Stuttgart, 2017-11-29

Selecta one trial on insect-friendly plants

When in autumn the leaves are turning into bright orange and yellow and are falling off not only birds go to warmer climates, but also butterfly species such as red admiral and painted lady move to the South. The natural food sources for insects are ebbing in late summer. From that moment on “bedding and balcony plants (B&B) such as Bracteantha and Heliotrop are seen as time extension for natural food sources. According to studies which were conducted by the NABU since 1989 the number of insects declined by 80 percent in some places in the last years. There is only few solid data and scientific evidence about which B&B varieties are really insect-friendly.

That’s where we want to take action to contribute to the receipt of the biodiversity. That is why we conducted a study on insect-friendly plants in cooperation with the public Teaching and Research Institute for Horticulture in Heidelberg, the nursery Staudenrausch and the Bee Research Institute of Hohenheim (Stuttgart) during the months from June to August 2017.

The aim of the project for the development and implementation of a biodiversity breeding program to increase the urban green for insects, was to get information about which varieties mostly attract insects and contribute to their nutrition by determining the preference of flower-visiting insects. Background of the project is to strengthen our assortment even more with insect-friendly plants.

The observation sites for the trial were at the university of Hohenheim, on our testing area in Stuttgart and at the LVG Heidelberg. All insects which contribute to the pollination were included in the project. These include besides honeybees also hoverflies, wild bees, butterflies and other pollinator insects. Different varieties of different species were included in the trials.

The evaluation of the trials showed that there was no variety which was not approached. However, it became obvious that the number of insects which were apparent on a variety during the two minutes of observation, depended heavily on the number of open flowers. Compared to others, the variety Mohave® Yellow is the most insect-friendly variety among our Bracteantha assortment.

The top 10 of insect friendly B&B-varieties of our assortment:

Variety

Dominant group of insects

Insect friendliness

Maximum numer of insects (in 2 min.  of period under review)

Dahlia Dalaya ‚Krishna‘

honeybees, bumblebees, bigger wild bees

Very good

14

Dahlia Dalaya ‚Shari‘

honeybees, bumblebees, bigger wild bees

Very good

11

Bidens Eldoro Yellow

honeybees, wild bees

Good

8

Gaura Belleza 048

honeybees, small wild bees, hoverflies

Very good

15

Bracteantha Mohave Orange

Big and small wild bees (e.g. furrow bees)

Good

7

Lavandula ‚Les Blues Antoine‘

honeybees, bumblebees, bigger hoverflies

 Very good *

26

Heliotrop Marino ‚Blue‘

honeybees

Very good

14

Dahlia Dalaya Bali

honeybees, bumblebees, größere Wildbienen

Good

7

Lavandula ‚Les Blues Thierry‘

honeybees, bumblebees, bigger hoverflies

Very good *

13

Bracteantha Mohave ‚Yellow‘

Big and small wild bees (e.g. furrow bees)

Very good

15