Selecta one took advantage of the summer 2017 to conduct 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). 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 the assortment of Selecta even more with insect-friendly plants.
When in autumn the leaves are turning into bright orange and yellow and are falling off, bedding and balcony plants are replaced by perennials and Callunas. In this time of the year 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. They support the existing pollinators or insects in times when flowers lack outside.”, states Ute Ruttensperger from the faculity Horticultural Research Insitute of the LVG Heidelberg.
There is only few solid data and scientific evidence about which B&B varieties are really insect-friendly. “Bee friendliness is currently an important topic everywhere. Everyone has a bee friendly concept. But often this is not filled with content because it is not much known about what insect-friendly in relation to ornamental plants means.”, announces Lea Kretschmer, postgraduate at the Bee Research Institute of the university of Hohenheim. “What we are sure about is that in the last years the number of insects declined by 80 percent in some places. This show studies which were conducted by the NABU since 1989. That’s where we want to take action to contribute to the receipt of the biodiversity”, says Sebastian Mainz, Senior Trade Marketing Manager at Selecta one.
For this reason, the cooperation project investigated the behaviour of insects at three locations during the months from June to August: at the university of Hohenheim, on the testing area of Selecta one in Stuttgart and at the LVG Heidelberg. 30 observations of two minutes were made at each location to identify which variety is most attractive for insects. All insects which contribute to the polli-nation were included in the project. These include besides honeybees also hoverflies, wild bees, butterflies and other pollinator insects. 36 bumblebee species, around 440 hoverflies species, over 500 wild bee species and about 3700 butterfly species of butterflies and moths are native in Germany. At the beginning, these subsist more and more on pollen and flower nectar of woody and non-woody flowering plants in the nature. During the summer, these sources dry up more and more and the insects fall back on bedding and balcony plants.
To ensure enough activity of the bees sunny, dry and warm days in the summer months were chosen for the studies. 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.
Following results could be made among others:
Compared to others, the variety Mohave® Yellow is the most insect-friendly variety among Selecta’s Bracteantha assortment. This variety is interesting especially for big and small wild bees (for example furrow bees - Halictus spec.). This assumption is confirmed by the fact that simple and semi-double Dahlia varieties are insect-friendly in contrast to double varieties and that they are a very good additional food source. Especially the varietes Dalaya Krishna, Dalaya Shari, Dalaya Shiva and Dalaya Yogi have many open flowers. This means the anthers are visible and the therefore the flowers are interesting for pollinator insects.
The top 10 of insect friendly B&B-varieties of the Selecta 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|