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

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J.A. JACAS & A. URBANEJA
Since the cost of production of these natural enemies is relatively low, the current
use of these IBCAs involves augmentative releases against their respective target pests
(Table 3). These strategies are also in use in other Mediterranean countries
(Katsoyannos, 1996), as well as in areas with a similar climate, such as Australia,
California, or South Africa (Charleston et al., 2003; UC, 1991; Smith et al., 1997).
As shown in Table 3, augmentative releases include both exotic and native
natural enemies. Consistent with latest trends in EU agriculture, which emphasizes
the role of indigenous natural enemies, Anagyrus pseudococci (Girault)
(Hymenoptera: Encyrtidae), a native parasitoid of the citrus mealybug, Planococcus
citri Risso (Hemiptera: Pseudococcidae), has been recently studied and could
successfully substitute the exotic L. dactylopii in the future (Campos & Martínez-
Ferrer, 2003). Similarly, studies are in progress to establish conditions for using the
native predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae)
against the two spotted spider mite, Tetranychus urticae Koch (Acari:
Tetranychidae) another native mite which is considered a key pest for clementine
mandarins in Spain (Aucejo, Gómez-Cadenas, & Jacas, 2004; Ansaloni, Pascual-
Ruiz, Hurtado, & Jacas, 2008). Likewise, releases of Neoseiulus californicus
(McGregor) (Acari: Phytoseiidae) and P. persimilis have also been proposed against
the citrus mite, Panonychus citri, and T. urticae, respectively, in nurseries (Table 3)
(Abad-Moyano, Pina, Pérez-Panadés, Carbonell, & Urbaneja, 2009).
4. FORTUITOUS BIOLOGICAL CONTROL
Anagyrus pseudococci is not the only example of an indigenous natural enemy
having a significant impact on an exotic pest. Although such pests are usually the
target of the Classical BC strategy, indigenous natural enemies can sometimes result
in excellent BC, which is then called fortuitous BC.
The native predator E. stipulatus provides a good example of such a situation in
Spain. This species is the most abundant Phytoseiidae in Spanish citrus (Ferragut et al.,
1988). If undisturbed, its populations are usually able to regulate Panonychus citri
populations below their economic threshold (Ripollés, Marsá, & Martínez, 1995).
Therefore E. stipulatus is considered as one of the most relevant natural enemies in
Spanish citrus orchards and its conservation is a key factor for IPM success (Urbaneja
et al., 2008). Most other indigenous natural enemies do not have such a dramatic
impact on their host/prey pests (Table 1). However, both the increasing legal
restrictions for importing exotic natural enemies into the EU (Bigler et al., 2005) and
the disappearance of many pesticides in the EU following the process of re-evaluation
of all pesticide active ingredients under EU Directive 91/414/EEC, have lead to a
renewed interest on these native species and their conservation (Table 1).
5. THE CORNERSTONE: CONSERVATION
Conservation biological control exploits resident, either native or naturalized,
natural enemies. This strategy is especially useful in permanent ever-green crops
(Barbosa, 1998; Landis, Wratten, & Gurr, 2000), such as citrus, where both pests
and their natural enemies are active and abundant throughout the year (Garrido &