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3.Environmental risks (this is the most diffi-
cult part for invertebrate biocontrol agents).
4.Efficacy (efficacy of a biocontrol agent is
defined as the ability to cause a significant
reduction in the number of pest organisms,
direct and indirect crop damage or yield loss.
The efficacy of biocontrol agents can be
highly variable if proper mass-rearing
(Chapter 12) and quality control methods
(Chapters 1, 2 and 19) are not applied.
Efficacy is treated differently from cases with
chemical control; as biocontrol agents often
form part of an integrated pest management
(IPM) programme, it is often not necessary to
reach 90–100% control by the biocontrol
agent alone, as long as the total IPM pro-
gramme results in sufficient reduction of the
pest or disease).

The environmental-risk assessment is the
most critical and difficult part of the risk
assessment procedure in biological control.
Environmental assessments related to the
release of exotic natural enemies are
expected to be based on two items (OECD,
2003): (i) identification of potential hazards
posed to the environment, based on collation
of information and data from experiments
and observations; and (ii) a summary of the
risks and benefits of the release of the exotic
natural enemy compared with alternative
control methods. Postrelease reporting of
any adverse effects on non-targets will be
used to adjust environmental-risk assess-
ments and to decide about future releases in
other areas. Most biocontrol projects include
postrelease studies to verify and monitor the
establishment of a natural enemy (e.g.
Cullen, 1997), but usually only the impact on
the target species is studied. Barratt et al.
(1999) propose to include non-target species
in such follow-up studies, because only then
can the predictive value of prerelease risk
evaluations be estimated and testing be
enhanced. Based on postrelease studies,
Barratt et al.(1999) were able to compare the
laboratory and field host ranges of two
related parasitoids with large differences in
their host ranges, and could conclude that
laboratory-measured host ranges (i.e. host-
specificity testing, see below) were indeed
indicative of field host ranges.

Below, we concentrate our discussion on

the identification of potential hazards

posed to the environment as a result of the

establishment, dispersal, host range and

direct and indirect effects of release of the

exotic natural-enemy species. Information

about these issues will form the main point

of the environmental risk assessment. The

issue of quality control is very relevant for

host risk-assessment testing: all this work

should be done with natural enemies that

are of good quality – otherwise risk will be

underestimated.

Evaluation of the Ecological Factors

Determining the Environmental Impact

of an Introduced Agent

Establishment

The potential of an exotic natural enemy to

establish will determine the extent of other

tests/information needed for the environ-

mental risk assessment. Conclusions can be

drawn about the potential for the establish-

ment of the natural enemy, based on informa-

tion from the literature on: (i) abiotic factors

(does the climate between area of origin and

area of release match?); (ii) biotic factors

(availability of non-target species suitable for

reproduction, temporal and/or spatial

matching of non-target organisms and bio-

control agent, diapause capabilities, winter

survival); and (iii) combined biotic and abi-

otic factors (are other resources for survival

and reproduction available?). Literature may

suffice, but it may also be necessary to carry

out laboratory and semi-field tests to prove

non-establishment in the target area. If infor-

mation indicates a very low probability that

an agent can establish, the environmental

assessment can be less extensive than in the

case of a high potential for establishment.

Dispersal

It is important to determine the potential

for dispersal of the biological control agent

in order to answer the question of what the

Regulation and Risk Assessment of Biocontrol Agents 195