeping practices and breeding, the change in climatic conditions, agricultural practices, and the use of pesticides. The global picture highlights the ectoparasitic mite Varroa destructor as a major factor in colony loss. Last but not least, microsporidian parasites, mainly Nosema ceranae, also contribute to the problem. Thus, it is obvious that there are many factors affecting honey bee colony losses globally. Increased monitoring and scientific research should throw new light on the factors involved in recent honey bee colony losses. The present review focuses on the main factors which have been found to have an impact on the increase in honey bee colony losses.

Despite the presence of a large number of pollinators of flowering plants worldwide, the European honey bee, Apis melifera, plays the most important role in the pollination of a number of crops, including all vegetables, non-food crops and oilseed crops, decorative and medical plants, and others. The experience of isolated cases of complete extinction of honey bees in individual regions has shown that this phenomenon leads to a dramatic pollination crisis and reduced ability or even total inability to grow insect-pollinated crops if relying solely on native, naturally occurring pollinators. Current scientific data indicate that the global bee extinction between the Cretaceous and the Paleogene (Cretaceous-Tertiary) occurred, which led to the disappearance of flowers because they could not produce viable fruit and germinate due to lack of pollination by bees or other animals. From the Middle Ages to the present day, there has been evidence that honey bees have always overcome the adverse factors affecting them throughout the ages, after which their population has fully recovered. This fact must be treated with great care given the emergence of a new, widespread stress factor in the second half of the 20th century—intoxication of beehives with antibiotics and acaricides, and treatment of crops with pesticides. Along with acute and chronic intoxication of bees and bee products, there are other new major stressors of global importance reducing the number of bee colonies: widespread prevalence of pathogenic organisms and pest beetles, climate change and adverse climatic conditions, landscape changes and limitation of natural habitats, intensification of agricultural production, inadequate nutrition, and introduction of invasive species. This report summarizes the impact of individual negative factors on the health and behavior of bees to limit the combined effects of the above stressors.

Wild and managed bees provide pollination services to crops and wild plants, as well as a variety of other services beneficial to humans. Honey bees are the most economically valuable pollinator worldwide. It has been calculated that 9.5% of the total economic value of agricultural production comes from insect pollination, thus amounting to just under USD 200 billion globally. More than 100 important crops depend on pollination by honey bees. The latter pollinate not only a wide number of commercial crops but also many wild plants, some of which are threatened by extinction and constitute a valuable genetic resource. Moreover, as pollinators, honey bees play a significant role in every aspect of the ecosystem by facilitating the growth of trees, flowers, and other plants that serve as food and shelter for many large and small creatures. In this paper, we describe how the reduction in honey bee populations affects various economic sectors, as well as human health.

Honey bees (Apis mellifera L.) are the most effective pollinators for different crops and wild flowering plants, thus maintaining numerous ecosystems in the world. However, honey bee colonies often suffer from stress or even death due to various pests and diseases. Among the latter, nosemosis is considered to be one of the most common diseases, causing serious damage to beekeeping every year. Here, we present, for the first time, the effects from the application of the herbal supplements NOZEMAT HERB® (NH) and NOZEMAT HERB PLUS® (NHP) for treating N. ceranae infection and positively influencing the general development of honey bee colonies. To achieve this, in autumn 2019, 45 colonies were selected based on the presence of N. ceranae infections. The treatment was carried out for 11 months (August 2019–June 2020). All colonies were sampled pre- and post-treatment for the presence of N. ceranae by means of light microscopy and PCR analysis. The honey bee colonies’ performance and health were evaluated pre- and post-treatment. The obtained results have shown that both supplements have exhibited statistically significant biological activity against N. ceranae in infected apiaries. Considerable enhancement in the strength of honey bee colonies and the amount of sealed workers was observed just one month after the application of NH and NHP. Although the mechanisms of action of NH and NHP against N. ceranae infection are yet to be completely elucidated, our results suggest a new holistic approach as an alternative therapy to control nosemosis and to improve honey bee colonies’ performance and health.

Nosema apis and Nosema ceranae are the two main microsporidian parasites causing nosematosis in the honey bee Apis mellifera. The aim of the present study is to investigate the presence of Nosema apis and Nosema ceranae in the area of Bulgaria. The 16S (SSU) rDNA gene region was chosen for analysis. A duplex PCR assay was performed on 108 honey bee samples from three different parts of the country (South, North and West Bulgaria). The results showed that the samples from the northern part of the country were with the highest prevalence (77.2%) for Nosema ceranae while those from the mountainous parts (the Rodopa Mountains, South Bulgaria) were with the lowest rate (13.9%). Infection with Nosema apis alone and co-infection N. apis/N. ceranae were not detected in any samples. These findings suggest that Nosema ceranae is the dominant species in the Bulgarian honey bee. It is not known when the introduction of Nosema ceranae in Bulgaria has occurred, but as in the rest of the world, this species has become the dominant one in Bulgarian Apis mellifera. In conclusion, this is the first report for molecular detection of Nosema infection of honey bee in Bulgaria. The results showed that N. ceranae is the main Nosema species in Bulgaria.