Phenology, population trend and natural enemies of Aleurothrixus floccosus ( Hom.: Aleyrodidae ) at a newly invaded area in Athens, Greece

Aleurothrixus floccosus (Homoptera: Aleyrodidae) first invaded eastern urban areas of Athens, Greece, in May 1991. At Zographou, Athens, in 1992–1994, most overwintering A. floccosus nymphs were of the 3rd and 4th instars, and pupae; during other periods of the year, all developmental instars were found, at fluctuating rates. In 1993, peaks in the numbers of eggs laid coinciding with sharp increases in percentage of 1st instar nymphs found permitted the distinction of 6 overlapping generations. High densities of A. floccosus infesting citrus in autumn 1992, in the range of 9.1–10.9 nymphs/cm 2 leaf surface, were brought under control by autumn 1993, with maximum densities of 1.1–1.7 nymphs/cm 2 . This reduction is attributed mostly to the action of the introduced parasitoid Cales noacki (Hymenoptera: Aphelinidae), released 3 km from Zographou in 1992 and at Zographou itself in 1993. No indigenous parasitoid was ever found parasitizing A. floccosus . The first record of Clitostethus arcuatus (Coleoptera: Coccinellidae) in Greece is reported. In summer 1992, eggs larvae and adults of C. arcuatus were noticed on citrus leaves infested with A. floccosus at Zographou. From 1992 to 1994, the adults were often detected in field samplings and on yellow sticky traps. C. arcuatus adults and larvae were successfully reared, under optimal laboratory conditions, on eggs and early-instar nymphs of A. floccosus and on eggs of Anagasta kuehniella (Lepidoptera: Pyralidae), but the adults did not reproduce.