bugs developed normally into fecund adults
(Grenier et al., 1989).
Salivary protein profiles of P. maculiventris
reared on artificial diet were not different
from those reared on caterpillar prey (Habibi
et al., 2001).
Some proteins are directly related to
reproduction capacity, such as vitellogenin
and vitellin. In P. maculiventrisand Orius
insidiosusvitellin content is determined in
haemolymph samples or whole-body
homogenates to quickly estimate the influ-
ence of diet on fecundity (Shapiro et al., 2000;
J.P. Shapiro and S.M. Ferkovich, unpublished
data). Vitellus content is a good parameter for
estimating fitness and discovering problems
of quality in mass-reared insects also in Lygus
hesperusand C. rufilabris(Cohen, 2000b).
Lipids and carbohydratesMost of the energy sources are constituted
by lipids (mainly triglycerides) and carbohy-
drates (glycogen, for example). Triglycerides
are reserve compounds that can be synthe-
sized from carbohydrates. The concentra-
tions in total fatty acids in the tachinid
parasitoid Phryxe caudatawere quite similar
when reared on different host species com-
pared with artificial diet, but the detailed
patterns are very different according to the
food. Tachinid larvae are able to modify the
host pattern towards their own pattern, but
the parasitoid pattern is not necessarily
reached in all situations (Delobel and
Pageaux, 1981). Exeristes roboratorreared in
vitrocontain half the total lipids of those
reared on the host insect, mainly due to a
lack of triglyceride synthesis and deposition
in parasitoids reared on artificial diets
(Thompson and Johnson, 1978). The total
amount of fatty acids as neutral lipids as
well as phospholipids could be a good esti-
mation of the quality of a parasitoid.
HormonesEcdysteroids added to an artificial diet, mainly
as 20-hydroxyecdysone, promote the growth
and development of different parasitoid larvae
(Grenier, 1987; Fanti, 1990; Nakahara et al.,
2000). In D. introita, the ecdysteroid titre in the
haemolymph of host-reared parasitoids was
higher than in diet-reared parasitoids. The
insufficient hormonal level in diet-reared para-
sitoids could in part be responsible for mortal-
ity and lower percentages of pupation and
emergence in vitro(Gelman et al., 2000). On the
other hand, the presence of juvenile hormones
exerts no beneficial effect and may even have
a negative influence (including the inhibition
of moulting) on the development of different
larval parasitoids (Beckage, 1985). Juvenile-
hormone mimetics, such as fenoxycarb, may
have strong negative effects, such as a delay in
or inhibition of moulting, morphological/
physiological abnormalities and even death,
on many entomophagous insects (Grenier and
Grenier, 1993).BehaviourThe effectiveness of entomophages produced
in or on artificial diets may be reduced when
they are directly released in the field, but
artificially reared natural enemies may be
readapted to their natural host or prey
through a process of learning (see also
Chapters 3 and 4). For instance, exposure of
the newly emerging adults of C. grandisto its
natural host will ‘train’ female wasps and
stimulate their egg production (Rojas et al.,
1999). Moreover, methods of artificial rearing
allowing the incorporation of semiochemi-
cals also open possibilities for preimaginal
conditioning of parasitoids and predators
(Greany et al., 1984; Grenier, 1994; De Clercq
et al., 1998a).Predation efficiency
Predation rates and food preferences have
been measured for a number of predators
reared for successive generations on artificial
diets. After 60 generations and over 6 years
on a bovine meat diet, there were no or only
slight differences in predatory capabilities, as
measured by handling times and consump-
tion rates, between domesticated G. punctipes
and feral predators (Cohen, 2000a; Hagler,
2000). In paired-choice experiments, in vitro-
reared G. punctipesshowed similar prey pref-
erences to those of their wild counterparts124 S. Grenier and P. De Clercq