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Explora: Environment
and Resource Data should determine biocontrol success

using natural enemies from these invasive species’ native program of Australian Acacia spp. in South Africa is a
ranges is an attractive option to reduce the effect of alien success story that has benefited invasive management
plants in the invaded environment. South Africa is a world actions that are purported to be an exemplar for other
3,4
leader in the biocontrol of weeds with extensive programs countries experiencing similar Acacia invasions.
on a multitude of different plant species. Among these This critical review highlights the weak scientific base
5,6
programs is the biocontrol of Australian Acacia spp. using for the current perceptions, which have been based on the
seed-reducing agents, which is lauded as a classic example predominance of expert opinion in shaping environmental
of biocontrol of invasive species management. 7-12 policy around the management of invasive plant species
We propose that the purported success of the mostly and motivation for government funding. We show here
gall-forming biocontrol agent programs on Australian that: (1) there is very little primary data to support the
Acacia spp. is largely unfounded, as it is not based on contention that alien Acacia biocontrol agents are in
ecological data but rather on scientific assumptions reality effective; (2) the available empirical data support
by experts. In reality, these weeds continue to remain the opposite effect (i.e., alien Acacia biocontrol are not
abundant and are still persisting and spreading in effective); (3) the perception of non-biocontrol scientists
invaded ecosystems despite the long-term presence of that the invasive plants are under control is based largely
their associated biocontrol agents. 13-16 We argue that the on expert opinion; and (4) the willingness to believe such
fundamental question, “Does introduction of host-specific a success story in dealing with a global change problem
biocontrol agents reduce the impact of the invasive plant influences the decision to release the same biocontrol
population?” is not being asked. Instead, the onus is on agents in other countries. Furthermore, this specific field
researchers to prove that biocontrol agents do not work. is so biased that to challenge the current paradigm that
In the case of biocontrol of alien Australian Acacia spp. current biocontrol agents are effective, data are required
in South Africa, recent data support an unpopular finding to prove that biocontrol does not work and that this has
that biocontrol agents have little or no effect in reducing delayed the proper use of the scientific method for several
the alien plant population levels and are not controlling decades. In other words, there is belief without sufficient
the spread, density, or area of occupancy of the alien proof.
plants. 13-15 Furthermore, if expert biocontrol practitioners Here, we will show that despite the lauded success
who are involved in the introduction process act as of the biocontrol program of Australian acacias, there
reviewers for work that shows contrary to their expert is no evidence to support the claims that these agents
opinion, we have a potential conflict of interest. Such a have been successful in reducing the invasive impact of
system of knowledge creation is broken and can lead to their target weeds. We also show how the application of
misinformed policy decision-making. Importantly, as pre- scientific hypothesis testing is inherently wrongly applied.
agent release invasive plant population-level data are not Regardless of whether the biocontrol agents have had any
canonically collected, there is a violation of the potentially measurable positive impact, the burden of proof should
powerful experimental approach that quantifies biocontrol not have to require data to show that biocontrol does not
agent impact. In addition, after agent establishment, work. Proper application of the scientific method should
studies quantifying the long-term success of the agent are entail collecting data that is statistically analyzed to prove
warranted. 17-20 However, what has happened in the case that these agents do work. The assertions of expert opinion
of biocontrol of Australian Acacia spp. in South Africa is from biocontrol practitioners are not sufficient for testing
that expert opinion of biocontrol practitioners is used to the null hypothesis that biocontrol has no effect on the
qualitatively assess biocontrol success. 12,21,22 The result of invasive impacts of Australian Acacia spp.
doing this is that effective management is misconstrued,
leading to the promotion of the so-called “success” of the 2. Context of invasive plant biological
biocontrol program despite being contrary to the actual control
data. Furthermore, of great concern is that this expert South Africa is one of the leading countries in the biocontrol
opinion process has fed into policy decision. 23 of weeds (invasive plants). Biological control of many
5,6
Science progresses by testing hypotheses with data invasive plant species is seen as a huge success. 5,6,12 This is
generated using accepted or defendable methods. To based on the perceived reduced rate of spread, the extent of
ensure rigor, such research requires peer-review, as such invasion, and management costs. Based on these benefits,
primary research papers are more important and reliable it has been suggested that biocontrol should form part of
than conference proceedings, book chapters, and reviews. any invasive plant management program. 5,6,12 One group
Here, we challenge the assertion that the biocontrol in particular, the seed biocontrol of invasive Australian

Volume 2 Issue 1 (2025) 2 doi: 10.36922/eer.5876