Resistance of some Pyrus communis cultivars and Pyrus hybrids to the pear psylla Cacopsylla pyri (Homoptera, Psyllidae).

摘要

Pear psylla (Cacopsylla pyri) is a very important problem in French pear orchards. Resistant cultivars would offer an alternative to chemical control. However, all major cultivars grown in France are susceptible to C. pyri. Some Pyrus interspecific hybrids are known to be resistant to pear psylla. However, the bad quality of fruits limit the usefulness of these genotypes in breeding programmes. To identify other resistant genotypes, a screening of 16 Pyrus genotypes was conducted in a mesh-covered tunnel for 4-5 months. The cultivar Williams, known to be sensitive to pear psylla, was considered as the susceptible control. The hybrids Katman and NY10355 were considered as the resistant controls. Observations were conducted on 7 or 8 plants per genotype. The eggs were recorded on the eight upper leaves of the shoots 15 days after the release of adults in the tunnel. The nymphs were recorded on the eight upper leaves of the shoots at 36, 63 and 98 days after infestation. The shoot and the leaf states were recorded after 134 days. Several interspecific hybrids (BP6, BP81, Gutui and P20R5A70) were identified as highly resistant. The results also confirmed the resistance of Spina Carpi, an old Italian cultivar. Furthermore, three P. communis genotypes were newly identified as resistant: cultivars Doyenne de Poitiers and D'Aout Lamer and the hybrid SEL80-79-69 (Docteur Jules Guyot x Bella di Giugno). However, these genotypes exhibited medium levels of resistance to pear psylla..