Development and parasitism of the horse-chestnut leafminer,Cameraria ohridella, in different leaf types and canopy levels

Abstract

Authors provide a 6-year study about aspects of development of Cameraria ohridella and its parasitoids in different leaf types of horse-chestnut trees. Investigations were carried out near Hédervár, North-West Hungary between 1999 and 2004.It was ascertained that in large leaves at low foliage levels as well as in large leaves exposed to direct sunlight developed more moths than in other leaf types of equal quantity (i.e. equal number of leaflets). On the other hand, there were not considerable differences between shaded and sun-exposed leaves in this regard if their quantity is measured in grams. Moreover, comparing the numbers of hatched moths per unit leaf weight, the values for minute leaves were the highest. The differences were explained on the basis of diverse microclimatic conditions in the mines, height preference of the moth or variations in dry weights per unit leaf area.Parasitism of Cameraria ohridella showed significant yearly differences between canopy levels and a tendency of changes during the years. Parasitism was higher in shaded than in sun-exposed leaves. Lowest values were found in minute leaves among all leaf types investigated what was explained with a presumed foraging behaviour of the parasitoids.Structure and species constitution of the parasitoid community and its changes in time are discussed in different leaf types. Temporal changes of several characteristics found in different leaf types refer to an adaptation process of the horse-chestnut leafminer.