Biology Reference
In-Depth Information
Chapter 7
NECTAR CONSUMERS
SUSAN W. NICOLSON
Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
1
INTRODUCTION
The emphasis in this chapter is on the enormous diversity of nectar consum-
ers, and the energetic and nutritional implications of a nectar diet for such
different animals. They include the following groups:
•
Pollinators, for whom the most important reward is floral nectar (Simpson
& Neff, 1983).
•
Predators or parasitoids that defend plants against herbivores and are re-
warded with extrafloral nectar (Koptur, 1992; Wäckers & Bonifay, 2004).
•
Nectar robbers (Maloof & Inouye, 2000).
All of them, legitimate or otherwise, benefit from a rich and easily util-
ized food that comes in attractive packaging, and sugar in the nectar fuels the
flight that enables them to be pollen vectors. Table 1 gives an indication of
the variety of animals involved. They range from the many holometabolous
insects and some birds and bats that feed primarily on nectar and are major
pollinators, to various arthropods and mammals that feed opportunistically
or occasionally on nectar. Most are flying animals and nectar sugars are used
to power their flight. The diversity of nectar consumers is emphasized by
Proctor et al. (1996), also for Australian flowering plants by Armstrong (1979),
and for a tropical dry forest in Costa Rica by Opler (1983). Nectar is appar-
ently one of the most ubiquitous foods on earth.
Plant products designed to attract mutualistic animals should be adapted
to the energetic and nutritional requirements of the animals. This is reflected
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