scholarly journals Some Unresolved Issues of Measuring the Efficiency of Pollinators: Experimentally Testing and Assessing the Predictive Power of Different Methods

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Ram Chander Sihag
Keyword(s):  
Foraging Behavior ◽  
Seed Set ◽  
Reproductive Potential ◽  
Pollen Grains ◽  
The Other ◽  
Transfer Efficiency ◽  
Optimum Number ◽  
Pollen Transfer ◽  
Pollen Transfer Efficiency ◽  
Northwest India

Knowledge of efficiency of pollinators is valuable in the derivation of (i) the degree of mutualism specialization of a flower visitor in the natural plant communities, (ii) the optimum number of pollinators needed for the maximum pollination in a plant population, and (iii) the pollinator risk assessment in the sustainable agriculture. Earlier researchers used many direct and indirect methods for measuring the pollination efficiency (PE) of flower visitors. However, a great ambiguity exists in the usage of this terminology that necessitated its fresh scrutiny. I tested the available three standard methods afresh to find the efficiency of pollinators. These included comparing the (i) number of pollen grains removed and deposited by the visitors; (ii) seed set resulting from a single and the multiple visits of the visitors; and (iii) “pollen transfer efficiency (PTE)” derived from the foraging behavior and abundances of the visitors. Observations were recorded on the visitors of four plant species in an agroecosystem of Northwest India. These plants represented a wide variety of the floral types across the angiosperms. The first two methods, namely, the “number of pollen grains removed and deposited” and the “seed set resulting from a single and the multiple visits,” were appropriate in finding differences between the efficiency ranks of the pollinators of those flowers where the number of deposited pollen grains was less than the number of ovules in the ovary. However, these two methods completely failed in situations where exactly reverse condition of pollen grains and ovules existed. Thus, these two methods of measuring the PE of visitors had limited approach and lacked a universal application over the entire angiosperm taxa. On the other hand, use of “pollen transfer efficiency”, derived from the foraging behavior and abundance of the visitors, seemed to have an edge over the other two methods as this was helpful in finding differences between the efficiency ranks of the pollinators of plants in all the three situations tested in this study. However, validation of all the three methods through the plant reproductive potential seemed to be an integral confirmatory step for drawing inferences about the efficiency of pollinators.

scholarly journals Pollen adaptation to ant pollination: a case study from the Proteaceae

2020 ◽  
Vol 126 (3) ◽  
pp. 377-386 ◽  
Author(s):  
Nicola Delnevo ◽  
Eddie J van Etten ◽  
Nicola Clemente ◽  
Luna Fogu ◽  
Evelina Pavarani ◽  
...  
Keyword(s):  
Seed Set ◽  
Germination Rate ◽  
Pollen Grains ◽  
Relative Effect ◽  
The Other ◽  
Pollen Load ◽  
Pollination Services ◽  
Ant Pollination ◽  
Negative Effect ◽  
Floral Visitors

Abstract Background and Aims Ant–plant associations are widely diverse and distributed throughout the world, leading to antagonistic and/or mutualistic interactions. Ant pollination is a rare mutualistic association and reports of ants as effective pollinators are limited to a few studies. Conospermum (Proteaceae) is an insect-pollinated genus well represented in the south-western Australia biodiversity hotspot, and here we aimed to evaluate the role of ants as pollinators of C. undulatum. Methods Pollen germination after contact with several species of ants and bees was tested for C. undulatum and five co-flowering species for comparison. We then sampled the pollen load of floral visitors of C. undulatum to assess whether ants carried a pollen load sufficient to enable pollination. Lastly, we performed exclusion treatments to assess the relative effect of flying- and non-flying-invertebrate floral visitors on the reproduction of C. undulatum. For this, we measured the seed set under different conditions: ants exclusion, flying-insects exclusion and control. Key Results Pollen of C. undulatum, along with the other Conospermum species, had a germination rate after contact with ants of ~80 % which did not differ from the effect of bees; in contrast, the other plant species tested showed a drop in the germination rate to ~10 % following ant treatments. Although ants were generalist visitors, they carried a pollen load with 68–86 % of suitable grains. Moreover, ants significantly contributed to the seed set of C. undulatum. Conclusions Our study highlights the complexity of ant–flower interactions and suggests that generalizations neglecting the importance of ants as pollinators cannot be made. Conospermum undulatum has evolved pollen with resistance to the negative effect of ant secretions on pollen grains, with ants providing effective pollination services to this threatened species.

scholarly journals Pollination and Seed Production in Viola

HortScience ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 633-639
Author(s):  
Daiichiro Miyajima
Keyword(s):  
Seed Set ◽  
Pollen Grains ◽  
Germination Percentage ◽  
Fertilization Success ◽  
The Other ◽  
Flowering Period ◽  
Flower Longevity ◽  
Ovule Number ◽  
Germination Of Pollen ◽  
Mature Seeds

The seed producing system in viola (Viola ×cornuta) was investigated to improve seed yield and to save labor. In a flower five anthers sequentially dehisced; pollen grains were continuously supplied to the anterior petal, which played a significant role in pollination, throughout the flowering period. Evidence from pollen and ovule number suggests that the species is facultative autogamy. Each flower opened more than 10 days was independent of the success in fertilization and kept seed producing ability during the flower longevity period. Pollen grains also maintained viability during the flower longevity period. Pollinators were indispensable for pollination of viola, but pollination in viola was done by a different mechanism from the typical insect-mediated pollination that sticky pollen grains adhere to the exposed stigmas. Pollen grains, accumulated around the entrance of the stigmatic cavity, entered into the cavity by the movement of pollinators. Although the visitation of pollinators was occasional, solitary bees primarily contributed to the pollination of viola. On the other hand, germination of pollen grains on the stigmatic surface was under 50%. Seed set was much lower than the germination percentage of pollen grains. A viola flower had the ability for additional pollinations and fertilization for some days after the fertilization success in some ovules in the flower. This characteristic suggested that repeated pollination is effective to increase the number of mature seeds in a capsule.

Why does the flower of Lonicera japonica open at dusk?

1998 ◽  
Vol 76 (10) ◽  
pp. 1806-1811 ◽  
Author(s):  
Takashi Miyake ◽  
Tetsukazu Yahara
Keyword(s):  
Pollen Grains ◽  
The Other ◽  
Lonicera Japonica ◽  
Pollination Syndrome ◽  
Pollen Transfer ◽  
Pollination Syndromes ◽  
Pollen Removal ◽  
Hawkmoth Pollination ◽  
Effective Pollinators ◽  
Pollen Consumption

We investigated contributions of diurnal pollinators and a nocturnal pollinator to pollen transfer in Lonicera japonica (Caprifoliaceae), whose flowers have traits typical of the hawkmoth-pollination syndrome. Diurnal bees, Tetralonia nipponensis and Lasioglossum sp., delivered more pollen grains than the nocturnal hawkmoth Theretra japonica per visit, suggesting that these bees were also effective pollinators. However, these bees removed over 10 times more pollen at one visit than the hawkmoth. Because of the higher pollen consumption by these bees, anthesis at dusk is considered to be optimal for Lonicera japonica to maximize overall pollen transfer under the visitation of both nocturnal and diurnal pollinators. Tetralonia japonica dispersed color dye farther than the other pollinators, which suggests that the nocturnal pollinator contributes more to cross-pollination than the diurnal pollinators.Key words: Lonicera japonica, hawkmoth-pollinated flowers, pollinator efficiency, pollen removal, pollination syndromes, timing of anthesis.

scholarly journals Pollinator effectiveness and importance between female and male mining bee ( Andrena )

2019 ◽  
Vol 15 (10) ◽  
pp. 20190479 ◽  
Author(s):  
Ju Tang ◽  
Qiu-Mei Quan ◽  
Jing-Zhu Chen ◽  
Ting Wu ◽  
Shuang-Quan Huang
Keyword(s):  
Foraging Behaviour ◽  
Pollen Grains ◽  
Pollen Foraging ◽  
Pollen Transfer ◽  
Natural Ecosystems ◽  
Pollinator Effectiveness ◽  
Visit Frequency ◽  
Pollen Transfer Efficiency ◽  
Food Provision ◽  
Effective Pollinators

Bees are often considered to be effective pollinators in both agricultural and natural ecosystems but could be ineffective pollinators in that they collect large quantities of pollen for food provision but deliver little to stigmas. Male bees do not collect pollen to feed larvae, and their pollination role has been underappreciated. Here we compare pollination effectiveness, visit frequency and pollen foraging behaviour between female and male individuals of a mining bee, Andrena emeishanica , visiting a nectariferous spring flower ( Epimedium pubescens ). Female bees were observed to forage for both pollen and nectar, but male bees foraged only for nectar. Female bees had large hairy hind tibiae with conspicuous scopae, and nearly 90% of the pollen grains they collected went onto the hind legs. Male bees removed less pollen from anthers than female bees but deposited more pollen on stigmas per visit. The higher pollen transfer efficiency of male bees was due to 48.4% of pollen grains remaining ungroomed on the thorax and abdomen, available for stigma contact, but their visitation rate to flowers was much lower. Our results indicate that male solitary bees could transfer more pollen on the stigma per visit but were less important (transferred less pollen in total, because they made fewer visits per unit time) than females.

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