Pollen Extraction Research Articles

The specialised buzz pollination syndrome poses a partial barrier to plant invasions

Abstract Plants that exhibit generalised pollination syndromes have been hypothesised to become invasive more easily compared with specialists, yet the degree to which specialised pollination traits inhibit plant invasions is unknown. One such specialisation is the buzz pollination syndrome, which encompasses specialised floral traits that restrict pollen access (typically poricidal anthers) and benefits from specialised insect behaviour for pollen extraction. We reviewed the literature on buzz pollination of invasive plants to assess whether: (1) plant species exhibiting specialised pollination syndromes are underrepresented as invasive species, and (2) species with specialised pollination syndromes that have become invasive can reproduce in the absence of specialist buzzing pollinators. Synthesis. We found 2.5% (117/4630) of invasive angiosperms have poricidal anthers, which is an underrepresentation of the proportion of global angiosperms that are estimated to have poricidal anthers (6%–10%). Most invasive buzz‐pollinated plants are genetically self‐compatible (97%), but only 43% can set fruit in the absence of a pollinator. Our findings highlight the importance of establishing new pollinator mutualisms for sexual reproduction. However, we identified six non‐buzzing behaviours used to extract pollen from plants with poricidal anthers, which is important where buzzing pollinators may be absent or not attracted to newly introduced plant species.

Pollen identification through convolutional neural networks: First application on a full fossil pollen sequence.

The automation of pollen identification has seen vast improvements in the past years, with Convolutional Neural Networks coming out as the preferred tool to train models. Still, only a small portion of works published on the matter address the identification of fossil pollen. Fossil pollen is commonly extracted from organic sediment cores and are used by paleoecologists to reconstruct past environments, flora, vegetation, and their evolution through time. The automation of fossil pollen identification would allow paleoecologists to save both time and money while reducing bias and uncertainty. However, Convolutional Neural Networks require a large amount of data for training and databases of fossilized pollen are rare and often incomplete. Since machine learning models are usually trained using labelled fresh pollen associated with many different species, there exists a gap between the training data and target data. We propose a method for a large-scale fossil pollen identification workflow. Our proposed method employs an accelerated fossil pollen extraction protocol and Convolutional Neural Networks trained on the labelled fresh pollen of the species most commonly found in Northeastern American organic sediments. We first test our model on fresh pollen and then on a full fossil pollen sequence totalling 196,526 images. Our model achieved an average per class accuracy of 91.2% when tested against fresh pollen. However, we find that our model does not perform as well when tested on fossil data. While our model is overconfident in its predictions, the general abundance patterns remain consistent with the traditional palynologist IDs. Although not yet capable of accurately classifying a whole fossil pollen sequence, our model serves as a proof of concept towards creating a full large-scale identification workflow.

Assessment of the botanical origin of Saudi Arabian honey samples to identify pollen with chromatographic tools and packing and storage.

The increasing demand for honey purification and authentication necessitates the global utilization of advanced processing tools. Common honey processing techniques, such as chromatography, are commonly used to assess the quality and quantity of valuable honey. In this study, 15 honey samples were authenticated using HPLC and GC-MS chromatographic methods to analyze their pollen spectrum. Various monofloral honey samples were collected, including Acacia, Hypoestes, Lavandula, Tamarix, Trifolium, and Ziziphus species, based on accurate identification by apiarists in 2023 from the Kingdom of Saudi Arabia. Honey analysis revealed the extraction of pollen from 20 different honeybee floral species. Pollen identified from honey samples using advanced chromatographic tools revealed dominant vegetation resources: Ziziphus species (23%), Acacia species (25%), Tamarix species (34%), Lavandula species (26%), Hypoestes species (34%), and Trifolium species (31%). This study uses HPLC to extract phenolic compounds, revealing dominant protocatechuic acid (4.71 mg g-1), and GC-MS to analyze organic compounds in honey pollen. Specifically, 2-dodecanone was detected with a retention time of 7.34 min. The utilization of chromatographic tools in assessing honey samples for pollen identification provides a reliable and efficient method for determining their botanical origins, thereby contributing to the quality control and authentication of honey products.

Effect of Temperature and Duration of Gasbio Heat Energy on Bee Pollen Bioactive Compounds and Bee Propolis Extraction Trigona sp

Processing of dried bee pollen and propolis extraction to optimize the use of processed by-products of Trigona sp bees in the general public by utilizing biogas as heat energy. This research uses bee pollen and raw bee propolis (Trigona sp). The aim of the research was to determine the effect of temperature and length of time for drying bee pollen and propolis extraction on bioactive compounds. The research method used a completely randomized design (CRD) with 5 treatments and 3 replications, consist with (1) Bee pollen drying temperature with sunlight, 45 oC, 55 oC, 65 oC, and 75 oC, (2) Long oven time 3 days, 2,5 hours, 2 hours, 1 hour, and 15 minutes. Meanwhile, the treatment for propolis extraction with distilled water solvent is (1) Temperature 70 oC, 75 oC, 80 oC, 85 oC, and 90 oC, (2) Length of extraction time is 220 minutes. Data were analyzed using Variant ANOVA. If there is a significant difference and effect (P<0.05) or highly significant (P<0.01), then proceed with least significant difference test. Dried bee pollen research results the best bioactive compounds were obtained at a temperature of 65 oC (T3) with protein content (14.09 %), total phenol (1.314 mgGAE/g), and antioxidant content (53.97 ug/mL). The best results for propolis extraction were at a temperature of 70 oC (T0) with antioxidants (21.15ug/mL) and total phenolics (0.357 mgGAE/g). Gasbio can be used as an alternative heat for drying bee pollen and propolis extraction, but when use gasbio must determine the right temperature and time.

Characterization of the Pollen Trapped by Populus L. Seeds during the Dispersion Season

Our study aimed to quantify the pollen trapped by the seeds and relate it with the airborne pollen concentrations. Individual Populus spp. tuft-like seeds were sampled while suspended twice a day in 2017 and 2018 during the seed dispersal season. The seeds were submitted to laboratory treatment for pollen extraction, which was quantified using an optical microscope. Airborne pollen was monitored using a seven-day Hirst-type volumetric spore sampler. A correlation analysis was performed between the airborne pollen, the pollen on the seeds, and the meteorological parameters. A total of 26 pollen grains/mg was counted in the airborne tuft-like seeds, with 26 different taxa being identified, compared with the 18 pollen taxa identified in the airborne samples. Quercus, Poaceae, Urticaceae, Pinus, and Platanus were the most frequent pollen found on the seeds, while in the atmosphere, pollen from Urticaceae, Quercus, and Cupressaceae were the most representative. A tendency of higher pollen concentrations found in the afternoon samples, both airborne and on the seeds, was observed. Correlations between the meteorological parameters and pollen concentration found airborne and in the seeds were overall not significant. Thus, airborne poplar tuft-like seeds can trap and transport pollen, most of which has been recognized to induce respiratory allergies.

Content of fixed and volatile oils of pollen grains of five male cultivar of date palm Phoenix dactylifera L.

This study was conducted on the pollen of five male date palm cultivars to determine their content of fixed and volatile oils. Male cultivars were selected: Ghanamy Akhder, Ghanamy Ahmar, khukri, Wardi and Smesmi. Mature pollens were taken before their covers were cracked and the pollen extraction process was performed. The volatile oils were extracted using the Clevenger device, and the fixed oils were extracted using the Sexolate device. The results of the study showed that the male variety of , Ghanamy Ahmar was significantly superior to the rest of the varieties in the content of fixed oils, while the male variety of Wardi recorded the lowest rate, and the varieties of Ghanamy Akhder, khukri, and Smesmi did not differ in their content of fixed oils. As for volatile oils, the results of the study showed that the male variety, Ghanami Akhdar, was significantly superior to the rest of the male varieties, and recorded the highest rate . While the male variety, Wardi, recorded the lowest rate of pollen content of essential oils, The other male varieties did not differ among themselves in terms of the essential oil content of their pollen grains. The results of the study also showed the difference between the male varieties in terms of the qualitative characteristics of the oils in terms of density and refractive index.

A comprehensive procedure for pollen extraction from bat guano deposits in organic and detrital matrices

Although bat guano deposits have been proven to be excellent environmental archives for paleoecological and paleoclimate studies, the development of a standardized method specially catering to pollen extraction has received no attention so far. In general, the processing procedure is quite similar among published studies, but adjustments must be made regarding the proportion of organic and particulate matter in the guano deposit. In this study, we present step-by-step optimized sample processing methods for pollen analysis. These procedures first apply a chemical treatment for the removal of siliceous and organic material, followed by a sieving step to remove the remaining inorganic matter from those samples with high detrital content. Overall, our methods can efficiently remove particulate matter and improve the quality of the final residue, resulting in cleaner slides and better visualization of pollen and spores.•Remove humic acid and organic material with Potassium hydroxide.•Remove inorganic matter with hydrofluoric acid and sieving.•Concentrate and store the pollen residues in glycerin.

Keanekaragaman polen sebagai sumber pakan lebah Trigona sp. di Desa Sukawening Kecamatan Dramaga Kabupaten Bogor

Stingless bees generally produce honey products, but there is also pollen that can be studied in melissopalinology to identify pollen morphology, type and geography of plants. Pollen can also reveal the feeding aspects of stingless bees that are useful for their survival. This study was conducted to identify the diversity of pollen used as a food source for stingless bees Trigona sp. in Sukawening Village, Dramaga District, Bogor Regency. The research method used was the extraction of pollen from honey, acetolysis, identification and calculated the percentage of pollen. The results obtained 24 types of pollen (4 species have not been identified) which belong to 19 families and the dominant source of pollen comes from herbaceous plants. The percentage of pollen collected from Trigona sp. in Sukawening Village, Dramaga District, Bogor Regency is dominated by Cocos nucifera which is 11.03% categorized as Important Minor Pollen Type (IMPT) (3-15%).

Influence of common palynological extraction treatments on ultraviolet absorbing compounds (UACs) in sub-fossil pollen and spores observed in FTIR spectra

IntroductionBiological life, atmospheric circulation and the Earth’s climate may be influenced by UV-B radiation. In plants, Ultraviolet Absorbing Compounds (UACs) are an indicator of UV-B exposure, and the abundance of UACs in pollen and spores of embryophytes is measurable using Fourier Transform Infrared (FTIR) micro-Spectroscopy. However, understanding the influence of common chemical pre-treatments on sub-fossil pollen and spores with a view to UV-B reconstruction still requires investigation.MethodsHere, peat samples collected from a Late Holocene raised bog were treated with different chemicals (HCl, KOH, and acetolysis) for varying treatment times (up to 210 min). Pollen or spores of three common taxa (Alnus, Calluna and Sphagnum) were isolated and FTIR spectra obtained on individual grains. The spectra were compared to modern pollen and spore samples collected nearby.ResultsSpectra of modern and sub-fossil samples show several visible differences related to lipid and protoplast contents. The results of chemical treatments on sub-fossil pollen and spores reveal that HCl produced limited changes, while KOH and acetolysis altered several peaks, including the UAC-related aromatic peak at 1516 cm−1. We observe that all treatments modify the FTIR spectra to some degree, from weakest (HCl) to strongest (acetolysis). With respect to reduction of UAC peak area and treatment time, we observe in some cases a significant log-decay relationship, notably for KOH treatment on Calluna pollen and acetolysis on Sphagnum spores. Compared to untreated control samples, UAC peak area in Alnus, Calluna and Sphagnum reduced by 68%, 69% and 60% respectively, after only 3 min of acetolysis treatment. After 60 minutes of acetolysis treatment UAC peaks were reduced by 77%, 84% and 88%.DiscussionDue to the potential for taxon-specific effects and significant reductions in UAC peak area even within short treatment times, our recommendation for future applications in palaeoecological studies on palynomorph chemistry is to avoid chemical digestions in the pollen extraction process in favour of separation methods including micro-sieving and density separation.

Membrane-processed honey samples for pollen characterization with health benefits

Better processing techniques must be utilized widely due to the rising demand for honey. The most common honey processing techniques are applied to melissopalynomorphs to check the quality and quantity of valuable honey using microporous ultrafiltration membranes. It is essential to have the ability to selectively filter out sugars from honey using ultrafiltration. This study authenticated 24 honey samples using membrane reactors ultrafiltration protocol to describe the pollen spectrum of dominant vegetation. The purpose of this study was also to explore nutritional benefits as well as the active phytochemical constituents of honey samples. Honey samples were collected and labeled Acacia, Eucalyptus, and Ziziphus species based on plant resources provided by local beekeepers. A variety of honeybee flora was collected around the apiaries between 2020 and 2021. Honey analysis revealed that the pollen extraction of 24 bee foraging species belonging to 14 families. The honey membrane technology verified the identities of honey and nectar sources. Also, pollen identified using honey ultrafiltration membranes revealed dominant resources: Acacia spp. (69%), Eucalyptus spp. (52%) and Ziziphus spp. Honey filtration using a membrane technology classified 14 samples as unifloral, represented by six dominant pollen types. The absolute pollen count in the honey sample revealed that 58.33% (n = 14) belong to Maurizio's class I. Scanning ultrasculpturing showed diverse exine patterns: reticulate, psilate, scabrate-verrucate, scabrate-gemmate, granulate, perforate, microechinate, microreticulate, and regulate to fossulate for correct identification of honey pollen types. Honey ultrafiltration should be utilized to validate the botanical sources of honey and trace their biogeographic authenticity. Thus, it is imperative to look at the alternative useful method to identify the botanical origin of filtered honey. It is critical to separate honey from adulteration by a standardized protocol. Membrane technology has yielded significant outcomes in the purification of honey.

Design and Research of a Harvesting Actuator for Camellia oleifera Flowers during the Budding Period

The collection of Camellia oleifera flowers is a key foundation of Camellia oleifera flower pollen extraction. Due to the current problems of low efficiency, high labor intensity and the high cost of manual collection of Camellia oleifera flowers, a harvesting actuator was designed. By analyzing the inherent characteristics of the Camellia oleifera flower and the harvesting method, a harvesting structure using a combination of friction roller twisting harvesting and pipeline pneumatic conveying was designed. The geometric model of the Camellia oleifera flower was established and the motion analysis of the flower was carried out, which indicated that the Camellia oleifera flower would tend to a stable state for easy picking after entering the actuator. Using Automatic Dynamic Analysis of Mechanical Systems 2015 software (ADAMS, MSC. Software Corporation, Santa Ana, CA, USA) to simulate the process of Camellia oleifera flower picking, a mechanical analysis was performed in the contact plane to prove the theoretical feasibility of friction roller picking these flowers, and the main influencing factor was obtained as the speed of the friction roller. The test prototype for Camellia oleifera flower picking was built, and the picking experiment was implemented to study the effect of motor speed on the picking time of single Camellia oleifera flowers and the effect of the success rate of the flower picking. The test results show that when the motor speed is 400 r/min, the picking success rate is 96%, the picking time of a single flower is 1.2 s, and the speed of the machine collection of Camellia oleifera flowers is 2.3 times that of manual collection, which proves the realistic feasibility of this picking actuator. This paper provides an important reference and basis for the research and development of a flower harvesting actuator.

Pollen Types Reveal Floral Diversity in Natural Honeys from Campeche, Mexico

The Yucatan Peninsula, located in southern Mexico, is a central honey-producing region with extraordinary biodiversity of melliferous plants. Approximately 900 plant species have been described as being a source of nectar and pollen for bees and other pollinators. They provide ecosystem services that help to keep plant biodiversity high and mitigate the effects of climate change. This study aimed to reveal the diversity of the pollen content in honey through a melissopalynological analysis of 22 honey samples collected in February–August 2021 from the north-central area of Campeche, Mexico. The extraction of pollen from the honey was carried out using standard methods for melissopalynological analysis. The honeys were classified by botanical origin to determine their floral sources and a diverse spectrum of 19 pollen types from 13 families was identified. Only eight were predominant: Milleria quinqueflora, Gymnopodium floribundum, Terminalia buceras, Amaranthus spinosus, Zea mays, Talisia floresii, Guazuma ulmifolia, and Croton icche. Our research shows the high quality of the honey analyzed and highlights the diversity and critical role of local melliferous flora and crops in beekeeping development in southern Mexico. The results in this study are useful for confirming the botanical origins of honey, generating information for designing nature conservation and agroecosystem management strategies, and increasing the knowledge of beekeepers in Campeche, Mexico.

Pollen collected by stingless bees Tetragonula laeviceps (Smith, 1857) (Hymenoptera: Apidae: Meliponini) from Central Sulawesi

The diversity of pollinating insects is used as conservation management. Pollen is gametophyte from male which can give characteristics to its offspring. The pollen carried by bees can be used as an identification of feed favored by bees. This study aims to identity pollen derived from the legs of stingless bees based on the color morphological characteristics of the pollen. The methods include color identification of pollen collected by stingless bees, pollen extraction, acetolysis, and pollen identification. Pollen with the same species at the study site has a color that is not much different. Stingless bees take pollen based on the size and distance of the plant to the hive. Smell and color as a secondary binder for stingless bees. Different plant pollen species can also be influenced by the protein requirements of each stingless bee colony. It can recognize the presence of flowering plants aroud the hive. The size of pollen can affect the bees in taking plant pollen.

Optimal Design and Experiment of Manipulator for Camellia Pollen Picking

In this paper, a four-degree-of-freedom camellia-pollen-picking manipulator is proposed and designed. It can solve the problem of having no mechanized equipment for picking camellia pollen in agricultural machinery as the labor intensity of manual pollen extraction is high. To make the manipulator reach the target space quickly and efficiently, a structural-parameter-optimization method that reduces the working space to a more versatile cube is proposed. The numerical optimization algorithm is used to calculate the optimization result. Through the static analysis of the manipulator, the stability of the manipulator structure is verified. The working space of the manipulator is simulated and analyzed, and the simulation results are further verified by experiments. This research provides reliable technical support for the structural optimization, manufacturing, and intelligent upgrading of the camellia-pollen-picking robot.

Carpenter bee thorax vibration and force generation inform pollen release mechanisms during floral buzzing

Approximately 10% of flowering plant species conceal their pollen within tube-like poricidal anthers. Bees extract pollen from poricidal anthers via floral buzzing, a behavior during which they apply cyclic forces by biting the anther and rapidly contracting their flight muscles. The success of pollen extraction during floral buzzing relies on the direction and magnitude of the forces applied by the bees, yet these forces and forcing directions have not been previously quantified. In this work, we developed an experiment to simultaneously measure the directional forces and thorax kinematics produced by carpenter bees (Xylocopa californica) during defensive buzzing, a behavior regulated by similar physiological mechanisms as floral buzzing. We found that the buzzing frequencies averaged about 130 Hz and were highly variable within individuals. Force amplitudes were on average 170 mN, but at times reached nearly 500 mN. These forces were 30–80 times greater than the weight of the bees tested. The two largest forces occurred within a plane formed by the bees’ flight muscles. Force amplitudes were moderately correlated with thorax displacement, velocity and acceleration amplitudes but only weakly correlated with buzzing frequency. Linear models developed through this work provide a mechanism to estimate forces produced during non-flight behaviors based on thorax kinematic measurements in carpenter bees. Based on the buzzing frequencies, individual bee’s capacity to vary buzz frequency and predominant forcing directions, we hypothesize that carpenter bees leverage vibration amplification to increase the deformation of poricidal anthers, and hence the amount of pollen ejected.

Prestigious early Roman gardens across the Empire: the significance of gardens and horticultural trends evidenced by pollen

The present study has two main goals. The first is to reconstruct the botanical components that grew in the impressive garden of Villa Arianna (Stabiae). The garden, which was extensively destroyed and covered by tephra ash in 79 CE, is considered the largest peristyle garden in the Vesuvian region. Its plants were revealed based on a unique palynological-archaeological method involving the extraction of pollen from plaster attached to structures that faced the garden. The second aim is to compare this prestigious garden with other early elite Roman gardens, located in the eastern part of the Empire, to trace the importation of plants, horticultural trends, etc. For this purpose, gardens of Herod the Great, the client king of Judaea, which the author recently studied palynologically (in Caesarea, Herodium and Jericho), were compared with the new pollen results of Villa Arianna. The comparison between the gardens’ botanical components and their different landscapes led to the following conclusions: (1) Plants were imported from both ends of the Empire as elite products (rather than cash crops). Hazelnut (Corylus) and cedar (Cedrus) were introduced from west to east, while the date palm (Phoenix dactylifera) was introduced along an east-west axis. (2) The gardening trend of tree dwarfism was observed both at Villa Arianna and Jericho. (3) The gardens flourished in challenging habitats. At Villa Arianna and Caesarea, efforts were devoted to sustaining splendid gardens in the relatively harsh, saline Mediterranean Sea environment; at Herodium and Jericho, special efforts were required for the success of Mediterranean plants in semi-arid climate. (4) Herod’s mausoleum garden in Herodium, whose dark evergreen trees on the whitish slopes of the artificial tumulus could be seen from the Temple in Jerusalem, may have been inspired by the architectural arrangement of the Pantheon and the Mausoleum of Augustus, the patron of Herod.

Reduced visitation to buzz-pollinated Cyanella hyacinthoides in the presence of other pollen sources in the hyperdiverse Cape Floristic Region.

Many plant species have floral morphologies that restrict access to floral resources, such as pollen or nectar, and only a subset of floral visitors can perform the handling behaviors required to extract restricted resources. Due to the time and energy required to extract resources from morphologically complex flowers, these plant species potentially compete for pollinators with co‐flowering plants that have more easily accessible resources. A widespread floral mechanism restricting access to pollen is the presence of tubular anthers that open through small pores or slits (poricidal anthers). Some bees have evolved the capacity to remove pollen from poricidal anthers using vibrations, giving rise to the phenomenon of buzz‐pollination. These bee vibrations that are produced for pollen extraction are presumably energetically costly, and to date, few studies have investigated whether buzz‐pollinated flowers may be at a disadvantage when competing for pollinators’ attention with plant species that present unrestricted pollen resources. Here, we studied Cyanella hyacinthoides (Tecophilaeaceae), a geophyte with poricidal anthers in the hyperdiverse Cape Floristic Region of South Africa, to assess how the composition and relative abundance of flowers with easily accessible pollen affect bee visitation to a buzz‐pollinated plant. We found that the number of pollinator species of C. hyacinthoides was not influenced by community composition. However, visitation rates to C. hyacinthoides were reduced when the relative abundances of flowers with more accessible resources were high. Visitation rates were strongly associated with petal color, showing that flower color is important in mediating these interactions. We conclude that buzz‐pollinated plants might be at a competitive disadvantage when many easily accessible pollen sources are available, particularly when competitor species share its floral signals.

Settling moths are the vital component of pollination in Himalayan ecosystem of North-East India, pollen transfer network approach revealed

Majority of the pollination related studies are based on the diurnal pollinators, and the nocturnal pollinators received less scientific attention. We reveal the significance of settling moths in pollination of angiosperm families in Himalayan ecosystem of North-East India. The refined and novel method of pollen extraction from the proboscides provides a more robust assessment of the pollen carrying capacity. The study is based on one of the largest data sets (140 pollen transporter moth species (PTMS)), with interpretation based on seasonal as well as altitudinal data. In the present study about 65% moths (91 species) carried sufficient quantities of pollen grains to be considered as potential pollinators (PPMS). Teliphasa sp. (Crambidae) and Cuculia sp. (Noctuidae) are found to carry the highest quantity of pollen. We found pollen grains of 21 plant families and the abundant pollen are from Betulaceae, Fabaceae, Rosaceae and Ericaceae. Species composition of PTMS and PPMS in pre-monsoon, monsoon, and post-monsoon revealed the dominance of Geometridae. Maximum diversity of PTMS and PPMS is found from 2000 to 2500 m altitude. The nocturnal pollen transfer network matrices exhibited high degree of selectivity (H2ʹ = 0.86).

Examining the Role of Buzzing Time and Acoustics on Pollen Extraction of Solanum elaeagnifolium.

Buzz pollination is a specialized pollination syndrome that requires vibrational energy to extract concealed pollen grains from poricidal anthers. Although a large body of work has examined the ecology of buzz pollination, whether acoustic properties of buzz pollinators affect pollen extraction is less understood, especially in weeds and invasive species. We examined the pollination biology of Silverleaf nightshade (Solanum elaeagnifolium), a worldwide invasive weed, in its native range in the Lower Rio Grande Valley (LRGV) in south Texas. Over two years, we documented the floral visitors on S. elaeagnifolium, their acoustic parameters (buzzing amplitude, frequency, and duration of buzzing) and estimated the effects of the latter two factors on pollen extraction. We found five major bee genera: Exomalopsis, Halictus, Megachile, Bombus, and Xylocopa, as the most common floral visitors on S. elaeagnifolium in the LRGV. Bee genera varied in their duration of total buzzing time, duration of each visit, and mass. While we did not find any significant differences in buzzing frequency among different genera, an artificial pollen collection experiment using an electric toothbrush showed that the amount of pollen extracted is significantly affected by the duration of buzzing. We conclude that regardless of buzzing frequency, buzzing duration is the most critical factor in pollen removal in this species.

Pollen Source Affects Development and Behavioral Preferences in Honey Bees.

Simple SummaryPollinators adjust their foraging preference based on the pollen cues of foraging plants. Honey bees, for example, prefer to collect one type of pollen from plants that bloom at the same time. In northern China, apricot and pear trees are the two main foraging plants in the early spring. However, honey bees tend to collect pollen from apricot trees. It is interesting to understand what affects the foraging decision of honey bees regarding these two pollen types. In this study, we observed the foraging preference of Apis mellifera workers with respect to apricot and pear pollen under laboratory conditions. The effect of pollen on the development of the hypopharyngeal gland (HG) and ovary was measured. The number of visits made to apricot pollen was significantly higher than that to pear pollen. Furthermore, the response of the HG and ovary to these two pollens was different. The development of the HG was significantly affected by pollen diet treatments. However, there was no significant difference in the ovarian development of caged workers supplied with the two different pollen diets. Overall, honey bees showed a significant preference for apricot pollen over pear pollen. Compared with the ovary, the HG of honey bee workers may be more sensitive to pollen nutrition.With the availability of various plants in bloom simultaneously, honey bees prefer to collect some pollen types over others. To better understand pollen’s role as a reward for workers, we compared the digestibility and nutritional value of two pollen diets, namely, pear (Pyrus bretschneideri Rehd.) and apricot (Armeniaca sibirica L.). We investigated the visits, pollen consumption, and pollen extraction efficiency of caged Apis mellifera workers. Newly emerged workers were reared, and the effects of two pollen diets on their physiological status (the development of hypopharyngeal glands and ovaries) were compared. The choice-test experiments indicated a significant preference of A. mellifera workers for apricot pollen diets over pear pollen diets (number of bees landing, 29.5 ± 8.11 and 9.25 ± 5.10, p < 0.001 and pollen consumption, 0.052 ± 0.026 g/day and 0.033 ± 0.013 g/day, p < 0.05). Both pollen diets had comparable extraction efficiencies (67.63% for pear pollen and 67.73% for apricot pollen). Caged workers fed different pollen diets also exhibited similar ovarian development (p > 0.05). However, workers fed apricot pollen had significantly larger hypopharyngeal glands than those fed pear pollen (p < 0.001). Our results indicated that the benefits conferred to honey bees by different pollen diets may influence their foraging preference.