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changing resources (H einrich , 1976
a,
1976
b
, 1979). Bumblebee choice is related to
their proboscis length (Pouvreau, 1984; B rian, 1951, 1957; T eras, 1976. 1985) and
the flower morphology (La vert у , 1994). Bumblebee species with long glossae have
access to nectar in a greater variety of flowers than those with short glossae and they tend
to feed from a larger number of plant species (Harder, 1985). Bumblebees generally
prefer flowers whose corolla lengths are in relation to their proboscis lengths but
additionally they have different habitat preferences, emergence times, nest sites, colony
development strategies that all indirectly affect flower choices (Teras, 1985).
Co-evolutionary determined relationships between plants and their bee pollinators
have been studied bv many scientists (Faegri, der P ijl, 1971; M o ld enk e, 1979
a,
1979
bt
1979
c:
Proctor et a!., 1996; D afni, N ea l, 1997), as well as food resource
sharing between bees in different plant communities (M acior, 1974; Reader, 1975;
M o ld enk e, Li ncol n, 1979; P lea san ts, 1980; Arroyo et a l, 1982, 1985; Teras,
1983, 1985; Hartman, 1988; Inouve and Руке 1988; Pe t ani dou and Vokou, 1990;
D a fn i, O ’Tool e , 1994; S te ffa n -D ew en te r , T scharn tke, 2000). Bee fauna is
connected to the plant community composition and colonisation dynamics depends on its
phenology (H ein rich , 1975; B ow e r s, 1985; Herrera, 1988; P etan idou , 1993;
W estrich , 1995).
The species composition and behaviour of the pollinators o f
Gentiana lutea
ssp.
symphiandra
(Murb.) H ayek,
G. punctata
L.,
G, asekpiadea
L.:
G. pneumonanthe
L.,
G.
cruciata
L.t G.
pyrenaica
L.,
G. verna
L., G.
utriculosa
L. and G,
nivalis
L. presented
Bulgarian flora have been investigated (Кож ухарова, 1994; K ozuharova, 1999;
K ozuharova, 2004; K ozuharova, Anchev 2001,2002)
The aim of this study is to analyze comparatively the flower choice and constancy
based on the corbicular pollen of bumblebees collected in bell shaped flowers o f some
Gentiana
species to which they are morphologically adapted.
MATERIAL AND METHODS
STUDY SITES
Tlie field investigations were conducted during the flowering seasons (May to
September) of years 1987 to 1995 in the mountains of SW Bulgaria: Ml. Vitosha, Ri'la
Mts, Pirin Mts, Western Stara Planina Mts. and Mt. Ljulin at altitudes between 1000 m
and 2000 m as follows: open lands within the deciduous forest belt at 1000 m, open lands
within the coniferous forest belt at 1200-1400 nt and sub alpine meadows at 1800-2000 m
(Fig. 1).
Pollinator behaviour and pollen analysis
Insect visitors of
Gentiana
spp. and (blue or yellow bell shaped flowers adapted to
bumblebee pollinators), were observed on transects within the study sites (Table 1, Dafni,
1992, Dlusskii, pers. comm.). A sample of bumblebees was collected for detail
identification (M. B erezin ), It is deposited in the National Museum of Natural History,
Bulgarian Academy of Sciences and in personal collections.
30
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