engleski

The development of Lymantria dispar larvae on juvenile and mature foliage of Quercus ilex

Lymantria dispar is one of the most important forest pests in Europe and North America. It is highly polyphagous and feeds on more than 300 plant species, among which oaks (Quercus sp.) are most preferred. Until now it was thought that population of Lymantria dispar in Croatia is identical in both continental and Mediterranean region, but recent population dynamics research (outbreaks in continental region occur every 10 – 11 years and 4 – 5 years in Mediterranean) and molecular genetic analyses showed that there is a difference between them. Since in the Mediterranean region one of the main host tree species is Quercus ilex we conducted a laboratory experiment to see what is the performance of a Mediterranean population of Lymantria dispar on the Quercus ilex juvenile and mature foliage. Individual experiment contained 50 larvae on juvenile foliage and 50 larvae on mature foliage. Parallel with the individual experiment, a group experiment with 120 larvae on each rearing group was conducted. Larvae in indvidual experiment were weighed daily and pupae were sexed at the end of the experiment, also mortality of larvae was recorded every day. Gypsy moth larval mortality was low and development time was shorter on juvenile foliage with high pupation success in both indvidual and group rearing experiment as opposed to mature foliage where larval mortality was high and development time was prolonged with low pupation success. Evident differences in development between Lymantria dispar larvae on juvenile and mature foliage has shown that mature foliage is not suitable for larvae even in later instars. Several factors could influence the development success of Lymantria dispar larvae in Quercus ilex stands such as synchronization between budbreak and larval emergence and also nutritive value of Quercus ilex foliage and toughness of larval mandibles.

defoliation ; gypsy moth ; holm oak ; host plant ; outbreak

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