First report of Phaedon brassicae in Italy: addition to the EPPO Alert List
The NPPO of Italy informed the EPPO Secretariat of the recent record of Phaedon brassicae (Coleoptera: Chrysomelidae) in Italy. This insect of Asian origin was found in a nursery at Parabiago (province of Milano) in Lombardia. P. brassicae is a polyphagous insect which is reported as a pest of Brassicaceae in its area of origin. As the Italian NPPO considered that this pest could present a risk to Europe, the EPPO Secretariat added P. brassicae to the EPPO Alert List.
Phaedon brassicae (Coleoptera: Chrysomelidae)
Why: The NPPO of Italy notified the EPPO Secretariat of the first record on its territory of Phaedon brassicae, a polyphagous pest of Asian origin. In the Paleartic region, the genus Phaedon includes 35 described species. In Europe, only P. cochleariae and P. armoraciae are pests of cabbages, rape mustard (Brassica rapa) and watercress (Nasturtium officinale). Although the distribution of P. brassicae is still very limited in Italy, it was felt that it could present a risk to the EPPO region.
EPPO region: Italy (1 nursery at Parabiago, Lombardia). Many adults were collected at Parabiago on bonsai plants recently imported from Asia. Adults were collected on Zelkova serrata and Ficus retusa in 2000, on Bambusa ventricosa in 2001 and on Pinus pentaphylla in 2003. In 2003, weeds growing under the benches of the infested glasshouses were examined. Larvae and adults were observed feeding on a weed, Cardamine hirsuta (Brassiceae). Larvae were only collected inside the glasshouses, whereas adults were also found outside. Although the first specimens of P. brassicae were collected on different bonsai plants, these are most probably occasional hosts, as the insect was feeding only on C. hirsuta.
Asia: China, Japan, Taiwan, Vietnam.
On which plants: Polyphagous insect. It is reported on cultivated plants: Allium cepa, Beta vulgaris, Brassica chinensis, Chrysanthemum coronarium, Daucus carota, Lactuca sativa, Raphanus sativum, or weeds such as Capsella bursa-pastoris and Rorippa atrovirens. In Southern China, it is reported as an important pest of Brassicaceae, such as Brassica alboglabra, B. juncea var. foliosa, B. chinensis, Brassica pekinensis, Nasturium officinale, and Raphanus sativus.
Damage: Adults and larvae feed on leaves, perforating them. Adults are oblong, convex, metallic beetles about 3-5 mm in length (male: 3 mm – female: 5 mm). They are lucifugous and during the day they remain still on the lower leaf surface. In Italy, mating was observed at the end of July. Eggs are laid on the lower leaf surface. In Chinese experiments, at 25 °C, HR 65-75% and photoperiod 12L:12D, the larval stage lasted 10 days. Mature larvae live close to the ground on the upper leaf surface, and they feed more intensively in the dark. Pupae are 5 mm long, bright yellow. From the literature, it is not clear whether pupation takes place in the soil or on lower leaf surface. Details are lacking on the biology of the insect and its damage.
Dissemination: No data is available on the natural dispersal of the insect. Over long distances, movements of host plants could spread the pest. In Italy, it is obvious that bonsai plants have transported the pest but it is not entirely clear how this was achieved (adults hidden in the pots, in the soil, feeding on host weeds growing in the pots?).
Pathway: Plants for planting of host plants of P. brassicae, bonsai plants, soil?
Possible risks: Brassicaceae are widely grown in the EPPO region but data is lacking on the economic impact of P. brassicae in its area of origin. More data would also be needed on the biology of the pest, especially on its host range and its potential for establishment in the EPPO region. Data is also lacking on control measures (biological control is mentioned in the literature with the use of Bacillus thuringiensis and Steinernema carpocapsae). Although other Phaedon species are already reported as pests of Brassicaceae in the EPPO region, it is desirable to avoid the introduction of an additional species which may present a risk to many crops.
EPPO RS 2006/129
Panel review date - Entry date 2006-06
Kimoto S (1962) Descriptions of immature stages of Japanese Chrysomelinae belonging to the generic groups Chrysolina, Gonioctena, Potaninia, Phola and Phaedon (Coleoptera). Journal of the Faculty of Agriculture, Kyushu University 12(2), 89-104.
Limonta L, Colombo M (2004) Record in Italy of Phaedon brassicae Baly (Coleoptera Chrysomelidae Chrysomelinae) Bollettino di Zoologia Agraria e di Bachicoltura Serie II 36(3), 369-371.
NPPO of Italy, 2005-10.