Field Experiments of Pollination Ecology: The Case of Lycoris sanguinea var. sanguinea

Summary

To reveal the pollinator effectiveness of a given plant species, multiple methods of field experiments have been developed. This study demonstrates the basic methods of field experiments for pollination ecology using the case study of Lycoris sanguinea var. sanguinea and the novel pollination mechanism, breaking-bud pollination.

Abstract

Plant-pollinator interactions have been studied for approximately one hundred years. During that time, many field methods have been developed to clarify the pollination effectiveness of each pollinator for visited flowers. Pollinator observations have been one of the most common methods to identify pollinators, and bagging and cage experiments have been conducted to show the effectiveness of specific pollinators. In a previous study of Lycoris sanguinea var. sanguinea, its effective pollinators, the visitation frequencies of each floral visitor, and its reproductive strategies were not identified. This study reports the observation that small bees visited flowers that were partially opened (breaking buds). To the best of our knowledge, this phenomenon has not been reported previously. Further, this study investigates the hypothesis that small bees can pollinate at that flowering stage. This study demonstrates the basic methods of field experiments in pollination ecology using L. sanguinea var. sanguinea. Pollinator observations and digital video showed the visitation frequencies of each floral visitor. Bagging and cage experiments revealed that these flowers could be pollinated fully and that breaking-bud pollination could be important for the pollination of this plant species. The advantages and disadvantages of each method are discussed, and recent developments, including laboratory experiments, are described.

Introduction

Plant-pollinator interactions are prime examples for the study of evolutionary biology and ecology. The mutualistic relationships between flowers and pollinators are thought to have promoted the diversification of angiosperm^1,2 as a result of natural selection, although other biotic and abiotic factors have also exerted influence^3,4,5. It is also thought that floral traits have changed to adapt to the most effective pollinators and to produce more fruit and seeds⁶. These beliefs have been constructed though large studies based on different indices, such as pollination effectiveness, that involve various interpretations⁷.

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Protocol

NOTE: This article is based on our previous work³⁰. Some parts are reprinted with permission from The Botanical Society of Japan and Springer Japan.

1 . Observation of Floral Visitors

1. Selection of the Observation Fields
   1. Search the areas where the plant materials are distributed, and select the candidate study sites using reliable resources, such as picture books, academic journals, etc. Adjust the number of study sites to fit the research objectives (e.g., a wide range of locations for the comparison of flower visitors throughout Japan).
   2. Check the locations of selected candidate po....

Results

Five populations were selected for pollinator observations. In the pre-observation phase, visitations of various insect species to opening flowers and small bees to breaking buds were confirmed. Floral visitor observations revealed that most of the visitors to all five study sites were individuals of the small bee species Lasioglossum japonicum. The total visitation record showed that the visitation ratios of this species were more than 90% at three sites (Figure 2

Discussion

Flower observations and bagging experiments were employed in this study to reveal the visitation frequencies and the female reproductive success of plants, respectively. In Dafni (1992)³⁸, the videotape method was effective because it could record the timing and duration of visitors for analysis and prevent observer bias. However, at the time, this method required expensive equipment, and the observation times were limited by battery life. Recently, the cost of equipment for producing video records has decline.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
recording sheet	any	NA
insect net	any	NA
pooter	any	NA
ethyl acetate	any	NA
100% Ethanol	any	NA
plastic tube	any	NA
plastic case	any	NA
soft bag	any	NA
digital video camera(s)	any	NA
tripod(s)	any	NA
bags	any	NA
wire or plastic mesh boards	any	NA
iron wires	any	NA
labeling tape	any	NA
stick supporters	any	NA
soft strings or wire	any	NA
pincette(s)	any	NA