Biology Reference
In-Depth Information
attributes, both taxonomic and ecological (flowering season, life form).
This means that plant-pollinator co-evolution is probably more important
in shaping nectar traits than ecological constraints or phylogenetic affini-
ties.
2.
In general, the discriminating nectar trait for the response of most insect
guilds is amino acid composition, not sugar composition or nectar vol-
ume.
3.
Bee response is mostly shaped by amino acid composition, whereas the
response of other anthophilous insect guilds is mainly shaped by sugar
composition.
4.
Among all amino acids, asparagine and H-serine always have a negative
effect on insect guilds, whereas phenylalanine has a positive effect (on
long-tongued bees), as does GABA (on long-tongued bees and other an-
thophilous insect guilds).
5.
Among major sugars, only fructose has a general positive influence on
different insect guilds, especially on short-tongued bees and insects other
than bees (hoverflies, anthomyiid flies, beetles, and wasps), while sucrose
has a positive influence on long-tongued bees and glucose a negative in-
fluence on wasps.
In conclusion, even in a generalized system like
phrygana
(Petanidou &
Potts, 2006), it appears that the nectar traits of plant species play an important
role in organizing the community and its plant-pollinator resources. Perhaps
we are at the beginning of unravelling the thread of the nectar secrets encom-
passing both gastronomy and the satisfaction of insects' physiological needs
(Gardener & Gillman, 2002).
6
NECTAR AND MANAGEMENT
OF MEDITERRANEAN HABITATS
6.1
Introduced and invasive plants: effects on wild
flowers and bees
Invasive plants represent a major threat to world biodiversity and especially
to the Mediterranean, one of the world hot spots for biodiversity (di Castri
et al., 1990). Such plants often bear “more attractive” flowers, i.e., larger or
more rewarding, which may bring about competition for pollination with the
native flora, and may result in reduced seed set in native species (Memmott
& Waser, 2002). The reduced seed set and biological fitness of the native
species will have detrimental repercussions at the levels of both economics
