Biology Reference
In-Depth Information
importance of Mediterranean areas for bee conservation, with results drawn
from this study, as well as considering the potential impact of human man-
agement on these communities, particularly the major managerial issues of
invasive species, beekeeping, and bumblebee-assisted crop pollination in
greenhouses.
Most of the data presented in this review are drawn from studies carried
out in Mediterranean habitats, especially East Mediterranean scrub, and in
particular from a 30 ha
phrygana
community at Daphni, 10 km west of the
city of Athens, Greece (see Petanidou & Ellis, 1993, 1996 for site descrip-
tion). Most of the data used have been published elsewhere, although some
new conclusions are proposed based on unpublished data sets.
2
CHARACTERISTICS OF MEDITERRANEAN
NECTARS
2.1
Nectar constituents of Mediterranean nectars
In general, floral nectars are mixtures of natural products consisting primar-
ily of carbohydrates (mono-, di-, and oligosaccharides) accompanied by a
wide variety of minor components, such as amino acids, proteins, enzymes,
lipids, phenolics, glycosides, salts, alkaloids, vitamins, and other organic
acids, and minor compounds (Lüttge, 1977; Baker & Baker, 1982, 1983;
Kearns & Inouye, 1993; Adler, 2000a; Dafni et al., 2005). Floral nectars in the
Mediterranean do not differ from these norms in term of composition.
2.1.1
Sugars
Sucrose, glucose, and fructose are the “big three” sugars most commonly found
in nectar (Percival, 1961; Baker & Baker, 1983; Dafni et al., 1988; see also
Nicolson & Thornburg, 2007, Chapter 5 in this volume). Minor sugars, such
as sorbitol, melibiose, maltose, and mannitol are usually also present (Baker
& Baker, 1983). This also applies to Mediterranean nectars (Petanidou, 2005).
Based on HPLC analyses of the nectars of 73 plant species, found in
phrygana
at Daphni, sucrose was present at an average of 702.5 ± 234.2
nmoles/flower, glucose at 869.4 ± 415.9 nmoles/flower, and fructose at
905.9 ± 412.0 nmoles/flower (Petanidou, 2005). In addition to these three
sugars, traces of minor sugars were also detected, such as sorbitol (9 spe-
cies); melibiose (7 species); maltose and mannitol (4 species each); ribose,
