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constancy o f
В. agrarian
and
B. lapidaries,
both with medium tongue length, that were
foraging in the flowers of
G, asdepiadea
was lowest (Table 8). Having on mind tluit this
was the end of the flowering season the reason explaining this behaviour was probably
llie reduced foraging resources rather then species specifics. Corbicular pollen analysis
collected by
B. agronun
and
B. lapidaries
earlier in the season are necessary to test
whether these species are really less constant to the food source. Also the long tongued
B.
hortorum
demonstrated comparatively wide spectrum of preferences (Table 8).
2. Flower constancy and the type of the attractant.
We could not find correlation between the flower constancy to
Gentiana
flowers
and the attractant nectar, pollen or both (Tables 2a, 3a, 4a, 6a).
3. Flower constancy and the blossom type o f the foraging plant.
In most o f the pollen loads dominated the pollen of dish-bowl blossom class in
which the bumblebees were foraging together with the main food source - the gentian.
These dish-bowl blossoms were often yellow coloured. Next dominating pollen was from
bell-shaped blossoms.
‘'Minors” were often but not necessarily the abandoned in the area flowering
plants.
The most abandoned dish-bowl plants flowering at the same time and in vicinity of
(7.
lutea-Crepis visddtda. Solidago virga-aurea, Knauiia midzoremis, Knauiia drymeja,
were presented were presented in many o f the pollen loads but with low pollen quantity.
The abandoned
Geranium sylvaticwn
was not presented at all in the pollen loads. On
contrast the significant content of
Hypericum-type
and
Fillpendula
-type pollen grains in
the pollen loads of some of bumblebees pollinating
G. lutea
did not correlate to ihe
“sparsae” distribution of these plants in the field (Tables
2 ,
2a),
The most abandoned dish-bowl plants in the vicinity o f G.
pimctata-Advllea
multipda, Veratntm lobelianum, Poteniilla iernata
, were presented better compared to
the previous case but still with low pollen quantity.
Geranium sylvaticum
pollen grains
were absent again. The presence Fillpendula-type pollen grains did not correspond to the
abundance of this plant in the fields. The abandoned bell-shaped blossom plants -
Vacdnium
spp. and
Campanula
spp. were respectively well presented in the pollen loads.
On contrast the well presented of Pedicularis-type (gullet blossom type) did not correlate
to the “solitariae” distribution of this plants in the field (Tables 3, 3a, Fig. 3).
The most abandoned dish-bowl plants in the vicinity o f
G. asdepiadea-Solidago
virga-aurea
,
Senecio nemorensis, Prenanthes purpurea
were presented in most of the
pollen loads but with low pollen quantity. On contrast the significant content of
Hypericum-type pollen grains in the pollen loads of some of bumblebees pollinating G.
asdepiadea
did not correlate to the “sparsae” distribution o f these plants in the field
(Tables 4, 4a, Fig. 3).
The abandoned plants in the vicinity of
G. pneumonanthe
were practically not
presented in the pollen loads (Table 5).
The most abandoned dish-bowl plants flowering at the same time and in vicinity of
G.
cruciata
were of the flag blossom type
Dorycnium herbaceum
,
Medicago falcata,
Medicago lupulina, Lotus corniculatus
as well as the dish-bowl
Heliantheimm
nummularium.
They were presented in the pollen load but in quantity less than expected
Tables 6 , 6a, Fig, 3).
50
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