Environmental Engineering Reference
In-Depth Information
nature cause a regular and tremendous mortality of many pests in many parts of the
world and do, in fact, constitute an e cient and extremely important natural con-
trol factor'. Historically, interest in trying to harness this control potential emerged
around the same time (1880-90) as the fi rst attempts to exploit insect natural
enemies. However, this was directed at mass producing and applying fungal inocu-
lum from naturally-occurring outbreaks on both indigenous and exotic pests to
increase their e cacy, especially using the ubiquitous white and green muscardine
fungi,
Beauveria banana
and
Metarhizium anisopliae
, respectively (Samson
et al
.
1988)
As with invasive arthropods, the history of biological control of invasive plants is
dominated by entomologists, and, indeed, the use of fungal pathogens as biological
control agents is a relatively modern event, not taking off until the 1970s (Evans
et al
. 2001). h e highly invasive plant,
Lantana camara
, from South America was
one of the fi rst targets and the same scientists who pioneered the biological control
of the cottony cushion scale took centre stage. Early success with this was limited,
however, due mainly to the complex of intra- and inter-specifi c hybrids involved.
But other targets had less problematic taxonomies, such as the New World prickly
pears (
Opuntia
spp.) which became a major problem in Australia in the late 19th
century. A well-publicized major success was achieved against these plants in the
1920s through the release of the moth
Cactoblastis cactorum
, which was collected
from the Americas. h is success stimulated eff orts against other invasive plants.
Classical biological control has grown since these early times and has now been
used extensively across the globe against approximately 550 invasive arthropods
and 130 invasive plants in agriculture (see Greathead and Greathead 1992 and
Julien and Gri ths 1998 for a review of projects and outcomes).
in natural ecosystems
Classical biological control is now being increasingly used for the management
of invasive species in natural ecosystems, particularly against invasive plants and
insects. But this effort to date has largely been driven by the fact that these plants
and insects are also a major problem in agriculture; in some countries, additional
analyses have highlighted the importance of the problems caused by invasive spe-
cies in natural ecosystems. Countries leading the way on this are Australia, New
Zealand, South Africa, and the USA but a few other countries across the globe have
a low level of activity. Australia is targeting several major invasive plants that affect
natural ecosystems: for example,
Acacia nilotica, Ageratina riparia, Cryptostegia
grandifl ora
, and several others. Success has been achieved against some of these
plants. For example, the European plant, St John's wort (
Hypericum perforatum
)
has been a problem in parts of south and west Australia since the mid-1880s. The
plant is mostly recorded as a problem in pasture (where it is poisonous to livestock)
but it also invades native forests where it is a fi re hazard in the summer months. A
long-standing biological control effort using introduced herbivorous insects has
