Large Amounts Of Pollen Research Articles

Assessment of pollen reward and pollen availability in Solanum stramoniifolium and Solanum paniculatum for buzz‐pollinating carpenter bees

The two widespread tropical Solanum species S. paniculatum and S. stramoniifolium are highly dependent on the visits of large bees that pollinate the flowers while buzzing them. Both Solanum species do not offer nectar reward; the rewarding of bees is thus solely dependent on the availability of pollen. Flower visitors are unable to visually assess the amount of pollen, because the pollen is hidden in poricidal anthers. In this study we ask whether and how the amount of pollen determines the attractiveness of flowers for bees. The number of pollen grains in anthers of S. stramoniifolium was seven times higher than in S. paniculatum. By contrast, the handling time per five flowers for carpenter bees visiting S. paniculatum was 3.5 times shorter than of those visiting S. stramoniifolium. As a result foraging carpenter bees collected a similar number of pollen grains per unit time on flowers of both species. Experimental manipulation of pollen availability by gluing the anther pores showed that the carpenter bees were unable to detect the availability of pollen by means of chemical cues before landing and without buzzing. Our study shows that the efficiency of pollen collecting on S. paniculatum is based on large inflorescences with short between-flower search times and short handling time of individual flowers, whereas that of S. stramoniifolium relies on a large amount of pollen per flower. Interestingly, large carpenter bees are able to adjust their foraging behaviour to drastically different strategies of pollen reward in otherwise very similar plant species.

Tree Pollen Spectra and Pollen Allergy Risk in the Osijek-Baranja County

The forests of north-eastern Croatia, as well as various plants and trees in the parks and streets of the Osijek-Baranja County, produce large amounts of pollen during the pollen season, which can cause allergy symptoms in pollen sensitive individuals. The aim of this study was to determine the most frequent types of pollen in this area and estimate possible health risks, especially the risk of allergy. In 2009 and 2010, the staff of the Health Ecology Department of the Osijek Public Health Institute monitored tree pollen concentrations in four cities from the Osijek - Baranja County (Osijek, Našice, Đakovo and Beli Manastir) using a Burkard volumetric instrument. The results were affected by weather conditions. Windy and sunny days facilitated the transfer of pollen, whereas during rainy days, the concentration of pollen grains decreased. High pollen concentrations of Cupressaceae/Taxaceae, Betulaceae, Salicaceae and Aceraceae could be the cause for symptoms of pollen allergy. In 2009, conifers, birch and poplar pollen were dominant at all monitoring stations with 5000 pollen grains (PG), 3188 PG and 3113 PG respectively. The highest number of pollen grains was recorded at measuring site Osijek. The variations in airborne pollen concentration between pollen seasons were recorded at all monitoring stations. The most obvious variations were recorded at measuring site Osijek. The usual pollination period lasts two to three months, which means that most pollen grains remain present from February to early June. However, the Cupressaceae / Taxaceae pollination periods last the longest and their pollen grains remain present until the end of summer. The risk of allergy was determined at four monitored measuring stations and the obtained data confirmed that the largest number of days with a high health risk was at the Đakovo measuring station for a species of birch. The research information aims to help allergologists and individuals allergic to plant pollen develop preventive measures and proper treatment therapies.

Juniper Pollen Hotspots in the Southwest

Rationale: Juniperus pollen is a major allergen in Texas, Oklahoma, and New Mexico. While the bulk of pollen may be released in rural areas, large amounts of pollen can be transported to urban areas. Major juniper species in the region include: Juniperus ashei, J. virginiana, J. pinchotii, and J. monosperma. Pollen release is virtually continuous beginning in late September with J. pinchotii and ending in May with J. monosperma. Urban areas in the region were evaluated for the potential of overlapping seasons in order to inform sensitive individuals. Methods: Burkard volumetric pollen traps were established for two consecutive spring seasons at 6 sites in northern New Mexico and 6 sites for two consecutive winter and fall seasons in Texas and Oklahoma Standard methods were used in the preparation and analysis of slides. Results: The Dallas-Fort Worth Metroplex is home to over 6 million people. It is adjacent to populations of J. pinchotii, J. virginiana, and J. ashei. Peak concentration near Dallas for J. ashei in 2011 was 5891 pollen grains/m3 in January 7th. The peak date for J. pinchotii at an upwind sampling location in San Marcos, TX was November 1, 2010 and peak for J. virginiana at a nearby station in Tulsa, OK was November 1, 2010 and peak for J. virginiana at a nearby station in Tulsa, OK was February 20, 2011. Amarillo, TX is adjacent to J. pinchotii, J. ashei, and J. monosperma populations and may be subject to juniper pollen from September through May. Conclusions: Considering the overlapping distributions of juniper trees and the overlapping temporal release of pollen, sensitive patients may benefit from avoiding hotspots.

A method for harvesting unfermented pollen from stingless bees (Hymenoptera, Apidae, Meliponini)

SummaryPollen traps used for harvesting pollen from Apis mellifera do not work for stingless bees, as most species have small entrances and rapidly deposit large quantities of propolis at any barrier in front of the nest. Some stingless beekeepers harvest pollen by removing it directly from pollen pots, but this pollen is normally fermented and unpalatable. The aim of this study was to test a new method for harvesting pollen from stingless bee colonies before it begins to ferment. Colonies of Scaptotrigona depiliswere removed and replaced by empty hives, which were occupied by the returning foragers and used for storing pollen and nectar. After one week, the pollen and honey were harvested directly from the storing pots and weighed. On average, the colonies produced 8.7 g of honey and 54.2 g of unfermented pollen (n = 10). This method is a viable option for harvesting unfermented pollen from stingless bees, especially with species that harvest large amounts of pollen. The unfermented pollen of S. depilis was well received in taste tests, receiving higher scores than fermented pollen, and similar scores to A. mellifera pollen, so could have great commercial possibilities. It is also a good method for studying the foraging of stingless bees because the amount of harvested food can be easily and precisely quantified.

Variation in Nectar and Pollen Availability, Sucrose Preference, and Daily Response in the Use of Flowers by Heliconius erato phyllis

The mechanisms mediating the use of flowers in the butterfly Heliconius erato phyllis (Nymphalidae) are poorly understood. Availability of nectar and pollen, nectar concentration, and abundance of Stachytarpheta cayennensis and Lantana camara (Verbenaceae), two flower species commonly used by H. erato phyllis in the Neotropics, as well as flower use by this butterfly species in the field were examined in southern Brazil. Under insectary conditions, the preference of H. erato phyllis for different sucrose concentrations (0, 10, 20, 40, and 80%) and the ability to associate sucrose concentrations with preferred and non-preferred flower colors were evaluated through choice tests. Lantana camara inflorescences were less abundant, but contained larger amounts of pollen and nectar than S. cayennensis, and H. erato phyllis utilized the flowers of the former species with higher frequency compared to the latter. In the choice tests, butterflies fed more intensely on 20 and 40% sucrose solutions, an interval in which the nectars of L. camara and S. cayennensis are situated, and were able to associate preferred sucrose concentrations with flower color efficiently within the color spectrum of L. camara flowers (i.e., preferred colors), but not within that of S. cayennensis (non-preferred colors). Thus, the greater use of L. camara flowers by H. erato phyllis is related to the plant’s superior floral rewards and not flower abundance, and to the cognitive abilities of these butterflies to adjust their feeding to the availability of pollen and nectar. To our knowledge, this is the first report showing sucrose preferences in a butterfly species.

Palynology of the Paravani burial mound (Early Bronze Age, Georgia)

Information from pollen and non-pollen palynomorphs was used to reconstruct ritual burial traditions in the first half of the third millennium b.c. The floor of the burial chamber of the Paravani barrow and a ceremonial wagon were covered with flax textiles (Linum), as evidenced by the abundance of flax microfibres. The wagon was made of pine (Pinus), oak (Quercus) and juniper (Juniperus) wood. This is demonstrated by parenchyma cells of wood which were linked to the destroyed remains of the wagon. The presence of an animal skin could be established. The presence of the skin is evidenced by large amounts of pollen, ascospores of coprophilous fungi, hairs of dermestid beetle larvae and the bristle of a moth grub. According to the taxonomic composition of the flowers used for decoration of the ceremonial wagon and numerous mite remains, the burial occurred during the first half of the summer.

On polyspermy in the sunflower

Polyspermy in the sunflower (Helianthus annuus L. cv. ‘Bismarckianus’) was studied. Flowers were pollinated with a mixture of small amounts of pollen from the pollinated florets' one-day circle (i.e., a whorl in the head comprising all the florets opening during one day) and large amounts of pollen from a single floret of Jerusalem artichoke, or girasole (Helianthus tuberosus L.). The artichoke pollen, but not the sunflower pollen, was labelled with P-32. In another experiment the labelled artichoke pollen was replaced by labelled pollen from another sunflower plant. The activity per pollen grain, as well as the activity per ovule, was determined by means of a Geiger-Müller counter. Main results: (1) When the sunflower's pollen tubes reach the ovule and double fertilization is effected by the plant's own sperm cells, the ovule also usually receives one or several pairs of sperm cells from the artichoke. (2) Each ovule in a one-day circle often receives the same number of sperm cells. (3) After pollination with labelled artichoke pollen from one floret, an activity corresponding to 1, 2, 4, 8 or 16 pollen grains per ovule was obtained. After pollination with active foreign sunflower pollen from one floret, the corresponding number was 2, 3, 5, 9 or 17. Besides the pair of sperm cells effecting double fertilization, the number of pairs received by an embryo sac thus corresponds to one of the members in the 2n series, with n representing the integer series from zero upwards. The highest n value found is 4. (4) When pollen from the same father is used, the number of sperm cells entering the embryo sac varies between the one-day circles. Thus, variation occurs among isogenic whorls of florets. An autoradiographic method was used to follow the localization after fertilization of the compounds containing the isotope. Literature on polyspermy in the Angiosperms is reviewed. The following general conclusions could be drawn: (1) Polyspermy is a widespread phenomenon among cross-fertilizing Angiosperms. (2) Polyspermy does not seem to occur among self-pollinating species. (3) When a large number of nuclei are involved, it is improbable that the number of pollen tubes reaching the embryo sac corresponds to the number of pairs of sperm nuclei entering the embryo sac. Hence, pollen tubes may sometimes empty their contents into other pollen tubes.

Pollinators of Eucalyptus regnans (Myrtaceae), the world's tallest flowering plant species

Insect visitors to the flowers of Eucalyptus regnans F.Muell. in a remnant natural stand were classified into 33 functional pollinator groups according to taxonomic affinity and body size. In total, 92% of insects caught were dipterans; however, most of these were small and did not contribute significantly to pollination. For the majority of taxa, which have short mouthparts and therefore need to intrude themselves into the flower while feeding on nectar, there was a highly significant relationship between body length and the number of E. regnans pollen grains carried on the body. Mean pollen loads ranged from 20 grains per insect for sepsid flies to 84 000 for large tachinid flies. An index of pollen-deposition potential, which is based on population size and pollen load, suggested that the larger tachinid, calliphorid and syrphid flies were the most important pollen vectors and that larger sphecid wasps also played a significant role. Many taxa appeared to contribute little to pollination because they were uncommon and/or did not carry large quantities of pollen. A convention is proposed whereby groups are weighted according to their contribution to total pollen-deposition potential. For E. regnans, a ratio of 5 Diptera/1 Hymenoptera + (Coleoptera/Lepidoptera) is described, with the taxa in parentheses contributing less than 10% of the total.

Bee pollen sensitivity in airborne pollen allergic individuals

Physicians who practice alternative medicine often prescribe bee pollen as a food supplement and a treatment for various ailments. To determine the qualitative and quantitative composition of bee pollen and to investigate the cutaneous reactivity of atopic patients to bee pollen extracts. The absolute number of pollen grains per gram of bee pollen was calculated, and morphologic identification of the botanical family was performed. Five extracts of bee pollen were prepared for skin prick testing, according to standard methods. Two hundred two volunteers participated in the study; 145 were atopic patients with respiratory allergy. The remaining 57 were healthy volunteers or nonatopic patients and served as a control group. All participants underwent skin prick testing with a standard battery of 6 aeroallergens (olive, grasses mix, Parietaria, mugwort, Dermatophagoides pteronyssinus, and Dermatophagoides farinae) and with all homemade bee pollen extracts. All samples of bee pollen contained Oleaceae pollen in high concentrations. Small amounts of anemophilous pollen (Compositeae, Chenopodiaceae) were detected in various samples. A strong positive correlation was observed between cutaneous reactivity to bee pollen extracts and olive, grasses, and mugwort. Bee pollen contains a large amount of pollen, which belongs to various allergenic families of plants. Bee pollen retains its allergenic potential as demonstrated by strong cutaneous responses to bee pollen extracts observed in atopic patients in contrast to nonatopic subjects. Regarding pollen allergic individuals, further studies are needed to evaluate the safety of ingesting large amounts of bee pollen.

In vitro germination and transient GFP expression of American chestnut (Castanea dentata) pollen

The development of the male reproductive structures of American chestnut (Castanea dentata) is described to advance our understanding of its reproductive behavior. This information has been vital in the development of a strategy to collect pollen grains from male catkins suitable for in vitro germination and transformation experiments. Cutting male catkins into small segments and rolling them over a culture plate resulted in evenly dispersed and large amounts of pollen with minimal unwanted accessory floral parts. To optimize pollen viability, the effect of various storage conditions on in vitro germination was examined. Our results showed that initial storage at 4 degrees C for 2 weeks significantly increased percent germination as compared to freshly collected pollen and those stored directly at -20 degrees C or -80 degrees C. This also means that for long-term storage of American chestnut pollen, the catkins should first be kept at 4 degrees C for a couple of weeks and then at -80 degrees C. The use of pollen grains with high viability is necessary for the transformation of American chestnut pollen. To optimize pollen transformation via particle bombardment, the effects of target distance, target pressure, and pollen developmental stage were examined. Statistical analysis showed that bombardment of ungerminated pollen at 1,100 psi resulted in the highest percent transient GFP expression (4.1%).

リアルタイム花粉モニター（ＫＨ‐３０００）の検討

We studied the usefulness of a real-time pollen counter (KH-3000, Yamato Manufacturing Co. Ltd.).Airborne pollen was measured with a Durham pollen counter and a KH-3000 from February 1, 2002 to April 30, 2002 in Wakayama city, and the results were analyzed and compared with each other statistically. We took account of the influence of weather conditions on the results. In addition, a characteristic of circadian rhythm of airborne pollen was examined.The features of the pollen scatter pattern in 2002 were as follows: The counts for Japanese cedar pollen and Japanese cypress pollen were smaller than the average year. The Japanese beech pollen count was larger than the average year. Correlations between the outcomes of the 2 pollen counters were r=0.65 for Japanese cedar pollen and r=0.61 for the total pollen, except pine pollen.The circadian rhythm of the airborne pollen observed with the KH-3000 did not correlated significantly to temperature, humidity, atmospheric pressure or wind velocity. However, a tendency did emerge: on a clear day, a large amount of pollen was observed in the evening and at night. On a cloudy day, no obvious peak of pollen dispersion was observed in a day. On a rainy day, a large number of pollen was observed before the start of rainfall, but no pollen grains were observed during the rain. No pollen was observed on snowy days, however unexpected peaks were recorded that were not related to the pollen count. The peaks were thought to be caused by snow.We concluded that the KH-3000 is a useful device for measuring pollen, however, the Durham pollen counter presently used is still needed to measure pollen, because the operation of the KH-3000 was influenced by weather: it could not distinguish pollen from snow. Our findings suggest the circadian rhythm of airborne pollen depends on the weather.

Effects of supplementary pollination on cropping success and fruit quality in pistachio

AbstractThe effects of pollen supplementation in pistachio orchards using an electrostatic pollination device were investigated in a 3‐year study (1996‐98) in San Joaquin Valley, California, USA. Both yield and fruit quality (per cent split fruit) were tested in several experiments. Applying smaller amounts of pollen (1.5 g per tree in early application only in 1996 or 0.5 g in two applications in 1997) resulted in higher yields than with open pollination or supplementary pollination using larger amounts of pollen (1.5 g per tree in four applications in 1996 or 1.0 g in two applications in 1997). Applying 1.0 g pollen in two applications in 1998 resulted in decreased yields compared with open pollination or non‐electrostatic pollination. Pollen germinability on the stigma was greatest for open pollination suggesting that overloading the stigmas with pollen in supplementary pollination may not only reduce yield but also increase competition between pollen grains. The per cent split fruit significantly increased only once in 1996. When pollination is a limiting factor, electrostatic pollination of pistachio can increase yield and may even increase fruit quality. However, when pollination is not a limiting factor, electrostatic pollination may even reduce yield.

NEW JAPANESE PEAR CULTIVAR 'YOUSUI'

'Yousui' is a new late maturing, russet-skin type cultivar of Japanese pear, released by the Aichi-ken Agricultural Research Center. This cultivar originated from a cross between 'Niitaka' and 'Kousui' made in 1990. In 2001, 'Yousui' was registered on March 13 under the Seeds and Seedlings Law of Japan. 'Yousui' trees are as vigorous as 'Niitaka' and twigs are thick. The tree form looks like that of 'Niitaka'. The tree exhibits few axillary flower buds on shoot as 'Kousui', but it is easy to maintain flower buds on spurs. It is considered that 'Yousui' is fairly productive as 'Niitaka'. It blooms at the same time as 'Housui', 3 to 4 days later than 'Niitaka'. 'Yousui' is cross-compatible with 'Kousui', 'Housui' and 'Niitaka'. It has large quantities of pollen. 'Yousui' matures between ‘Housui’ and 'Niitaka', late September to early October in Aichi prefecture. Fruit is oblate in shape and the skin is yellowish brown at maturity. Fruit is very large like that of 'Niitaka', about 900g. The flesh is white, soft, juicy and crisp. It is considered superior to 'Niitaka' in these points. Brix values are 14 to 15% in a usual year, 0.5 to 1% higher than 'Niitaka'. pH values are 5.2 to 5.3, less acid than 'Niitaka'. The shelf life is shorter than those of other late maturing cultivars such as 'Niitaka' and 'Shinsei'. The fruit quality remains good for about 15 days when the fruit is kept at room temperature (about 15°C). ‘Yousui’ is resistant to black spot disease (Alternaria alternata Japanese pear pathotype) and pear necrotic spot virus. 'Yousui' may be tolerant to other diseases and insect pests under standard cultivation condition. Furthermore, as for ‘Yousui’, a physiological disorder is not being observed at present.

Erratum to: Transformation of wheat (Triticum aestivum L.) microspore-derived callus and microspores by particle bombardment

The development of the male reproductive structures of American chestnut (Castanea dentata) is described to advance our understanding of its reproductive behavior. This information has been vital in the development of a strategy to collect pollen grains from male catkins suitable for in vitro germination and transformation experiments. Cutting male catkins into small segments and rolling them over a culture plate resulted in evenly dispersed and large amounts of pollen with minimal unwanted accessory floral parts. To optimize pollen viability, the effect of various storage conditions on in vitro germination was examined. Our results showed that initial storage at 4◦C for 2 weeks significantly increased percent germination as compared to freshly collected pollen and those stored directly at −20◦C or −80◦C. This also means that for long-term storage of American chestnut pollen, the catkins should first be kept at 4◦C for a couple of weeks and then at −80◦C. The use of pollen grains with high viability is necessary for the transformation of American chestnut pollen. To optimize pollen transformation via particle bombardment, the effects of target distance, target pressure, and pollen developmental stage were examined. Statistical analysis showed that bombardment of ungerminated pollen at 1,100 psi resulted in the highest percent transient GFP expression (4.1%).

Exploitation of pollen by mycorrhizal mycelial systems with special reference to nutrient recycling in boreal forests.

Very large quantities of pollen are released annually by wind-pollinated trees, which dominate northern forest ecosystems. Since pollen is enriched in both nitrogen and phosphorus, this recurrent pulse of deposition constitutes a significant potential source of these elements in what are known to be severely nutrient-limited systems. Here, we demonstrate for the first time, to our knowledge, that an ectomycorrhizal fungus, Paxillus involutus, is able to scavenge effectively for nitrogen and phosphorus in pollen and to return a significant proportion of each nutrient to its autotrophic host, Betula pendula. More than 75 and 96%, respectively, of the nitrogen and phosphorus were removed from pollen in microcosms containing the mycorrhizal fungus, 29 and 25%, respectively, being transferred to the plants. In contrast, in microcosms without the mycorrhizal fungus only 42 and 35%, respectively, of nitrogen and phosphorus were lost from the pollen, presumably as a result of export by saprotrophs, and only 12 and 7%, respectively, were transferred to the plants. We hypothesize that this process of resource recapture, by contributing significantly to the ability of the trees to sustain the necessary annual investment in pollen production, will have a major impact upon their reproductive capabilities and hence 'fitness'.

Pollen analysis of faeces as a method of demonstrating seasonal variations in the diet of Svalbard reindeer (Rangifer tarandus platyrhynchus)

Analysis of the pollen and spore content of 40 fresh samples of faeces collected from Svalbard reindeer during 1994/5 and 1996 shows variations among and within seasons, with distinct species/pollen types dominating each season. Winter samples were characterized by high amounts of Salix and moss spores, while spring samples contained decreasing amounts of the plants grazed in winter and increasing values of species grazed in summer, such as Oxyria digyna and Pedicualaris spp. Summer samples had a large quantity of pollen and a great number of pollen types. Autumn samples indicated that grasses are the most important forage species in this period. The seasonally varying proportions of pollen types are related to such factors as plant phenology, abudance, palatability and nutritional quality, as well as the prefereence of reindeers for grazing in low, wet areas in the summer but on higher, wind-blown ridges during the winter. The results mostly confirm other studies of Svalbard reindeer diet and grazing behavior. The advantages and limitations of the pollen analysis method for such investigations are discussed.

Inhibition of Flower Bud Formation in Betula platyphylla and Betula pendula by Gibberellin (GA3) Application

Birch (Betula) trees produce a large amount of pollen, which is a cause of serious pollinosis. To control the pollen scattering, we examined the inhibitory effect of gibberellin (GA3) on flower bud formation of birch. Field-grown trees ofBetula pendula, nine years of age, were treated with a foliar spray of GA3 (1, 10, and 100 mg L−1), Betula platyphylla trees, 17–23 years of age, were treated with a stem injection of GA3 (5, 50, and 500 mg per plant) in June or July, 1998. Male flower buds were not observed at the top of new shoots in June, but were observed in July. The number of inflorescence that emerged from randomly sampled branches was counted the next spring. The foliar spray of GA3 in June at the dose of 10 or 100 mg L −1 decreased the number of inflorescence. Stem injection in June at a dose higher than 50 mg per plant completely inhibited flower bud formation, although it increased bud mortality in some trees. The most effective dose of GA3 for stem injection to inhibit flower bud formation was between 0.04 and 0.44 mg per cm2 of stem cross-section area at breast height. These results indicate that GA3 applied during the period of floral differentiation markedly inhibits flower bud formation in birch.

Pollen analysis of faeces as a method of demonstrating seasonal variations in the diet of Svalbard reindeer (Rangifer tarandus platyrhynchus)

Analysis of the pollen and spore content of 40 fresh samples of faeces collected from Svalbard reindeer during 1994/5 and 1996 shows variations among and within seasons, with distinct species/pollen types dominating each season. Winter samples were characterized by high amounts of Salix and moss spores, while spring samples contained decreasing amounts of the plants grazed in winter and increasing values of species grazed in summer, such as Oxyria digyna and Pedicualaris spp. Summer samples had a large quantity of pollen and a great number of pollen types. Autumn samples indicated that grasses are the most important forage species in this period. The seasonally varying proportions of pollen types are related to such factors as plant phenology, abudance, palatability and nutritional quality, as well as the prefereence of reindeers for grazing in low, wet areas in the summer but on higher, wind-blown ridges during the winter. The results mostly confirm other studies of Svalbard reindeer diet and grazing behavior. The advantages and limitations of the pollen analysis method for such investigations are discussed.

UK Regional Variations in Betula Pollen (1993-1997)

Betula pollen is known to be an important aeroallergen in Europe and the UK, with very large quantities of pollen released into the air at the height of the season, making it the most abundant tree pollen present in the UK spring air. There has been long term pollen monitoring in Cardiff, Derby and London but in recent years the number of regional sites has increased. Seven sites throughout the UK have monitored Betula pollen using Burkard samplers for the period 1993–1997 and for this study regional differences in Betula pollen and climate were investigated. Detailed analysis revealed considerable variation in the start dates, duration and quantity of Betula pollen for the seven UK sites throughout the five year period. These regional variations in Betula pollen duration and intensity of season, indicate the importance of maintaining sites throughout the UK as an aid to clinicians, researchers and the general public.

Sonication Dispensing of Pollen from Solanum laciniatum Flowers

1. Sonication is a seemingly effective method for foraging insects to extract pollen rapidly from poricidal anthers. However, without a dispensing mechanism to limit the pollen extraction a single forager might be able to glean all of the pollen from a flower in a single visit. 2. The vibratory release mechanism of a buzz-pollinated flower species, Solanum laciniatum, and its relationship with time was investigated. 3. The sonication vibration magnitude required to eject pollen from the anthers increased with frequency ; vibrations at frequencies below 180 Hz were particularly effective owing to the low (124 Hz) natural frequency of the stamens and the good transmission of low-frequency vibration by the anthers. The natural frequency of stamens was low compared with the sonication frequencies of bumble-bees and did not change significantly when sonicated. 4. Large amounts of pollen (72 000 grains) were released in initial sonications, but this was a small percentage (18%) of the total available pollen ; pollen release continued in metered quantities over time. 5. The stamen vibration mode created centrifugal forces, which forced pollen out of the apical pores, and the gradual dehydration of the tapetal fluid remaining in lower regions of dehiscent poricidal anthers produced a timed release mechanism. 6. The frequency increase from the flight wing-beat frequency to the sonication buzz enables bumble-bees to generate high accelerations, which are able to release pollen from the anthers, using thoracic vibrations, which are limited by the maximum possible displacement of the indirect flight muscles.