0851996884.pdf

mated that – expressed in monetary value –
80% of the commercial natural enemies are
used in greenhouses. The vast amount of
natural enemies used on about 16 million ha
of field crops mainly consist of non-commer-
cial products that are reared in state-funded
laboratories. For these biological control
agents cost estimates are often lacking. The
most applied natural enemies in green-
houses are E. formosa, accounting for 25% of
the total market, P. persimilis, accounting for
12%, and A. cucumeris, also accounting for
12%. Another good indicator of the signifi-
cance of groups of natural enemies is the
investment in money for control of the vari-
ous groups of pests (Fig. 11.2). Four groups
of pests – whiteflies, thrips, spider mites and
aphids – account for 84% of the costs of bio-
logical pest control.
Large differences in prices for biological
control agents exist among the commercial
companies (for details, see van Lenteren et al.,
1997). A general observation is that there are
many more species of natural enemies com-
mercially available in Europe than in the
USA, as a result of the much larger green-
house industry in Europe. In comparison
with the USA, it can also be concluded that
commercial biological control suppliers in
Europe are of larger size than their partners
in the USA. When comparing the data of

Cranshaw et al.(1996) with European data, a

number of specific conclusions can be drawn.

Comparisons between other continents are

difficult to make because of lack of data.

Parasitoids

It appears that parasitoids of Diptera are

hardly used in Europe, whereas they are

widely available in the USA. The main rea-

son for this is the large differences in poultry

production between the two continents. A

second difference is that most natural ene-

mies in the USA are sold for application in

open-field crops, while in Europe the major

part of commercial biological control takes

place in greenhouses. Sales of Trichogramma

spp. are more common in the USA than in

Europe, where these parasitoids are used on

fewer than 10,000 ha for control of European

cornborer in maize. Also, parasitoids of scale

species seem to be marketed on a much

larger scale in the USA than in Europe. In the

USA, scale parasitoids are applied, for exam-

ple, in citrus orchards, whereas, in Europe,

they are applied in greenhouses and interior

plantscapes. Natural enemies are used for

controlling pests in orchards in Europe, pri-

marily for inoculative releases with a long-

term effect instead of inundative releases. In

Commercial Availability of Biocontrol Agents 177

Russia

10

Europe

0.1

Asia

2.5

North America

0.07

Latin America

4.4

Fig. 11.1.Estimated areas (in million hectares) under augmentative forms of biological control (after van
Lenteren, 2000).