ticides disrupts the natural enemies, which
then requires additional pesticide use, i.e. the
pesticide treadmill. Thus, it is the total pest-
management cost for economic suppression
that is the criterion, not the cost of producing
a particular natural enemy or the cost of sup-
pressing a particular pest.
Many pest-management researchers and
practitioners will tend to dismiss the
Fillmore Citrus Protective District results as
unique to this specific crop and locality and
assume that it has little applicability to other
situations or circumstances. While the partic-
ular solutions discussed above are specific to
certain citrus regions in southern California,
‘such thinking misses the point. The specific
solution is not as important as the process ...
What is important are the factors and
process by which these people recognised,
approached, confronted, and solved their
problems’ (Graebner et al., 1984).
Lessons from Augmentative Biological
Control with Trichogramma
History of use and mass production of
TrichogrammaTrichogramma species (Hymenoptera:
Trichogrammatidae), which have become the
most widely released augmentative biologi-
cal control agent worldwide (Li, 1994; Smith,
1996; Chapter 1), are the quintessential aug-
mentative biological control agents. They are
easily reared in large numbers at low cost
and they parasitize a variety of lepidopteran
pests. Smith (1996) reported that
Trichogrammaspecies have been used against
pests in some nine commodities on 32 million
ha, but this might be an overestimate (see
Chapter 1). The largest users have been the
People’s Republic of China (Huffaker, 1977;
Li, 1994) and the former USSR (Beglyarov
and Smetnik, 1977). The best examples docu-
menting the effectiveness of these parasitoids
as augmentative biological control agents,
however, are those by Voegelé and his col-
leagues in France (Voegelé et al., 1975); by
Hassan and his colleagues in Germany
(Hassan, 1981); and by Bigler and his col-
leagues in Switzerland (Bigler, 1986). These
programmes involve the suppression of the
one to two generations of the European corn-
borer, Ostrinia nubialisHübner, occurring in
maize in northern Europe.
The first use of Trichogrammaof which we
are aware arose from an attempt to release
and establish two exotic species from Austria
for the control of the exotic brown-tail moth,
Nygmia phaerorrhoea(Donovan) (= Euproctis
chrysorrhoeaL.) (Lepidoptera: Lymantridae),
in the north-eastern USA during the early
1900s (Howard and Fiske, 1911, pp. 256–260)
(but see Decaux, 1899). An endemic
American Trichogrammaspecies, T. minutum
Riley (= T. pretiosumRiley (see Pinto, 1998)),
was also collected from brown-tail moth egg
masses in the north-eastern USA. Both the
American and the European species were
reared on brown-tail moth egg masses and
the parasitized eggs were stored at cool tem-
peratures during the winter to synchronize
their emergence with the presence of the
moth’s egg masses in the field. In 1908/9,
large numbers of the European species were
reared and released but, as expected from
laboratory observations, these releases were
unsuccessful. Trichogrammahad difficulty in
penetrating the chorion of the moth eggs or
reaching the lower layers of the multilay-
ered, setae-covered egg mass.
It was the development of a mass-produc-
tion system for Trichogrammaby Flanders
(1930), however, that finally spurred the use
of these parasitoids as augmentative biologi-
cal control agents. His development of a pro-
duction system for this wasp was stimulated
when codling-moth eggs were detected as
being heavily parasitized by a Trichogramma
species in 1926 in a southern California wal-
nut grove. This level of parasitization was
thought to have arisen from the presence of
eggs of a migrating butterfly, the painted
lady, Vanessa cardui L. (Lepidoptera:
Nymphalidae), which laid its eggs on herba-
ceous species in spring, especially in dis-
turbed habitats (Scott, 1986). Flanders
assumed that the availability of these butter-
fly eggs early in the season allowed
Trichogrammato parasitize and build up its
density on them and then move on to
codling-moth eggs. Thus, Flanders reasoned,
if these parasitoids could be reared in suffi-Behavioural Approaches for Quality Control 235