Environmental Engineering Reference
In-Depth Information
Classical biological control has also been considered for invasive species in
other taxa that have impacts on biodiversity; for example, land snails, amphibians,
and mammals. h ere has also been research eff ort on biological control for use
against invasive sea- and freshwater organisms: comb jellies, mussels, crabs, and
fi sh. Much of the work on biological control has been on researching potential but
some projects have been implemented.
One of the most disastrous biological control projects was that conducted
against the giant African snail (
Achatina fulica
) on several tropical islands, e.g. the
Hawaiian islands in 1955. Several predatory snails and a predatory fl atworm were
used but major problems arose because the predatory snails, and possibly the fl at-
worm, attacked snails native to the islands and in some cases seem to have driven
the species to extinction (Civeyrel and Simberloff 1996). h is was one example
project that reinforced the principle of the need always to use host-specifi c natural
enemies and the need for ecological risk assessment (see below).
In Australia the potential of using viruses for the control of the cane toad (
Bufo
marinus
), a species introduced into several countries for control of white grubs, has
been investigated but these have been found to be lethal to native frogs so will not
be used. Other options are being investigated. Viruses have also been used for the
control of some invasive mammals; the most well publicized example being that
of the myxoma virus for the control of the European rabbit (
Oryctolagus cuniculus
)
in Australia and in the UK (Fenner and Myers 1978), but more recent work on
viruses in Australia has raised public concern about the use of pathogens. More
recent research in biological control in Australia and the USA has focussed on
fertility control for a range of species.
Active research is being conducted on the potential for the biological con-
trol of marine and freshwater invasive species but a central issue has been the
di
culty of how to measure the host specify of potential control agents in such
complex environments h e European green crab (
Carcinus maenas
) has become
invasive on the coasts of Australia, Japan, North America, and South Africa.
Physical and chemical control measures have been tried but are not eff ective
and thus studies have been underway in Australia and in the USA on biological
control. Many pathogens, parasites, and predators are known to attack the crab
but the focus of research has been on a rhizocephalan (a barnacle) parasitic cas-
trator from Europe and the mechanisms of host location and compatibility
(Kuris
et al
. 2005). Success has been achieved though against the Atlantic comb
jelly (
Mnemiopsis leidyi
) which is a serious invader of the Azoz, Black, Caspian,
Marmara, and Mediterranean Seas. It was probably spread to these areas via
ballast water in trade ships. Several natural enemies of the comb jelly are known
but concern has always been about possible non-target eff ects and how these can
be assessed, but in the end biological control has been fortuitous. A predaceous
comb jelly,
Beroe ovata
, arrived accidentally in the Black Sea sometime in the late
1990s and seems to have been responsible for the collapse in the Atlantic comb
jelly (Anon. 2004).
