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Levels and components of resistance to Amphorophora idaei in raspberry cultivars containing different resistance genes
Author(s) -
BIRCH A. N. E.,
JONES A. T.
Publication year - 1988
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1988.tb03334.x
Subject(s) - cultivar , biology , nymph , aphid , instar , blowing a raspberry , horticulture , fecundity , infestation , botany , population , larva , demography , sociology
SUMMARY Levels and components of resistance to Amphorophora idaei in raspberry cultivars containing different A. idaei resistance genes were studied under infestation tunnel, glasshouse and laboratory conditions. Each test consistently ranked raspberry cultivars, with increasing levels of resistance in the order, non‐resistant (cv. Mailing Jewel), resistant cultivars containing minor genes, major gene A 1 , gene A 10 (red raspberry) and gene A 10 (black raspberry) respectively. Resistance was expressed in three different ways; decreased alatae settling and feeding, decreased apterae settling and decreased aphid fecundity and rate of nymphal development. Following exposure to a large population of alatae, significantly fewer aphids settled on A 1 , A 10 and to a lesser extent, minor gene‐containing cultivars, compared to cv. Mailing Jewel. More alatae settled on the top than the bottom zone of non‐resistant, minor gene resistant and two of four A 1 ‐containing cultivars; alatae settling was low on all zones of A 10 ‐containing raspberries. Aphid fecundity and nymph development patterns on different cultivars and resistance classes were similar to those found for alatae settling. After 7 days reproduction more than 30% of the nymphs developed to third or fourth instar on cv. Mailing Jewel, whilst on minor gene and major gene‐containing cultivars the total number of nymphs and the proportion of later instars decreased. On resistant cultivars the nymphs were found mainly on the middle and bottom leaf zones, compared to cv. Mailing Jewel. A rapid (48 h) screening test using floating leaflets was developed and, on the basis of apterae settling, ranked cultivars reliably; it was particularly effective in distinguishing moderate and strong resistance to strain 1 A. idaei. Gene A 1 ‐containing cultivars bred in England were much more resistant to strain 1 A. idaei than those bred in Scotland. Possible reasons for this difference are discussed, in relation to modified screening procedures and to the control of the viruses transmitted by this aphid vector.