Pollen Chemistry Research Articles

Dietary effects on body weight of predatory mites (Acari, Phytoseiidae).

Pollen is offered as alternative or supplementary food for predacious mites; however, it may vary in its nutritional value. Body weight appears a representative parameter to describe food quality. Thus, we assessed the body weight for adults of the generalist mites Amblyseius swirskii, Amblydromalus limonicus, and Neoseiulus cucumeris reared on 22, 12, and 6 pollen species, respectively. In addition, A. swirskii and A. limonicus was reared on codling moth eggs. In all mite species, female body weight was higher than that of males, ranging between 4.33 and 8.18µg for A. swirskii, 2.56-6.53µg for A. limonicus, and 4.66-5.92µg for N. cucumeris. Male body weight ranged between 1.78 and 3.28µg, 1.37-3.06µg, and 2.73-3.03µg, respectively. Nutritional quality of pollen was neither consistent among the mite species nor among sex, revealing superior quality of Quercus macranthera pollen for females of A. swirskii and Tulipa gesneriana pollen for males, Alnus incana pollen for females of A. limonicus and Aesculus hippocastanum pollen for males, and Ae. hippocastanum pollen for both sexes of N. cucumeris. The results are discussed against the background of known or putative pollen chemistry and mite's nutritional physiology.

The impact of oxidation on spore and pollen chemistry

Sporomorphs (pollen and spores) have an outer wall composed of sporopollenin. Sporopollenin chemistry contains both a signature of ambient ultraviolet-B flux and taxonomic information, but it is currently unknown how sensitive this is to standard palynological processing techniques. Oxidation in particular is known to cause physical degradation to sporomorphs, and it is expected that this should have a concordant impact on sporopollenin chemistry. Here, we test this by experimentally oxidizing Lycopodium (clubmoss) spores using two common oxidation techniques: acetolysis and nitric acid. We also carry out acetolysis on eight angiosperm (flowering plant) taxa to test the generality of our results. Using Fourier Transform infrared (FTIR) spectroscopy, we find that acetolysis removes labile, non-fossilizable components of sporomorphs, but has a limited impact upon the chemistry of sporopollenin under normal processing durations. Nitric acid is more aggressive and does break down sporopollenin and reorganize its chemical structure, but when limited to short treatments (i.e. ≤10 min) at room temperature sporomorphs still contain most of the original chemical signal. These findings suggest that when used carefully oxidation does not adversely affect sporopollenin chemistry, and that palaeoclimatic and taxonomic signatures contained within the sporomorph wall are recoverable from standard palynological preparations.

Better safe than sorry? A Fabaceae species exhibits unfavourable pollen properties for developing bee larvae despite its hidden anthers

Empirical evidence suggests that pollen chemistry plays an important role in shaping the pollen host spectra of many bee species. Although the underlying mechanisms are poorly understood, pollen diets of several plant taxa have experimentally been found to impede larval development of unspecialized bees. The pollen of all plant taxa, for which such a detrimental effect on bee larval development has been observed so far, is freely accessible in the flowers and thus easily harvestable for flower visitors, suggesting that this pollen might be chemically protected in order to reduce its loss to pollen-feeding animals. In the present study, we compared larval performance of five solitary bee species on pollen diets of the two Fabaceae species Onobrychis viciifolia and Lotus corniculatus, which have their anthers concealed inside the flowers, with that on control diets composed of host pollen provisions. As the complex flower morphology of the two Fabaceae species already considerably narrows the spectrum of pollen harvesting bee taxa, which might supersede costly chemical protection of the pollen, we expected bees that usually do not exploit Fabaceae to develop well on Onobrychis and Lotus pollen diets. Larval survival on the Onobrychis pollen diet was successful for all five bee species tested. In contrast, larval survival on the Lotus pollen diet was reduced in three species despite the fact that Lotus flowers are more difficult to exploit for pollen than Onobrychis flowers. We conclude that there is no trade-off between pollen concealment and pollen defence in Lotus and that pollen of morphologically complex flowers with a restricted visitor spectrum is not necessarily an easy-to-use nutritional source.

How Does Pollen Chemistry Impact Development and Feeding Behaviour of Polylectic Bees?

Larvae and imagos of bees rely exclusively on floral rewards as a food source but host-plant range can vary greatly among bee species. While oligolectic species forage on pollen from a single family of host plants, polylectic bees, such as bumblebees, collect pollen from many families of plants. These polylectic species contend with interspecific variability in essential nutrients of their host-plants but we have only a limited understanding of the way in which chemicals and chemical combinations influence bee development and feeding behaviour. In this paper, we investigated five different pollen diets (Calluna vulgaris, Cistus sp., Cytisus scoparius, Salix caprea and Sorbus aucuparia) to determine how their chemical content affected bumblebee colony development and pollen/syrup collection. Three compounds were used to characterise pollen content: polypeptides, amino acids and sterols. Several parameters were used to determine the impact of diet on micro-colonies: (i) Number and weight of larvae (total and mean weight of larvae), (ii) weight of pollen collected, (iii) pollen efficacy (total weight of larvae divided by weight of the pollen collected) and (iv) syrup collection. Our results show that pollen collection is similar regardless of chemical variation in pollen diet while syrup collection is variable. Micro-colonies fed on S. aucuparia and C. scoparius pollen produced larger larvae (i.e. better mates and winter survivors) and fed less on nectar compared to the other diets. Pollen from both of these species contains 24-methylenecholesterol and high concentrations of polypeptides/total amino acids. This pollen nutritional “theme” seems therefore to promote worker reproduction in B. terrestris micro-colonies and could be linked to high fitness for queenright colonies. As workers are able to selectively forage on pollen of high chemical quality, plants may be evolutionarily selected for their pollen content, which might attract and increase the degree of fidelity of generalist pollinators, such as bumblebees.

Phylogeny and floral hosts of a predominantly pollen generalist group of mason bees (Megachilidae: Osmiini)

Within the genus Osmia, the three subgenera Osmia, Monosmia, and Orientosmia form a closely-related group of predominantly pollen generalist (‘polylectic’) mason bees. Despite the great scientific and economic interest in several species of this clade, which are promoted commercially for orchard pollination, their phylogenetic relationships remain poorly understood. We inferred the phylogeny of 21 Osmia species belonging to this clade by applying Bayesian and maximum likelihood methods based on five genes and morphology. Because our results revealed paraphyly of the largest subgenus (Osmia s.s.), we synonymized Monosmia and Orientosmia under Osmia s.s. Microscopical analysis of female pollen loads revealed that five species are specialized (‘oligolectic’) on Fabaceae or Boraginaceae, whereas the remaining species are polylectic, harvesting pollen from up to 19 plant families. Polylecty appears to be the ancestral state, with oligolectic lineages having evolved twice independently. Among the polylectic species, several intriguing patterns of host plant use were found, suggesting that host plant choice of these bees is constrained to different degrees and governed by flower morphology, pollen chemistry or nectar availability, thus supporting previous findings on predominantly oligolectic clades of bees. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 78–91.

Bee Food: The Chemistry and Nutritional Value of Nectar, Pollen and Mixtures of the Two

Bees are herbivorous insects, consuming nectar and pollen throughout their life cycles. This paper is a brief review of the chemistry of these two floral resources and the implications for bee nutrition. Nectar is primarily an energy source, but in addition to sugars contains various minor constituents that may, directly or indirectly, have nutritional significance. Pollen provides bees with the protein, lipids, vitamins and minerals that are essential for larval rearing. Chemical analyses of pollen have tended to focus on the protein component of bee-collected pollens as an index of nutritional quality. However, the substantial nectar content of such samples (~ 50% dry mass) should not be ignored, especially in view of current interest in measuring the nutritional quality of floral resources for bees.

UV-B absorbing pigments in spores: biochemical responses to shade in a high-latitude birch forest and implications for sporopollenin-based proxies of past environmental change

Current attempts to develop a proxy for Earth’s surface ultraviolet-B (UV-B) flux focus on the organic chemistry of pollen and spores because their constituent biopolymer, sporopollenin, contains UV-B absorbing pigments whose relative abundance may respond to the ambient UV-B flux. Fourier transform infrared (FTIR) microspectroscopy provides a useful tool for rapidly determining the pigment content of spores. In this paper, we use FTIR to detect a chemical response of spore wall UV-B absorbing pigments that corresponds with levels of shade beneath the canopy of a high-latitude Swedish birch forest. A 27% reduction in UV-B flux beneath the canopy leads to a significant ( p <0.05) 7.3% reduction in concentration of UV-B absorbing compounds in sporopollenin. The field data from this natural flux gradient in UV-B further support our earlier work on sporopollenin-based proxies derived from sedimentary records and herbaria collections. Keywords: FTIR, spores, ferulic acid, p -coumaric acid, shade, sporopollenin (Published: 23 August 2011) Citation: Polar Research 2011, 30 , 8312, DOI: 10.3402/polar.v30i0.8312

The occurrence of p-coumaric acid and ferulic acid in fossil plant materials and their use as UV-proxy

The applicability of p-coumaric acid and ferulic acid concentrations or ratios in (sub)fossil plant remnant as UV-B proxies relies on various aspects, which are discussed in this paper and will be illustrated with some experimental data. A newly developed THM-micropyrolysis–gas chromatography–mass spectrometry method was tested on various spores, pollen and other plant remains, which were analysed for the presence of the UV-absorbing compounds p-coumaric acid and ferulic acid. This revealed that these supposed building-blocks of sporopollenin appear to be present in pollen of many plant species but also in moss spores. The development of this micropyrolysis method paved the way for the quantitative analysis of UV-absorbing compounds in case only a small amount of analyte is available, for example for fossil pollen and spores but also other small palynomorphs and plant fossils. The use of this technique will provide a better insight in the plant responses to UV-radiation, the chemistry of pollen and spores, their fossil counterparts and furthermore the means for a further development of a proxy for the reconstruction of past UV-B radiation.

Specks of Evidence For Ancient Sunburn

EARTH SYSTEM PROCESSES 2 MEETINGCALGARY, ALBERTA-- From 8 to 11 August, an interdisciplinary meeting organized by the Geological Society of America and the Geological Association of Canada covered topics including inferring ancient ozone holes from the chemistry of pollen and spores.

Macronutrient chemistry of pollen

Abstract Concentrations of total and water‐extractable macronutrients varied with pollen species and genus. Total nitrogen and organic carbon levels were found to be greater in Ambrosia than Pinus. The same trends were not observed for total sulfur or phosphorus. About 60% of the sulfur in Pinus pollen was water‐extractable, while the proportion in Ambrosia was only 5%. Trends for nitrate were similar, but the portion that was water‐extractable was lower by an • order of magnitude. Nitrate levels were highest in Wisconsin pollen, indicating that levels of this nutrient may be related to region of origin. The proportion of phosphate to total phosphorus, approximately 60%, was fairly similar for all species of pollen. Potassium concentrations were consistently lower in the commercially available pollen, which may indicate that the levels of this nutrient are sensitive to sample handling and storage procedures. Water‐extractable nutrients probably represent a nutrient reserve that is used during pollen tube ...

Biologia da polinização em Lecythidaceae

A família Lecythidaceae apresenta grande diversidade em matas higrófilas localizadas abaixo de 1000 m de altitude. Poucas espécies ocorrem em cerrados, várzeas, e em matas acima de 1000 m. O Brasil, onde ocorrem 54% das espécies de Lecythidaceae do Novo Mundo, tem mais espécies desta família que qualquer outro país no mundo, sendo especialmente rico ém espécies com flores zigomorfas. A evolução floral ocorreu principalmente no androceu que pode ser do tipo actinomorfo ou do tipo zigomorfo. Os polinizadores principais são abelhas sendo a única exceção a polinização por morcegos em Lecythis poiteaui. As abelhas da tribo Euglossini parecem ser muito importantes na evolução de Lecythidaceae com flores zigomorfas. As flores de Lecythidaceae oferecem três recompensas aos seus polinizadores: pólen não diferenciado, pólen diferenciado, e néctar. Ainda há muito para pesquisar sobre biologia da reprodução em Lecythidaceae. Estudos sobre a composição química do pólen, a quantidade e qualidade do néctar, e o sistema de compatibilidade são especialmente importantes.

Effects of air pollutants on pollen

In vivo and in vitro pollen germination and pollen tube growth are affected by air pollutants. The stimulation and inhibition of these pollen characteristics depend on the pollen species as well as on the pollutant and its concentration, the exposure time, the relative humidity during exposure and some other factors. Mitosis, gas exchange, size and chemistry of pollen can also be influenced by air contaminants. Pollen germination and tube elongation differ in their response to air pollution stress, and both are more susceptible in vitro compared to the in vivo situation. Some possible mechanisms of action are reported in this review study. The effects of air contaminants on pollen are discussed in relation to sexual reproduction, gametophytic selection and adaptation to stress. Pollen may be used as sensitive biological indicators of pollution

Floral Rewards: Alternatives to Pollen and Nectar

In angiosperms selection has led to the utilization of numerous substances other than pollen and nectar that help to insure repeated visitation by pollinating animals. Here, we group the various substances into nonnutritive and nutritive rewards and discuss within each group the specific kinds that occur. In our discussion of nutritive rewards, we emphasize floral oils, lipids produced by one of two types of specialized secretory organs called elaiophores and which serve as nutritive rewards for certain New World anthophorine bees. Although discovered only within the last 15 years, the syndrome of oil production now appears to be one of the most widespread kinds of floral rewards. We report here for the first time the occurrence of oil production in the Solanaceae (Nierembergia). It is apparent that oil production has evolved independently many times, but plants which produce oils that are collected by female anthophorine bees show similarities in the chemistry of the oils and the types of structures that produce them. It is not clear whether other groups of plants reported to produce oils but which are not pollinated by anthophorine bees possess an analogous system or not. Floral rewards can be considered any component of a flower or inflorescence that is used by animals and, because of this use, insures repeated visitation that will lead to pollination. Without doubt, pollen and nectar are the primary rewards offered by flowers to visiting animals in order to buy their services as pollinating agents. Of the two, nectar is sought by a wider array of animals than pollen. On the other hand, pollen is the primary reward for which bees, probably the single most important group of pollinators, visit flowers. The role of pollen and nectar in the attraction of potential pollinators has been appreciated for hundreds of years, but we have only recently begun to realize the complex nature of these two rewards. Nectar, for example, formerly considered to be a simple sugar solution, has been shown to consist of a variety of chemicals dissolved, or suspended, in an aqueous solution. These range from mixtures of one to three common sugars (glucose, sucrose and fructose) to more complex sugar solutions (Percival, 1961) or combinations of sugars, free amino acids, vitamins, lipids, and other compounds (Baker & Baker, 1975; Baker, 1978). The complex chemical nature of pollen has been realized for a century (refs. in Barbier, 1971), but only in the last twenty years have researchers begun to explore the varied nature of specific enzymes contained in the pollen walls and their possible roles in incompatibility reactions (Stanley & Linskens, 1974). These same enzymes may play a role in pollen recognition by specific pollinators. The chemistry of pollen is in fact so complex that it has been impossible to provide a precise description of pollen chemistry that is all-inclusive. The continued elucidations of the intricate nature of these common rewards has spurred studies of pollination biology and provided an impetus for the investigation or reinvestigation of other floral rewards.