New Zealand Journal of Agricultural Research abstracts
Impact of clover root weevil Sitona lepidus (Coleoptera:
Curculionidae) larvae on herbage yield and species composition in a
ryegrass-white clover sward
P. J. Gerard
D. L. Hackell
N. L. Bell
AgResearch
Ruakura Research Centre
Private Bag 3123
Hamilton 3240, New Zealand
pip.gerard@agresearch.co.nz
Abstract The effects of root herbivory at five
densities of Sitona lepidus larvae (overall means between 4
and 333 larvae m–2) were assessed over 2 years on newly
established perennial ryegrass-white clover swards in a small plot
trial. Initial larval establishment in autumn 2003 was positively
related to clover content in plots, and there was no significant impact
on clover herbage yield in the first year. Nodule damage in winter 2003
increased with larval density, and results suggested an
overcompensatory response in nodule production. A 34–35% reduction in
clover yield between highest and lowest S. lepidus densities
was recorded for both cultivars in the second year, with greatest
losses in spring 2004. This coincided with reductions in clover root
and stolon weights. Plant parasitic nematodes and grass grub larvae
were most abundant in the plots with lowest weevil numbers. These
results confirm field observations that S. lepidus is a major
pest of pastures.
Keywords clover; Costelytra zealandica;
nematodes;
root herbivory; Sitona lepidus
A07005; Online publication date 5 July 2007; Received 12 January
2007; accepted 30 May 2007
New Zealand Journal of Agricultural Research, 2007, Vol. 50:
381–392
0028–8233/07/5003–0381 © The Royal Society of New Zealand 2007
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