Recent information on Cameraria ohridella
In Germany, Cameraria ohridella (Lepidoptera: Gracillariidae - formerly on the EPPO Alert List) is now established throughout the country, and the public is increasingly concerned at the defoliation it causes to horse chestnut trees (Aesculus hippocastanum) in urban environments. A Symposium was organized by BBA in Braunschweig on ‘strategies for reducing infestations by the horse chestnut leafminer in public places on 2003-06-24/25. A special session was also dedicated to C. ohridella during the 2nd International Symposium on Plant Health in Urban Horticulture, held in Berlin, on the 2003-08-27/29.
Much information on possible control measures has been presented during these symposia. In large cities such as Berlin, Bonn and Hamburg, it is generally considered that the most efficient measure is the destruction of fallen leaves in autumn to reduce insect populations. New techniques to destroy leaves, such as the use of heated organic foam (originally designed for weed control), have been tested on a small scale and gave good results. The application of insecticide is difficult in urban environments but soil injections or drenches with systemic insecticides, or the use of biological products (e.g. Bacillus thuringiensis or neem extracts) are also being studied. Pheromone traps could also be useful to assess populations levels, and it is also envisaged to study ‘attract and kill’ or sexual confusion methods.
First record in Greece
During the Symposium in Berlin, the presence of C. ohridella in Greece was also reported (new record according to the EPPO Secretariat). The pest was first observed in Greece in 1996, although observations made by gardeners suggest that it was probably present at an earlier date. C. ohridella occurs both in wild and urban environments, but its damage is moderate due to the limited occurrence of horse chestnut in Greece (Avtzis & Avtzis, 2003).
EU project (Control of Cameraria – CONTROCAM)
An EU project is running from 2001 to 2004 and has the aim of:
- assessing the present and future potential impact of the pest on urban and natural ecosystems;
- developing integrated management strategies ;
- using the case of C. ohridella to make recommendations on the development of European strategies against biological invasions.
Spread continues in France
In France, a map published in Phytoma clearly shows that C. ohridella continues to spread towards the West. At the end of 2002, more than 40 départements were infested. In 2003, outbreaks were reported in the region of Ile-de-France. All regions are being consulted to assess the present situation of the pest over the whole French territory.
Anonymous (2003) Phyto Régions. Cameraria sur marronnier – Toujours plus à l’ouest.
Phytoma – La Défense des Végétaux, no. 565, p 4.
Avtzis, N.; Avtzis, D. (2003) Cameraria ohridella Deschka & Dimic (Lep : Gracillariidae) : a new pest on Aesculus hippocastanum in Greece
Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft, no. 394, 199-202.
Papers presented at the BBA Symposium on Cameraria ohridella, Braunschweig, DE, 2003-06-24/25.
Nachrichtenblatt des Deutschen Pflanzenschutzdienstes, 55(10), 201-244.
Papers presented at the 2nd International Symposium on Plant Health in Urban Horticulture, Berlin, 2003-08-27/29.
Balder, H.; Strauch, K.H.; Backhaus, G.F. (eds.) (2003) Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft, no. 394, 304 pp.