Table Of ContentPLANT SCIENCE RESEARCH AND PRACTICES
N
ECTAR
P , C
RODUCTION HEMICAL
C B
OMPOSITION AND ENEFITS
A P
TO NIMALS AND LANTS
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P S R
LANT CIENCE ESEARCH
P
AND RACTICES
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PLANT SCIENCE RESEARCH AND PRACTICES
N
ECTAR
P , C
RODUCTION HEMICAL
C B
OMPOSITION AND ENEFITS
A P
TO NIMALS AND LANTS
ROBIN L. PECK
EDITOR
New York
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Library of Congress Cataloging-in-Publication Data
Nectar : production, chemical composition and benefits to animals and plants / editor: Robin L. Peck.
pages cm. -- (Plant science research and practices)
Includes index.
ISBN: (cid:28)(cid:26)(cid:27)(cid:16)(cid:20)(cid:16)(cid:25)(cid:22)(cid:23)(cid:25)(cid:22)(cid:16)(cid:25)(cid:26)(cid:28)(cid:16)(cid:26) (eBook)
1. Honey plants. 2. Nectar. I. Peck, Robin L., editor. II. Series: Plant science research and practices.
SF535.N43 2015
638'.13--dc23
2014045014
Published by Nova Science Publishers, Inc. † New York
CONTENTS
Preface vii
Chapter 1 Impact of Microorganisms on Nectar Chemistry,
Pollinator Attraction and Plant Fitness 1
María I. Pozo, Bart Lievens and Hans Jacquemyn
Chapter 2 Effect of Nectar Composition on Bee
Attraction for Onion Seed Production 41
Verónica Soto, María Fernanda Silva
and Claudio Galmarini
Chapter 3 Extrafloral Nectar Production and Plant
Defense Strategies 59
Akira Yamawo and Makoto Tokuda
Chapter 4 Nectar Plant Species Richness Explains Butterfly
Diversity in and Around a Primeval Woodland
of Mount Fuji, Central Japan 77
Masahiko Kitahara
Chapter 5 Some Melliferous Aspects of Cohabiting Lamiaceae
Species Competing for Efficient Pollinators 99
Marina Mačukanović-Jocić, Gojko Jocić,
Zora Dajić Stevanović and Mića Mladenović
Index 165
PREFACE
This book discusses several benefits of plant nectar. It also discusses the
production and chemical composition of nectar.
Chapter 1 - Floral nectar is a sweet, aqueous secretion that mainly consists
of sugars and to a lesser extent amino acids. It is offered by plants to entice
pollinators and to ensure pollination and thus sexual reproduction. Although
floral nectar is initially sterile, some yeasts and bacterial species frequently
inhabit floral nectar, once they have been dispersed into the nectar via the air
or flower-visiting insects such as pollinators. Identification of microorganisms
in floral nectar from broad-scale surveys has shown that nectar yeasts are
widespread and occur in a wide range of habitats. No such surveys are
currently available for bacteria, but the few available studies suggest that
bacteria may also be widespread in nectar. However, the high sugar content
(sometimes till 50% w/w) and consequentially low water activity (typically
between 0.90 and 0.99 a ) that characterize the nectar of many plant species
w
limit the number of microbial species that are capable of surviving and
proliferating in the harsh environment of nectar, leading to species-poor
communities that are often dominated by one or few culturable species per
nectar sample. Other factors that determine nectar communities are nitrogen
availability, pH, sugar composition, temperature and the presence of secondary
or antimicrobial compounds. The presence of microbes in nectar has been
shown to decrease sugar concentrations and alter sugar ratios. Besides, the
metabolic activity of nectar-inhabiting microorganisms also affects other floral
attractive traits, including temperature, scent and amino acid content. In the
few cases that have been examined, changes in nectar chemical properties
impacted on pollinator behaviour and as a result on plant reproductive success.
A broader investigation of the impact of bacteria and yeasts on the chemical
viii Robin L. Peck
and physiological properties of nectar, coupled with behavioural assays of
pollinators, are needed to translate microbial presence in floral nectar to plant
population dynamics.
Chapter 2 - Onion is the second most cultivated vegetable crop in the
world. Two types of onion varieties are usually grown around the world; open
pollinated (OP) and first generation (F1) hybrids. Honey bees are the main
pollinators of onion seed production, but owing to low attractiveness of
flowers, pollination is often inadequate. Pollination problems result in low
seed yields. Field observations indicate that F1 hybrid seed yields are much
lower than open-pollinated varieties seed yields, with a decrease of up to 60%.
Nectar is the most important floral reward offered by plants. Floral nectar
composition has been studied as the potential cause of bee preferences in many
species, among them onion. Nectar usually does not repel bees, but some
nectar may be less attractive than nectar of competing flowers. Honeybees
have distaste for onion flowers and avoid visiting them. Frequently, onion
nectar potassium concentration and nectar sucrose concentration have been
mentioned as potential causes of bee unattractiveness. Also, minor
components of nectar such as phenols, amino acids, proteins, organosulfur
compounds and alkaloids might directly affect bee foraging. There are
differences in the chemical composition of nectar and floral morphology
between open pollinated and F1 Hybrids and also within F1 Hybrids. These
differences are correlated with the number of visits and seed yield. Therefore,
it would be possible to select indirectly the most promising seed production
lines analyzing nectar or floral morphological characters.
Chapter 3 - In plant-ant mutualism, plants often provide foods, such as
extrafloral nectar and food bodies, to ants. In return, the visiting ants protect
the plants against herbivores. However, these plants also possess various direct
defenses, including physical defense via trichomes and tough leaves, chemical
defense using secondary metabolites. Why have plants evolved defensive
mutualisms with ants even when possessing these direct defenses? To answer
this question, the authors must clarify the costs and benefits of each defense
trait, as well as its role in the overall defense strategy of the plant. Previous
studies, however, have mostly dealt with the costs and benefits of particular
defenses. Here, the authors review recent advances in the study of plant
defense strategies involving the indirect defense provided by extrafloral nectar
production and other defenses. First, they explain the benefits of each defense
trait, with special reference to its efficacy against herbivores. Second, they
review the costs of each defense trait. Next, the authors focus on differences in
