Favourite plants of our bumblebees

Text Meelis Uustal
Photo Imbi Ruber
Translation Liis
Red-shanked carder bee
We launched the bumblebee monitoring project this year with support from the Estonian Environmental Investments Centre (KIK), to find out more about the well-being and favourite plants of Estonian bumblebees with the help of the public.
Many thanks to the 45 bumblebee observers who sent us their observations of the flower visits of bumblebees. Altogether 22 species of bumblebees were observed, 15 of them so-called proper bumblebees and 7 cuckoo bumblebees. This makes up nearly 2/3 of Estonian bumblebees.
The observers noted in all 149 plant species that the bumblebees visited. Mainly these are garden plants but in the TOP 15 several roadside and meadow plants also contribute to the picture.
The 15 most frequently visited plants were as follows:
1.     Archangel (White deadnettle) (Lamium album)
2.     Knapweeds (Centaurea sp)
3.     Dahlias (Dahlia sp)
4.     Hyssop (Hyssopus officinalis)
5.     Marjoram (Origanum vulgare)
6.     Chives (Allium schoenoprasum)
7.     Dandelion (Taraxacum sp)
8.     Coneflowers (Echinacea sp)
9.    Garden cornflowers (Centaurea cyanus ssp)
10.  Thistles (Cirsium sp)
11.  Field scabious (Knautia arvensis)
12.  Elecampane (Inula helenium)
13.  Narrow-leaved lavender (Lavandula angustifolia)
14.  Viper’s bugloss  (Echium vulgare)
15.  Garden nasturtium (Indian cress) (Tropaeolum majus)
Thus in order to attract different bumblebee species the garden should have:
-        a number of different nectar plant species, with
-        different flower shapes and
-        different flowering periods;
And moreover the lawn, roadside and field plants beyond the garden fence should not be mowed too diligently because they too can be highly important to the pollinators.
The largest number of observations were noted for white-tailed bumblebees, tree bumblebees, and red-tailed bumblebees.
White-tailed bumblebees (Bombus lucorum) were most frequently observed on the flowers, and among the bumblebee species also visited the greatest number of plant species – 59 plant species. This is nearly one and a half times as many as the numbers for the tree bumblebee and the red-tailed bumblebee. Since there are many plants that suit the white-tailed bumblebee with its short mouth parts, a conclusion could be that the species does not concentrate on a few nectar plants but visits many flowers, exploring and pollinating them. Sturdy platform flowers (such as coneflowers, Echinacea) where the bumblebees won’t need any acrobatics are prominent among the most frequently visited flowers.
Tree bumblebees (Bombus hypnorum) visited 40 plant species. Their liking for bell-shaped flowers clearly stands out. In raspberries or a flowering asparagus clump the tree bumblebees are the most common bumblebees. The tree bumblebee helps to remind us that although it has short mouth parts like the white-tailed bumblebee, different pollinator species may prefer differently-shaped flowers.
The favourites of red-tailed bumblebees (Bombus lapidarius) are round platform flowers where they can safely hold their position, and shorter tube-shaped flowers where the mouth parts must be tucked in deeply to get hold of the nectar. Chives and white deadnettle are good examples of such plants.
Male proper bumblebees and cuckoo bumblebees both have short mouth parts and catch attention ”lazing” on platform flowers. Male bumblebees were seen on 25 plant species during the summer, cuckoo bumblebees on 20 species. Mainly we have to do with large sturdy flowers. Male bumblebees liked elecampane and Cosmos, while knapweed and scabious were typical plants for cuckoo bumblebees.
More details from the results of the bumblebee monitoring project and other bumblebee projects here: LINK




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