New Zealand Journal of Crop and Horticultural Science abstracts
Pear sawfly (Caliroa cerasi) (Hymenoptera: Tenthredinidae) host
preference and larval development on six Pyrus genotypes
P. W. Shaw
D. R. Wallis
P. A. Alspach
L. R. Brewer
The Horticulture and Food Research
Institute of New Zealand Limited
Nelson Research Centre
P.O. Box 220
Motueka, New Zealand
email: pshaw@hortresearch.co.nz
V. G. M. Bus
The Horticulture and Food Research
Institute of New Zealand Limited
Hawke’s Bay Research Centre
Private Bag 1401
Havelock North, New Zealand
Abstract The larvae of the sawfly Caliroa cerasi
can cause serious damage to pear (Pyrus sp.) foliage particularly in
organic or reduced-spray orchards. Six pear cultivars and selections, three
with low susceptibility to pear slug damage and three with high susceptibility,
were subjected to oviposition choice tests in the field and subsequent larval
development rates were monitored to clarify the nature of the variable susceptibility.
Observed differences in oviposition rates corresponded with the low and high
susceptibility categories of the genotypes. Larval development rates differed
among genotypes and were inversely related to density of hatched eggs (a surrogate
measure of leaf damage). These results confirm that host oviposition preference
is a key factor influencing susceptibility to pear slug. It is further argued
that feeding-induced plant resistance and larval migration could be important
factors influencing pear sawfly populations on pear trees.
Keywords pear slug; resistance breeding; oviposition;
larval development; organic production
H04035; Received 14 April 2004; accepted 1 July 2004; Online publication
date 9 September 2004
New Zealand Journal of Crop and Horticultural Science, 2004, Vol. 32:
257-262
0014-0671/04/3203-0257 $7.00 © The Royal Society of New Zealand
2004
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