A preliminary palynological characterization of Spanish thyme honeys

Pollen was analysed in 25 thyme honey samples from Spain. The honey samples were provided by professional beekeepers, and pollen was obtained by centrifugation. A minimum of 8% of Thymus sp. pollen is considered sufficient to typify a honey as unifloral when considering pollen grains from anemophilous and nectarless plants. The quantitative analysis showed that nectar is the main honey source in the samples studied. The qualitative analysis of the samples revealed the presence of 53 taxa belonging to 27 families. The Spanish thyme honeys of the studied region are characterized by their medium to high numbers of grains of pollen (NGP; mean = 155 000) and their medium to high content of honeydew indicator elements (HDE; mean = 8300). Genista type (present in 100% of the samples), Echium plantagineum and Reseda luteola (90%), Eucalyptus type (80%), Calendula type and Olea europaea (75%), and Cistus monspeliensis (70%) may be mentioned among the characteristic accompanying species of this honey type.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 323–330.     

The effects of natural variation in pollinator visitation on rates of pollen removal in wild radish,Raphanus raphanistrum (Brassicaceae)

Pollen removal from flowers is an important component of male fitness, but the effects of natural variation in visitation rates on pollen removal are poorly understood. We measured pollen removal over 2 yr in experimental field populations of wild radish, Raphanus raphanistrum. Pollen removal and pollinator visitation over 1-hr periods were measured on previously unvisited flowers. The effects of pollen production and visitation by different insect taxa on pollen removal were determined using multiple regression. Pollen removal rates were extremely high; a median of 84% of pollen produced was removed in 1 hr. Pollen production was far more important than visitation in determining the number of pollen grains removed. Pollen removal increased with increasing numbers of visits by honey bees and small native bees, but increased numbers of syrphid fly visits had no effect. Average visit duration had no effect on pollen removal in 1991, and a marginally negative effect in 1992.     

Floral resources foraged by Geotrigona argentina (Apidae,Meliponini) in the Argentine Dry Chaco forest

This study is the first contribution to knowledge of the relationships between Geotrigona argentina and the plants of the Argentine Dry Chaco forest. A total of 1260 g of honey (corresponding to 146 pots) and 763 g of pollen (63 pots) stored in four underground nests was studied. The honey pots from each nest were homogenised and the four honey samples were analysed by melissopalynological methods, whereas the pollen pots were studied individually. Both classical counts and counts affected by the volume of the pollen types were carried out. Pollen data were statistically analysed. Additional data on both protein and lipid content is also provided. A total of 39 pollen taxa were identified. Pollen collection was focused on a few pollen taxa: Prosopis, Castela coccinea, Maytenus and Capparis; these taxa, together with Ziziphus mistol and Pisonia zapallo, were also important nectar sources. The preliminary results show that pollen collection varied seasonally, being most diverse in the summer when G. argentina incorporates herbaceous plants into its diet. The pollen collection spectrum of G. argentina is similar to that of other Trigonina bees in that the main plant species collected are a few large shrubs or trees, whose flowering consists of small and clustered flowers. Pots with large amounts of monofloral loads with pollen from only a few species suggests an organised foraging behaviour that includes the recruitment of foragers, such as that observed in other eusocial bees.     

The effects of landscape on bumblebees to ensure crop pollination in the highland agricultural ecosystems in China

Honey bees and wild bees provide critical pollination services to agricultural ecosystems; however, the relative contributions of different bee taxa are not well understood. The natural habitats surrounding farmland support food and nesting resources for wild bees and therefore play an important role in the maintenance of crop pollination. In this study, we selected Cucurbita pepo L. (squash) as a model crop to investigate the relative importance of honey bees and bumblebees in pollinating the crop. Thirteen fields, which were surrounded by a gradient of natural habitat, were investigated on the Yunnan‐Guizhou Plateau in China. We measured the visit densities of honey bees and bumblebees, the number of pollen grains deposited in a single visit by the two bee taxa, as well as the overall pollen grains deposited on stigmas during a flowering day, and then used Bayesian inference to decouple the pollen grains deposited by either the honey bees or the bumblebees. Compared with honey bees, bumblebees deposited a higher number of pollen grains on stigmas in a single visit, but had a lower visit density than honey bees. Meanwhile, the bumblebee visit density increased along the proportion of natural habitat, while the honey bee visit density was not affected by the surrounding natural habitat. Data simulations using Bayesian inference showed that on a flowering day, the number of pollen grains deposited by bumblebees increased with the proportion of natural habitat in the surrounding landscape, but the number of pollen grains deposited by honey bees did not. Moreover, the total numbers of pollen grains deposited by honey bees or bumblebees alone were all below 2000 (the critical level to satisfy the pollination requirement of this crop). Pollen calculations demonstrated that the number of pollen grains deposited by the two bee taxa was greater than 2000 in fields surrounded by more than 13% natural habitat (grasslands and forests). The results revealed that bumblebees ensured C. pepo pollination in combination with honey bees in the highland agricultural ecosystems.     

Pollen of Apis honey from Maharashtra

Melissopalynological investigations are important in establishing an apiary industry. Pollen analyses of the nectar sources of Apis florea Fabr. from the Saoner region indicate the importance of this region for commercial bee keeping enterprises. Twenty seven samples were collected during winter season in the months of October 1997 to January 1998 and November 1998 to January 1999. In addition, 245 pollen loads were analyzed from 19 honey combs collected from the same region. Pollen grains were identified from reference slides. Of the 27 honey samples, 17 samples were unifloral and ten multifloral. A total of 39 pollen types were classified into 21 families. In the analyses of the 245 pollen loads Lagascea mollis Cav. was dominant in 57 pollen loads and Parthenium hysterophorus L. in 55 pollen loads. Weeds such as Parthenium hysterophorus, Sphaeranthus indicus L., Lagascea mollis, Bidens pilosa L. and Justicia procumbens L. were the common sources of nectar and pollen for Apis florea in the region. Agricultural tracts of the Saoner region in the Nagpur District have a good potential for sustaining beekeeping ventures because of the diversity of nectar and pollen taxa.     

Honey bee‐collected pollen in agro‐ecosystems reveals diet diversity,diet quality,and pesticide exposure

European honey bees Apis mellifera are important commercial pollinators that have suffered greater than normal overwintering losses since 2007 in North America and Europe. Contributing factors likely include a combination of parasites, pesticides, and poor nutrition. We examined diet diversity, diet nutritional quality, and pesticides in honey bee‐collected pollen from commercial colonies in the Canadian Maritime Provinces in spring and summer 2011. We sampled pollen collected by honey bees at colonies in four site types: apple orchards, blueberry fields, cranberry bogs, and fallow fields. Proportion of honey bee‐collected pollen from crop versus noncrop flowers was high in apple, very low in blueberry, and low in cranberry sites. Pollen nutritional value tended to be relatively good from apple and cranberry sites and poor from blueberry and fallow sites. Floral surveys ranked, from highest to lowest in diversity, fallow, cranberry, apple, and blueberry sites. Pesticide diversity in honey bee‐collected pollen was high from apple and blueberry sites and low from cranberry and fallow sites. Four different neonicotinoid pesticides were detected, but neither these nor any other pesticides were at or above LD₅₀ levels. Pollen hazard quotients were highest in apple and blueberry sites and lowest in fallow sites. Pollen hazard quotients were also negatively correlated with the number of flower taxa detected in surveys. Results reveal differences among site types in diet diversity, diet quality, and pesticide exposure that are informative for improving honey bee and land agro‐ecosystem management.     

Pollen–vegetation relationships along steep climatic gradients in western Amazonia

Question: How accurately do Amazonian montane forest pollen spectra reflect the vegetation? Can compositional changes observed in the vegetation along environmental gradients be identified in the pollen spectra? How well do herbarium collection data and bioclimatic envelopes represent abundance changes along elevation gradients? Location: Amazonian montane forests, Peru. Methods: Moss polsters collected along five altitudinal transects spanning over 3000 m a.s.l. were used to characterize pollen spectra. Vegetation plot data from a network of 15 1‐ha permanent plots were used to correlate pollen spectra with present‐day vegetation. Probability density functions (PDFs) fitted to pollen and plot data allowed comparisons using Spearman correlation coefficients. Ordination analyses were used to summarize changes in pollen spectra. Correlations between pollen‐based PDFs and previously‐published herbarium collection PDFs were also evaluated. Results: Pollen spectra closely reflected changes in species composition along elevation gradients. A mid‐elevation shift in pollen spectra was identified using ordination analyses. Pollen spectra from the driest forest in our data set were statistically different from those of wet forests. Pollen abundance PDFs along the altitudinal gradient were significantly correlated (P<0.01) with PDFs fitted to plot abundance, basal area and herbarium collection data for ten out of 11 taxa analysed. Conclusions: Pollen spectra closely reflected the vegetation composition of Amazonian montane forests. The differentiation of pollen spectra from dry localities showed the potential of genus‐level pollen data to reflect precipitation gradients. Pollen spectra also reflected mid‐elevation compositional changes well along the lower elevation limit of ground cloud formation. Despite collection biases, herbarium‐based bioclimatic envelope PDFs also represented well forest compositional changes along elevation gradients.     

Importance of pollen grain volumes for calculating bee diets

Pollen grains harvested by bees differ greatly in volume, thus pollen grains contribute differentially to larval and imaginal nutritional ecology, and ultimately to bee fitness. Simple proportions are inadequate when disentangling the importance of various pollen taxa found on foraging bees, their scopal loads or in their nest provisions. Disparate volumes of pollen grains are an essential feature to be considered in any foraging or dietary study. To document the importance of pollen volume on diet we mixed equal amounts (by weight) of ten morphologically diverse pollen taxa commonly collected by honey bees in the Sonoran desert of Arizona. These taxa were: Cereus giganteus, Ephedra trifurca, Fouquieria splendens, Helianthus annuus, Prosopis juliflora, and Simmondsia chinensis. Additionally, a small grain, Solanum rostratum, and two large grains, Cucurbita foetidissima and Opuntia phaeacantha, rarely harvested by honey bees, were included in the mixture. The mixture was inoculated with calibrated spore tablets, acetolyzed, counted, and % volumes calculated. Pollen grain numbers obtained from the middle of the coverslip were compared with those along the coverslip edge (x²) with no apparent statistically significant difference. The percent by pollen grain number was compared with percentage by pollen grain volume using a Chi-square test.     

欧报春二型花柱的繁育特性研究

二型花柱植物通常具有自交不亲和性,在不同植物中所表现的可育性不同。欧报春(Primula vulgaris)是典型的二型花柱植物,为了探究欧报春的繁育特性,通过温室栽培,对欧报春的长花柱和短花柱的花部特征、花粉和花柱形态、花粉活力、柱头可授性、花粉/胚珠比、杂交指数、杂交亲和性、花粉管观察进行研究。结果表明,(1)长花柱和短花柱的花冠直径、花冠筒长度、柱头高度、花药高度和花筒中部直径均表现出两型性;(2)花粉和柱头观察发现花粉极轴长、花粉赤道轴长、花柱直径、柱头乳突细胞和花粉数量均有差异;(3)长花柱的花粉/胚珠比为384.20,短花柱为369.70,属于兼性异交类型;长花柱和短花柱的花粉活力和柱头可授性能在较长时间内维持较高活力;(4)长花柱杂交指数值为5,短花柱为4,表明繁育系统类型为异交,部分自交亲和,需要传粉者;6种授粉组合均能结实,异型花间授粉的结实数明显高于同型自花授粉和异株同型授粉;短花柱为母本的异型花间授粉组合亲和性优于其他组合;欧报春存在自交不亲和性,长花柱的自交不亲和性低于短花柱。     

Pollen analyses of honey from Finland

The present study reports results of qualitative melissopalynological analyses of Finnish honey between the years 2000–2007 and changes in its pollen content from the period 1960–2007. Altogether the pollen content of 734 honey samples was analysed with an average of 415 pollen grains counted from a sample. Pollen of Trifolium repens type, Rubus spp., Salix spp. and the Brassicaceae family were present in more than 90% of the samples, and these pollen types were also found in the highest proportions. Annual variation in the relative amounts of the most numerous pollen types could be as high as 10%. On the basis of the pollen spectra of the honey samples, four regions of forage plants for bees could be identified in Finland. In the period between 1960 and 2007, the most marked change observed was that the percentage of the Trifolium spp. pollen type had decreased from 70% to 10%, while the proportions of Brassicaceae and Rosaceae pollen types showed a corresponding increase.     

Evaluating multiplexed next‐generation sequencing as a method in palynology for mixed pollen samples

The identification of pollen plays an important role in ecology, palaeo‐climatology, honey quality control and other areas. Currently, expert knowledge and reference collections are essential to identify pollen origin through light microscopy. Pollen identification through molecular sequencing and DNA barcoding has been proposed as an alternative approach, but the assessment of mixed pollen samples originating from multiple plant species is still a tedious and error‐prone task. Next‐generation sequencing has been proposed to avoid this hindrance. In this study we assessed mixed pollen probes through next‐generation sequencing of amplicons from the highly variable, species‐specific internal transcribed spacer 2 region of nuclear ribosomal DNA. Further, we developed a bioinformatic workflow to analyse these high‐throughput data with a newly created reference database. To evaluate the feasibility, we compared results from classical identification based on light microscopy from the same samples with our sequencing results. We assessed in total 16 mixed pollen samples, 14 originated from honeybee colonies and two from solitary bee nests. The sequencing technique resulted in higher taxon richness (deeper assignments and more identified taxa) compared to light microscopy. Abundance estimations from sequencing data were significantly correlated with counted abundances through light microscopy. Simulation analyses of taxon specificity and sensitivity indicate that 96% of taxa present in the database are correctly identifiable at the genus level and 70% at the species level. Next‐generation sequencing thus presents a useful and efficient workflow to identify pollen at the genus and species level without requiring specialised palynological expert knowledge.     

Nectar and Pollen Sources for Honeybee （Apis cerana cerana Fabr.） in Qinglan Mangrove Area, Hainan Island, China

In the present study, nectar and pollen sources for honeybee （Apls cerana cerana Fabr.） were studied in Qlnglan mangrove area, Hainan Island, China, based on microscopic analysis of honey and pollen load （corblcular and gut contents） from honeybees collected In October and November 2004. Qualitative and quantitative melittopalynologlcal analysis of the natural honey sample showed that the honey is of unlfloral type with Mimosa pudlca L. （Mlmosaceae） as the predominant （89.14%） source of nectar and pollen for A. cerana cerana In October. Members of Araceae are an Important minor （3%-15%） pollen type, whereas those of Arecaceae are a minor （〈3%） pollen type. Pollen grains of Nypa fruticans Wurmb., Rhlzophora spp., Excoecarla agallocha L., Lumnitzera spp., Brugulera spp., Kandella candel Druce, and Ceriops tagal （Perr.） C. B. Rob. are among the notable mangrove texa growing In Qinglan mangrove area recorded as minor taxa In the honey. The absolute pollen count （I.e. the number of pollen grains/10 g honey sample） suggests that the honey belongs to Group V （〉1 000 000）. Pollen analysis from the corblcular and gut contents of A. cerana cerana revealed the highest representation （95.60%） of members of Sonneratia spp. （Sonneratlaceae）, followed by Bruguiera spp. （Rhizophoraceae）, Euphorblaceae, Poaceae, Fabaceae, Arecaceae, Araceae, Anacardlaceae, and Rublaceae. Of these plants, those belonging to Sonneratla plants are the most Important nectar and pollen sources for A. cerana cerana and are frequently foraged and pollinated by these bees in November.     

Challenges in estimating past plant diversity from fossil pollen data: statistical assessment, problems, and possible solutions

Fossil pollen data from sediment cores may be used as a measure for past plant diversity. According to the theory of probability, palynological richness is positively related to the pollen count. In a low pollen count, only common taxa are detected, whereas rare taxa are only detected by chance. The detection of all pollen taxa requires a very high pollen count, which is time-consuming. In regular palynological investigations, the detected richness in pollen spectra varies with the pollen count. Rarefaction analysis estimates palynological richness in an exactly equal-sum count for all samples, so that comparison between samples is meaningful. However, the over-representation of some taxa suppresses the detection probability of rare taxa; low total pollen abundance in a sample enhances the detection probability of rare taxa and long-distance transported pollen grains. These factors bias the observed palynological richness and distort comparisons. Palynological richness in a pollen count proportional to its pollen influx may be one proxy for reconstructing diversity trends through time. The use of this proxy overcomes most problems encountered in rarefaction analysis, but is constrained by inaccuracy in estimating pollen influx due to the imprecise time control of sediment cores. Estimating palynological richness by mathematical methods may be another way of reconstructing pollen diversity. Pollen data tend to reflect diversity on a regional scale. Sites from small basins have the advantage of recording diversity at both local and regional scales, if the detection of each taxon is independent. By associating one site from a large basin with a series of sites from very small basins (e.g. forest-hollows), information about both regional and local diversity may be obtained. Entomophilous pollen taxa may have to be measured using a different strategy than anemophilous taxa.     

Distyly and pollen dimorphism in<Emphasis Type="Italic"> Damnacanthus</Emphasis> (Rubiaceae)

We document distyly in Damnacanthus (Rubiaceae) and investigate pollen morphology in the genus. Within nine taxa in Japan (four species, four varieties and one form), five show distyly. Non-distylous taxa of Damnacanthus always have a long style and short stamens. We examined the pollen morphology of all taxa of Damnacanthus in Japan. The pollen grains of Damnacanthus are 3- to 5-orthocolporate or sometimes loxocolporate. Polymorphic pollen is sometimes observed even within a single flower. Pollen dimorphism is associated with distyly; pollen grains from short-styled (thrum) flowers are significantly larger than those from long-styled (pin) flowers, and the muri are smooth in pin flowers whereas the pollen grains of thrum flowers have minute granules on the top and/or on the sides. In non-distylous taxa, in which the style is longer than stamens, the muri are always provided with minute granules. Interestingly, the pollen grains with granules in the non-distylous taxa contrast with the pollen of the distylous taxa, because granulate pollen grains are found only in thrum flowers. Although Damnacanthus is a stenopalynous genus, the number of colpi is useful for delimiting taxa. Based on palynological characters, we conclude that Damnacanthus should be revised. Electronic Publication     

Characterization of pollen profile of Apis mellifera L. in arid region of Pakistan

Honeybees rely exclusively on pollen and nectar-producing plants for strengthening their colonies and manufacturing honey. Little is known about the indigenous melliferous flora of arid zones of Khyber Pakhtunkhwa (KPK) which is crucial for honey production and how different pollen assessment techniques effect the identification of indigenous melliferous pollen flora. Visual survey and loads ensnaring through pollen traps were used to identify the botanical profile of melliferous pollen flora of Dera Ismail Khan (DIKhan), Khyber Pakhtunkhwa. The test time extended for two consecutive years 2018 and 2019. The study revealed 56 plant species as pollen flora with 18 significant pollen producing species in visual survey technique while 8 species as predominant flora in pollen trapping technique. The major pollen species found common in both the techniques were Brassica napus L., Brassica campestris L., Trifolium alaxandrinum L., Zea mays L., Acacia modesta L., Citrus aurantium L., Euclyptus spp., and Morus alba L. Pollen interception and palynological analysis of pollen were found to be more reliable techniques as compared to focal observations. More than fifty % differences were found by comparing the results of the visual survey and pollen trapping technique in major flora of DIKhan. Based on the availability, utility status and flowering duration of apiphilic flora, mid-February to mid-May was found to be a significant pollen flow period in the study area. Maximum benefit can be taken in this period through trapping ample amount of pollen and stored for using in artificial diets, selling and feeding bees during dearth period.     

THE CYTOCHEMICAL REDUCTION OF NITRO BLUE TETRAZOLIUM AS AN INDEX OF POLLEN VIABILITY

A new technique for estimating pollen viability utilizing Nitro Blue Tetrazolium (Nitro-BT) is given. Pollen of 16 taxa was studied and scored for stainability. A comparison was made between Nitro-BT-stained pollen samples and aniline-blue-lactophenol-stained samples, because the validity of the latter stain has been questioned in recent years. It is demonstrated that Nitro-BT can discriminate between pollens which have a capacity for oxidative metabolism, representing potential viability, and those which do not. Suggestions for pollen stainability studies are given.     

螺序草属(茜草科)的花粉形态

首次对螺序草属(Spiradiclis B1.)的11种和1变型共16份植物的花粉样品在光镜和电镜下进行了观察。结果表明,本属植物花粉为单粒,小型和中型花粉,近球形至椭球形,辐射对称,常具3孔沟,偶为4孔沟,外壁表面纹饰为孔状。花粉外壁由不连续的具穿孔的覆盖层、柱状结构和基层组成,内外壁明显。此外,本属植物的花粉具有花粉2型和“芽状”结构的现象。螺序草属植物的花粉形态在属下分类上有一定的局限性,但是在个体的系统发育上却可以提供极有价值的信息,如具有花粉单型的种类比花粉二型的种类进化。     

花粉破壁法对花粉蜂蜜酒中氨基酸含量的影响

以蜂蜜为主料,加入花粉,经过调配、发酵、过滤、陈酿后获得氨基酸含量丰富的酒精饮料。花粉破壁分别采用超声破碎法、酶法和温差破壁法这几种不同方式处理,并添加于蜂蜜发酵液中,经酒精发酵,制得富含活性成分的花粉蜂蜜酒。最后利用毛细管电泳法来测定成品酒中的氨基酸,通过分析优化出最佳的花粉破壁方法。研究结果表明花粉经过温差破壁法处理后加入发酵液中,其成品的氨基酸含量最高。该产品不仅营养价值高,风味独特,而且还具有良好的保健作用。     

15. Brve (Czech Republic): Vegetation development over the last about 2.5 millennia in the Bohemian Lowland close to Prague

Two Burkard seven-day recording traps have been in operation in the cities of Johannesburg and Pretoria since 1987. Pollen calendars average data for 1987 and 1988. Grass pollen is the most significant contributor in absolute and relative terms. This taxon comprises 52% of total regional pollen for the study period. Pollen of alien northern hemisphere trees is abundant, relative to that of native trees. This is attributed partly to the paucity of trees in the natural vegetation, and partly to their entomophilous nature. The flowering season for exotics is very short, possibly due to the short spring season. The greatest proportion of pollen, 58,8%, is nonseasonal. Species in this category flower throughout the year. 28.4% of taxa are spring-flowering. Annual variability is marked for most taxa.     

Foraging behaviour of the stingless bee Melipona orbignyi (Hymenoptera: Apidae: Meliponini) in a dry forest assessed by multivariate analysis from palynological data

Pollen analysis was applied to study the botanical composition of honey and pollen stored by Melipona orbignyi in its southernmost distributional range. Many studies have revealed that robust buzzing bees of this genus are associated with diverse plant families, some of which are different to those exploited by the remaining genera of Meliponini. Cluster analysis was performed to assess similarity in botanical composition between pot-pollen and pot-honey provisions from different colonies. The results indicated that each colony was capable to access to different plant species for obtaining nectar and pollen, a fact observed when discarding the contaminated honey samples. As honey samples were not clustered together with other ones but with pollen samples indicating a similar botanical composition, it could be assumed that a same plant species provided nectar and pollen to bees. Resource partitioning was not clearly observed among a subset of late spring colonies, as two families of high richness of species and abundant in this dry forest (the mimosoid clade in Fabaceae and Capparaceae) were foraged. A higher number of synchronously sampled colonies would be necessary to detect this ecological aspect. The botanical composition of samples of M. orbignyi was governed by both random factors such as local and temporary flower availability plus preferences for particular plant species such as those from Solanaceae and Ximeniaceae. The Capparaceae and Ximeniaceae are here reported for the first time as intensively foraged pollen resources by the genus Melipona.