high-quality natural enemies is a prerequi-
site for increasing the use of entomophagous
insects for pest control. For biological control
strategies, the ultimate quality criterion for a
mass-produced natural enemy is excellent
field performance against the target pest
insect (Thompson and Hagen, 1999).
However, very few field evaluations have
been done for artificially reared beneficials.
Egg parasitoids, especially Trichogramma, are
used worldwide for biological control on
many crops (van Lenteren, 2000). In China,
Trichogrammaspp. and Anastatusspp. pro-
duced at an industrial scale on artificial eggs
have been released on thousands of hectares
of different crops, with parasitism rates of
usually more than 80% (Dai et al., 1991; Liu et
al., 1995). In the USA, biocontrol companies
have started to integrate artificial diets in
their production process, and some preda-
tors are at least partially being reared on var-
ious artificial diets (P.D. Greany, Gainesville,
USA, 2001, personal communication), but
there are no reports on their field perfor-
mance. Field assessments of artificially
reared natural enemies are only useful, how-
ever, when basic parameters during the pro-
duction process in the laboratory are strictly
controlled and changes in the rearing proce-
dure are carefully monitored.
Quality control of mass-produced ento-
mophagous insects can be based on pro-
cedures developed earlier for non-
entomophagous insects (Chapter 2; Leppla
and Ashley, 1989; Leppla and Fischer, 1989;
Williams and Leppla, 1992). For example,
quality control during storage, packaging
and shipment of all kinds of mass-reared
insects could be similar. There are already
quality control processes recommended for
in vivoproduction that could be used as a
guideline for in vitro production (Bigler,
1994). Comparative analyses of the repro-
ductive attributes of commercially in vivo-
produced Trichogramma species were
described by Kuhlmann and Mills (1999).
Both these latter authors and Liu and Smith
(2000) chose fecundity, longevity, sex ratio
and adult size as quality parameters.
Parasitization rate is another key parameter
tested for quality evaluation (Losey and
Calvin, 1995).
For quality control of insects no absolute
criteria exist, but different criteria could be
defined in relation to the objectives for which
they are produced. The degree of difference
between insects produced in vivoand in vitro
that we can accept will depend on the goals
of the production (Moore et al., 1985), in this
case the pest-control efficiency to be obtained
in the field. For in vitro rearing of ento-
mophages we are only at the very first steps
of developing quality control, except for a
few species of parasitoids and some preda-
tors (Table 9.1). The main question will be:
what kinds of parameters are reliable
enough to be used in the assessment of qual-
ity? In this chapter we shall not develop a
quality control scheme. Instead, we shall
conduct in vivo–in vitrocomparisons, which
form the starting-point for establishment of
quality control parameters for artificially
reared entomophages.Different Kinds of Artificial Diets for
Parasitoids and Predators
It would be convenient if the different kinds
of diets used in mass rearing could be typi-
fied by simple terms. Long ago some terms
were used based on the presence or absence
of complex components, but they were not
very clearly defined: holidic media (chemi-
cal structure of all ingredients known),
meridic media (holidic base to which at
least one substance or preparation of
unknown structure or uncertain purity is
added) or oligidic media (crude organic
materials). However, we are of the opinion
that these distinctions are not very relevant,
because only a complete description of the
composition of a diet would be able to char-
acterize it. Nevertheless, for practical con-
siderations, a critical characteristic is the
presence or the absence of insect compo-
nents. Thus, considering that synthetic diets
were supposed to replace the insect host or
prey, it is worth distinguishing two main
kinds of media: those including and those
excluding insect components. Addition of
insect materials implies the necessity to cul-
ture not only the host but often also the
host’s food plant, rendering entomophage116 S. Grenier and P. De Clercq