Abstract:

Introduction

Alien invasive plants such as Giant Hogweed (Heracleum mantegazzianum) are having a severe impact on biodiversity in Europe. No successful solutions stopping invasion has been found so far. A new project was commenced in January 2002. It is carried out under EU 5th FW, "Energy, Environment and Sustainable Developement" - Assessing and Conserving Biodiversity. The overall objective of the project is therefore to develop an integrated management strategy that comprises effective, practicable and sustainable means of controlling an alien non-agricultural weed (H. mantegazzianum).

Objectives

The overall objective of the project is to develop an integrated management strategy that comprises effective, practicable and sustainable means of controlling an alien non-agricultural weed (Heracleum mantegazzianum). This will provide a generic control strategy to safeguard the biodiversity of Europe from the increasingly serious threat of other alien invasives. In addition to the effective control of this species, a concept would be produced which could serve as a template by which other exotic species could be controlled or prevented from reaching the invasive phase.

Activities

The overall objective will be achieved through the following activities:

• creating a knowledge base for H. mantegazzianum including genetics, taxonomy, biology and ecology
• modelling the invasion of the species at the local and continental scale
• searching for, and assessing potential biological control agents in the area of origin of H. mantegazzianum for potential future use in Europe, including a risk-benefit analysis, an evaluation of existing European guidelines for the importation of exotic organisms, and an implementation plan
• investigating presently applied mechanical and chemical control methods together with possible measures to reduce and prevent further dispersal of H. mantegazzianum and other alien invasive weeds
• integrating the resultant knowledge and experience to produce best practice guidelines and an integrated control strategy disseminating this knowledge to practitioners across Europe to implement effective and economic sound control measures

Background information

Classical biological control

Classical biological weed control aims to control alien invasive plant species by introducing host-specific natural enemies (biological control agents) from their area of origin. It is recognised that the lack of specialised natural enemies in the new range puts the invading plant at a competitive advantage over the native flora, thus facilitating its invasion success. Fungal plant pathogens and herbivorous insect species associated with Heracleum mantegazzianum will be sought in the Caucasus region from where the plant species originates. A selected number of these organisms will be investigated for their safety and suitability (i.e. host-specificity and impact) as biological control agents. However, it is NOT intended to release any of these organisms in Europe during the course of this project. Biological control of invasive weeds is presently practised in all continents except Europe 7, and major sustainable success has been achieved in these areas. Development of biological control as a component of an integrated approach to control of Heracleum mantegazzianum provides an opportunity to initiate this valuable and sustainable control method in Europe and to pave the way for its use with other species.

Hogweed

Around 40 years ago silage production with Heracleum sosnowskyi, which is closely related to H. mantegazzianum and also originating from the Caucasus was initiated in the Baltic States as well as in other parts of the former Soviet Union. However, due to health problems for the staff during harvesting, the cultivation of the plant ceased around 1980. The sap of the plant is phytophototoxic to humans and produces severe blistering and a rash that can last for several months.

Giant Hogweed, is indigenous to the Caucasus mountains but, since its introduction to botanical gardens during the 19th century, it has become widespread across Europe and in parts of North America. It is now a serious invasive weed. The plant is tall (approx. 3 m in height) and belongs to the plant family Apiaceae (umbellifera). It has large leaves and multiplies by seed propagation, a single plant producing up to 100,000 of seeds. The invasive nature of the species implicates that it has become a significant threat to floral and faunal biodiversity in a wide range of habitats across Europe in which it is becoming established. In some countries Heracleum mantegazzianum is the only plant species against which many municipalities and counties are still applying chemical herbicides (glyphosate), and is thus the last hindrance in a chemical free weed control strategy for these authorities. In some European countries municipalities and counties are requested to cease any application of pesticides. These authorities will therefore need management strategies against not only Heracleum mantegazzianum but also other alien invasive plant species.

Invasive plant species

An alien invasive species is a species introduced to a region from elsewhere, usually as a result of human activity, the distribution and/or abundance of which in the wild is in the process of increasing regardless of habitat. After a species (e.g. a plant species) has been introduced, it will slowly establish in the new environment. Several decades may pass without any further spread of the exotic species. However, after this period, termed the lag phase, the spread of the species often becomes exponential. When the species has reached the exponential phase it becomes difficult and often uneconomic to control by chemical and mechanical control methods. However, several examples of the application of classical biological control have resulted in successful management of invasive plant species (e.g. Opuntia sp. in Australia, Euphorbia esula in North America, Salvinia molesta in tropical countries, and many others). Until now, no classical biological control of plant species has taken place in Europe.

Contacts

Coordinator

• Danish Forest and Landscape Research Institute DENMARK

Participant

• Petr PYSEK / Academy of Sciences of the Czech Republic Institute of Botany / CZECH REPUBLIC
• CABI Bioscience Switzerland Centre SWITZERLAND
• Annette OTTE / Justus-Liebig University of Giessen Landscape Ecology and Landscape Planning / GERMANY
• Ilze PRIEKULE / Latvia State Centre of Plant Protection LATVIA
• Eckart WINKLER / UFZ - Centre for Environmental Research Leipzig-Halle Department of Ecological Modelling / GERMANY
• Wolfgang NENTWIG / University of Berne Zoological Institute, / SWITZERLAND
• Max WADE / University of Hertsfordshire Dept. of Environmental Sciences / UNITED KINGDOM