(Colvée, 1880)
Diagnosis
Scale cover of adult female in life 1.0-2.0 mm diameter, circular to elliptical, white to very light grey with darker, subcentral to terminal exuviae (these appear dark brown but are often dark green or marked with yellow) PAOLL5.jpg and PAOLL2.jpg . Male scale cover white, oblong, about 1.0 mm long, with a brownish-yellow terminal exuviae often marked with dark green PAOLL2.jpg and PAOLL.jpg . Body of adult female deep purple (Gill, 1997) PAOLL3.jpg . The eggs and immature stages are pink to violet. Adult male winged (Ghauri, 1962).
Body of slide-mounted adult female 1-1.5 mm wide, pyriform to elongate pyriform, membranous, with two-bar ducts; up to 10 duct tubercles present in 3-5 submarginal groups on each side of the cephalothorax; and fringed plates extending as far forward as abdominal segment 2 PAOLS.jpg . Pygidium with three pairs of rounded unilibulate lobes, fourth and fifth lobes much reduced, fourth lobe represented by a tiny spur; four plates present between third and fourth lobes on each side; and usually with 1 or 2 submedian macroducts present on either side within the frame formed by the perivulvar pores PAOLP.jpg .
McKenzie, 1945, gives a detailed morphological description, illustrations and a key to the many species of Parlatoria.
Host range
Parlatoria oleae is a highly polyphagous species that has been recorded from over 200 host species belonging to 39 plant families (McKenzie, 1952a; Borchsenius, 1966). It is reported to infest species in over 80 genera in Central Europe (Kosztarab and Kozár, 1988); however, many of these hosts will not support the development of olive scale. Rosaceae, Leguminosae and Oleaceae (especially Olea europaea) are favoured hosts. Hosts include species of: Acacia, Aesculus, Ailanthus, Arbutus, Asparagus, Berberis, Buddleja, Buxus, Cactaceae, Camellia, Caragana, Catalpa, Cistus, Citrus spp., Convallaria, Cornus, Corylus, Cotoneaster, Crataegus, Cydonia, Diospyros, Elaeagnus, Eriobotrya, Eugenia, Ficus, Forsythia, Fraxinus, Gleditsia, Hedera, Ilex, Jasminum, Juglans, Laurus, Ligustrum, Lonicera, Maclura, Mahonia, Malus, Mespilus, Michelia, Morus, Myrtus, Nerium, Olea europaea, Orchis, Philadelphus, Phormium, Phorodendron, Photinia, Pistacia vera, Platanus, Populus, Prunus spp., Punica, Pyrus, Rhamnus, Rhus, Ribes, Robinia, Rosa, Rubus, Ruscus, Salix, Saxifraga, Schinus, Sophora, Sorbus, Spiraea, Symphoricarpos, Syringa, Tamarix, Tecoma, Ulmus, Viburnum, Vitis vinifera and Ziziphus jujuba.
Affected plant stages: vegetative growing, flowering, fruiting and post-harvest stages
Affected plant parts: aerial parts of the plant; as often found on trunk and branches PAOLL4.jpg as on leaves PAOLL1.jpg or fruit.
Biology and ecology
In P. oleae, reproduction is sexual and overwintering is as adult females (Kosztarab and Kozár, 1988). Each female produces an average of about 90 (8-152) eggs (Garcia, 1973), although egg numbers are rather lower than this in Central Europe (Kosztarab and Kozár, 1988). The development and number of eggs produced depends on temperature, humidity and host plant (Habib et al., 1969). There are two generations per year in California and the southern USA (Kosztarab, 1996; Gill, 1997), but up to four generations per year in the Mediterranean region (Habib et al., 1969; El Hakim and Helmy, 1985); the species overwinters as fertilized adult females or second instar females on the bark (Kozár, 1990b; Gill, 1997). Its winter diapause is facultative (Kozár, 1990b). In the autumn population in California, Huffaker et al., 1962, found that males represented about 80% of the population on the leaves, with the reverse true for those scales on the limbs.
Parlatoria oleae occurs on the bark, leaves and fruit of its host. Initially, the scale aggregates on the mid-ribs of the leaves, on the stems, and at the blossom end of the fruits. As the population increases, individuals settle at sites of opportunity. Heavy infestations often result in an encrustation of the twigs and limbs. The upper branches of the tree are usually more heavily infested than the lower branches (Selim et al., 1981), with the highest density occurring on the limbs and spurs of the host. However, Hafez et al., 1967, found that this pest prefers to infest the lower parts of pear trees in Egypt. Later generations settle on the fruit rather than the leaves.
The first instar crawlers are the dispersive phase, although they cannot walk far. Distribution over greater distances is by wind and animal agency, and by human transport of infested material.
Symptoms
Heavy infestations of P. oleae cause leaf wilting, yellowing PAOLL1.jpg and dieback; discoloured and distorted fruit and premature fruit drop; discoloured fruit and reduced oil content in olives; and weakened or killed branches (Kosztarab, 1990; Gill, 1997). The upper branches of the tree are usually more heavily infested than the lower branches (Selim et al., 1981). Infestations may cause purple discoloration of olives; other fruits (apples and peaches, for example) may exhibit a dark red spot around the feeding site of the scale.
Economic impact
Parlatoria oleae is a polyphagous pest of deciduous fruit of world importance (especially apple, pear, peach and plum, other deciduous fruit), olives (Kozár, 1990b) and ornamental plants (Kosztarab and Kozár, 1988); in addition, it has been reported to be an occasional economic pest of nut trees (Barnes et al., 1979). Direct financial loss is incurred from this pest due to the marking and discoloration of smooth-skinned fruits such as plums, apricots and olives (Huffaker et al., 1962). Losses in quantity and quality of marketable produce may be attributed to infestations by the olive scale. Westcott, 1973, considered this pest to be a major agricultural pest in the USA. It was regarded as one of the most important pests of apple in the Central Asia, the western Transcaucasus (Konstantinova, 1976) and Afghanistan (Fowjhan and Kozár, 1994). Olive scale causes serious damage to olives, primarily the table variety, in Greece (Argyriou and Kourmadas, 1981) and damages olives in the rest of the Mediterranean region, Iraq and the Canary Islands (Argyriou, 1990). In Iran, P. oleae is a pest of olives, apples, pears and plums (Kozár et al., 1996; Abivardi, 2001) and in Argentina it is abundant on olive and Rosaceae (Claps et al., 2001a). It is a serious pest of fruits in Bulgaria (Gomaa, 1978) and eastern Georgia (Yasnosh and Mindiashvili, 1972). Danzig and Pellizzari, 1998, describe this species as a dangerous pest in the Palaearctic region, and Foldi, 2001, lists it as an economically important pest in France. It has been mentioned as a pest of almond (Prunus dulcis) (Chua and Wood, 1990).
Parlatoria oleae used to be a very serious pest of olives and deciduous fruit crops in California until biological controls were successfully established; however, it does not have the devastating effect on trees that Diaspidiotus perniciosus has. Successful biological control is now established in California, which resulted in estimated savings to olive growers of US$19,900,000 for 1962-1984 (Huffaker and Gutierrez, 1990); P. oleae is now a 'B'-rated pest in California (Gill, 1997).
Detection and inspection methods
In good light, examine limbs, leaves PAOLL1.jpg and fruit of the host plant for circular to elliptical, white to very light grey scale covers, each with dark brown or green, subcentral to terminal exuviae. The upper branches of the tree are usually more heavily infested than the lower branches (Selim et al., 1981).
Phytosanitary protection
Parlatoria oleae is mentioned on quarantine lists (Burger and Ulenberg, 1990).
Natural enemies
The parasitoids and predators listed below are taken from Kosztarab and Kozár, 1988; Nachev and Grenchev, 1987, and CABI, 2000. An important factor in the selection of biocontrol agents for use against P. oleae is the ability of the parasitoid or predator to impact the host at both high and low population densities (Rosen, 1986).
Parasitoids:
- Ablerus chrysomphali
- Aphytis hispanicus
- Aphytis maculicornis, in Egypt, introduced to: USA (California)
- Aphytis mytilaspidis
- Aphytis paramaculicornis, attacking: nymphs, adults, in India, Iraq, Iran, Pakistan, Egypt. Introduced: USA (California)
- Aphytis proclia
- Coccophagoides similis
- Coccophagoides utilis, attacking: nymphs, adults, in Pakistan. Introduced: USA (California)
- Encarsia citrina
- Encarsia inquirenda, in Israel
- Habrolepis pascuorum
- Pteroptrix lauri
Predators:
- Amblyseius cucumeris
- Bdella iconica
- Cheletogenes ornatus, attacking: nymphs, adults, in Egypt, Bulgaria
- Cheyletia flabellifera
- Chilocorus sp.
- Chilocorus bipustulatus
- Chilocorus renipustulatus, attacking: nymphs, adults, in Israel. Introduced: USA [note: this could refer to C. kuwanae]
- Karnyothrips flavipes
- Thyreophagus entomophagus
Distribution
See Parlatoria oleae distribution.
In life, Diaspidiotus perniciosus is very similar to P. oleae and often occurs on the same hosts. Oleander scale (Aspidiotus nerii ) is also similar to olive scale, but can be distinguished by its tan, centrally positioned exuviae and yellow body. Parlatoria oleae is also morphologically similar to the greedy scale (Hemiberlesia rapax ) but may be distinguished by the purple body colour of P. oleae.
McKenzie, 1945, considered olive scale to be similar to Parlatoria pergandii, but it differs from P. pergandii and other species of Parlatoria in the presence of four fimbriated plates between the third and fourth pygidial lobes, whereas other species of Parlatoria have only three plates in this location. Authoritative identification requires microscopic study of slide-mounted females: McKenzie, 1945, provided a key to species.
Comments
Parlatoria oleae was described from Spain; it is probably native to the area between the eastern Mediterranean and India (Boyce, 1952; Gill, 1997). Although relatively restricted in its range within countries throughout Europe and the Middle East, Kozár and Konstantinova, 1981, noted that it was often found in very high abundance. It is now widespread in the Mediterranean and subtropical areas of the world; its distribution has not changed significantly for several decades (Kozár, 1990b). Parlatoria oleae has not been recorded from the Pacific islands.
Europe
Belgium: present, no further details (Danzig and Pellizzari, 1998)
Bulgaria: restricted distribution (Gomaa, 1978; Nakahara, 1982; Danzig and Pellizzari, 1998)
Cyprus: present, no further details (Nakahara, 1982)
Former Czechoslovakia: restricted distribution (Kozár and Konstantinova, 1981)
Former USSR
Armenia: present, no further details (Nakahara, 1982)
Azerbaijan: present, no further details (Nakahara, 1982)
Crimea: present, no further details (Nakahara, 1982)
Dugestan: present, no further details (Nakahara, 1982)
Georgia, Republic of: restricted distribution (Kozár et al., 1982; Aleksidze, 1995)
Kazakhstan: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Krasnodar Territory: present, no further details (Nakahara, 1982)
Middle Asia: present, no further details (Danzig and Pellizzari, 1998)
Russian Federation: present, no further details (Huffaker et al., 1962; Kozár et al., 1982)
South European Territory: present, no further details (Danzig and Pellizzari, 1998)
Tadzhikistan: present, no further details (Nakahara, 1982)
Transcaucasus: present, no further details (Danzig and Pellizzari, 1998)
Turkmenistan: restricted distribution (Huffaker et al., 1962; Myartseva, 1972; Myartseva, 1984)
Uzbekistan: present, no further details (Nakahara, 1982)
Former Yugoslavia: restricted distribution (Nakahara, 1982; Velimirovic, 1990; Danzig and Pellizzari, 1998)
France: restricted distribution (Viggiani, 1978; Danzig and Pellizzari, 1998; Foldi, 2001)
Germany: present, no further details (Danzig and Pellizzari, 1998)
Greece: restricted distribution (Viggiani, 1978; Paloukis, 1979; Argyriou and Kourmadas, 1981)
Hungary: restricted distribution (Kozár and Konstantinova, 1981; Danzig and Pellizzari, 1998)
Italy: present, no further details (Vacante and Gerson, 1987; 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 (Nakahara, 1982; Danzig and Pellizzari, 1998)
Poland: restricted distribution (Kozár and Konstantinova, 1981)
Portugal: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Romania: present, no further details (Danzig and Pellizzari, 1998)
Spain: present in Albacete, Almería, Badajoz, Barcelona, Córdoba, Granada, Madrid, Málaga, Murcia, Sevilla, Tarragona, Toledo and Valencia (Amparo Blay Golcoechea, 1993)
Canary Is: present, no further details (Nakahara, 1982; Amparo Blay Golcoechea, 1993)
Asia
Afghanistan: restricted distribution (Ramaseshiah, 1985; Fowjhan and Kozár, 1994)
Bangladesh: The Natural History Museum collection, London, UK
China: restricted distribution (Tang, 1984; Danzig and Pellizzari, 1998)
Shaanxi: present, no further details (Tao, 1999)
Xinjiang: restricted distribution (Tang, 1984; Tao, 1999)
India: restricted distribution (Huffaker et al., 1962; Butani, 1975; Nakahara, 1982)
Bihar: present, no further details (CIE, 1962b)
Jamu and Kashmir: present, no further details (CIE, 1962b)
Maharashtra: present, no further details (CIE, 1962b)
Punjab: present, no further details (CIE, 1962b)
Rajasthan: present, no further details (CIE, 1962b)
Tamil Nadu: present, no further details (CIE, 1962b)
Uttar Pradesh: restricted distribution (Hayat, 1979; The Natural History Museum collection, London, UK)
West Bengal: present, no further details (CIE, 1962b)
Iran: restricted distribution (Farahbakhch and Moini, 1975; Seghatoleslami, 1977; Abivardi, 2001)
Iraq: restricted distribution (Selim et al., 1981; Danzig and Pellizzari, 1998)
Israel: restricted distribution (Nestel et al., 1995; Pinhassi et al., 1996; Danzig and Pellizzari, 1998)
Jordan: present, no further details (Nakahara, 1982)
Lebanon: present, no further details (Nakahara, 1982)
Pakistan: widespread (Ahmad and Muzaffar, 1974; Muzaffar, 1974)
Saudi Arabia: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Syria: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Turkey: restricted distribution (Kozár et al., 1979; Kozár et al., 1982; Kozár and Konstantinova, 1981)
Africa
Algeria: present, no further details (Danzig and Pellizzari, 1998)
Egypt: restricted distribution (Zaher et al., 1982; El Hakim and Helmy, 1985; Moursi and Mesbah, 1985)
Kenya: restricted distribution (Rosen, 1978)
Libya: present, no further details (CIE, 1962b)
Morocco: present, no further details (Danzig and Pellizzari, 1998)
Sudan: present, no further details (Nakahara, 1982)
Tunisia: present, no further details (Danzig and Pellizzari, 1998)
Western Hemisphere
Argentina: abundant (Claps et al., 2001a)
Catamarca: present, no further details (Claps et al., 2001a)
Entre Rios: present, no further details (Claps et al., 2001a)
Jujuy: present, no further details (CIE, 1962b)
La Rioja: present, no further details (Claps et al., 2001a)
Mendoza: present, no further details (Claps et al., 2001a)
Salta: present, no further details (Claps et al., 2001a)
San Juan: present, no further details (Claps et al., 2001a)
Tucumán: present, no further details (CIE, 1962b)
Bolivia: restricted distribution (Squire, 1972a; Nakahara, 1982)
Brazil: present, no further details (Nakahara, 1982)
Bahia: present, no further details (Claps et al., 2001a)
Guanabara: present, no further details (Silva et al., 1968)
Rio de Janeiro: present, no further details (Claps et al., 2001a)
Rio Grande do Sul: present, no further details (Silva et al., 1968)
Sao Paulo: present, no further details (Claps et al., 2001a)
Cayman Is: present, no further details (Nakahara, 1982)
Central America: present, no further details (Danzig and Pellizzari, 1998)
Mexico: restricted distribution (Nakahara, 1982; Miller, 1996)
USA
Arizona: restricted distribution (Huffaker et al., 1962; Kosztarab, 1996)
California: quite widespread (Gill, 1997)
Delaware: restricted distribution (Kosztarab, 1996)
Maryland: restricted distribution (Kosztarab, 1996)
Texas: restricted distribution (Hart, 1980)
Oceania
Australia: present, no further details (CSIRO, 2001)