[Edited_by_A._Ciancio,_C.N.R.,_Bari,_Italy_and_K.(Bookos.org)

CITRUS PEST MANAGEMENT IN ITALY
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treated with fumigants or with low temperatures (2 weeks at 1°C), in order to
eliminate all living instars present inside the fruits.
3. SECONDARY PESTS
Whiteflies, and namely the Woolly whitefly A. floccosus, are among the arthropod
pests whose infestations in Italy greatly decreased over the last decades. Initially A.
floccosus was considered of great economic importance because of the serious
damage it can cause, mainly due to the very large amount of phloem sap sucked out
from all parts of the tree both by the adults and the nymphs and the consequent
production of huge amounts of honeydew. In case of strong infestations by this
whitefly, blacken of citrus plants by sooty moulds is conspicuous and in such
situations, honeydew, sooty mould and waxy secretions tend to mix up together,
forming a continuous and hardly permeable cover on the lower surface of the leaves.
Moreover, this whitefly has a strict relation with ants which protect the colonies
interfering with the activity of natural enemies of this and also of other pests.
However, biological methods have proved effective in controlling this species.
In particular after the arrival of A. floccosus in Italy (in the 1970s), the parasitoid
Cales noacki Howard (Hymenoptera: Aphelinidae) was introduced. This species,
native to South America, had already been imported in France in the 1970s (Onillon
& Onillon, 1972) and was then introduced in Southern Italy in 1980 (Liotta &
Maniglia, 1983; Longo, 1985). The beneficial insect was reared on its natural host,
feeding on citrus trees both in insectaries and in the field. From these “bank plants”
branches bearing parasitized whitefly colonies were collected and used to spread out
the parasitoid in the field, directly by farmers. The parasitoid showed an intense
activity reaching levels of parasitization higher than 80%, and managed to
permanently establish also feeding on other hosts. It did not require further
inoculations, except in orchards submitted to several chemical treatments (Longo et
al., 1994). In the citrus growing areas where the climatic conditions are not
unfavourable to the parasitoid (it is mainly affected by high summer temperatures)
and where integrated pest management is performed with rational use of pesticides,
the Woolly whitefly is almost always kept under adequate control by the aphelinid,
without requiring further specific control treatments.
Together with C. noacki, another parasitoid, the platygastrid Amitus spiniferus
(Bréthes) was introduced, reared and released following the same technique used for
the aphelinid. Although this second entomophagous was at first only found in low
numbers and immediately after the releases, it is now quite widespread in all citrus
growing areas and contributes to the control of A. floccosus infestations. Chemical
control is therefore normally not necessary against the Woolly whitefly, at least in
areas where natural enemies are protected and their action is promoted.
Similarly, two other exotic whitefly species, D. citri and P. myricae, have been
successfully contained in the framework of classical biological control programs.
The first species, native to India, was first recorded in Italy in 1965 and initially
caused very heavy infestations. Presently it has almost disappeared, thanks to the
effective control performed by the parasitoid Encarsia lahorensis (Howard)