International Congress BIOLOGICAL PRODUCTS - Gruppo di ...

Preparation of the medium
(plant or diet)
Figure 1 - Breeding process in a commercial insectary.
Multiplication of the victim
Multiplication of the auxiliary
Collection
Packaging
Product quality control
Delivery
The high cost involved, together with the need to have a sure market has until now limited considerably the field of use
to protected environments which, on the one hand, usually host highly precious and expensive cultures and, on the
other, do not allow the dispersion of the antagonists, optimising their efficacy. Among the species to be found in
breeding there are numerous Hymenoptera parasitoids as the Aphelinidae Encarsia formosa Gahan, active against
whiteflies, or the Eulophidae Diglyphus isaea (Walker) which attacks the Agromyzidae Lyriomiza trifolii (Burgess),
and among the predators the Neuroptera Crysopidae Chrysoperla carnea (Stephens) an enemy of many aphids and the
Phytoseiid mite Phytoseiulus persimilis Athias-Henriot an antagonist of spider mites. To be fair, it has to be said that
many micro-organisms, in a broad sense, are produced commercially for the same purpose as Bacteria (Bacillus
thuringiensis Berliner), fungi (Beauveria bassiana (Bals.)) or Nematodes (Steinernema feltiae (Filipjev) and S.
carpocapsae (Weiser)).
For cultures to be found exclusively in the open field, an example of a nearly optimal situation can be supplied by
viticulture, which in the last decades has led to the affirmation of different practices of biological control which cover
all the kinds of strategies that have been mentioned above. This evolution has been made easier by the pre-existence of
a remarkably complex arthropod coenosys and therefore highly stable (Boller and Remund, 1986; Boller and Basler,
1987). The brief description of the different measures in the following paragraphs allows us to understand what are the
lines of research and what is the path that makes the practical enactment possible.
The first measure, the elimination of a worrying source, has been the rationalisation of the use of pesticides which, since
the 80’s has helped to rebuild the populations of Phytoseiids, predator mites responsible for the biological control of
Tetranychidae and Eriophyidae. It has been proved that the choice of products, in particular of fungicides are
fundamental for the maintenance of Phytoseiids and since the effects tend to accumulate, even substances which are
relatively little toxic can be extremely harmful if they are used repeatedly or in particular moments of the season.
However, in answer to specific conditions it may be possible to use active toxic substances as dithiocarbamates, dinocap
or powdery sulphur. In this case it is necessary to know the characteristics and the critical moments for the dominating
species in the concerned area, since they are different in the various Italian regions. For example, Kampimodromus
aberrans (Oudemans) is really sensitive and requires the use of the least harmful active ingredient possible from those
on offer. Typhlodromus pyri Scheuten is more tolerant instead but has moments of high sensitivity when it has to be
protected fully. In the more northern areas this period coincides with the regrowth of the vegetation, when there are a
few females and in addition they are very “stressed” due to the adverse winter conditions. In the more southern areas
this normally takes place in the summertime, as T. pyri does not like high temperatures very much. If done correctly, the
effects can be limited to a selection pressure which favours the affirmation of the more resistant Phytoseiids without
compromising their efficacy. The protection of these predators is furthermore enhanced by the support offered by the
practices of habitat management aimed at the diffusion of tree areas. Here, populations of Phytoseiids settle undisturbed
which interact with the culture thanks to the passive diffusion of individuals carried over by the air currents and which
give the possibility to overcome critical moments through the repopulating of populations decimated by erroneous
cultural practices or even by the recolonisation of the culture (figure 2).
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breeding of the victim
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