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

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F. KARAMAOUNA ET AL.
predator preys mainly on soft scales, such as S. oleae and Coccus
pseudomagnoliarum (Kuwana) (Hemiptera: Coccidae), which maintain at
acceptable levels (Katsoyannos, 1997).
Populations of the cottony-cushion scale Icerya purchasi Kaussari (Hemiptera:
Margarodidae) were regulated by the introduced coccinellid predator Rhodolia
cardinalis Mulsant (Katsoyannos, 1996a). Localized outbreaks of the pest have
been occurring until recently but nowadays the predator is available to the growers
for augmentative releases.
Besides the classical biological control, naturally occurring biological control is
a widespread phenomenon in Greek citrus orchards. Many indigenous parasitoids
and predators are found to parasitize and prey on citrus scale insects. Three
indigenous parasitoids [Aphytis chrysomphali (Mercet), Aphytis chilensis Howard
and Encarsia citrina (Craw)] and three predators [the coccinellids Rhyzobius
lophanthae (Blaisdell) and Chilocolus bipustulatus (L.) and the nitidulid
Cybocephalus fodori (Endrodi-Younga)] are the most common species that
contribute to the suppression of the armoured scales in citrus, with the predator R.
lophanthae being the most important one (Katsoyannos, 1996a).
A considerable number of indigenous natural enemies are related to the control
of the citrus mealybug; the parasitoids Anagyrus pseudococci (Girault) and
Leptomastidea abnormis (Girault) (both Hymenoptera: Encyrtidae) along with the
predators Nephus includens (Kirsch) and N. bisignatus (Boheman) (Coleoptera:
Coccinellidae) contribute substantially to its control (Katsoyannos, 1996a;
Kontodimas, Eliopoulos, Stathas, & Economou, 2004). Among the various
parasitoid species associated with soft scales in citrus, Tetrastichus ceroplastae
(Girault) (Hymenoptera: Eulophidae) and Scutellista cyanea Motschulsky
(Hymenoptera: Pteromalidae) are the most frequent species that parasitize
Ceroplastes rusci and C. floridensis Comstock (Katsoyannos, 1996a; Stathas,
Kavallieratos, & Eliopoulos, 2003).
In general citrus-infesting scale insects are adequately retained at low levels by
the activity of introduced and/or native parasitoids and predators. However, in
cases where locally outbreaks occur due to various factors, further action is needed
to suppress the infestation below the economic injury level. Augmentative releases
of natural enemies were performed in the past against the citrus mealybug P. citri
and the soft scales S. oleae and C. pseudomagnoliarum using the coccinellid
predators Cryptolaemus montrouzieri and Exochomus quadripustulatus (L.)
respectively (Katsoyannos, 1996a). Presently augmentative releases are performed
sporadically against P. citri using the coccinellid predators Nephus includens and
N. bisignatus with very satisfying results, especially in organic citrus orchards. Growers
occasionally use Rhodolia cardinalis to suppress local outbreaks of I. purchasi; the
predator has been commercially available in the Greek market since 2006.
2.2.3. Cultural Practices
Cultural techniques involve a series of modifications of the standard management
practices in order to prevent or make the environment less favorable for the