EFFECT OF CULTIVATION AREA ON LOWBUSH BLUEBERRY NECTAR PRODUCTION AND POLLINATOR COMPOSITION

The aim of the research was to study floral nectar characteristics and pollinators of lowbush blueberry (Vaccinium angustifolium Ait.) in different cultivation areas. The data were collected from three commercial blueberry farms in Tartu County, South Estonia. One plantation was located on peat soil (harvested peat field) and the area was surrounded with natural pine forest. Two plantations were located on mineral soil: one of these was surrounded with natural forest and meadow; the second area was surrounded with apple and strawberry plantations. In all plantations the lowbush blueberry plants were five years old. In the full blooming time (the end of May) the insect visitors were observed during 30 min. All flower visitors were visually identified by species. The volume of floral nectar production over a 24-h period was measured using 1-μl micropipettes (with the tube length 32 mm). The nectar solute concentration was measured by using a hand-held refractometer modified for small quantities. The taxonomic composition of pollinators strongly varied depending on the cultivation area. Minimum number of species was identified in the plantation surrounded with other cultivated horticultural plants. In harvested peat field condition we could identify nine Bombus species, but Apis mellifera was not found. Bombus pascuorum was a high incidence taxon in all observed areas. In peat soil condition the blueberry flowers had the highest nectar production, but solute content was the lowest.