Reduction of infestation levels of the horsechestnut leafminer Cameraria ohridella Deschka & Dimic (Lep., Gracillariidae) through customary horticultural methods.

摘要

The horsechestnut leafminer Cameraria ohridella Deschka & Dimic (Lep., Gracillariidae) was introduced into Austria in 1989. Since then this small lepidopteran insect has spread over vast areas in Central and Eastern Europe, the Balkans and the Baltic. In Germany, it is a major pest of white flowering horsechestnut trees, leading to leaf dissication and early leaf fall. All currently known countermeasures have not been capable of controlling C. ohridella so far due to various reasons. The aim of this study, carried out during 1999-2000 in Bonn, Germany, was to prove the efficacy and feasability of customary horticultural methods in the reduction of infestation levels of C. ohridella. The emergence rates of C. ohridella were investigated by collecting infested leaves in the field, placing them in customary plastic boxes of defined size and treating them in different ways. Six different treatments and one control were examined. The most effective treatment was the coverage of the boxes with a thicklayer of earth or grass. Just few moths could emerge but not a single moths was able to penetrate these layers. Only 17.4% of the pupae could emerge when the leaves had been shredded and worked into the soil, whereas 28.1% emerged from intact leaves. Allother methods did not lead to a significant reduction in the number of emerged moths compared with the control.