The resistance of hazel (Corylus avellana) to hazelnut weevil (Curculio nucum L.- Coleoptera, Curculionidae). Part II. The physicochemical characteristics of the pericarp and dynamics of nut development and cultivar resistance to the pest

Abstract

Significant differences were found among the 22 studied hazel cultivars (Corylus avellana L.) in their resistance to hazelnut weevil (Curculio nucum L.) which is the main pest of this crop in Europe. The study investigated the relationships between the resistance of the cultivars to the pest and the physicochemical properties of the pericarp, i.e. the lignification dynamics, changes in thickness and hardness during nut development and the rate of nutlet development. Correlation analysis showed that there was no dependence between the physicochemical properties of the pericarp and the resistance of the hazel cultivars to the hazelnut weevil. Nut development dynamics were also found to be unrelated to resistance to the pest. Laboratory feeding experiments showed that during the initial feeding phase and at the time the insect searches for an oviposition site, it seems to prefer cultivars with the largest nutlets. However, in the period of intensive oviposition, traits other than nutlet size seem to be decisive for the beetles choice of cultivar.