NAME OF THE ORGANISM: Aleurothrixus floccosus (ALTHFL)

Not candidate

Aleurothrixus floccosus is reported as a polyphagous whitefly species, having been recorded on more than twenty different plant genera of various families (Martin et al., 2000; Malumphy et al., 2015). Poncirus trifoliata is cited as a host in Turkey (Ulusoy et al., 2003). However, citrus is the most preferred host (Pauloson and Beardsley, 1986). In the Mediterranean region where the whitefly was introduced, it infests almost exclusively species of the genus Citrus (CABI, 2021; Barbagallo et al., 1986 in García-Marí, 2012).
Plants for planting is a pathway for entry in a new area (CABI, 2021).
Although, according to Katsoyannos (1991), adults rarely fly and, even when they do so, they fly rather short distances, García-Marí (2012) reports that they fly actively and are borne by the wind, thus dispersing to other trees and/or nearby plantations. The rapid spread of this pest after its introduction in Spain and Italy (reviewed by García-Marí, 2012) is compatible with a dissemination mainly through other means than plant reproductive material.
The Fruit SEWG concluded that plants for planting was not their main means of dissemination in areas where the pest is already present.

Remark: Although CABI (2021) indicates that C. noacki does not attack populations with heavily pigmented nymphs and pupae, no other reference to this fact has been found in the bibliography consulted. See also remarks on taxonomy.

Yes

As with most whitefly species, A. floccosus affects the host plant by the suction of sap from the infested young leaves. High infestations can be detrimental to young plants. Indirect damage is also caused by the large amount of honeydew produced by the nymphs. Another type of indirect damage is the formation of sooty moulds on the honeydew which impairs the photosynthetic process of the plant part affected (CABI, 2021).
However, A. floccosus has only the status of occasional pest in several EU countries because it is very effectively controlled by Cales noacki (it only causes economic damage in circumstances where control by this parasitoid is interfered with e.g. inadequate treatments with broad spectrum insecticides) (Franco et al., 2006; García-Marí, 2012; MAPA, 2022).
C. noacki was first introduced into Europe in 1970, in France - imported from Chile (Onillon and Onillon, 1972). One year after its release, it had achieved total control of A. floccosus populations (Onillon, 1990). Also in 1970, three species of parasitoids were introduced into Spain: C. noacki, Amitus spiniferus and Eretmocerus paulistis (Beitia, 1984). Of these, only C. noacki was able to establish and reproduce in the field, and its high parasitoid activity and expansion throughout the Spanish citrus-growing area was reported. A. spiniferus also became established in some areas where currently it appears parasitizing A. floccosus together with C. noacki and exerting a complementary action in whitefly control (reviewed by Castañé et al., 2010 and García-Marí, 2012).
Before 1978, Amitus spiniferus and Cales noacki were accidentally introduced into Italy through the French border. A. spiniferus was successfully established in north-western Italy with appreciable activity (Arzone and Vidano, 1983; Barbagallo et al., 1992; Viggiani, 1993) but failed to establish in the southern regions of the country (Longo et al., 1985; Maniglia, 1988). Cales noacki showed better adaptation throughout Italy, with high levels of parasitism (Arzone and Vidano, 1983; Longo et al., 1985; Ortu and Prota, 1986; Guerrieri and Viggiani, 1988) (reviewed by García-Marí, 2012).
C. noacki was imported into Greece in 1991 from Valencia (Spain) (Katsoyannos, 1991). Later, Katsoyannos et al. (1998) considered that, in Greece, C. noacki is an effective natural enemy against woolly whitefly with parasitism rates exceeding 82 %.
C. noacki is considered widespread in citrus growing countries of the EPPO region and economic impact is nowadays much reduced.

Minor

Yes

No

Not candidate

Considering that there may be a time lapse between pest occurrence and parasitoid action, the Fruit SEWG rated economic impact as ‘minor’ (this pest may cause some damage). Its 'Minor' economic impact does not qualify it as RNQP.