product of the proper matching of the intrin-
sic conditions of the searching female with
the target environment. Thus, we shall dis-
cuss our need and approaches for managing
both sides of this interaction.
The value and potential of managing the
environmental component of the interaction
would be important in all approaches for
using natural enemies, including enhance-
ment of wild populations, as well as maximiz-
ing the performance of laboratory-reared and
released natural enemies. On the other hand,
management of intrinsic variations in the nat-
ural enemy’s response behaviour is more
applicable in the situations where natural ene-
mies are laboratory reared and released.
Managing the parasitoid componentWe have discussed various aspects of geno-
typic and phenotypic diversity between and
within parasitoid individuals that contribute
to substantial variability in their foraging
behaviour. In the case of natural parasitoid
populations, natural selection is operating
continuously to select and shape the features
most effective for that environment, as
depicted in Fig. 4.1. However, by laboratory
colonization we remove the parasitoids from
the context of natural selection and place
them into an artificial environment, which
may change genotypic frequencies and phe-
notypic consequences (Chapters 1, 6 and 12;
Wardle and Borden, 1986; Hérard et al.,
1988b). These consequences are a particular
danger in the case of inundative and sea-
sonal inoculative programmes (van
Lenteren, 2000), where propagation and
release are continuously artificial and the
genotypic and phenotypic traits of the field
populations are dependent upon their prior
laboratory colonization conditions (Chapters
1 and 6; Lewis et al., 1981). In the case of
inoculative-type releases, there is still an
important need to manage the quality of
propagated and released material, although
perhaps less critical than in inundative and
seasonal inoculative releases. In these inocu-
lative cases, natural selection ‘screens’ the
released material for the effective compo-
nents for establishment. However, proper
management of the colonized and released
insects could greatly increase the success and
speed of establishment.
We still know little of the specific features
critical for parasitoid foraging behaviour and
how to monitor those features. Thus, we can-
not now provide a prescription for managing
the variables during the production and
release of parasitoid populations. Rather, our
intent here is to argue for the importance of
and to provide a conceptual framework for
developing greater knowledge of this area.
The basic intent of this chapter is to
expand our appreciation of the need for
quality control procedures in the establish-
ment, maintenance and use of colonized par-
asitoids and to develop methods for
implementing the procedures. The quality
control considerations will have to include
both the genotypic and phenotypic aspects
of subtle but important behavioural traits
and the significant but not readily apparent
ways in which various rearing and release
methods might affect these traits.Genetic qualities
When selecting a sample of a parasitoid
species for establishing a laboratory colony,
we need to screen the diversity of genotypic
traits and ensure that the traits of the colo-
nized population are appropriately matched
with targeted use situations. To do this, we
must develop bioassays that can be used to
evaluate diversity, behaviour and other
traits. Successful parasitism of a target host
in a confined situation does not guarantee
that released individuals will be suitable for
that host under field conditions. The
sequence of host-selection behaviours may
be circumvented in laboratory confinement
(Chapter 1). Various techniques and appara-
tuses such as olfactometers (e.g. Vet et al.,
1983; Vet and van Opzeeland, 1985), flight
tunnels (e.g. Drost et al., 1986; Elzen et al.,
1987; Zanen et al., 1989; Noldus et al., 1990;
Geervliet et al., 1998), ranked behavioural
assays (e.g. Vinson, 1968; Lewis and Jones,
1971; Wilson et al., 1974) and small field
assays (e.g. Keller and Lewis, 1989; Silva et
al., 2000), can be used in screening and
selecting material for establishing the colony.Variations in Foraging Behaviour 51