Saissetia oleae (olive scale)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Saissetia oleae (Olivier, 1791)
Preferred Common Name
- olive scale
Other Scientific Names
- Bernardia oleae (Bernard) Marlatt, 1892
- Chermes oleae (Bernard) Signoret, 1869
- Coccus oleae Olivier, 1791
- Coccus palmae Haworth, 1812
- Coccus testudo Curtis, 1843
- Lecanium oleae (Bernard) Signoret, 1896
- Lecanium oleae testudo (Curtis) Cockerell, 1896
- Lecanium palmae (Haworth) Douglas, 1887
- Lecanium testudo (Curtis) Signoret, 1874
- Neobernardia oleae (Bernard) Cockerell, 1893
- Parasaissetia oleae (Bernard) Ezzat & Hussein, 1969
- Saissetia obae (Bernard) Rutherford, 1915
International Common Names
- English: black scale; black shield scale; brown olive scale; citrus black scale; mediterranean black scale; olive soft scale
- Spanish: cappareta negra; cochinilla del olivo; cochinilla negro del olivo; conchuela negra del olivo; escama glorosa; escama negra del citricos (Mexico)
- French: cochenille noire de l'olivier
Local Common Names
- Brazil: cochonilha parda; cochonilha parda
- Denmark: sort olivenskjoldlus
- Germany: Schwarze Oelbaum-Schildlaus; Schwarze Oliven-Schildlaus
- Israel: knimat hazyit haraka
- Italy: Cocciniglia grande nera dell'olivo
- South Africa: swart dopluis
- Turkey: kara kosnil
- SAISOL (Saissetia oleae)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Hemiptera
- Suborder: Sternorrhyncha
- Unknown: Coccoidea
- Family: Coccidae
- Genus: Saissetia
- Species: Saissetia oleae
Notes on Taxonomy and NomenclatureTop of page It is thought that there are several biologically different races of Saissetia oleae (De Lotto, 1965; Bartlett, 1960).
Signoret mistakenly attributed the authorship of Lecanium oleae to Bernard in 1896. For quite a few years other authors followed him. De Lotto (1971) recognised the mistake and correctly attributed the authorship to Olivier.
DescriptionTop of page Mature adult S. oleae appear as sessile dark grey or brown-to-black lumps attached to leaf undersides and stems. The limbs of each insect are short and are hidden beneath the body, and eyes are only visible in younger specimens with pale bodies.
Early instars are difficult to distinguish from those of other species of soft scale. First-instar crawlers (0.35 mm long) and intermediate immature instars are translucent light brown, with two black eyes placed anterolaterally. Adult females lack wings; they are 2-5 mm across, approximately circular in outline, fairly flat, yellow or grey and granular in appearance initially, becoming hemispherical and dark grey or brown to black and matt with age (Gill, 1988). Adult females develop an egg-filled hollow under the body as they become increasingly convex in shape. The small, winged males are rare.
For an authoritative identification, slide-mounted adult female specimens should be examined under a compound light microscope. Diagnostic characters of slide-mounted females are: dorsal reticulation absent, areolation present; large discal seta present on each anal plate; dorsal setae conical; 2-13 blunt or only slightly frayed marginal setae present between the anterior and posterior stigmatic clefts on each side; ventral submarginal tubular ducts of one type only; tibio-tarsal articulatory scleroses usually present. Thorough descriptions and comments on morphological variation of S. oleae are given by De Lotto (1965).
DistributionTop of page S. oleae is thought to have originated in South Africa (De Lotto, 1965, 1976).
The distribution map includes several records from the Natural History Museum, London, UK. These records are indicated as NHM (date). The record for Netherlands in 1977 is a quarantine interception.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Risk of IntroductionTop of page The occurrence of races of S. oleae with different host preferences and natural enemies is of quarantine importance, and the movement of this species should be restricted even between countries where it is already established. Its potential geographical range in temperate areas may increase as a result of global warming.
Hosts/Species AffectedTop of page S. oleae is polyphagous and has been recorded from 113 host-plant species in 49 families. In California it prefers citrus, olive and oleander (Gill, 1988). S. oleae can be cultured on oleander or sprouts of planted potatoes (Bartlett, 1978). Methods of mass rearing are given by Blumberg and Swirsky (1977).
Growth StagesTop of page Flowering stage, Fruiting stage, Vegetative growing stage
SymptomsTop of page S. oleae colonies extract large quantities of sap, causing general host debilitation and build-up of sticky honeydew deposits on nearby surfaces. The honeydew may attract attendant ants. Sooty moulds grow on the sugary deposits. Badly fouled leaves may be dropped prematurely. The older insects are usually quite easy to see as dark grey or brown-to-black lumps on leaf undersides and stems.
List of Symptoms/SignsTop of page
|Leaves / abnormal leaf fall|
|Leaves / abnormal leaf fall|
|Leaves / honeydew or sooty mould|
|Leaves / honeydew or sooty mould|
|Leaves / wilting|
|Stems / external feeding|
Biology and EcologyTop of page Reproduction in S. oleae is generally parthenogenetic, although males do occur rarely. The female lays 1000-4000 eggs in a cavity under her body, where they are protected for the 16-40 days they take to hatch (Gill, 1988; Hamon and Williams, 1984). The first instar (crawler) walks about actively to locate a feeding site. There are three instars.
In California, one generation occurs each year in inland areas and two near the coast; overwintering takes place at the intermediate immature stage. In culture, optimum growth occurs at about 21°C and a complete generation takes 70-90 days (Bartlett, 1978).
Honeydew production is greatest during periods of rapid growth and oviposition. Ants may be attracted to colonies by the honeydew excreted and may deter natural enemies from attacking the scales (Gill, 1988).
The main dispersal stage of S. oleae is the crawler, but individuals remain capable of locomotion until oviposition begins (Gill, 1988). Dispersal by crawlers is limited to the same plant, or adjacent plants if they are touching. However, crawlers can be carried between plants and sites on larger animals including man, and all life cycle stages can be transported on ornamental plants, propagation material or produce.
The range of S. oleae in California is restricted by high temperature combined with low humidity, which affects immature stages adversely (Gill, 1988). Hot, dry conditions influence the distribution of the insects on the plant, as they avoid these extremes by colonizing the shaded, more humid parts of the plant (usually the lower part of the canopy) (Briales and Campos, 1988).
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
|Chilocorus sp. nr. distigma||Predator||Adults/Nymphs||USA||Citrus|
|Chrysoperla carnea||Predator||Adults/Nymphs||Cyprus||Nerium oleander; olives|
|Coccidoctonus dubius||Parasite||New Zealand||Citrus|
|Coccophagus anthracinus||Parasite||Adults/Nymphs||Israel; USA||Citrus|
|Coccophagus basalis||Parasite||Adults/Nymphs||California; USA||Citrus|
|Coccophagus capensis||Parasite||Adults/Nymphs||California; Chile; Israel||Citrus|
|Coccophagus ceroplastae||Parasite||Adults/Nymphs||France; USA||Citrus; olives|
|Coccophagus cowperi||Parasite||Adults/Nymphs||California; Israel||Citrus; shrubs|
|Coccophagus modestus||Parasite||Adults/Nymphs||Chile||avocados; Citrus; olives|
|Coccophagus ochraceus||Parasite||Adults/Nymphs||Chile; Israel||avocados; Citrus; olives|
|Coccophagus probus||Parasite||Adults/Nymphs||California; Israel||Citrus|
|Coccophagus pulvinariae||Parasite||Adults/Nymphs||California; Chile; Israel; USA||Citrus; shrubs|
|Coccophagus rusti||Parasite||Adults/Nymphs||California; Greece; Israel||Citrus; olives|
|Coccophagus semicircularis||Parasite||Diab et al., 2014|
|Diversinervus elegans||Parasite||California; France; Honduras; Italy||Citrus; Hibiscus; olives|
|Exochomus muelleri||Predator||Adults/Nymphs||Cyprus||Nerium oleander; olives|
|Exochomus nigromaculatus||Predator||Adults/Nymphs||Cyprus||Nerium oleander; olives|
|Exochomus quadripustulatus||Predator||Adults/Nymphs||France; Greece|
|Lecanobius utilis||Parasite||California; Chile; Peru||avocados; Citrus; olives|
|Marietta picta||Parasite||Diab et al., 2014|
|Metaphycus bartletti||Parasite||Nymphs||California; Corsica; Cyprus; France; Israel; Italy; Mediterranean region||Citrus; olives|
|Metaphycus flavus||Parasite||Cyprus; USA||Citrus; Nerium oleander; olives|
|Metaphycus inviscus||Parasite||Israel; USA||Citrus|
|Metaphycus lounsburyi||Parasite||Nymphs||Argentina; Australia; California; Chile; Cyprus; France; Greece; Iran; Israel; Italy; Mediterranean region; New Zealand; Peru; Spain; Tunisia||avocados; Citrus; Nerium oleander; olives; orchards|
|Metaphycus luteolus||Parasite||USA; USSR||Citrus|
|Metaphycus swirskii||Parasite||Nymphs||Corsica; France; Israel; Italy||Citrus; olives|
|Microterys flavus||Parasite||Italy; New Zealand; USA||Citrus; olives|
|Rhyzobius forestieri||Predator||Adults/Eggs/Nymphs||Cyprus; France; Greece; Israel; New Zealand||Citrus; olives|
|Rhyzobius ventralis||Predator||Adults/Nymphs||California; Chile||Citrus|
|Scutellista caerulea||Parasite||Eggs||Australia; California; Chile; Cyprus; France; New Zealand; Peru; Spain; USA; USSR||Citrus; Nerium oleander; olives; orchards|
|Spilomicrus trifasciata||Parasite||California; Chile||avocados; Citrus; olives|
Notes on Natural EnemiesTop of page S. oleae natural enemies have been studied extensively since the beginning of the 20th century in order to find biological control agents. Over the years large numbers of natural enemies have been introduced, particularly into California and more recently into Israel (Argov and Rossler, 1993), chiefly from its area of origin in southern Africa. Most of these have been ineffective or did not become established (Lampson and Morse, 1992).
It is thought that the different physiological races of S. oleae are attacked by different parasites (Bartlett, 1960). Gill (1988) remarks that serious outbreaks of black scale often occur when ants are not controlled, because ants protect the scales from natural enemies.
The species included in the table are those that became established in at least one country. Misidentification, name changes and improvements in taxonomy make the identity of some species mentioned in earlier reports uncertain.
ImpactTop of page S. oleae is one of the most important pests of citrus in the Mediterranean Basin, Florida, California and South America (Bartlett, 1978). Gill (1988) considered it to be the most injurious soft scale in California, and the most important pest of citrus there until 1940; he also reports it as a serious pest of olives. Removal of large quantities of sap debilitate the plant and can cause wilting, desiccation of tissues and dieback. Sooty mould growth on honeydew deposits screen light and air from the leaves and impair photosynthesis, promoting premature leaf drop. Such damage reduces overall yield and quality of produce.
DiagnosisTop of page For authoritative identification of S. oleae it is necessary to examine slide-mounted adult females under a compound light microscope.
Detection and InspectionTop of page Examine plants closely, especially shrubs or trees, for signs of sooty mould or sticky honeydew on leaves and stems, or ants running about. Look for scales on leaves (especially the midribs on the underside), twigs, branches and fruits. Good light conditions are essential; in poor light, a powerful flashlight is helpful. A large hand lens may help recognition of 'H'-shaped dorsal ridges.
Similarities to Other Species/ConditionsTop of page S. oleae can be confused with Parasaissetia nigra or other species of Saissetia. However, in all stages, S. oleae has a raised 'H'-shaped ridge on the dorsum that is normally lacking in P. nigra and convex adults of S. coffeae. Mature S. oleae are more convex and less shiny than P. nigra.
S. oleae can only be separated from other species of Saissetia by examination of slide-mounted specimens under a compound light microscope (Hamon and Williams, 1984). S. oleae differs from S. neglecta in having the marginal setae only slightly frayed and tibio-tarsal scleroses normally present, whereas in S. neglecta the marginal setae are flattened and extremely frayed, and tibio-tarsal scleroses are normally absent. S. oleae differs from S. miranda in having fewer than 15 marginal setae present between the anterior and posterior stigmatic clefts on each side, whereas S. miranda has 17-20. S. oleae has only one type of tubular duct in the ventral submarginal band, whereas S. coffeae has two types in distinct zones (Williams and Watson, 1990).
Prevention and ControlTop of page
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.Regulatory Control
Planting material of host-plant species of S. oleae should be inspected in the growing season before shipment and should be free of infestation. A phytosanitary certificate should guarantee absence of the pest from consignments of either planting material or produce.
The intermittent feeding habits and waxy dorsal surface of S. oleae make it difficult to control with pesticides. Use of insecticides is likely to kill any parasitoids and make biological control ineffective. In addition, ornamental plants may be adversely affected by insecticides (Copland and Ibrahim, 1985).
As an introduced pest in most of the countries where it occurs, S. oleae is particularly suitable for classical biological control. However, ants attracted to the scales by honeydew may deter natural enemies from attacking them. The biological control of S. oleae in California is discussed by Bartlett (1978).
Biological control of S. oleae in Florida is discussed by Browning (1994), who reports that the most important natural enemy of Saissetia species there is Scutellista caerulea. However, biological control is not completely effective because problems in identifying Saissetia species have resulted in unsuccessful introductions of parasitoids that were inappropriate to the target pest species. S. oleae is less important on citrus than S. neglecta in Florida.
The following information is from Bartlett (1978). Numerous natural enemies have been introduced to California but relatively few species are important control agents for S. oleae there now. In coastal areas, Metaphycus helvolus is a successful control agent, but inland it does not prosper because of intolerance of the colder winters. In these areas, control by M. lounsburyi, Scutellista caerulea and Coccophagus lycimnia is rather less successful. M. lounsburyi does best in areas where the scale is bivoltine, as in univoltine scale populations there is a severe shortage of hosts at an appropriate stage for 7 months of the year.
From California, Metaphycus helvolus has been introduced successfully to Greece, Crete and Iran to control S. oleae. This parasitoid is also the most effective introduced natural enemy of the scale in Chile.
The situation in California has changed recently with the introduction of M. bartletti in 1986. M. bartletti has now become the most important control agent in the coastal region. Likewise when M. bartletti was introduced into European countries and Israel it displaced M. helvolus and became the most effective parasitoid (Lampson and Morse, 1992; Argov and Rossler, 1993).
In Australia, control of S. oleae is mainly by Metaphycus lounsburyi, Scutellista caerulea, M. helvolus and the native ladybird, Rhyzobius forestieri. Details of the life history of Scutellista caerulea are given by Jadhav and Ajri (1984).
ReferencesTop of page
Albuquerque FAde; Pattaro FC; Borges LM; Lima RS; Zabini AV, 2002. Insects associated to Barbados cherry (Malpighia glabra L.) in the region of Maringá, PR. (Insetos associados à cultura da aceroleira (Malpighia glabra L.) na região de Maringá, Estado do Paraná.) Acta Scientiarum, 24(5):1245-1249.
Bartlett BR, 1960. Biological races of the black scale, Saissetia oleae, and their specific parasites. Annals of the Entomological Society of America, 53:383-385.
Ben-Dov Y, 1993. A systematic catalogue of the soft scale insects of the world (Homoptera: Coccoidea: Coccidae) with data on geographical distribution, host plants, biology and economic importance. Gainesville, USA: Sandhill Crane Press, Inc., 536 pp.
Blumberg D; Swirsky E, 1977. Mass breeding of two species of Saissetia (Hom.: Coccidae) for propogation of their parasitoids. Entomophaga, 22:147-150.
Browning HW, 1994. Classical biological control of citrus scale insects. In Rosen D, Bennett FD, Capinera JL, eds. Pest management in the subtropics: biological control - a Florida perspective. Andover, UK: Intercept Limited, 49-78.
De Lotto G, 1965. On some Coccidae (Homoptera), chiefly from Africa. Bulletin of the British Museum (Natural History), 16:175-239.
De Lotto G, 1976. On the black scales of southern Europe (Homoptera: Coccoidea: Coccidae). Journal of the Entomological Society of Southern Africa, 39:147-149.
De Lotto; G, 1971. The authorship of the Mediterranean black scale (Homoptera: Coccidae). Journal of Entomology (B) 40:149-50.
Diab N; Asslan L; Basheer AM, 2014. Parasitoids of the soft scale insects (Homoptera: Coccidae) in fruit orchards at al Qunaetera, Syria. Egyptian Journal of Biological Pest Control, 24(2):341-346. http://www.esbcp.org/index.asp
Gill RJ, 1988. The scale insects of California. Part 1. The soft scales (Homoptera: Coccoidea: Coccidae). Technical Services in Agricultural Biosystematics and Plant Pathology. California Department of Food and Agriculture, 1:1-132.
Hamon AB; Williams ML, 1984. The soft scale insects of Florida (Homoptera: Coccoidea: Coccidae). Arthropods of Florida and Neighboring Land Areas, 11:1-94.
Henderson RC; Sultan A; Robertson AW, 2010. Scale insect fauna (Hemiptera: Sternorrhyncha: Coccoidea) of New Zealand's pygmy mistletoes (Korthalsella: Viscaceae) with description of three new species: Leucaspis albotecta, L. trilobata (Diaspididae) and Eriococcus korthalsellae (Eriococcidae). Zootaxa, 2644:1-24. http://www.mapress.com/zootaxa/2010/f/z02644p024f.pdf
Hrncic S, 2002. A survey of olive pests in Montenegro. Acta Horticulturae [Proceedings of the 4th International Symposium on Olive Growing, Valenzano, Italy, 25-30 September, 2000. Volume 2.], No.586:819-821.
Koren T; Milevoj L; Jancar M, 2004. Altered development of black scale (Saissetia oleae Bern.) in Slovenian Istria. (Spremljanje razvoja oljkovega kaparja (Saissetia oleae Bern.) v Slovenski Istri.) In: Zbornik referatov 1. Slovenskega sadjarskega kongresa z mednarodno udelezbo, Kr?ko, Slovenia, 24-26 marec 2004. Del 2 [ed. by Hudina, M.]. Ljubljana, Slovenia: Slovenian fruit growing association, University of Ljubljana, Biotechnology Faculty, 431-436.
Ricalde MP; Nava DE; Loeck AE; Coutinho EF; Bisognin A; Garcia FRM, 2015. Insects related to olive culture in Rio Grande do Sul State, Brazil. Ciência Rural, 45(12):2125-2130. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782015001202125&lng=pt&nrm=iso&tlng=en
Tang FD, 1991. The Coccidae of China. Taiyuan, China: Shanxi United Universities Press.
Distribution MapsTop of page
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