Bumblebees and pollination of endemic Onobrychis pindicola (Fabaceae) in the subalpine habitats of Pirin Mts.

Onobrychis pindicola subsp. urumovii Degen & Dren. is an endemic with restricted distribution on Pirin Mts. and Slavjanka Mts. (Balkan Peninsula, SW Bulgaria). It is obligatorily dependent upon insect vectors for pollen transport, being a self-incompatible plant. The aim of this study was: 1) to identify which bumblebees pollinate Onobrychis pindicola, 2) to identify which plants compete for these pollinators with O. pindicola, 3) to use pollen load analysis to assess bumblebee flower constancy and spatial foraging patterns of bumblebee pollinators of O. pindicola. The nectar is accessible to a wide spectrum of bees including short tongued bumblebees and honey bees. Onobrychis pindicola is pollinated most actively by Bombus pyrenaeus. Other bumblebees visited the flowers more or less actively. These were B. lapidarius, B. terrestris and B. pratorum. The bumblebees tended to utilize plant resources in guilds and follow particular plants for foraging. Observed in the field high flower constancy was confirmed by the pollen analysis

Autecology and ex situ growth of Onobrychis pindicola Hausskn. subsp. urumovii Deg. & Dren. (Fabaceae) – endemic with medicinal potential

Onobrychis pindicola subsp. urumovii Degen & Dren. is an endemic with very restricted distribution on just two mountains Pirin Mts. and Slavjanka Mts. SW Bulgaria. The taxon is evaluated as least concerned by the IUCN criteria but it is an element in several Natura 2000 habitats with conservation significance. The aim of this study is to investigate the microhabitat specifics of O. pindicola subsp. urumovii, namely slope, exposure, bed rock, soils, and vegetation as well as spatial distribution and phenology regarding the possible future cultivation. Basically O. pindicola subsp. urumovii demonstrates high tolerance to its environment although it is a calciphilous species. It grows successfully ex situ in experimental plot in the foothills of the mountains, which indicates prospects for successful cultivation. This will be important in case of future industrial necessity of the plant substance for medicinal purposes

Arylnaphthalene lignans with a focus Linum species: a review on phytochemical, biotechnological and pharmacological potential

Lignans are a large group of dimeric phenylpropanoids with a long and distinguished history of medicinal use in the ancient cultures of many peoples. The two main groups, -aryltetralin and arylnaphthalene lignans, are leading compounds with important pharmacological properties and a wide range of biological activities. While the first group is well studied mainly for the production of podophyllotoxin, for arylnaphthalene lignans, the data on the availability of a sustainable resource for their production is are still insufficient. The Linum genus, comprising approximately 180 species, is notable for its arylnaphthalene lignans production like justicidin B and isojusticidin B. The pharmacological potential of arylnaphthalene lignans includes cytotoxic, antiviral, anti-inflammatory and antiprotozoal effects. The review highlights the use of biotechnology by in vitro cultures for optimising lignan production. Structural elucidation of novel lignans underscores the ongoing diversity and potential discoveries in this botanical domain, providing an important additional information of arylnaphthalene lignans

Chemical composition and comparative analysis of lavender essential oil samples from Bulgaria in relation to the pharmacological effects

Lavender essential oil is economically important and widely used in aromatherapy perfumery, food industry and pharmacy. Bulgaria is a global leader in lavender cultivation overtaking countries such as France, UK, China, India, and Spain during the last few years. The aim of this research is: 1) to characterize a lavender essential oil sample obtained from agricultural plantation near Pomorie, Bulgaria; 2) to perform descriptive statistical test based on a data set of 13 samples available in 4 publications, 3) to compare the varieties regarding the quantity of the most important components such as linalool and linalyl acetate 4) to summarize the pharmacological effects of the main components. As a result of GS/MS analysis of the essential oil sample obtained from agricultural plantation near Pomorie, we identified 44 compounds. The major constituents were linalyl acetate (27.5%) linalool (24.1%), E-β-ocimene (7.0%), terpinen-4-ol (5.1%) caryophyllene (4.5%), carvacrol (4.4%), lavandulyl acetate (3.5%), Z-β-farnesene (3.3%), and -Z-β-ocimene (3.2%). Linalool and linalyl acetate are the main ingredients based on which the quality of the essential oil is evaluated. In the studied samples they fluctuated between varieties depending on the year of extraction and the locations of origin in Bulgaria. Some varieties were characterized by a more stable ratio of linalool – linalyl acetate, compared to others. The main other components of our sample as well as the other examined Bulgarian samples fit the standards according to the requirements of ISO (2002) and the of European Pharmacopoeia (10th edn., Council of Europe 2020) with few exceptions. Lavender oil has numerous pharmacological applications based on its anxiolytic, sedative, antioxidant, anti-inflammatory, antitumor and antimicrobial activities. Although linalool and linalyl acetate largely contribute to these effects, the overall efficacy of lavender oil is proven to be due synergistic relationships between the components

Flower Constancy of Bumblebees – The Case of Onobrychis pindicola (Fabaceae) Pollinators

Pollination in high mountain habitats is an important ecosystem service in climate change conditions. The aim of this study was to use pollen load analysis to assess flower constancy and foraging choices of bumblebees foraging on Onobrychis pindicola, a high-mountain endemic plant. The flower constancy to the foraging source O. pindicola was very high - over half of the bumblebees had pure Onobrychis-type pollen loads. In the mixed pollen loads we found one to seven pollen types other than Onobrychis-type and the functional flower morphology was different from the flag type. Some were gullet while others were dish/bowl functional morphology type. Thus the theory/belief that once discovering the flag blossom as a foraging resource bumblebees tended to visit other plants with such functional morphology was rejected. An abundance of plants did not determine food choice. We could not trace an obvious pattern of the bumblebees’ preference to functional blossom morphology but they were attracted to dish-bowl blossoms

Autecology and ex situ growth of Leontopodium nivale subsp. nivale (Asteraceae) from North Pirin marbles (SW Bulgaria)

Kozuharova, E., Panayotov, M. & Spadaro, V.: Autecology and ex situ growth of Leontopodium nivale subsp. nivale (Asteraceae) from North Pirin marbles (SW Bulgaria). — Fl. Medit. 28: 187-206. 2018. — ISSN: 1120-4052 printed, 2240-4538 online. Leontopodium nivale subsp. nivale is a local and disjunct endemic of the central Apennines in Italy and the Pirin Mountains in Bulgaria. The aim of this study is to investigate in situ microhabitat specifics and ex situ ontogenesis regarding the possible future cultivation and to evaluate hazards for wild populations in conditions of human impact and climate change. Leontopodium nivale subsp. nivale is stenobiont which is difficult to grow ex situ and therefore particularly vulnerable. Its wild habitats and populations in Pirin Mts. should be efficiently protected. The results of our study indicate that the stenobiontic plants such as Leontopodium nivale subsp. nivale are particularly subject to hazard

Monitoring bumblebee pollinator visits to the medicinal plant Gentiana asclepiadea L. (Gentianacese) – a comparison between the periods 1990–1994 and 2017–2020

Ever increasing data continue to indicate the decline of bumblebee populations. The key factors causing declines in their abundance and diversity are: 1) habitat destruction, 2) loss of floral resources, 3) emerging diseases, 4) increased use of pesticides (particularly neonicotinoids). The aim of this study is to monitor bumblebee visits to Gentiana asclepiadea L, recording pollinator species, and taking measurements of seed set. This plant species is chosen for two reasons: 1) similar data is available from our previous research in the 1990’s and 2) this montane plant species is supposed to be less exposed to hazards from pesticides and habitat destruction. Three study sites were chosen in Mt. Vitosha (SW Bulgaria) where natural populations of G. asclepiadea occur in 1990. The observations of bumblebee activity in the flowers of G. asclepiadea were conducted during the flowering seasons (August and September) of 2017 – 2020 at the same study sites and compared to the data obtained in the previous period (1990–1994). The free pollination fruit set was tested by monitoring of 100 G. asclepiadea flowers each year for development of fruit capsules. The seed set was tested by counting the matured seeds and non-fertilised ovules of 10 fruit capsules each year. A slight decline in bumblebee activity was recorded in 2017 – 2020 in comparison to 1990–1994. This is reflected in the fruit set and the seed set. Our data demonstrates that even in a mountain habitat, where there are fewer direct hazards to bumblebees, that pollination effectiveness has been suppressed over time. This corresponds to a research study which provides evidence that insect biomass fell by 76% in German nature reserves between 1989 and 2016

The invasive alien species Amorpha fruticosa in Bulgaria and its potential as economically prospective source of valuable essential oil

The high tolerance of various habitat conditions and potent propagation ability of Amorpha fruticosa L. (Fabaceae) promote its aggressive invasive behaviour. The aim of this study is to evaluate 1) several populations of this plant by the potential yield of the fruit, 2) the approximate yield of the essential oils, and 3) composition of the essential oil. The potential yield of fruit is evaluated based on extrapolations of weight and number of fruits per infrutescence, number of infrutescences per plant and number of individuals per population. Steam extraction of the essential oil was performed and GS/MS analysis of the composition of the essential oil. The populations on our key plots are big enough for harvesting with fruit/infrutescence 152 ±15 (n = 20) and infrutescences/shrub 436 ±157 (n = 20). The yield is 0.83 ml/100g. We identified 22 components with major constituents caryophyllene (17.64%) α-guaiene (14.70%), naphthalene (6.75%), γ-muurolene + (5.98%)

Pollinators of Lavandula angustifolia Mill., an important factor for optimal production of lavender essential oil

Lavender essential oil is widely used in pharmacy, perfumery and the food industry. It is one of the key essential oils in aromatherapy due to its valuable pharmacological properties. The producers of lavender essential oil are well aware that the greatest quantity of oil is obtained near the end of the inflorescence anthesis and that oil quantity is correlated with the pollination as unpollinated flowers drop down. In addition, it has been demonstrated that oil quality is also highest at the end of the flowering period, related to the gradual increase of monoterpenes (particularly the valuable linalool) and the decrease of sesquiterpenes during flower ontogenesis. The aim of this preliminary study was to measure the occurrence of spontaneous self-pollination in Lavandula angustifolia Mill. and to identify external pollinators. The field experiments were performed in a lavender plantation near Gorna Lipnitza Village, north Bulgaria and in the ex-situ lavender collection in the experimental plot of the Botanical Garden of Sofia University. It was revealed that spontaneous self-pollination did not occur in flowers from which external pollinators had been excluded. Exposed flowers were pollinated by polylectic insects, such as honeybees, several species of bumblebees and butterflies. Wild pollinators (particularly bumblebees) dominated over honeybees at both study sites. Our observations showed that all pollinators actively collected nectar. The pollen baskets of most bees were full, indicating the active consolidation of pollen adhering to the pollinators’ bodies. Although lavender growers tend to place beehives in the fields for optimal essential oil production, it is also crucial to conserve wild pollinators