New Zealand Journal of Crop and Horticultural Science abstracts
Bioassays for measuring the resistance of different apple cultivars to the
development of leafrollers (Lepidoptera: Tortricidae)
C. HOWARD WEARING
KATE COLHOUN
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 resistance
of different apple (
Malus domestica Borkh.) cultivars to the development
of three leafroller species,
Planotortrix octo Dugdale,
Epiphyas
postvittana (Walker), and
Ctenopseustis obliquana (Walker). Neonate
larvae were released onto individual leaves of each cultivar in square plastic
petri dishes kept at 20deg.C. The development rate, size of larvae, and
survival, and the weight and sex of pupae were recorded and compared between
cultivars. No
C. obliquana larvae developed fully on `Granny Smith',
`Royal Gala', and `Prima', whereas 90-100% pupated on `Liberty' and `Red
Dougherty'.
P. octo larvae had high survival rates (80-100%) on all
cultivars but pupal weights were highest on `Red Delicious'.
E.
postvittana larvae also survived well (80-100%) on all cultivars but
development rates differed between cultivars, in part related to significant
differences in the proportion completing six instars. The bioassay method gave
repeatable results and successfully identified antibiosis and susceptibility to
leafroller development in apple cultivars.
Keywords tortricid; larval size and development; survival;
apple cultivar; plant resistance; antibiosis
H98048
Received 7 October 1998; accepted 10 March 1999
PDF file of entire paper: medium quality (656K); (scanned from paper original: notes about this process)
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