Unaspis citri (citrus snow scale)
Index
- Pictures
- Identity
- Taxonomic Tree
- Description
- Distribution
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- Symptoms
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Impact
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- References
- Distribution Maps
Don't need the entire report?
Generate a print friendly version containing only the sections you need.
Generate reportPictures
Top of pageIdentity
Top of pagePreferred Scientific Name
- Unaspis citri (Comstock, 1883)
Preferred Common Name
- citrus snow scale
Other Scientific Names
- Chionaspis annae Malenotti
- Chionaspis citri Comstock, 1883
- Dinaspis annae Malenotti
- Dinaspis veitchi Green & Laing, 1923
- Prontaspis citri (Comstock) MacGillivray, 1921
- Unaspis annae Malenotti
International Common Names
- English: orange chionaspis; orange snow scale; white louse scale
- Spanish: cochinilla blanca de los citrus; cochinilla blanca del tronco; escama de nieve de los cítricos; escama de nieve de los citricos (mexico); guagua nevada de los cítricos; piojo bianco; piojo blanco de los citricos (mexico); piojo harinoso de los citricos; queresa del naranjo
- Portuguese: cochonilha branca da aranjeira (brasil)
Local Common Names
- Brazil: cochonilha branca da aranjeira
- Germany: schneeweisse citrus-schildlaus
EPPO code
- UNASCI (Unaspis citri)
Taxonomic Tree
Top of page- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Hemiptera
- Suborder: Sternorrhyncha
- Unknown: Coccoidea
- Family: Diaspididae
- Genus: Unaspis
- Species: Unaspis citri
Description
Top of pageAuthoritative identification involves detailed microscopic examination of slide-mounted, teneral, adult females. Detailed morphological descriptions, illustrations and keys to Unaspis are provided by Balachowsky (1954), Ferris (1937) and Williams and Watson (1988).
Distribution
Top of pageSee also CABI/EPPO (1998, No. 154).
Distribution Table
Top of pageThe 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.
Last updated: 12 May 2022Continent/Country/Region | Distribution | Last Reported | Origin | First Reported | Invasive | Reference | Notes |
---|---|---|---|---|---|---|---|
Africa |
|||||||
Benin | Present | ||||||
Cameroon | Present | ||||||
Comoros | Present | ||||||
Congo, Democratic Republic of the | Present | ||||||
Congo, Republic of the | Present | ||||||
Côte d'Ivoire | Present | ||||||
Egypt | Present | ||||||
Gabon | Present | ||||||
Guinea | Present | ||||||
Madagascar | Present | ||||||
Mauritius | Present | ||||||
Niger | Present | ||||||
Nigeria | Present | ||||||
Senegal | Present | ||||||
Sierra Leone | Present | ||||||
Togo | Present | ||||||
Asia |
|||||||
China | Present | ||||||
-Guangdong | Present | ||||||
-Hubei | Present | ||||||
Hong Kong | Present | ||||||
Indonesia | Present | ||||||
-Java | Present | ||||||
Japan | Present | ||||||
Malaysia | Present | ||||||
-Peninsular Malaysia | Present | ||||||
Singapore | Present | ||||||
Syria | Present | ||||||
Vietnam | Present | ||||||
Yemen | Present, Widespread | ||||||
Europe |
|||||||
Malta | Absent, Unconfirmed presence record(s) | ||||||
Netherlands | Absent, Confirmed absent by survey | ||||||
Portugal | Present, Localized | ||||||
-Azores | Present, Localized | ||||||
Slovenia | Absent | ||||||
North America |
|||||||
Antigua and Barbuda | Present | ||||||
Barbados | Present | ||||||
Bermuda | Present | ||||||
British Virgin Islands | Present | ||||||
Costa Rica | Present | ||||||
Cuba | Present | ||||||
Dominica | Present | ||||||
Dominican Republic | Present | ||||||
El Salvador | Present | ||||||
Grenada | Present | ||||||
Guadeloupe | Present | ||||||
Haiti | Present | ||||||
Honduras | Present | ||||||
Jamaica | Present | ||||||
Martinique | Present | ||||||
Mexico | Present | ||||||
Montserrat | Present | ||||||
Panama | Present | ||||||
Puerto Rico | Present | ||||||
Saint Kitts and Nevis | Present, Localized | ||||||
Saint Lucia | Present | ||||||
Saint Vincent and the Grenadines | Present | ||||||
Trinidad and Tobago | Present | ||||||
U.S. Virgin Islands | Present | ||||||
United States | Present, Localized | ||||||
-California | Present | ||||||
-Florida | Present | ||||||
-Georgia | Present | ||||||
-Louisiana | Present | ||||||
Oceania |
|||||||
Australia | Present | ||||||
-New South Wales | Present, Localized | ||||||
-Queensland | Present, Widespread | ||||||
-South Australia | Present | ||||||
-Victoria | Present | ||||||
Cook Islands | Present | ||||||
Federated States of Micronesia | Present | ||||||
Fiji | Present | ||||||
Kiribati | Present | ||||||
New Caledonia | Present | ||||||
New Zealand | Absent, Invalid presence record(s) | ||||||
Niue | Present | ||||||
Papua New Guinea | Present | ||||||
Samoa | Present | ||||||
Solomon Islands | Present | ||||||
Tonga | Present | ||||||
Vanuatu | Present | ||||||
Wallis and Futuna | Present | ||||||
South America |
|||||||
Argentina | Present | ||||||
Bolivia | Present | ||||||
Brazil | Present | ||||||
-Espirito Santo | Present | ||||||
-Rio de Janeiro | Present | ||||||
-Rio Grande do Sul | Present | ||||||
-Sao Paulo | Present | ||||||
Chile | Present | ||||||
Colombia | Present | ||||||
Ecuador | Present | ||||||
French Guiana | Present | ||||||
Guyana | Present | ||||||
Paraguay | Present | ||||||
Peru | Present | ||||||
Uruguay | Present | ||||||
Venezuela | Present |
Risk of Introduction
Top of pageU. citri is a more tropical species than the closely related U. yanonensis. In West Africa, it is confined to the humid tropical zone along the coast and does not occur where there is a dry season (Vilardebo, 1974). In Queensland and New South Wales, in Australia, U. citri is confined to the non-irrigated humid coastal regions and does not occur in the semi-arid irrigated citrus-cultivation areas inland (Maelzer, 1979).
U. citri also has less of a tendency to attack fruits than U. yanonensis.
Hosts/Species Affected
Top of pageHost Plants and Other Plants Affected
Top of pagePlant name | Family | Context | References |
---|---|---|---|
Ananas comosus (pineapple) | Bromeliaceae | Main | |
Annona muricata (soursop) | Annonaceae | Main | |
Artocarpus heterophyllus (jackfruit) | Moraceae | Main | |
Capsicum (peppers) | Solanaceae | Main | |
Citrus | Rutaceae | Main | |
Citrus aurantiifolia (lime) | Rutaceae | Main | |
Citrus aurantium (sour orange) | Rutaceae | Main | |
Citrus limon (lemon) | Rutaceae | Main | |
Citrus limonia (mandarin lime) | Rutaceae | Unknown | |
Citrus maxima (pummelo) | Rutaceae | Main | |
Citrus reticulata (mandarin) | Rutaceae | Main | |
Citrus sinensis (sweet orange) | Rutaceae | Main | |
Citrus x paradisi (grapefruit) | Rutaceae | Main | |
Cocos nucifera (coconut) | Arecaceae | Main | |
Fortunella (kumquats) | Rutaceae | Main | |
Hibiscus (rosemallows) | Malvaceae | Main | |
Musa (banana) | Musaceae | Main | |
Poncirus trifoliata (Trifoliate orange) | Rutaceae | Main | |
Psidium guajava (guava) | Lithomyrtus | Main | |
Tillandsia usneoides (Spanish moss) | Bromeliaceae | Main |
Symptoms
Top of pageList of Symptoms/Signs
Top of pageSign | Life Stages | Type |
---|---|---|
Fruit / discoloration | ||
Fruit / external feeding | ||
Leaves / abnormal colours | ||
Leaves / abnormal leaf fall | ||
Leaves / abnormal leaf fall | ||
Leaves / honeydew or sooty mould | ||
Leaves / necrotic areas | ||
Stems / dieback | ||
Stems / external feeding |
Biology and Ecology
Top of pageLaboratory studies of the population dynamics of U. citri showed that the net reproductive rate, intrinsic rate of increase and finite rate of increase were higher on orange than on lemon. The longevity of female scales on orange was approximately 13 weeks compared to 17 weeks on lemon (Fernandez and Garcia, 1988). Population studies in Colombia have shown that at any given time, 86.5 to 95.5% of U. citri are not feeding and that 43.9 to 79.3% of first instars are males which cease to feed after the second moult (Mosquear, 1979).
Like other diaspids, the main dispersal stage of U. citri is the first instar which as well as being mobile may be naturally dispersed by wind and animals. Once a feeding site has been selected the insect becomes sessile and is not naturally dispersed. However, it is readily carried on consignments of plant material and fruit.
Natural enemies
Top of pageNatural enemy | Type | Life stages | Specificity | References | Biological control in | Biological control on |
---|---|---|---|---|---|---|
Aphytis lingnanensis | Parasite | Adults; Arthropods|Nymphs | Australia; Queensland; Florida; Solomon Islands; USA | Citrus | ||
Aphytis yanonensis | Parasite | Adults; Arthropods|Nymphs | ||||
Arrhenophagus chionaspidis | Parasite | Adults; Arthropods|Nymphs | ||||
Batrachedra arenosella | Predator | Adults; Arthropods|Nymphs | ||||
Cheletogenes ornatus | Predator | |||||
Chilocorus circumdatus | Predator | Queensland | ||||
Cosmospora aurantiicola | Pathogen | Adults; Arthropods|Nymphs | ||||
Encarsia aurantii | Parasite | Adults; Arthropods|Nymphs | ||||
Encarsia citrina | Parasite | Adults; Arthropods|Nymphs | ||||
Encarsia herndoni | Parasite | Adults; Arthropods|Nymphs | ||||
Encarsia lounsburyi | Parasite | Adults; Arthropods|Nymphs | Honduras | Citrus | ||
Encarsia perniciosi | Parasite | |||||
Fusarium | Pathogen | Adults; Arthropods|Nymphs | ||||
Hemisarcoptes malus | Predator | Adults; Arthropods|Nymphs | ||||
Lecanicillium lecanii | Pathogen | Adults; Arthropods|Nymphs | ||||
Mataeomera dubia | Predator | Queensland | ||||
Myriangium duriaei | Pathogen | Adults; Arthropods|Nymphs | ||||
Nectria flammea | Pathogen | Adults; Arthropods|Nymphs | ||||
Sphaerostilbe fulva | Pathogen | |||||
Sukunahikona prapawan | Predator | |||||
Telsimia elainae | Predator |
Notes on Natural Enemies
Top of pageSee Rosen (1990) for a discussion and further references to the natural enemies of Diaspididae.
Impact
Top of pageDetection and Inspection
Top of pageSimilarities to Other Species/Conditions
Top of pageOn citrus fruit, the female scales can be confused with the common Lepidosaphes spp.. Adult female U. citri scales often have a distinct longitudinal dorsal ridge which is absent in Lepidosaphes spp.. Secondly, the male U. citri are white, felted, elongate oval in shape with three longitudinal ridges. Male scales of Lepidosaphes spp. are mussel or oyster-shell shaped, purplish or brown and similar in appearance to, but smaller than, the female scales.
Prevention and Control
Top of pageDue 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 (Plant Quarantine and Certification)
Importation of citrus plants for planting from countries where U. citri occurs should be prohibited. Fruits should be subject to requirements such as area freedom, place of production freedom or treatment.
Biological Control
Existing biological control agents include the hymenopterous parasitoids Aphytis lingnanensis used in Florida (USA), the Solomon Islands and Cuba, and Aspidiotiphagus lounsburyi in Cuba. Construction of field cages to enclose citrus trees has facilitated the release and establishment of A. lingnanensis in citrus groves in Florida (Brooks and Vitelli, 1976). U. citri increased greatly in numbers after 1963 in Florida and was not effectively suppressed by biological methods. High-volume pesticide sprays were required for control (Simanton, 1974). Browning (1994) provided an up-to-date assessment of biological control in Florida. Partial success has been obtained with A. lingnanensis and efforts are being made to make additional introductions.
Chemical Control
Chemical control is possible but the waxy surfaces, sessile nature, intermittent feeding and overlapping generations of U. citri make it difficult to control. In Cuba, the insecticides sulphur, carbaryl, dimethoate and malathion are commonly used (Castineiras and Obregon, 1986). In laboratory and field trials, mineral oil or a mineral oil/dimethoate mixture was found to be the most effective against the mobile stages and against the general population (Fernandez and Rodriquez, 1988).
References
Top of pageBalachowsky AS, 1954. Les cochenilles paléarctiques de la tribu des Diaspidini. Paris, France: Institut Pasteur.
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.
CIE, 1962. Distribution Maps of Plant Pests, No. 149. Wallingford, UK: CAB International.
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Rosen D, 1990. Armoured Scale Insects: their Biology, Natural Enemies and Control. World Crop Pests 4B. Amsterdam, Netherland: Elsevier.
Servicio para el Agricultor, 1973. Control of the Citrus scale. Noticias Agricolas, 6(26):106
Distribution References
CABI, Undated. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
NPPO of the Netherlands, 2013. Pest status of harmful organisms in the Netherlands., Wageningen, Netherlands:
Distribution Maps
Top of pageSelect a dataset
Map Legends
-
CABI Summary Records
Map Filters
Unsupported Web Browser:
One or more of the features that are needed to show you the maps functionality are not available in the web browser that you are using.
Please consider upgrading your browser to the latest version or installing a new browser.
More information about modern web browsers can be found at http://browsehappy.com/