OBSERVATION ON THE RESISTANCE OF THE HAZELNUT (CORYLUS AVELLANA L.) TO THE HAZELNUT WEEVIL (CURCULIO NUCUM L., COLEOPTERA, CURCULIONIDAE)
In the course of a 9-year investigation (1981–1989) considerable differences were found in the resistance to hazelnut weevil of 25 hazelnut cultivars grown in southern Poland. Resitance was determined on the basis of the percentage of the total yield of nuts damaged by the pest larvae. Six classe of resistance were established, from class 1 (resistant cultivars), to class 6 (very susceptible cultivars). A close positive correlation was found between the number of punctures on the growing nut pericarp resulting from feeding by the adult beetles and the class of cultivar resitance, with the correlation coefficient r = 0.957 significant at 1% level. A higher level of total and reducing sugar in the endosperm tissue of the growing nuts increased the attractiveness of the hazelnut cultivar as a food and oviposition site the pest beetles. Correlation coeficients of relations between the total and reducing sugar content in the endosperm, and the class of cultivar resistance, were significant at 1% level (r = 0.974 for total sugars, and r = 0.880 for reducing sugars). It is suggested that sugar content, i.e. the quality of the food of the pest beetle during the oviposition period, is one of the reasons for differential hazelnut cultivar resistance to the hazelnut weevil.
Piskornik, Z. (1992). OBSERVATION ON THE RESISTANCE OF THE HAZELNUT (CORYLUS AVELLANA L.) TO THE HAZELNUT WEEVIL (CURCULIO NUCUM L., COLEOPTERA, CURCULIONIDAE). Acta Hortic. 317, 163-170