RESISTANCE TO PEAR PSYLLA NYMPHAL FEEDING OF GERMPLASM FROM CENTRAL EUROPE

Pear psylla (Cacopsylla pyricola Foërster) is the most serious pest of the European pear (Pyrus communis L.) in the production regions of Europe and North America. Nine plant germplasm introductions of pear from Central Europe recently released from plant quarantine were evaluated for nymphal feeding antixenosis, a primary mode of resistance known to be correlated with ovipositional antixenosis and antibiosis (i.e. nymphal mortality and reduced developmental rate). Five single-shoot budded trees were grown in the greenhouse without pesticide application. The top two youngest fully expanded leaves were infested with ten 2nd and 3rd instar nymphs from a young laboratory colony. The number of surviving nymphs and the number of actively feeding nymphs was recorded after two days. Three cultivars from Yugoslavia, ‘Karamanka’, ‘Jerisbasma’, and ‘Vodenjac’, plus NY 10353 (a resistant control of P. ussuriensis Max. ancestry) were significantly more resistant to nymphal feeding than the susceptible control, ‘Bartlett’, and the cultivars ‘Junsko Zlato’, ‘Lida’, ‘Orlovskaya’, ‘Oranzhevaja’, ‘Nadejda’, and the selection IV 12. These objective data confirm field observations made in Europe of the Yugoslavian cultivars, and increases the number of psylla-resistant genotypes available for breeding new cultivars.

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