Environmental Engineering Reference
In-Depth Information
ranges (e.g. Raghu
et al
. 2006). h ese authors also highlight the logistical and
other problems of conducting such studies and thus suggest the use of models to
simulate plant population dynamics. On another front, the importance of gather-
ing data on the response and/or impact of natural enemies on their host has been
emphasized. h e use of simulated herbivory has been used to make predictions
about insect attack on plants (Wirf 2006) while a wide range of methods have
been suggested to assess insect impact on insect hosts (e.g. Jervis and Kidd 1996).
h ese papers have, however, largely been produced by workers from countries
where resources for biological control have generally been good, e.g. Australia.
Also, few examples exist where data from such studies have clearly helped in the
selection of a successful agent. Another issue is that not all these ideas and meth-
ods have been universally agreed on such that a best practice can be made available
more generally to all.
Safety is the single, most important issue for biological control. Unfortunately,
however, there is still much misinformation, deliberate or accidental, surround-
ing this pest management strategy which leads to a climate of apprehension espe-
cially directed at the classical biological control approach and the movement and
release of exotic natural enemies to control invasive species. There is considerable
mileage to be gained by investigative journalists and television-programme makers
from highlighting the perceived dangers and actual 'disasters' of the strategy (few,
and, all non-specifi c), whist never reporting on the successes (many; the majority
ignored because the invasive species problem no longer exists and by nature, there-
fore, is not newsworthy). The same questions emerge in any debate on biological
control, even in specialist fora: 'what will the agents move on to once the target is
eliminated?'; 'will not the pathogen mutate and attack crop plants?' Perhaps some
of the terminology used—biotic agents, microbial control, fungal pathogens,
exotic or alien natural enemies, and even biological control—needs to be modifi ed
or toned down in this increasingly risk-adverse world, perhaps replaced by terms
such as 'natural control' (as a general term), 'ecosystem balancing', or 'benefi cial
organism'?.
To illustrate the situation, the risks associated with the introduction of nat-
ural enemies to control invasive species have been seriously questioned in North
America (Howath 1991; Simberloff and Stiling 1996a, b) which traditionally has
been a very active region in biological control. h is has resulted in animated scien-
tifi c exchanges (Frank 1998; Simberloff and Stiling 1998), as well as to poor public
presentations of the issues involved and to bad journalism in general. Specifi cally,
detractors have focused on the example of the European weevil,
Rhinocyllus conicus
,
released in North America for the control of invasive thistles species, and which
has since established on native thistles, in order to highlight the risks posed by bio-
logical control, and the classical approach, in particular (Strong 1997). However,
the arguments are somewhat fl awed since it was already known, and considered
during the initial risk assessment, that the weevil has a broad host range within the
