“…Quamme (1984) evaluated several pear species and also a number of European per cultivars from the point of view of psylla resistance and has found some of them to be more or less resistant to this pest. Several authors investigated great many further European pear genotypes in the past twenty five years (Quarta & Puggioni 1985, Briolini et al 1988, Butt et al 1988, Berrada et al 1995, Puterka et al1993, Kocsisné et al 2005, Robert & Raimbault 2005, Bell & Stuart 1990, Bell 1992, 2003, Bell & Puterka 2004, Sestras et al 2009, Bell 2009) and detected several cultivars, clones, wild seedlings, ancient and local genotypes to be resistant or highly tolerant to this pest. Most studies were made with field observations (Quarta & Puggioni 1985, Briolini et al 1988, Berrada et al 1995, Puterka et al1993, Kocsisné et al 2005, Robert & Raimbault 2005, Sestras et al 2009, Bell 2009 and great many studies were made in the laboratory, too, by rearing psylla larvae on plant material (Harris 1973, Butt et al 1988, Bell & Stuart 1990, Bell 1992, 2003, Puterka et al 1993, Bell & Puterka 2004.…”