Nectar Production and Spectrum of Insect Visitors in Six Varieties of Highbush Blueberry (Vaccinium corymbosum L.) in SE Poland

Abstract

The attractiveness of plants to pollinators depends strongly on flower rewards, especially nectar and pollen. Nectar mass, sugar concentration, and sugar mass are known to influence the spectrum and abundance of insect visitors. Respective data on nectar secretion in highbush blueberry ( Vaccinium corymbosum ) under the climatic conditions of Poland are scarce. This study was conducted in 2002–2005 to assess flower abundance, nectar production, and insect visitors in six varieties of V. corymbosum in Niemce, SE Poland. Flower abundance ranged from 1.63 ± 0.64 (‘Darrow’) to 4.07 ± 0.95 in thousands of flowers per shrub (‘Northland’). Nectar mass, sugar concentration, and nectar sugar mass increased with flower age, peaking between the sixth and ninth day. Significant differences in nectar characteristics occurred between years and between varieties. ‘Bluecrop’ and ‘Darrow’ produced the largest nectar mass (19.08 ± 7.09 and 16.60 ± 8.31 mg nectar per flower, respectively) and nectar sugar mass per flower (6.39 ± 1.52 and 5.76 ± 1.51 mg sugar per flower, respectively). The estimated sugar yield in the studied V. corymbosum varieties ranged from 9.4 ± 3.3 to 20.7 ± 3.8 g sugar per shrub (‘Croatan’ and ‘Bluecrop,’ respectively). Regarding insect visitors, only honey bees and bumble bees were observed. Honey bees comprised 81%–98% of the total number of observed insect visitors. Highbush blueberry, due to abundant blooming and high per-flower sugar yield, is thus a good source of nectar sugars for honey bees.

The brown honeyeater (Lichmera indistincta) is an effective pollinator in Australian blueberry orchards

“…Blueberry flowers are urn‐shaped with a small corolla opening and produce pollen as well as large amounts of nectar with a high per‐flower sugar yield (Bożek, 2021). In Australia, rabbiteye blueberry flowers between late August and October and is partially self‐incompatible, achieving better fruit set when flowers are visited by pollinators able to promote cross‐pollination (Kendall et al, 2020).…”

Observations of nectarivorous birds and potential biological control agents in berry orchards

“…The abundant clusters of bell‐shaped blueberry flowers produce large amounts of nectar with high per‐flower sugar yield (Bożek, 2021), which can make flowers very attractive to nectar feeders. However, while there is evidence of birds pollinating other plant species in the family Ericaceae (Georgian et al, 2015; Turner et al, 2012) and assessments of wild bird densities in vegetation bordering blueberry fields (Smith et al, 2021), there is no evidence in the literature of birds pollinating blueberry flowers.…”

Non-Forest Woody Vegetation: A Critical Resource for Pollinators in Agricultural Landscapes—A Review

“…Woody plant species are known to offer abundant amounts of sugars in their nectar, e.g., [67,69,70,[73][74][75][76][77][78][79][80][81][82]. For example, the total sugar content was 10-40 mg per floral unit in willow (Salix spp.…”