What Have We Learned from Our
Experience with
H. axyridis?
In classical biological
control programmes, specialist and generalist biocontrol agents are compared
according to their efficacy and innocuity. It is now recognized that generalist
biocontrol agents have a lower success rate in classical biological control
programmes and a higher probability to generate non-target effects (van
Lenteren
et al
., 2003; Kimberling, 2004). As illustrated by the generalist
biocontrol agent
H. axyridis
, non-target impacts can be surprising and
the situation can quickly get out of control. It also highlights the fact that
insects have no frontiers (the beetle reached relatively northern latitudes of
Canada in just a few years) and that agents often spread to distant areas where
they are unwanted (Simberloff
et al
.,
2005). It is impossible to evaluate the overall biological and economic impact
of this lady beetle, now and in the future. This case could, however, be a key
tool in identifying characteristics that need to be evaluated in a cost–benefit
analysis and risk assessment procedures prior to the introduction of new
biocontrol agents (Perrings
et al
.,
2005; Simberloff, 2005; Colautti
et al
.,
2006).
The Final Word
Before the arrival of
H.
axyridis
in North America, natural and agricultural systems suffered from
the arrival of at least three other exotic lady beetles (
Coccinella
septempunctata
,
Propylea quatuordecimpunctata
and
Hippodamia
variegata
). Composition of the guilds has been impacted by these
successive waves of immigrants, but was only of concern to entomologists and
ecologists. As pointed out by Elliott
et al
.
(1996) for the release of
C. septempunctata
, it
is essential to weigh the potential benefits of the release of a polyphagous
predator such as
C. septempunctata
or
H.
axyridis
. The story of
H. axyridis
should
serve as a wake-up call to all biocontrol specialists and should constitute a
lesson for researchers, civil servants and all persons involved in the
programmes. This was an example of a human action with huge economic and
ethical consequences. Learning from this experience may allow us to select and
adopt a legislative framework for the future.
Acknowledgements
We thank Douglas J. Parker
(Canadian Food Inspection Agency, Ottawa) and Christie Bahlai (University of Guelph) for commenting on the manuscript.