Scirtothrips aurantii (South African citrus thrips)
- Taxonomic Tree
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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IdentityTop of page
Preferred Scientific Name
- Scirtothrips aurantii Faure
Preferred Common Name
- South African citrus thrips
Other Scientific Names
- Scirtothrips acaciae Moulton
International Common Names
- French: thrips sud-africain des agrumes
Local Common Names
- Germany: Zitrusblasenfuss
- SCITAU (Scirtothrips aurantii)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Thysanoptera
- Family: Thripidae
- Genus: Scirtothrips
- Species: Scirtothrips aurantii
DescriptionTop of page Members of the genus Scirtothrips are readily distinguished from all other Thripidae by the following characters: surface of pronotum covered with many closely spaced transverse striae; abdominal tergites laterally with numerous parallel rows of tiny microtrichia; sternites with marginal setae arising at posterior margin; metanotum with median pair of setae arising near anterior margin. Most of the 59 species described in Scirtothrips were defined originally by their authors on unreliable colour and silhouette characters; Mound and Palmer (1981) describe many structural details by which each pest species may be distinguished. Many undescribed species are known from Central America (Mound and Marullo, 1996). Scirtothrips spp. primarily infest young growing buds, so these should be examined particularly carefully.
S. aurantii eggs are bean-shaped, minute (less than 0.2 mm) and inserted into soft plant tissues. The two feeding nymphal stages are yellow to orange, cigar-shaped and just visible to the naked eye. Adult males can be distinguished from all other members of the genus by the presence of a comb of stout setae on the posterior margin of the hind femora. The ninth abdominal tergite of males bears a pair of long curved dark lateral processes (drepanae). Females have the following characters: median ocellar setae on the head arising close together and in line with the anterior margins of the posterior pair of ocelli; forewing posteromarginal cilia wavy not straight; median abdominal sternites fully covered with microtrichia; abdominal tergites and sternites with a transverse anterior dark line; tergites with a dark median area. The larvae are yellow, with the body surface finely granulate.
DistributionTop of page S. aurantii is native to Africa, and the only records considered to be valid (supported by voucher specimens in an available collection) from outside this continent are from Yemen (CIE, 1961; EPPO/CABI, 1996; CABI/EPPO, 1998; EPPO, 2003).
See also CABI/EPPO (1998, No. 140).
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.Last updated: 23 Apr 2020
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Cabo Verde||Present||EPPO (2020)|
|Senegal||Present||Davis and Venette (2004)|
|South Africa||Present||EPPO (2020); Rafter and Walter (2012)|
|Lithuania||Absent, Confirmed absent by survey||EPPO (2020)|
|Netherlands||Absent, Confirmed absent by survey||NPPO of the Netherlands (2013); EPPO (2020); CABI (Undated)||Absent, confirmed by survey, intercepted only.|
|Slovenia||Absent, Confirmed absent by survey||EPPO (2020)|
|Australia||Present||Rafter et al. (2008)|
Risk of IntroductionTop of page S. aurantii is mainly present in Africa, where it is a damaging pest of citrus, requiring insecticide treatments. Its importance has also increased on mangoes, where insecticide treatments are applied, and concerns have also been raised for banana and tea. Since its present range includes areas with tropical, subtropical and Mediterranean climates, any such area elsewhere in the world, growing its four main hosts, could be at risk. There is no direct evidence that S. aurantii has been dispersed beyond its natural range by human activity (except possibly to African islands such as Cape Verde, Mauritius and Réunion). S. aurantii is not likely to be transported on traded fruit, which limits the risk of introduction. It could however, be carried on plants for planting.S. aurantii has been declared to be a quarantine pest for the following Regional Plant Protection Organizations: APPPC, EPPO, OIRSA, PPPO.
Hosts/Species AffectedTop of page
Although usually considered to be associated with Citrus, especially oranges (C. sinensis) in southern Africa, S. aurantii has been found on more than 50 plant species in a wide range of different plant families. It has been reported as a pest of mangoes (Mangifera indica), especially when these are grown close to citrus trees in South Africa, tea (Camellia sinensis) and banana (Musa paradisiaca). Its native hosts are probably Acacia and Combretum trees, but it has also been taken on a range of crops that are not only botanically unrelated but differ widely in form, including Arachis hypogaea, Asparagus spp., Gossypium spp., Ricinus communis and Vitis vinifera. Studies conducted on windbreak trees have shown that Grevillea robusta can harbour this pest (Grout and Richards, 1990a), whereas Casuarina, Eucalyptus and Pinus do not. In a recent survey of S. aurantii hosts in South Africa, the pest was found to be abundant on C. sinensis, Gloriosa superba, Kalanchoe delagoensis, Caesalpinia pulcherrima, Macadamia integrifolia and Punica granatum (Rafter and Walter, 2012).
Host Plants and Other Plants AffectedTop of page
|Acacia (wattles)||Fabaceae||Wild host|
|Arachis hypogaea (groundnut)||Fabaceae||Other|
|Asparagus officinalis (asparagus)||Liliaceae||Other|
|Caesalpinia pulcherrima (peacock flower)||Fabaceae||Other|
|Camellia sinensis (tea)||Theaceae||Other|
|Citrus limon (lemon)||Rutaceae||Main|
|Citrus sinensis (navel orange)||Rutaceae||Main|
|Gloriosa superba (glory lily)||Liliaceae||Other|
|Grevillea robusta (silky oak)||Proteaceae||Other|
|Kalanchoe delagoensis (chandelier plant)||Crassulaceae||Other|
|Kalanchoe pinnata (cathedral bells)||Crassulaceae||Wild host|
|Macadamia integrifolia (macadamia nut)||Proteaceae||Other|
|Mangifera indica (mango)||Anacardiaceae||Other|
|Musa x paradisiaca (plantain)||Musaceae||Other|
|Punica granatum (pomegranate)||Punicaceae||Other|
|Ricinus communis (castor bean)||Euphorbiaceae||Other|
|Vitis vinifera (grapevine)||Vitaceae||Other|
Growth StagesTop of page Flowering stage, Fruiting stage, Vegetative growing stage
SymptomsTop of page On Citrus, S. aurantii causes silvering of the leaf surface, linear thickenings of the leaf lamina, brown frass markings on the leaves and fruits, grey to black markings on fruits often forming a ring around the apex, and ultimately fruit distortion and early senescence of leaves. If flushes of young leaves are severely attacked later in the season, then the crop of the following season may be reduced (Kamburov, 1991). On mangoes, S. aurantii causes lesions on the fruit, leaf malformation and stunting of new growth (Brink, 1994). It causes fruit spotting on bananas in Yemen.
List of Symptoms/SignsTop of page
|Fruit / frass visible|
|Fruit / lesions: black or brown|
|Fruit / malformed skin|
|Growing point / discoloration|
|Growing point / dwarfing; stunting|
|Growing point / frass visible|
|Leaves / abnormal colours|
|Leaves / abnormal forms|
|Leaves / frass visible|
Biology and EcologyTop of page All stages feed on epidermal or palisade cells of young leaves, and on the apex of young fruit often concealed under the calyx (Milne and Manicom, 1978). They do not feed on mature leaves (Hall, 1930). Eggs are inserted into young tissues. There are two nymphal (feeding) stages, followed by two pupal (non-feeding) stages. Pupation occurs on the ground amongst leaf litter; pupae occur rarely beneath the calyx of fruits. Breeding is almost continuous, although development is slow in winter, and the life history can be completed in less than 30 days.
Adults are probably dispersed downwind, but observations in South Africa have suggested that early-season infestations in citrus orchards develop mainly from thrips that have overwintered within each orchard, rather than from adults flying in from wild plants (Gilbert, 1990). Later in the season (November and December), wild hosts probably assume greater importance as a source of the pest. Citrus trees close to windbreaks of Grevillea robusta trees (that harbour S. aurantii) had more severe fruit scarring than citrus trees close to windbreaks of Pinus radiata, Casuarina cunninghamia or Eucalyptus torelliana trees (which do not support S. aurantii) (Grout and Richards, 1990a, Grout and Stephen, 1995a).
Means of Movement and Dispersal
The potential of Scirtothrips spp. for natural spread is relatively limited. In international trade, S. aurantii could be carried on plants for planting, but in fact interceptions are relatively rare. Unlike many Thysanoptera, Scirtothrips spp. seem to require access to soft green tissues, except when pupating in leaf litter and soil. Only seedlings or cuttings with young growing leaf buds are liable to carry these pests. The youngest fruits are attacked, so the risk of these thrips being carried on harvested fruits is small. There is no direct evidence that S. aurantii has been dispersed beyond its natural range by human activity. It has, however, been intercepted in the Netherlands (EPPO/CABI, 1996).
Natural enemiesTop of page
Notes on Natural EnemiesTop of page Most natural enemies of S. aurantii are predators, mostly mites of the subfamily Amblyseiinae. Grout (1994) reviews the distribution and abundance of phytoseiid mites on Citrus in southern Africa and their possible value as predators of S. aurantii. Only one parasitoid, the hymenopteran, Goethana incerta, has been identified (Grout and Stephen, 1995b). The influence of windbreak trees on the maintenance of some natural enemies has been studied (Grout and Stephen, 1995a).
ImpactTop of page At least ten Scirtothrips spp. are known as pests of various crops in different parts of the tropics, but most of them have restricted geographic ranges and tropical host plants, such as S. kenyensis which damages tea and coffee in eastern Africa, or S. manihoti which causes serious leaf distortion of cassava in Central and South America. Scirtothrips spp. are particularly associated with plants that grow in warm, dry conditions; they are usually more abundant on terminal shoots rather than within the canopy of a tree. With S. citri and S. dorsalis (EPPO/CABI, 1996), S. aurantii is, as a pest of Citrus, one of the most important Scirtothrips spp. for international agriculture.
In South Africa and Zimbabwe, S. aurantii causes reduction in Citrus yields through serious damage to young leaves, and reduces the proportion of export-quality fruits. It is a most serious pest at low altitudes (Hill, 1983). It is not generally regarded as harmful to crops further north in Africa, although this might be due to less intensive cultivation practices. Damage to tea plants has been reported from plantations in Malawi (Rattan, 1992) and losses have been studied (Rattan, 1996). S. aurantii is the primary cause of banana fruit-spotting in Yemen (Nasseh and Mughni, 1990). It is also recorded as the most important thrips species on mangoes in South Africa (Brink, 1995).
Similarities to Other Species/ConditionsTop of page S. aurantii resembles other Scirtothrips spp. occurring throughout tropical and subtropical areas (see Morphology). In Africa, however, there are no other important species on citrus with which it is likely to be confused. The only similar non-Scirtothrips species is Drepanothrips reuteri, a native European pest of grapevine, but that has 6-segmented antennae (the 3 terminal segments being fused) instead of 8-segmented antennae.
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.
On Citrus, it is normally accepted practice to spray fruits towards the end of a main flowering period, when three-quarters of petals have fallen, using a water solution of lime sulfur (Hill, 1983). Grout (1994) refer to the use of sabadilla alkaloids and tartar emetic in South Africa, and to their side-effects on predatory mites. Nasseh and Mughni (1990) refer to the use of dimethoate and natural insecticides in Yemen. Rattan (1992), for control of the pest on tea in Malawi, notes that dimethoate is to be preferred to fenitrothion or malathion, and that quinalphos and acephate are also effective.
Specific Problems with Resistance/Tolerance
Grout et al. (1996) report tolerance to tartar emetic baits in Swaziland. They comment that alternation of products should provide effective control. Rattan (1992) notes that resistance has developed to synthetic pyrethroids, used for the control of the pest on tea in Malawi.
Field Monitoring/Economic Threshold Levels
Field monitoring using yellow card traps and treatment thresholds are used to time treatment (Grout and Richards, 1990b). Brink (1995) recommends that growers should inspect their mango orchards regularly to detect this pest.
Several species of predacious mites have been shown to contribute to control (Grout and Richards, 1992). Recently, the hymenopteran parasitoid Goethana incerta was shown to parasitize S. aurantii in Swaziland and Malawi (Grout and Stephen, 1995b). Moreover, studies have shown that surrounding windbreak trees could favour the maintenance of natural enemies (Grout and Richards, 1990; Grout and Stephen, 1995a). Grout (1996) mentions that Typhlodromalus spp. may be effective thrips predators, and that combinations of several natural enemies may provide better control. He also considers whether Amblydromella spp. may compete with the other predatory mites.
Importation of Citrus plants for planting from countries where S. aurantii occurs should be prohibited or restricted, as it is, in general, already on account of other important pests.
IPM has been investigated in South Africa (Grout and Richards, 1992).
ReferencesTop of page
Davis EE; Venette RC, 2004. Methyl bromide provides phytosanitary security: a review and case study for Senegalese asparagus. Plant Health Progress, November:1-6. http://www.plantmanagementnetwork.org/pub/php/review/2004/senegal/
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Grout TG, 1994. The distribution and abundance of phytoseiid mites (Acari: Phytoseiidae) on citrus in southern Africa and their possible value as predators of citrus thrips (Thysanoptera: Thripidae). Experimental & Applied Acarology, 18(2):61-71.
Grout TG; Richards GI, 1990. Monitoring citrus thrips, Scirtothrips aurantii Faure (Thysanoptera, Thripidae), with yellow card traps and the effect of latitude on treatment thresholds. Journal of Applied Entomology, 109(4):385-389.
Grout TG; Richards GI, 1990. The influence of windbreak species on citrus thrips (Thysanoptera: Thripidae) populations and their damage to South African citrus orchards. Journal of the Entomological Society of Southern Africa, 53(2):151-157.
Grout TG; Richards GI, 1992. Euseius addoensis addoensis, an effective predator of citrus thrips, Scirtothrips aurantii, in the eastern Cape Province of South Africa. Experimental & Applied Acarology, 15(1):1-13.
Hall WJ, 1930. The South African citrus thrips in Southern Rhodesia. The British South Africa Company Publication No. 1, 1-55.
Mound LA; Marullo R, 1996. The thrips of Central and South America: An Introduction. Memoirs on Entomology, International, 6:1-488.
Nasseh OM; Mughni AAA, 1990. Efficacy of chemical and natural insecticides for suppression of Scirtothrips aurantii (Faure) (Thripidae - Thysanoptera) causing banana fruit spotting disease in the Yemen Arab Republic. Proceedings: Integrated Pest Management in Tropical and Subtropical Cropping Systems Frankfurt am Main, Germany; Deutsche Landwirtschafts- Gesellschaft, 3:749-756.
Rafter MA; Gillions RM; Walter GH, 2008. Generalist herbivores in weed biological control - a natural experiment with a reportedly polyphagous thrips. Biological Control, 44(2):188-195. http://www.sciencedirect.com/science/journal/10499644
Rafter MA; Walter GH, 2012. Sampling of South African citrus thrips (Scirtothrips aurantii Faure) (Thysanoptera: Thripidae) across host plant species in South Africa. African Entomology, 20(2):408-410. http://journals.sabinet.co.za/essa
Rattan PS, 1996. Thrips [Scirtothrips aurantii], red spider mite [Oligonychus coffeae], and crop [tea] loss [in Malawi]. Proceedings of the 1st Regional Tea Research Seminar, Blantyre, Malawi, 22-23 March, 1995., 58-67.
Samways MJ; Tate BA; Murdoch E, 1987. Population levels of adult citrus thrips Scirtothrips aurantii Faure (Thysanoptera, Thripidae) relative to season and fruit-scarring. Journal of Applied Entomology, 104(4):372-377.
Smith IM; McNamara DG; Scott PR; Holderness M, 1997. Quarantine pests for Europe. Second Edition. Data sheets on quarantine pests for the European Union and for the European and Mediterranean Plant Protection Organization. Quarantine pests for Europe. Second Edition. Data sheets on quarantine pests for the European Union and for the European and Mediterranean Plant Protection Organization., Ed. 2:vii + 1425 pp.; many ref.
CABI, Undated. Compendium record. Wallingford, UK: CABI
Davis E E, Venette R C, 2004. Methyl bromide provides phytosanitary security: a review and case study for Senegalese asparagus. Plant Health Progress. 1-6. http://www.plantmanagementnetwork.org/pub/php/review/2004/senegal/
NPPO of the Netherlands, 2013. Pest status of harmful organisms in the Netherlands., Wageningen, Netherlands:
Rafter M A, Gillions R M, Walter G H, 2008. Generalist herbivores in weed biological control - a natural experiment with a reportedly polyphagous thrips. Biological Control. 44 (2), 188-195. http://www.sciencedirect.com/science/journal/10499644 DOI:10.1016/j.biocontrol.2007.09.011
Rafter M A, Walter G H, 2012. Sampling of South African citrus thrips (Scirtothrips aurantii Faure) (Thysanoptera: Thripidae) across host plant species in South Africa. African Entomology. 20 (2), 408-410. http://journals.sabinet.co.za/essa DOI:10.4001/003.020.0220
Distribution MapsTop of page
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