Tasmanian grass grub - a significant threat to pastoral farming
in dryland regions
M.W.A. SLAY AND M.W. FISHER
AgResearch Poukawa Research Station, PO Box 8144, Havelock
North, New Zealand
E-Mail:
Proceedings of the New Zealand Society of Animal Production 2001. 61:
13-15
Tasmanian grass grub, first recorded in Canterbury in 1920, is
now well established in several areas of New Zealand. The adult beetles
fly in January and lay their eggs in the soil after mating. After
hatching, the larvae live in the soil and construct vertical tunnels
from which they emerge at night to feed on and denude pasture plants.
The effects of this pest on pasture were estimated by measuring pasture
with larval densities ranging from 21-574 m². Larval infestation
significantly reduced pasture mass in a linear fashion by around 5% per
100 larvae. For example, at one site from July to September, pasture
mass Y = -0.816X + 1852, R+ = 0.3; where Y = pasture mass (kg DM per ha)
and X = larvae per m². Losses in stock carrying capacities have been
estimated to vary between 0.5 and 5 stock units per hectare depending on
the farm carrying capacity and larval damage to pasture, resulting in
losses of up to $315 per hectare.
Keywords: NZSAPAB;
Tasmanian grass grub; pasture damage; production losses
Last Updated 7/08/01
