June 1997, Volume 18 No. 2

Conference Reports

European Weed Control Workshop

The 9th Workshop of the Main Subject Area Biological Weed Control of the European Weed Research Society (Europäische Gesellschaft für Herbologie/Société Européenne de Malherbologie; EWRS) was held on 17-18 February 1997 at the Meeting Hall, Technical University of Braunschweig, Germany

The EWRS Workshop was organized at the request of Professor Dr Heinz Müller-Schärer, Institut de Biologie Végétale, Université de Fribourg (Switzerland) by Dr Christine Boyle, Institute of Microbiology, Technical University of Braunschweig and Dr Thomas Eggers, Weed Research Institute, Federal Biological Research Centre for Agriculture and Forestry (BBA), Braunschweig (Germany). There were 65 participants from 12 nations. A brochure containing the programme, abstracts of the contributions, and an address list of the participants is available.

A third of the one-and-a-half-day workshop was devoted to the perspective of biological control of weeds belonging to the genera Orobanche and Striga. Parasitic plants such as these are gaining significance as weeds, owing to the growing intensification of Mediterranean and subtropical plant cultivation. For this reason, the European working group has taken up work on this subject. The introduction was made by the FAO Weed Officer, Dr R.E. Labrada. Under the chairmanship of Dr J. Sauerborn, University of Giessen and Dr J Kroschel, University of Hohenheim, seven reports concerning pathogens and phytophagous fauna attacking these weed species were presented.

Among the general contributions on biological weed control, attention was particularly focused on the presentation by Dr E. Bode (Biology Division, BBA Department for Plant Protection Products and Application Techniques) on regulations (including the FAO Code of Conduct for the Import and Release of Exotic Biological Control Agents, February 1996) and laws governing import and release of agents for biological control of pathogens. Special attention was drawn to the proposal of the European Council concerning recommendations covering bio-diversity. This proposal could seriously limit the possibility of introducing biological agents.

Eight oral presentations and five posters concerned European investigations of classical biological weed control overseas (Parthenium hysterophorus, Salsola kali and Tripleurospermum perforatum in North America, Hieracium pilosella in New Zealand and North America, Cynoglossum officinale in Canada and the USA, as well as Chondrilla juncea and Cytisus scoparius in Australia).

Investigations of native weeds and their antagonists in central European crops were the topic of seven further presentations (amongst others Chenopodium album/Ascochyta caulina, Amaranthus spp., Convolvulus arvensis/Phomopsis convolvulus and Rumex obtusifolius). Possible uses of control agents (as well as formulation of biological pesticides with bioencap-sulation ) were discussed.

Dr. Paul Hatcher, Department of Agricultural Botany, University of Reading, was elected as the new chairman of the EWRS Main Subject Area.

A visit to the BBA (Institute for Plant Protection of Field Crops and Grassland, Institute for Plant Protection in Horticulture, Institute for Weed Research) met with great interest among the participants.

After the workshop some 30 colleagues, currently working on the biology and ecology of Cirsium arvense, followed the invitation of Dr. A. Gassmann, IIBC, Delémont, Switzerland, to meet for an exchange of experiences and ideas. In addition the working groups Chenopodium album, Orobanche spp. and Senecio vulgaris of the COST Action 816 Biological Weed Control in Europe met at the BBA to discuss their working programmes.

The programme of the meeting and additional information on projects of biological control of weeds are available on the Internet at:

http://www.unifr.ch/plantbio/cost816

A written version of this report can be obtained by sending an e-mail to: heinz.mueller@UNIFR.CH

By: Christine Boyle and Thomas Eggers, Braunschweig

Water Hyacinth

A meeting of experts in the biological control of water hyacinth (Eichhornia crassipes) was held in Washington DC on 18-19 March 1997, organized by USDA Agricultural Research Service and hosted by World Bank. The meeting reviewed the status of biological control of water hyacinth, particularly in the context of its alarming recent spread in Africa and the economic and environmental problems of using mechanical or chemical control methods against it. Participants in the meeting included groups currently implementing water hyacinth biological control in Mexico, Malawi, Côte d'Ivoire, Benin, Papua New Guinea, South Africa, Australia, and the USA, as well as international organizations like World Bank, IIBC, the International Institute of Tropical Agriculture (IITA), the Food and Agriculture Organization of the United Nations (FAO) and the Commonwealth Science Council.

The meeting heard of new biological control activities against water hyacinth, often on a small scale, in Mexico, Mali, Côte d'Ivoire, Ghana, Benin, Zambia, Malawi, Zimbabwe, Uganda, Kenya, South Africa and Papua New Guinea. Most involve well-known weevil agents, Neochetina eichhorniae and N. bruchi and the moth Sameodes albiguttalis, but the Plant Protection Research Institute of South Africa is studying some exciting new agents from tropical America, including a mirid bug and a grasshopper, and CSIRO Australia is studying a new moth. The project in Papua New Guinea, assisted by CSIRO, has had very substantial success in clearing large areas of water hyacinth in just a few years.

Much attention focused on Africa, where in the past decade, water hyacinth has spread to infest virtually all water systems on the continent, causing particular and new problems to the river and lagoon systems of coastal west Africa and the Great Lakes of East Africa, particularly Lake Victoria. A number of donor-funded projects were underway, the most signficant of which was a World Bank project on Lake Victoria which included an US$ 8 million component for water hyacinth management. So far, much interest had focused on mechanical and chemical control, despite 30 years worldwide experien-ce in the limitations of this approach. Companies promoting these tech-nologies stand to make large sums from donor-funded African prog-rammes. Proponents of biological control have been less aggressive in this recent explosion of interest in water hyacinth, perhaps because they have comparatively fewer resources and less to gain financially.

The workshop went a long way in redressing this imbalance with donors, and reconfirmed the importance of biological control as the foundation of any sustainable water hyacinth management strategy. It ended with a proposal for the establishment of a Global Working Group on Water Hyacinth under the International Organization of Biological Control (IOBC), with the objectives of promoting further exploration and development of biological control agents, ensuring that biological control is a key component of water hyacinth management programmes, and the development of mycoherbicides for water hyacinth.

Please contact BNI if you are interested in more information on this Workshop or Working Group.

Insect Parasitoids Workshop

The 6th European Workshop on Insect Parasitoids was held in Valencia, Spain on 1-4 March 1997. The meeting was organized by Maria Jesus Verdú and her colleagues of the University of Valencia. Over 80 participants from 13 countries presented 41 papers and 30 posters. Abstracts have been published in the Boletin de la Asociacion Espanola de Entomologia, Suplemento al Volumen No. 21 (1997).

The workshop was divided into six sessions: parasitoid physiology, development and behaviour; physical sensory ecology; genetics; ecosystem effects, parasitoid communities and multitrophic relationships; host (habitat) location and host dis-crimination; foraging, sex and survival.

Although no session focused specific-ally on biological control, several presentations and posters were of special interest for biocontrol and IPM practitioners. J.M. Delpuech (University of Lyon) provided evidence for a substrate-borne sex pheromone in Trichogramma and inhibition of sexual communication by insecticides. F. Gracia-Mari (University of Valencia) presented a study on the impact of native and introduced natural enemies of the citrus leaf-miner in Spain. F.L. Wäckers (ETH Zürich) showed that food supplements increase the effectiveness of Anisopteromalus calandrae, a parasitoid of the cowpea weevil Callosobruchus chinensis. S. Grenier (INSA, Villeurbanne, France) and M.L. Dindo (University of Bologna, Italy) presented a review and their latest findings on artificial rearing of parasitoid insects.

The next workshop will be held in Delft, The Netherlands, in April 2000.

Horse Chestnut Leaf-mining Moth

A workshop on the horse chestnut leaf-mining moth (Cameraria ohridella) was held in Vienna on 17-18 March 1997. It was organized by the Federal Forest Research Institute in Vienna and the International Society of Arboriculture. The workshop was attended by more than 100 people.

The meeting started with presentations describing the pest biology and the situation in Austria and the neigh-bouring countries. Cameraria ohridella was first observed in Macedonia in 1983 and described in 1986. It was accidentally introduced into Austria in 1989 and has since extended its distribution to Italy, Germany, the Czech Republic, Slovakia and Hungary. Damage is severe, especially in Austria where total defoliation is often observed. Cameraria ohridella damage attains great public attention, especially in Austria because horse chestnut is a very common ornamental tree, frequently planted in gardens, parks and along roads. The origin of the pest is unknown. It was first suggested that it originates from the Balkans, the area of origin of its main host, Aesculus hippocastanum, but there are several arguments suggesting that it may originate from other regions where native Aesculus spp. are found, i.e. North America, the Himalayas, Japan or China.

The second part of the workshop consisted of presentations on potential control methods. Among these, classical biological control by the importation of exotic natural enemies was proposed by M. Kenis (IIBC). M. Stolz and C. Lethmayer (Federal Office and Research Centre for Agriculture, Vienna) presented the native para-sitoids found on C. ohridella in Central Europe and their potential for inunda-tive releases. Other control methods included aerial application of Dimilin and closely related substances, cultural practices such as the removal or composting of dead leaves, systemic insecticides by stem injection or infusion, or a less conventional electrotechnic method using cosmic energy.

The conclusion of the workshop was that classical biological control offers the only potential long-term solution for this pest. IIBC and the Federal Office and Research Centre for Agriculture in Vienna decided to develop a collaborative programme for the introduction of exotic natural enemies into Central Europe.