INVASIVE ALIENS
Some notable wins in alien bio-control
T
he Gauteng
Smallholder has
highlighted before the
use of biocontrol in the battle
against invasive alien plants.
In a recent edition of the
journal Bothalia - African
Biodiversity & Conservation, a
paper was published giving
the status of this battle. Dr
Costas Zachariades and his
colleagues have found that
there have been an encourag-
ing number of successes in
the use of natural enemies
such as insects, mites, and
pathogens, which are
organisms such as fungi that
cause diseases in plants.
South Africa has a history of
more than a century of the
use of biological agents to
combat invasive alien plants
(IAP), with significant control
of several Cactaceae,
Australian Acacia species and
floating aquatic plants, and
many other IAPs having been
achieved since 1913.
Recently, biological control
has benefited from improved
international collaboration, a
streamlined application
process for the release of new
biological control agents
(resulting in the approval of
19 agents against 13 IAP
species since 2013), and
increased funding and
capacity.
The inclusion of biocontrol as
part of the Working for Water
programme led to significant
increases in funding for the
campaign. After 1994 there
was much greater collabora-
tion possible with many other
countries, including the
regions of origin of the
invasives. South Africa is a
signatory to the international
Convention on Biodiversity,
which has enabled a more
structured approach to
biological diversity transfer.
The work was further enabled
by a streamlining in 2013 of
the process that has to be
followed for the release of
biological agents.
So what progress has there
been in the use of biological
control in Gauteng?
One of the greatest successes
has been against the Queen
19
www.sasmallholder.co.za
of the Night cactus (Cereus
jamacaru). Although one still
sees it in gardens, in the wild
it has been brought under
complete control through the
release of the mealybug and
the longhorn beetle.
The first time a biological
agent was released against
the water hyacinth
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