عنوان مقاله [English]
Introduction: Increasing beekeeping activities, it is important to identify the main sources of pollen in a region and their value for bee colonies and pollen production. The latter may have a significant impact on the morphology, behavior, and physiology of all individuals and on the quality of pollination services as well. Therefore, pollen has a great impact on colony health. Several researches have shown that pollen quality varies in terms of the type and quality of amino acids and the amount of total protein, depending on the origin of the flower. For this reason, the palynological diversity of pollen is a good measure of the quality of bees' lives. Pollen and nectar of plants used by bees in some regions of Iran have been investigated in the literature However, there are no data about the status of bee pollen sources in Semnan province. The present work aims to consider changes in the plant composition and pollen concentrations of honey samples during the investigation period. Especially, to determine honey bee forager’s pollen preferences in the study area, and to prepare a guide of a year round floral calendar for beekeepers and farmers for better understanding the blooming periods of bee pollinated plants.
Material and Methods: This research was conducted in 2017 in different regions of Semnan province. Semnan province with an area of 97491 square kilometers occupies 5.8 percent of the country's area. This province located between 34º, 13´ to 37 º, 20´ N latitude and from 51 º, 51´to 57 º, 3´ E longitude. In this study, for quantitative analysis of pollen grains, the amount of one kilogram of honey was prepared from 25 beekeepers in Semnan province at the end of summer and the geographical coordinates of the hive locations were recorded using a GPS device. All samples were analysed using the standard pollen analysis a hemocytometer was used to count the number of pollens in a certain volume of solution. Pollen grains were counted using a light microscope with a magnification of 100. These steps were repeated ten times for each sample of honey. To identify pollen grains, one drop of the well-homogenised pollen grain suspension was applied to a microscope slide, covered with a 22 mm × 22 mm cover glass and sealed with nail varnish. For each sample, several microscopic slides were prepared and were observed using light and polarised light microscopy. Pollen grains were identified to species level where possible by comparison to the reference pollen collection prepared from hand-collected pollens from known ﬂowering plants in the study area. The frequency of occurrence was calculated as the percentage of samples, in which one pollen type was observed. Honey samples were classified using the method of Liux et al. (16).
Results and Discussion: In this research, 505 types of pollen grains were identified in honey samples collected from the study areas, which belonged to 83 plant families. Among these grains, pollen grains of 474 plant species were identified in honey of Abrsaj, Abar, Shahkooh paeen, Bastam, Dibaj Damghan and Rameh Garmsar regions and 31 species of honey from other regions of the province and from the honey supplied by beekeepers migrated to Semnan province. Based on the comparison of the means between the number of pollen grains in standard samples, the highest number of pollen grains was recorded in Qatari and Folad mahalle regions (respectively with an average of 1174 000 and 169000).The lowest number of pollen grains was observed in Comercial sample and Abrsaj2 (with the mean of 17000 and 140000, respectively) (Figure 3). The results of comparing the means as well as the classification table of pollen grains showed that 72% of the studied areas (18 areas) placed in class 3 (100000 to 500000 grains in the standard sample), 16% (4 regions) in class 4 (500000 to 1000000 pollen grains), 8% (2 regions) in class 5 (above 1000000) and 4% (1 region) in class 1 (less than 20000), in terms of the number of pollen grains per 10 grams of honey. In this study, no sample was included in class 2. The results of identifying pollen grains and their abundance in honey samples showed that the most important plant species used by foraging bees were related to Asteraceae, Leguminosae, Lamiaceae, rosaceae, Apiaceae, and Brassicaceae, Liliaceae and Ranunculaceae families, respectively. The results also showed that the range and diversity of plants in the composition of the honey spectrum of each region are of particular importance. The higher density of a plant species and the wider level of its distribution, the more dramatic use of bees. These results help to prove the complexity and heterogeneity of environmental and ecological phenomena in feeding and grazing bees’ process.
Conclusion: The present study complements previous melissopalynological studies from other provinces of Iran and provides additional and new information on regional plant resources for pollen in honey. In this study all honey samples were obtained directly from local beekeepers and the melissopalynological analysis was completed with direct observations of the search behavior of worker bees. Therefore, we were able to determine the origin of the pollen in the honey using the location of the hive, the season and the available flower source. However, more studies are needed to fully understand the preferential behavior of grazing bees and the pollen of honey produced in the area.