Pollination biology of the endangered orchid Cypripedium japonicum in a fragmented forest of Japan

Pollination biology studies of the endangered orchid Cypripedium japonicum were conducted in its natural habitat using pollinator observation and hand‐pollination experiments. The observed fruit set was as follows: artificial outcross‐pollinated, 100%; artificial self‐pollinated, 100%; pollinator‐excluded, 0%; and emasculated flowers, 0%. These results show that this species, although self‐compatible, is neither autogamous nor agamospermous. The fruit set for open‐pollinated flowers was 14.9%, which suggests that the study population was subject to pollinator limitation. The nectarless flowers of C. japonicum were exclusively visited and pollinated by the queens of two bumblebee species (Bombus ardens and B. diversus diversus). It is probable that the nectarless flowers of C. japonicum attract pollinators through a generalized food deceptive system.     

Pollen-Foraging Dynamics of Subalpine Bumblebees (Bombus Latr.)

Abstract A 23-year study on Mount Rainier of nectar-foraging hummingbirds and pollen-foraging bumblebees (Bom-bus Latr.) indicated a constant relative frequency of Bombus species in the area and a wide occurrence of insect species on flowers plus a wide range of flower species pollinated by a single insect. Early-blooming plants had a high queen/worker pollinator ratio, while workers predominated on later-blooming plants. No altitudinal difference in distribution of Bombus species occurred. Analysis of 955 corbicular pollen loads from 1158 bumblebees collected yielded 49.5% monolecty for queens and 34.5% for workers with a wider range for queens than for workers. Colors of corollas photographed in visible and ultraviolet light corresponded to the visual spectra of animal pollinators. In the stable plant-pollinator community investigated, pollinating insect activity appears phenologically controlled by floral anthesis and behaviorally related to floral form and function. Bumblebee tongue length, however. Is not a valid determinant for foraging niche separation except in Castilleja with a deep corolla tube accommodating long tongues of hummingbirds and bumblebees. It is concluded that in a biotic community well-coordinated with the physical environment, limited flower constancy of pollen-foraging pollinators appears to contribute a necessary degree of adaptive versatility through sharing of insect and floral resources. Flower constancy is primarily a function of the circumstance in which a pollinator operates and not simply a characteristic of the pollinator itself.     

Measuring foraging activity in bumblebee nests: a simple nest‐entrance trip recorder

We describe a new, electronic, apparatus for measuring the activity of bumblebees as they fly from and to their nests. The bee activity recorder (BAR) works on the principle that bees leaving and returning to their nest crawl through a tube equipped with infrared emitters and detectors so that when the beam is interrupted by the passage of a bee, the event is recorded as either an exit or an entry. Tests of BARs indicate that they are highly accurate, BAR counts and visual counts highly correlated with an almost one‐to‐one correspondence. We suggest that BARs can be used for recording the foraging activities of bumblebees through nest exit and entry counts in many practical and research applications.     

Phenological patterns and pollination network structure in a Venezuelan páramo: a community-scale perspective on plant-animal interactions

ABSTRACT

Background: Little information is available about life history of páramo plants such as phenology and plant-animal interactions.

Aims: We analysed phenological patterns of flowering and characterised the structure of a plant-pollinator network in a Venezuelan páramo in order to identify key species in this ecosystem.

Methods: We counted the number of individuals with flowers of 76 native plant species and recorded their pollinators in 16 permanent plots between 3000 and 4200 m monthly for three years. We used this dataset to develop a plant-pollinator network, on which nine different metrics related to structural properties were calculated.

Results: The flowering of most species concentrated during the rainy season (between May and November), however some species have continuous flowering. The guild of floral visitors included hummingbirds, flower piercers, bumblebees, Diptera and Lepidoptera. The plant – flower visitor interaction network did not exhibit nestedness, but showed a significant specialization index (H2) and high values of functional complementarity.

Conclusions: Páramo plants have the capacity of maintaining a resident nectarivorus fauna (bumblebees and hummingbirds) because of continuous flower offer during the year. However, the plant – pollinator network identified could be very sensitive to the loss component species, owing to high levels of specialisation and functional complementarity.     

Influence of pollinator grooming on pollen‐mediated gene dispersal in Mimulus ringens (Phrymaceae)

Pollinator foraging patterns and the dynamics of pollen transport influence the quality and diversity of flowering plant mating opportunities. For species pollinated by grooming pollinators, such as bees, the amount of pollen carried between a donor flower and potential recipient flowers depends on how grooming influences pollen transfer. To investigate the relationship between grooming and pollen‐mediated gene dispersal, we studied bumblebee (Bombus fervidus) foraging behavior and resulting gene dispersal in linear arrays of Mimulus ringens. Each of the 14 plants in an array had a unique multilocus genotype, facilitating unambiguous assignment of paternity to 1050 progeny. Each plant was trimmed to a single flower so that pollinator movements could be linked directly to resulting gene dispersal patterns. Pollen‐mediated gene dispersal was very limited. More than 95% of the seeds sired by a donor flower were distributed over the first three recipient flowers in the visitation sequence. However, seeds were occasionally sired on flowers visited later in the pollinator's floral visitation sequence. Intensive grooming immediately following pollen removal from a donor flower significantly increased the decay rate of the donor flower's gene dispersal curve. These results suggest that the frequency and relative intensity of grooming can have significant effects on patterns of pollen‐mediated gene dispersal from individual pollen donors.     

Pollen-size comparisons among animal-pollinated angiosperms with different pollination characteristics

Pollen volume varies among angiosperm species over five orders of magnitude, presumably because the functional advantages of pollen size depend on each species' particular pollination and fertilization conditions. This paper reports two studies that assess whether animal-pollinated species with different pollination systems differ correspondingly in pollen size, as would be expected if pollen size affected pollen transport. Analysis of nine Pedicularis species detected significant interspecific variation in pollen size; however, the overall mean pollen volume of species pollinated primarily by nectar-collecting bees did not differ significantly from that of species pollinated by pollen-collecting bees. Similarly, comparison of bee- and bird-pollinated congeners in 16 genera (nine families) from Australia and North America found considerable variation in pollen diameter within and between genera, but this variation was not associated consistency with differences in primary pollinator type (bee>bird for three genera, bee > bird for five genera, bee相似文献   

The Floral Biology of Tricyrtis affinis Makino (Liliaceae)

Abstract The floral biology of Tricyrtis affinis was investigated and compared with that of four species of Tricyrtis which had been reported by the author. The flower opens for two days and is protandrous as in T. latifolia, T. flava , and T. ohsumiensis. The primary pollinators of T. affinis were Bombus diversus diversus and Amegilla sp., which were not different from those of the previous species although the shape and the color of the T. affinis flower are somewhat different from the others. The whole perianth of T. affinis absorbs UV light fairly well, and the large purple spotted area near the base absorbs it markedly well. The UV absorption pattern of the T. affinis flower is similar to that of T. latifolia. T. affinis is also self-compatible, like the others, and seeds obtained by self-pollination germinated well. Pollination of T. affinis is characterized by a refined system.     

开花式样对传粉者行为及花粉散布的影响

理解植物花的特征可以从单花特征和群体特征两个层次入手。开花式样是植物的花在群体上的特征体现, 通过在开花数目、开花类型以及花的排列上的变化, 不同的开花式样对传粉者具有不同的吸引力, 影响昆虫在植株上的活动, 使花粉运动的方向发生相应变化, 从而影响着植物最终的交配结果。此外开花式样随环境改变也会发生一些变化。本文介绍了开花式样研究的进展, 对开花数目、开花类型以及花的排列等3个方面的已有研究进行了分别阐述, 并提出开花式样研究应更多地考虑影响传粉的各种因素。