New Zealand Journal of Crop and Horticultural Science abstracts
Bioassays for measuring ovipositional and larval preferences of leafrollers
(Lepidoptera: Tortricidae) for different cultivars of apple
C. HOWARD WEARING
The Horticulture and Food Research
Institute of New Zealand Ltd
Clyde Research Centre
RD 1 Alexandra
Central Otago, New Zealand
email: hwearing@hort.cri.nz
Abstract Bioassays are described for measuring the
ovipositional and larval preferences of three leafroller species,
Planotortrix octo,
Epiphyas postvittana, and
Ctenopseustis
obliquana, for different apple (
Malus domestica) cultivars.
In four-cultivar choice tests, mated female moths were offered terminal shoots
in a large screen cage; first instar larvae selected terminal leaves in a
smaller test arena. There were high levels of oviposition and settlement on all
cultivars which agreed with field evidence of their susceptibility. However,
there was overall higher oviposition of the three leafroller species (combined)
on `Royal Gala' compared to `Jonafree', and for
E. postvittana, higher
oviposition on `Liberty' than `Jonafree'. These cultivar preferences were also
expressed in the responses of the first instar larvae of the respective
species. The preference of
E. postvittana larvae for `Liberty' and
`Royal Gala' rather than `Fiesta', and the preference of
P. octo larvae
for `Liberty' rather than `Jonafree', were not matched by adult oviposition
behaviour of the species.
C. obliquana showed no significant cultivar
preferences but the acceptance ranking of the cultivars was the same in both
the oviposition and larval tests. The bioassays are considered suitable for
testing of leafroller oviposition and larval preferences using a wider genetic
pool of apple cultivars in parallel with measurements of leafroller
colonisation in the field.
Keywords tortricid; larval preferences; oviposition; apple
cultivar; plant resistance
H98024
Received 29 May 1998; accepted 8 July 1998
PDF file of entire paper: medium quality (732K); (scanned from paper original: notes about this process)
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