Classical and augmentative biological control against ... - IOBC-WPRS

Chapter 3
Potential of biocontrol based on published research.
3. Research and Development in classical biological control with
emphasis on the recent introduction of insect parasitoids
Nicolas Ris and Jean Claude Malausa
INRA, UE 1254, Unité expérimentale de Lutte Biologique, Centre de recherche PACA,
400 route des Chappes, BP 167, F-06903 Sophia Antipolis, France
Scope of the review
Defined as “the intentional introduction of an exotic, usually co-evolved, biological control
agent [hereafter BCA] for permanent establishment and long-term pest control’, classical
biological control [hereafter ClBC] is a pest control strategy that has crystallized numerous
studies since more than one century and provided numerous efficient solutions for pest
control. The main advantages and risks of this strategy can be summarized as follows. In a
context of the globalisation of international trade and human mobility, an ever growing
number of exotic pests emerge locally. Such species can rapidly pullulate and jeopardize
cultural practices. This general trend can also be favoured by global climatic changes that
may allow the development of agronomic pests beyond their initial distribution area and
increase their demography. Within this context, ClBC appears often to be the first way to try
to regulate such pest populations. Moreover, when successful, ClBC appears to be very
economic insofar as financial costs are only associated with the identification, evaluation and
initial releases of exotic BCA. Contrary to other pest control strategy, the implication of
practitioners and other costs are not necessary after the establishment of the BCA. The
overall financial costs of such operations are consequently rather limited with regard to the
durability of the pest control, in particular when the local introduction of a new BCA benefits
from the previous experiences in other countries. Nevertheless, at least two kinds of risks are
usually associated with ClBC. First of all, the average success rate of ClBC varies between
10 and 30% according to the authors for a total of more than 5000 introductions worldwide
during the last century. As consequence, such operations may also appear too risky to be
funded. Another risk is those associated with the non-target effects. Although few cases have
been reported, their echoes may have contributed to a more harmonized approach and in
some countries to more or less stringent regulations.
As consequences, classical biological programmes are at the crossroad of several
concerns:
- agronomic; insofar as each introduction of exotic BCA is obviously an hope for the
producers ;
- scientific; ClBC namely questions both ecologist and evolutionist in order to optimize the
probability of establishment while minimizing the non-target effects. Their implication on
such issues nevertheless depends on their own interest (in term of scientific question
and/or possibility or publishing);
- political; since the introduction of BCA may depend on regulation or homologation
decided at national or international levels;
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