(Signoret, 1869)
Diagnosis
In life, female scale cover circular, flat or slightly convex, 0.75-1.6 mm diameter, usually white or light grey or whitish yellow, with yellow or brown central or subcentral exuviae EPLEPL1.jpg and EPLEPL2.jpg . Male scale cover elongate, white or light grey, with terminal yellow exuviae EPLEPL.jpg and EPLEPL1.jpg . Body of living female light pink to orange-yellow, becoming dark red-brown with age EPLEPL3.jpg . The insects are often found sheltering under lichens on the bark (Gill, 1997). Adult male wingless, with orange-yellow body (Kosztarab, 1996).
Body of slide-mounted adult female less than twice as long as wide, 0.7-1.0 mm long, body widest at mesothorax, not at head EPLEPS.jpg . Pygidium with median lobes not zygotic, parallel and fairly close together (not forming an apical notch), with a pair of setae between their bases; and bases of marginal segmental setae on pygidium obviously enlarged and sclerotized EPLEPP.jpg .
Host range
Epidiaspis leperii has been recorded from hosts belonging to 8 plant families, particularly Rosaceae (Borchsenius, 1966); it prefers walnut, stone and pome fruit trees and is common on Heteromeles in California (Gill, 1997). Hosts include species of: Aesculus, Berberis, Cornus, Crataegus, Cydonia, Gleditsia, Heteromeles, Juglans, Malus sylvestris, Mespilus, Olea, Photinia, Prunus spp., Pyrus, Ribes and other Rosaceae.
Affected plant stages: vegetative growing, flowering and fruiting stages
Affected plant parts: on twigs, branches and trunk EPLEPL1.jpg ; often found sheltering under lichens on the bark
Biology and ecology
Reproduction is sexual, and overwintering is as fertilized adult females in obligate winter diapause (Geier, 1949). In California and Central Europe, this species has one generation per year and overwinters as fertilized adult females; crawlers often settle near the female scales, which often results in several layers of scale covers forming on top of each other (Kosztarab and Kozár, 1988; Gill, 1997). In the former USSR, each female produced 20-90 eggs (Danzig, 1972).
The importance of E. leperii has increased proportionately to the decrease in the density of Diaspidiotus perniciosus (Kozár and Viktorin, 1978), indicating there has been a shift in the competitive relationship between these species. Epidiaspis leperii apparently prefers warm climates (Kosztarab and Kozár, 1988).
The sex pheromone of E. leperii has been extracted and bioassayed (Abdel Kareim and Kozár, 1988).
Symptoms
At the feeding sites of E. leperii plant tissue stops growing, making the branches become deformed so that they break easily at these sites (Kosztarab and Kozár, 1988); twigs and branches may be pitted by infestations (Kosztarab, 1990). Heavy infestations cause distortion and death of branches, especially on pear and plum (Kosztarab, 1996).
Economic impact
Epidiaspis leperii causes pitting of the young stems of pear and apple (Gill, 1997), and plum. It was listed as a pest of deciduous fruit trees of world importance but especially as an important pest of pear and plums by Kosztarab and Kozár, 1988, and Kozár, 1990b, and on pear and cherry in Turkey (Kozár et al., 1979). Danzig and Pellizzari, 1998, describe E. leperii as a dangerous pest in the Palaearctic region, and it is an economically important pest of pear and plum in France (Bianchi and Bénassy, 1979; Foldi, 2001), and of plum in Italy (Bassi, 1994). It was regarded as one of the most important pests of apple in the southern USSR (Konstantinova, 1976). In Hungary, E. leperii is one of the most important scale insect pests of ornamental trees and shrubs (Ripka, 1999). In California it is not particularly injurious except on walnut trees with heavy lichen growth, where large populations weaken trees and reduce nut size and yield (Gill, 1997). Argyriou, 1990, lists it as damaging to olive in Greece, Spain, Algeria, Morocco, Turkey; and in Italy (where it has been seriously damaging). The importance of E. leperii has increased proportionately to the decrease in the density of Diaspidiotus perniciosus in Central Europe (Kozár and Viktorin, 1978).
Detection and inspection methods
Examine twigs closely for circular white scale covers, each with yellow or brown central or subcentral exuviae.
Phytosanitary protection
Epidiaspis leperii is mentioned on quarantine lists (Burger and Ulenberg, 1990).
Natural enemies
Efficient parasitoids of this species are not known (Kozár et al., 1982). However, the following natural enemies are listed by Kosztarab and Kozár, 1988.
Parasitoids
- Ablerus marchali
- Aphytis maculicornis, in Republic of Georgia
- Aphytis mytilaspidis, in France, Republic of Georgia
- Aphytis proclia, in Hungary, Republic of Georgia
- Coccophagoides similis
- Encarsia maritimus
- Encarsia perniciosi, in Republic of Georgia
- Pteroptrix dimidiata
Predators
- Chilocorus bipustulatus, in Republic of Georgia
- Chilocorus renipustulatus, in Republic of Georgia
- Cymbaeremus sp.
- Exochomus quadripustulatus
- Hemisarcoptes malus, in Bulgaria
Distribution
See Epidiaspis leperii distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species.
Slide-mounted adult female similar to members of Diaspis but body widest at mesothorax, not at head; median lobes not inset to form a notch; and bases of marginal segmental setae on pygidium obviously enlarged and sclerotized (not so in species of Diaspis).
Comments
Epidiaspis leperii is probably native to Europe (Gill, 1997) but has spread widely; its rate of spread seems to have slowed down in the last 20 years (Kozár, 1990b). The species is not established in the United Kingdom (C.P. Malumphy, Central Science Laboratory, UK, pers. comm.), and has not been recorded from Australia, or from the Pacific islands.
Europe
Albania: present, no further details (Danzig and Pellizzari, 1998)
Austria: present, no further details (Danzig and Pellizzari, 1998)
Belgium: present, no further details (Danzig and Pellizzari, 1998)
Bulgaria: present, no further details (Danzig and Pellizzari, 1998)
Former Czechoslovakia: present, no further details (Amparo Blay Golcoechea, 1993; Danzig and Pellizzari, 1998)
Former USSR
Georgia, Republic of: present, no further details (Aleksidze, 1995)
Transcaucasus: present, no further details (Danzig and Pellizzari, 1998)
Ukraine: present, no further details (Danzig and Pellizzari, 1998)
Former Yugoslavia: present, no further details (Danzig and Pellizzari, 1998)
France: present, no further details (Danzig and Pellizzari, 1998; Foldi, 2001)
Germany: present, no further details (Danzig and Pellizzari, 1998)
Hungary: present, no further details (Danzig and Pellizzari, 1998; Ripka, 1999)
Italy: present, no further details (Longo et al., 1995; Danzig and Pellizzari, 1998)
Sardinia: present, no further details (Longo et al., 1995)
Sicily: present, no further details (Longo et al., 1995)
Malta: present, no further details (Danzig and Pellizzari, 1998)
Netherlands: present, no further details (Danzig and Pellizzari, 1998)
Norway: present, no further details (Gertsson, 2001)
Portugal: present, no further details (Danzig and Pellizzari, 1998)
Azores: present, not further details (Nakahara, 1982)
Madeira Is: present, not further details (Nakahara, 1982)
Poland: present, no further details (Danzig and Pellizzari, 1998)
Romania: present, no further details (Danzig and Pellizzari, 1998)
Spain: quite widespread (Amparo Blay Golcoechea, 1993)
Switzerland: present (Kozár et al., 1994; Kozár and Hippe, 1996)
Asia
Iran: present, not further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Turkey: present, not further details (Kozár et al., 1979; Danzig and Pellizzari, 1998)
Africa
Algeria: present, not further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Libya: The Natural History Museum collection, London, UK
Morocco: present, not further details (Nakahara, 1982)
Tunisia: present, not further details (Nakahara, 1982)
Western Hemisphere
Argentina: infrequent (Claps et al., 2001a)
Buenos aires: present, no further details (Claps et al., 2001a)
Entre Rios: present, no further details (Claps et al., 2001a)
Chile: common on abandoned fruit trees (Claps et al., 2001a)
Antofagasta: present, no further details (Claps et al., 2001a)
Atacama: present, no further details (Claps et al., 2001a)
Biobío: present, no further details (Claps et al., 2001a)
Coquimbo: present, no further details (Claps et al., 2001a)
Maule: present, no further details (Claps et al., 2001a)
O'Higgins: present, no further details (Claps et al., 2001a)
Santiago: present, no further details (Claps et al., 2001a)
Valparaiso: present, no further details (Claps et al., 2001a)
Mexico: present, not further details (Nakahara, 1982; Miller, 1996)
Uruguay: present, not further details (Nakahara, 1982)
USA
California: patchy distribution (Gill, 1997)
Connecticut: present, not further details (Nakahara, 1982)
Maryland: present, not further details (Nakahara, 1982)
Montana: present, not further details (Nakahara, 1982)
New York: present, not further details (Nakahara, 1982)
Oklahoma: present, not further details (Nakahara, 1982)
Rhode Island: present, not further details (Nakahara, 1982)