When lilac flowers bloom

Some species of exotic plants can grow better in their new homeland than where they originated. This may be due to genetic modification or by herbivores like insects that have not learned how to adapt to newcomers.

This is the conclusion of researchers from the Helmholtz Center for Environmental Research (UFZ) after completing their research on lilacs (Buddleja davidii) and mallow (Mahonia aquifolium). Therefore, imported species have an advantage over other native plants. Since then, they have become a threat to ecological balance. The research article is published on the Diversity and Distributions science journal.

Lilacs are usually green, white or purple. Buddleia (Dog Beetle) was introduced into European territory about 100 years ago originating from China. Since then they are grown in gardens. The shrub that makes this scene quickly became popular but not only within a garden. They spread in the ruins of bombed cities in Germany during the postwar period. At the same time, they grow wild into large clusters in western and southwestern Germany. Only in the east, winter frosts limit their proliferation.

Although lilac flowers are very beautiful, in addition to being a source of food for butterflies, its beauty also hides a bad side. They produce seeds easily and quickly develop into a dense population. It is therefore possible to replace local tree species and become a threat to the safety of the railway area when they spread there. Switzerland, Spain and France are working hard to fight Buddleia, while in the US they grow at tremendous speeds. In New Zealand, Buddleia species are causing significant economic consequences as they overwhelm native plants.

Lilacs were introduced to Europe from China about 100 years ago;Since then it is grown in the garden so far.(Photo: Sarah Brunel, EPPO)

In order to enhance knowledge of the mechanism of plant introduction, UFZ researchers compared 10 Buddleia populations in Germany with 10 populations in their original homeland - Yunnan province in the southwest. China. Although climate conditions in China are even better for growth, they are more prolific in Germany, producing more seeds with higher grain quality.

Susan Ebeling of UFZ said: 'In their Chinese homeland, this plant has about 15% loss of leaf-eating insects compared to 0.5% in Germany. This intruder is not named in the menu of insects at the new residence. There are no relatives of Buddleia living in Central Europe, so insects need a longer time to adapt. ' Two Asian insects have been used to control shrubs in New Zealand but have not yet been implemented in Europe.

This is completely different from a more carefully studied plant - Mahonia aquifolium mallow plant originates in the western United States. In the state of Oregon, the year-round green shrub with these striking yellow flowers is the state's signature flower, so it also has the name 'Oregon grapes'. In Europe, mallow flowers also have a close relative: European barberry (Berberis vulgaris). Native insects have had millions of years of adaptation to barberry, so they can easily be turned to mallow plants. Meanwhile, the mallow tree cannot develop any defense mechanism against the attacker.

However, they grew very well in Central Europe, making the Swiss Commission - the Swiss plant of local conservation, forced to ask people not to cultivate mallow. 'If someone has planted this plant in the garden, they must absolutely ensure no further breeding; just to remove the trees that have just been planted and constantly pluck the seedlings'.

Although it exists in an enemy environment, mallow flowers are still capable of growing vigorously, covering the entire forest floor thus causing problems. Dr. Harald Auge of UFZ explains: 'The main obvious cause is the process of growing this plant. Through selection and breeding, they are genetically altered, making them grow stronger in Europe than in the United States. ' He and his colleagues from Halle collected mallow seeds in the United States, Canada, Germany and the Czech Republic and planted them in a strictly controlled greenhouse environment.

Mahonia aquifolium is native to the western United States.(Photo: University of Utah)

Plants and plants that occupy the majority in the imported plant group have become a big problem. They are considered by experts to be biological intruders. Human biological invasion is also one of the reasons for the rapid decline of flora and fauna worldwide.

According to a study conducted by the Federal Environmental Organization, the economic cost of 20 introduced species is about 67 million Euro in 2002 in Germany. No other numbers have been collected yet. In the near future, UFZ will learn about the cost of health treatment for rag allergy with the support of the Federal Ministry of Research.

Reference publications:

Ebeling, SK, Hensen, I., Auge, H. (2008):
Imported shrubs Buddleja davidii grows stronger in the new homeland
Diversity Distrib. 14 (2), 225-233
http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1472-4642.2007.00422.x

Ross, CA, Auge, H. (2008):
Cam kneeling has surpassed native relatives
Plant Ecology (online): DOI 10.1007 / s11258-008-9408-z
http://www.springerlink.com/content/j7q5304562j54674/

Ross, CA, Faust, D., Auge, H. (2008):
Cam kneeling introduced in different habitats: local adaptation or versatile genetics?
Biological Invasions (online) DOI 10.1007 / s10530-008-9261-y
http://www.springerlink.com/content/y7002j2414271347/