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the plant species blooming simultaneously at each study site were classified after the
scheme of Faegri and van der Pijl (1971) with some modifications as follows 1)
dish/bowl - free access to the nectar and pollen, radial symmetry of the “blossom”; (here
is included capitulum which combines dish/bowl with the funnel/tube effect of its single
flower 2) bell and funnel - more or less hidden nectar, radial symmetry to slight
zygomorphy; 3) flag (sexual organs are found in the lower part, pollen is deposited on the
abdominal side o f the insect, stemotribic pollination) and gullet (sexual organs are
restricted to the functionally upper side, pollen is deposited on the abdominal side o f the
insect back and upper part o f the head, nototribic pollination); more or less hidden nectar,
medial zygomorphy, These categories correspond to those accepted by Leppik (1953,
1956, 1957) as follows: actinomorphic, stereomorphic and zygomorphic. Approximate
abundance evaluation o f the flowering plant species was done after Drude scale
(JarQshenko, 1961).
RESULTS AND DISCUSSION
Bumblebees as flower visitors of
Gentiana
species
Observations on the pollination ecology o f
Gentiana
was done on G.
lutea
ssp.
symphiandra
(Murb. ) Hayek,
G. punctata
L,,
G. asclepiadea
L„
G. pneumonanthe
L.,
G. cruciata h., G. pyrenaica
L.,
G. verna
L.,
G. utricidosa
L. and
G. nivalis
L. presented
in the Bulgarian flora (Fig. 1). The flowers o f the first six gentians are bell-shaped to
wide funnel shaped. In other words they are morphologically adapted to bumblebee
pollination. Bumblebees were the most important pollinators for five o f these gentians -
G. lutea
ssp.
symphiandra, G. punctata
, G.
asclepiadea
,
G. pneumonanthe, G. cruciata
(Table 1). Bumblebees were very rare visitors of the sixth morphologically со-adapted to
them gentian - G.
pyrenaica
(Кож ухарова, 1994; Kozuhar ova 1999, 2002, 2004,
Kozuharova, Anc he v 2001, 2002).
Pollen analysis
Pollen loads for analysis carried the bumblebees as follow:
Gentiana lutea -
18
workers, G.
punctata
- 30 workers; G.
asclepiadea
- 19 workers and non-hibemated
queens, G.
pneumonanthe -
2 workers, G.
cruciata -
6 workers.
Gentiana lutea
ssp.
symphyandra
(Mu r b . ) Hayek
The most effective though second most numerous visitors after the flies
Tricops
spp. (Muscidae, Diptera) were the bumblebees - 25.9% o f all insects visiting the flowers
of this gentian, Nectar collectors were 90.1% o f all bumblebees.
Bombus pratoum
were
the most frequent visitors - 91.2% o f all bumblebees (Table 1). The bumblebees were
dusted with pollen and they often brushed the pollen adhered on their bodies into the
pollen baskets on their way between the flowers,
The high flower constancy o f bumblebees workers observed in the fields
correlated with high percentage o f
Gentiana-type
pollen found in their pollen baskets
(mean “ 80.7%, min = 4.0% max = 100.0%, Table 7). Their “minors” were 0-7 plant
species (Table 8). These plants were more or less abundant in the area (Tables 2, 2a).
32
Электронная Научная СельскоХозяйственная Библиотека