Bulletin of Insectology (2009) 62, 203-208

Elisa Marchetti, Stefano Civolani, Marilena Leis, Milvia Chicca, W. Fred Tjallingii, Edison Pasqualini and Piero Baronio (2009)
Tissue location of resistance in apple to the rosy apple aphid established by electrical penetration graphs
Bulletin of Insectology 62 (2), 203-208
Abstract: A study of the constitutive resistance of the apple cultivar Florina, Malus domestica Borkh. (Rosaceae), to the rosy apple aphid, Dysaphis plantaginea (Passerini) (Homoptera Aphididae), was performed for the first time by the electrical penetration graph (DC-EPG) system, using the susceptible apple cultivar Smoothe as control. All experiments were conducted with apterous adult virginoparae. The results showed a constitutive resistance in Florina due to a much longer period before the first probe reflecting surface factors. Some weak indications were found for pre-phloem resistance and initiating phloem access was not affected as inferred from equal time to show phloem salivation. However, the complete absence of phloem ingestion indicates a major resistance factor in the phloem sieve elements, most likely in the sieve element sap. Surface factors could have affected tissue related variables and this should be studied further. Anyhow, the strong constitutive resistance in Florina, either on the surface alone or in the phloem as well, effectively prevented reliable experiments on induced resistance, previously detected by molecular methods.
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Database assignments for author(s): Stefano Civolani, Marilena Leis, W. Fred Tjallingii, Piero Baronio, Edison Pasqualini

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Dysaphis plantaginea	Apple (Malus)	Italy