Introduced insects not such a pest
Lincoln, New Zealand 14 January 2014... Concerns are often raised about the introduction of non-native insects around
the world to control weeds, citing the risk the introduced insects may cause to other desirable plant species. Yet a new
study suggests there may not be as much evidence for this concern as people perceive.
An international collaboration - including Max Suckling of Plant & Food Research in Lincoln, New Zealand and René Sforza of the European Biological Control Laboratory in Montpellier,
France - has completed a study on the effects of all recorded cases since the 1800s of insects as weed biological
control agents thanks to funding from an OECD Fellowship and as part of NZ’s Government funded Better Border Biosecurity
programme (www.b3nz.org(http://plantandfood.us5.list-manage.com/track/click?u=1b46d14e528ad30bae8b3663c=70ffed9fa9=5b367992d8) ).
The research characterised the magnitude of unwanted effects by these insects on other plants using a five step scale
adapted from invasive species biology and looked at 512 cases of deliberately introduced biocontrols dating back more
than 150 years.
Dr Suckling said “A total of 43 weed biocontrol insects worldwide have been reported to feed on non-target plants after
release, but the real surprise comes when you look at the level of this feeding and what little effect it is having on
the plants, compared with calls for concern about biosafety in the scientific literature”.
The study particularly looked at whether insect feeding affected the reproductive rate of the non-target plant and
discovered decreases in plant reproduction in non-target plants to be very rare.
The scientists found only four insects causing plant populations to decline significantly anywhere.
“Weeds are a major long term drain to our quality of life. Our concern is that worry about biosafety needs to be
tempered with the benefit scenario. Our analysis shows that as far as is known, weed biological control agents have
historical had an excellent biosafety track record, with more than 99% of cases avoiding significant non-target impacts
on plant populations” says Dr Suckling.
“Biological control of weeds through the introduction of specific insects is an environmentally sustainable solution
compared to chemical sprays and an area of science we aim to investigate further” notes Dr Sforza, currently visiting
New Zealand on an OECD Fellowship for biological control.
The study estimates that in the nearly 85 year history of weed biological control in New Zealand, 34 % of insects
deliberately introduced against weeds have worked successfully, in some cases with real benefits. Two key success
stories have occurred from insects introduced to control St John’s Wort and Ragwort, with long-term ecosystem recovery
over large areas.
The study notes that in future it is expected that even fewer non-target impacts and greater benefits can be expected
due to improved science and increased incorporation of wider societal values and that suitably-screened organisms can be
released with a very high degree of specificity against weeds. The research paper is available online in PLoS ONE
(10.1371/journal.pone.0084847).
View the research paper online
PLoS ONE – article by Suckling and Sforza,
What magnitude are observed non-target impacts from weed biocontrol? (http://plantandfood.us5.list-manage1.com/track/click?u=1b46d14e528ad30bae8b3663c=5f3a0792d9=5b367992d8)
10.1371/journal.pone.0084847 (http://plantandfood.us5.list-manage2.co
ends