Invasive Species Compendium

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Datasheet

Scirtothrips aurantii
(South African citrus thrips)

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Datasheet

Scirtothrips aurantii (South African citrus thrips)

Summary

  • Last modified
  • 19 November 2019
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Preferred Scientific Name
  • Scirtothrips aurantii
  • Preferred Common Name
  • South African citrus thrips
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta
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    Compendia
    CAB International
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    OX10 8DE
    UK
    compend@cabi.org
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Identity

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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

EPPO code

  • SCITAU (Scirtothrips aurantii)

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Thysanoptera
  •                         Family: Thripidae
  •                             Genus: Scirtothrips
  •                                 Species: Scirtothrips aurantii

Description

Top 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.

Distribution

Top 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 Table

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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

Africa

AngolaPresentEPPO (2020)
Cabo VerdePresentEPPO (2020)
EgyptPresentEPPO (2020)
EswatiniPresentEPPO (2020)
EthiopiaPresentEPPO (2020)
GhanaPresentEPPO (2020)
KenyaPresentEPPO (2020)
MalawiPresentEPPO (2020)
MauritiusPresentEPPO (2020)
NigeriaPresentEPPO (2020)
RéunionPresentEPPO (2020)
SenegalPresentDavis and Venette (2004)
South AfricaPresentEPPO (2020); Rafter and Walter (2012)
SudanPresentEPPO (2020)
TanzaniaPresentEPPO (2020)
UgandaPresentEPPO (2020)
ZimbabwePresentEPPO (2020)

Asia

YemenPresentEPPO (2020)

Europe

BelgiumAbsentEPPO (2020)
LithuaniaAbsent, Confirmed absent by surveyEPPO (2020)
NetherlandsAbsent, Confirmed absent by surveyNPPO of the Netherlands (2013); EPPO (2020); CABI (Undated)Absent, confirmed by survey, intercepted only.
SloveniaAbsent, Confirmed absent by surveyEPPO (2020)

Oceania

AustraliaPresentRafter et al. (2008)

Risk of Introduction

Top 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 Affected

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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).

Growth Stages

Top of page Flowering stage, Fruiting stage, Vegetative growing stage

Symptoms

Top 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/Signs

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SignLife StagesType
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 Ecology

Top 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 enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Amblyseius tutsi Predator Adults/Nymphs
Euseius addoensis Predator Adults/Nymphs
Euseius citri Predator Adults/Nymphs
Euseius orygmus Predator Adults/Nymphs
Goetheana incerta Parasite
Typhlodromus Predator

Notes on Natural Enemies

Top 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).

Impact

Top 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/Conditions

Top 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 Control

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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.

Chemical Control

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.

Biological Control

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.

Phytosanitary Measures

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 Programmes

IPM has been investigated in South Africa (Grout and Richards, 1992).

References

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Brink T, 1994. The occurrence of thrips on mango inflorescences. Yearbook - South African Mango Growers' Association, 14:78-81; 19 ref.

Brink T, 1995. The occurrence of citrus thrips (Scirtothrips aurantii Fuare) on mango fruit. Yearbook - South African Mango Growers' Association, 15:99-101; 6 ref.

Brink T; Dreyer S, 1996. Citrus thrips on mangoes. Inligtingsbulletin - Instituut vir Tropiese en Subtropiese Gewasse, No. 286:12-16; 14 ref.

CABI/EPPO, 1998. Distribution maps of quarantine pests for Europe (edited by Smith IM, Charles LMF). Wallingford, UK: CAB International, xviii + 768 pp.

CIE, 1961. Distribution Maps of Pests, Series A, No. 137. Wallingford, UK: CAB International.

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

Gilbert MJ, 1990. Relative population levels of citrus thrips Scirtothrips aurantii on commercial Citrus and adjacent bush. South African Journal of Zoology, 25(1):72-76.

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.

Grout TG; Stephen PR, 1995. Goetheana incerta parasitizing citrus thrips in southern Africa. Citrus Journal, 5(4):30-32; 11 ref.

Grout TG; Stephen PR, 1995. New windbreak tree contributes towards integrated pest management of citrus. Citrus Journal, 5(4):26-27.

Grout TG; Stephen PR; Croix NJSla, 1996. Citrus thrips (Thysanoptera: Thripidae) in Swaziland develop tolerance to tartar emetic bait. African Entomology, 4(1):15-20; 14 ref.

Hall WJ, 1930. The South African citrus thrips in Southern Rhodesia. The British South Africa Company Publication No. 1, 1-55.

Hill DS, 1983. Agricultural Insect Pests of the Tropics and their Control. 2nd edition. Cambridge, UK: Cambridge University Press.

Kamburov SS, 1991. Damage to fruit and the impact on crop set from late infestations of citrus thrips (Scirtothrips aurantii Faure). Citrus Journal, 1(1):33-34.

Milne DL; Manicom BQ, 1978. Feeding apparatus of the South African citrus thrips, Scirtothrips aurantii Faure. Citrus and Subtropical Fruit Journal, 535:6-11.

Mound LA; Marullo R, 1996. The thrips of Central and South America: An Introduction. Memoirs on Entomology, International, 6:1-488.

Mound LA; Palmer JM, 1981. Identification, distribution and host-plants of the pest species of Scirtothrips (Thysanoptera: Thripidae). Bulletin of Entomological Research, 71(3):467-479.

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, 1992. Thrips (Scirtothrips aurantii), synthetic pyrethroid insecticides and alternatives. Quarterly Newsletter - Tea Research Foundation of Central Africa, 106:9-11.

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.

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