Seed Production and Insect Visitation Rates in Hesperis matronalis Are Not Affected by Floral Symmetry

2007 ◽  
Vol 168 (5) ◽  
pp. 611-617 ◽  
Author(s):  
Elizabeth Lauren Weeks ◽  
Frank M. Frey
2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Margaret J. Couvillon ◽  
Chandra M. Walter ◽  
Eluned M. Blows ◽  
Tomer J. Czaczkes ◽  
Karin L. Alton ◽  
...  

We quantified insect visitation rates by counting how many flowers/inflorescences were probed per unit time for five plant species (four native and one garden: California lilac, bramble, ragwort, wild marjoram, and ivy) growing in Sussex, United Kingdom, by following individual insects (n=2987) from nine functional groups (honey bees (Apis mellifera), bumble bees (Bombusspp.), hoverflies, flies, butterflies, beetles, wasps, non-Apidae bees, and moths). Additionally, we made a census of the insect diversity on the studied plant species. Overall we found that insect groups differed greatly in their rate of flower visits (P<2.2e-16), with bumble bees and honey bees visiting significantly more flowers per time (11.5 and 9.2 flowers/minute, resp.) than the other insect groups. Additionally, we report on a within-group difference in the non-Apidae bees, where the genusOsmia, which is often suggested as an alternative to honey bees as a managed pollinator, was very speedy (13.4 flowers/minute) compared to the other non-Apidae bees (4.3 flowers/minute). Our census showed that the plants attracted a range of insects, with the honey bee as the most abundant visitor (34%). Therefore, rate differences cannot be explained by particular specializations. Lastly, we discuss potential implications of our conclusions for pollination.


Botany ◽  
2013 ◽  
Vol 91 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Diana Bizecki Robson

Pollination facilitation can occur when plant species share pollinators. Whether facilitation occurs depends on the flowering period overlap (synchrony), number of shared insect visitors (similarity), quantity and quality of insect visits, and the subsequent impact on seed production. Western Silvery Aster (Symphyotrichum sericeum (Vent.) G.L. Nesom) is a rare, self-incompatible plant visited by a wide range of generalist insect species. There are 22 common plant species that may facilitate insect visitation to the rare plant by supporting shared pollinators. Plant species with low synchrony and high similarity with S. sericeum are potential facilitators. In contrast, plant species with high synchrony and similarity likely act as competitors as the aggregative response to increasing plant density was saturating, suggesting that synchronously flowering species do not increase insect visitations. Hymenoptera responded more strongly than Diptera to increases in flowering stem density. These data suggest that facilitation of insect visitation between plant species via a numerical response that extends the flower season is possible but not likely via an aggregative response. Restoration of S. sericeum may therefore be more successful if potentially facilitating plants are grown with it; further testing of the impact of potential facilitators on seed production in S. sericeum is required.


Diversity ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 286 ◽  
Author(s):  
Daniela Scaccabarozzi ◽  
Andrea Galimberti ◽  
Kingsley W. Dixon ◽  
Salvatore Cozzolino

Floral deception has been observed in several genera in angiosperms, but is most common in the Orchidaceae. Pollination mechanisms in food deceptive plants are often difficult to assess, as visitation frequency by insects requires numerous hours of field observations to ascertain. Here, for the first time, we describe in detail and validate a simple and effective method that extends previous approaches to increase the effectiveness of pollination studies of food deceptive orchids. We used an orchid of southwest Australia, Diuris brumalis (Orchidaceae), that visually mimics model plants belonging to the genus Daviesia (Faboideae). Arrays of orchid flowers were placed and moved systematically in proximity to model plants, resulting in rapid attraction of the pollinators of D. brumalis. We compared pollinaria removal (as an indicator of pollination success) in naturally growing orchids with pollinaria removal in arrays of orchid flowers in the same sites. We showed that the proposed method greatly enhances pollinator attractiveness in food deceptive systems with very low pollination rates, and we compared its efficiency with other similar methods. The approach can be used for observing pollinator behavioural patterns and confirming effective pollinators for food deceptive species with low insect visitation rates.


2006 ◽  
Vol 84 (3) ◽  
pp. 412-420 ◽  
Author(s):  
Vivi-Irèn Hansen ◽  
Ørjan Totland

We looked at whether flower visitation rates, pollen limitation on seed production, and phenotypic selection on flower size through female function varied across a sharp gradient in light intensity (open meadow vs. forest) within a population of the perennial plant Campanula persicifolia L. (Campanulaceae). Flower visitation rates of putative pollinators were similar in both habitats. Seed number per fruit was strongly pollen limited, with no difference in the magnitude of pollen limitation between the two habitats. This strong pollen limitation set the basis for significant phenotypic selection, through female function, on a trait that probably is important for pollinator attraction: flower size. This was revealed by path analysis and structural equation modelling. The lack of difference in pollen limitation on seed production in the two habitats may be explained by the similarity in flower visitation rates in the two habitats. Moreover, the similarity in pollen limitation in the two habitats probably resulted in a similar magnitude and direction of selection on flower size through female function. Our results suggest that pollen limitation and selection through female function may vary little across space within a popualtion despite large variation in the environmental conditions experienced by plants.


2012 ◽  
Vol 28 (4) ◽  
pp. 343-351 ◽  
Author(s):  
Carol L. Landry ◽  
Beverly J. Rathcke

Abstract:Insect-pollinated Laguncularia racemosa has a variable breeding system; some populations are androdioecious, with male and hermaphroditic plants, while others lack male plants. We observed the foraging behaviours of insects in three androdioecious and three hermaphrodite-only populations of L. racemosa in Florida. In each population, insect visitation rates were estimated from 30–108 timed intervals. We recorded the number of flowers visited by 144–224 insects during foraging bouts made to 15–40 male and hermaphroditic plants. Male plants in androdioecious populations had significantly more visitors than hermaphroditic plants, increasing the number of vectors carrying pollen from male plants. Further, many insects visited few flowers during foraging bouts, which should increase outcrossing frequency. According to mathematical models, male plants benefit from these combined factors. Plants in hermaphrodite-only populations had significantly more visitors than hermaphroditic plants in androdioecious populations. Proportionately more insects visited many flowers during foraging bouts in hermaphrodite-only versus androdioecious populations. The increased likelihood of geitonogamous self-pollination could help explain the lack of male plants in hermaphrodite-only populations. Differences in pollinator assemblages and the relative abundances of several species were responsible for differences in foraging behaviours: Apis mellifera, Bombus sp., Melissodes sp., Xylocopa sp., Euodynerus sp. and a calliphorid species.


1985 ◽  
Vol 63 (11) ◽  
pp. 1928-1935 ◽  
Author(s):  
John D. Ambrose ◽  
Peter G. Kevan ◽  
Randy M. Gadawski

In Canada, Ptelea trifoliata L. (Rutaceae) is restricted in its natural distribution primarily to the Lake Erie shoreline. Although it is locally successful as a colonizing species, it appears inhibited from either exploiting a large area of shoreline habitat or extending its range inland. The morphological descriptions of the hop tree's sexual expression have been ambiguous; however, our observations show this species to be clearly dioecious, with only about 2% of the otherwise male plants producing a few hermaphroditic flowers, and fruit. The sex ratio is strongly skewed toward the males, which produce more and showier inflorescences than female plants. Despite this, the insect visitation rates are not significantly different between the sexes. For pollination, the hop tree is a polyphilic generalist, dependent on a diverse array of insects, including short-tongued bees, wasps, and flies. It is totally dependent on wind-dispersed seeds for establishment, lacking the ability to grow clonally. In a dioecious species of disturbed habitats, this is exceptional.


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