The Fate of the Grassland Froghopper
The creatures in this photo are not locusts; they are a species of large, flightless
grasshopper known as the Grassland Froghopper (Perelytrana rana Sj�stedt).
These rare grasshoppers were first identified in a native grassland reserve
near Mitiamo, in the summer of 2004. Prior to this, the Grassland Froghopper was not
known to occur in Victoria.
Another species of native grasshopper, the Australian Plague Locust (Chortoicetes
terminifera), also occurs
naturally in the Mitiamo area. Locusts and Froghoppers have co-existed in these
grasslands for thousands, if not millions, of years. It was cause for great concern
when the prospect of spraying this site for locusts arose in late 2005. Unfortunately,
before the issues could be raised, approval was given for the Department of Primary
Industries (Victoria) to spray this, and many other grassland reserves, with the biological
insecticide Green Guard®,
containing Metarhizium fungus.
An inspection of the site was carried out a few weeks after the spraying. As expected,
there were dead locusts everywhere, but also many other grasshopper species. At
least ten other native grasshopper species occur in this area. It was quite a gloomy
scene compared to that of a few weeks earlier when the site was teeming with life;
with locusts, grasshoppers, fat-tailed dunnarts, lizards and insectivorous birds
abounding.
Only dead Grassland Froghoppers could be found during the inspection. Despite the
fact that on this particular site, only the edges were supposed to be sprayed, there
were dead Froghoppers right throughout the reserve. It's possible the authorities,
through their locusts spraying, have now rendered the Grassland Froghopper extinct
in Victoria.
Victoria's native grassland remnants are all relatively small, isolated patches,
surrounded by agricultural land. Being an Australian native species, the Australian
Plague Locust showed preference for these grassland remnants as sites for over-wintering
egg-beds. According to the
Department of Primary Industries website, a total of
7000 hectares of national park and reserve, were sprayed for Locusts around Mitiamo;
this would have to include all of the native grasslands in that location. This means
that most of the potential habitat for Grassland Froghoppers in Northern Victoria
was also sprayed. The chances of this species surviving such attacks are remote.
Being flightless, they won't be able to recolonize these isolated grassland sites.
Green Guard® is a relatively new insecticide and has not previously been trialled
for broad-scale use in Victoria. Therefore, little is known about its level of persistence,
and effects, on Victoria's fragmented environment. It's a mistake to assume that
simply because something is biological that it is therefore safe for the environment.
Whilst it is currently a far better alternative than chemical insecticides, for
use on farmland; no broad-scale use of insecticides should have occurred on Victoria's
isolated grassland reserves.
The most recent publicised use of Metarhizium, was to manage locusts, on irrigated
dairy farms on Gunbower Island. In this situation, the locusts were intruding on
an artificial irrigated landscape, where the use of Metarhizium may pose a minimal
risk to natural ecosystems.
Victoria's native grassland remnants have been set aside to protect our indigenous
species and what took place with the spraying, is nothing short of an environmental
tragedy. Several species of native grasshopper were killed, including special examples
like the Grassland Froghopper that might never be seen again.
Eris O'Brien,
Mitiamo
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