title: Two pear accessions evaluated for susceptibility to pear psylla Cacopsylla bidens (Šulc) in Israel.
abstract: BACKGROUND
  The pear psylla, Cacopsylla bidens (Šulc), is one of the most damaging pests of commercial pear orchards in Israel. Psylla control is a major obstacle to efficient integrated pest management, necessitating research on cultivars with natural resistance to pear psylla. Recently, two pear accessions (Py.760-261 and Py.701-202) from the local Newe Ya'ar fruit tree live collection were identified as having apparent resistance to pear psylla. Our goal was to evaluate the resistance of these two accessions relative to the commercial cultivar Spadona Estiva, and to identify whether the resistance mechanisms in the former interfere with insect colonisation of the plant (antixenosis) or inhibit insect growth, development, reproduction and survival (antibiosis).
  
  
  RESULTS
  Settlement and development of C. bidens was evaluated under natural conditions (pear orchard), semi-natural conditions (potted plants), and on detached branches and leaves (laboratory). Our results indicate that the selection Py.760-261 is 10 times more resistant than Spadona while Py.701-202 is five times more resistant.
  
  
  CONCLUSIONS
  The resistance mechanism in both accessions appears to be antibiosis affecting nymph survival. These resistant accessions may be used as rootstock or as a source of resistant genes in breeding programmes.
authors.affiliation: Migal Galilee Research institute, P.O. Box 831, Kiryat Shmona, 11016, Israel.
authors.forename: Liora
authors.initials: L
authors.lastname: Shaltiel-Harpaz
authors.forename: Victoria
authors.initials: V
authors.lastname: Soroker
authors.forename: Rika
authors.initials: R
authors.lastname: Kedoshim
authors.forename: Roy
authors.initials: R
authors.lastname: Hason
authors.forename: Tamar
authors.initials: T
authors.lastname: Sokalsky
authors.forename: Kamel
authors.initials: K
authors.lastname: Hatib
authors.forename: Irit
authors.initials: I
authors.lastname: Bar-Ya'akov
authors.forename: Doron
authors.initials: D
authors.lastname: Holland
mesh_terms: D000818:Animals; D060467:Disease Resistance; D004198:Disease Susceptibility; D006430:Hemiptera / Q000502:physiology*; D007557:Israel; D031989:Pyrus / Q000276:immunology*; D012098:Reproduction; D016019:Survival Analysis
keywords: Cacopsylla bidens; antibiosis; oviposition; pear psylla; resistant accessions