Trioza erytreae (African citrus psyllid)
Index
- Pictures
- Identity
- Summary of Invasiveness
- 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
- Species Vectored
- Biology and Ecology
- Natural enemies
- Means of Movement and Dispersal
- Impact
- Risk and Impact Factors
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- References
- Contributors
- Distribution Maps
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Top of pageIdentity
Top of pagePreferred Scientific Name
- Trioza erytreae (Del Guercio)
Preferred Common Name
- African citrus psyllid
Other Scientific Names
- Aleurodes erytreae Del Guercio
- Spanioza eritreae Del Guercio
- Spanioza erythreae Del Guercio
- Spanioza erytreae Del Guercio
- Spanioza merwei
- Trioza citri Laing
- Trioza erythreae Del Guercio
- Trioza merwei Pettey
International Common Names
- English: African citrus psylla; African citrus psyllid; citrus psylla (African); two-spotted citrus psyllid
- Spanish: piojillo de los cítricos
- French: chermes des agrumes
- Portuguese: psila africana dos citrinos
Local Common Names
- Germany: ostafrikanischer Zitrusblattfloh
EPPO code
- TRIZER (Trioza erythreae)
Summary of Invasiveness
Top of pageThe invasive African psyllid, Trioza erytrea, transmits the causal agent of the African form of citrus huanglongbing (greening) disease, Liberibacter africanum, a very destructive disease of citrus plants. It does this under natural conditions in Africa and the Middle East, and has been shown experimentally to transmit the Asian form, Liberibacter asiaticum. The psyllid itself severely distorts leaves, which become stunted and galled. T. erytreae affects species in the family Rutaceae, occurring on wild hosts as well as on Citrus species.
T. erytreae is listed as an A1 quarantine pest by EPPO (OEPP/EPPO, 1988) and is also a quarantine pest for CPPC and OIRSA. The importation of plants for planting and cut branches of citrus from countries where either citrus greening bacterium or either of its vectors occur has been prohibited (OEPP/EPPO, 1990). T. erytreae occurs in Africa and parts of the Middle East but could probably establish and spread in Mediterranean countries without difficulty.
Besides its role in citrus greening, the psyllid has itself significant damage potential.
Taxonomic Tree
Top of page- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Hemiptera
- Suborder: Sternorrhyncha
- Unknown: Psylloidea
- Family: Triozidae
- Genus: Trioza
- Species: Trioza erytreae
Description
Top of page EggsOrange, cylindrical, with a sharp point anteriorly; laid on leaf margins of young, actively growing foliage.
Nymph
Dorso-ventrally compressed and varying in colour from yellow, olive-green to dark grey; has a marginal fringe of white, waxy filaments; largely sedentary; forms distinct colonies and settles on the underside of young leaves, where, after a few days of feeding, it produces distinctive cup-shaped, open galls.
Adult
Winged, pale and delicate initially, later becoming light brown. Males are smaller than females and have a blunt tip to the abdomen, the latter ending in a sharp point in females. When feeding, adults take up a distinctive stance, with the abdomen raised at an angle of about 35° to the feeding surface.
Distribution
Top of page
The distribution of T. erytreae is wider than that of Liberibacter africanum (the African form of citrus huanglongbing (greening) disease), which is the major pathogen it transmits (EPPO/CABI, 1997). It occurs in the Congo Democratic Republic, St. Helena, Sudan, Uganda, Zambia and, recently, Madeira, where the bacterium has not been recorded.
See also CABI/EPPO (1998, No. 151).
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.
Risk of Introduction
Top of pageLike the other vector of citrus greening (Diaphorina citri), T. erytreae is listed as an A1 quarantine pest by EPPO (OEPP/EPPO, 1988) and is also a quarantine pest for CPPC and OIRSA. It is primarily a pest in tropical climates and as such could certainly become established in citrus-growing countries in the Americas and Asia. In Asian countries where the Asian form of citrus huanglongbing (greening) disease is present, its presence could facilitate spread and considerably add to the difficulties of huanglongbing control. It could probably also establish and spread without difficulty in citrus-growing countries with a Mediterranean climate. Though biological control may be possible, there is no guarantee that it could keep populations to a sufficiently low level to prevent transmission of huanglongbing. Besides its role in the spread of citrus huanglongbing disease, the psyllid itself has significant damage potential.
Hosts/Species Affected
Top of pageT. erytreae affects species in the family Rutaceae, occurring on wild hosts (e.g. Clausena anisata) as well as on Citrus species.
Host Plants and Other Plants Affected
Top of pagePlant name | Family | Context |
---|---|---|
Atalantia buxifolia | Rutaceae | Other |
Balsamocitrus dawei | Rutaceae | Other |
Casimiroa edulis (white sapote) | Rutaceae | Other |
Citrus | Rutaceae | Other |
Citrus aurantiifolia (lime) | Rutaceae | Main |
Citrus jambhiri (rough lemon) | Rutaceae | Other |
Citrus limon (lemon) | Rutaceae | Main |
Citrus maxima (pummelo) | Rutaceae | Other |
Citrus nobilis (tangor) | Rutaceae | Other |
Citrus sinensis (navel orange) | Rutaceae | Other |
Clausena indica | Rutaceae | Other |
Clausena lansium (wampi) | Rutaceae | Other |
Limonia acidissima (elephant apple) | Rutaceae | Other |
Microcitrus australasica | Rutaceae | Other |
Triphasia trifolia (limeberry) | Rutaceae | Other |
Growth Stages
Top of page Vegetative growing stageSymptoms
Top of pageT. erytreae severely distorts leaves, which become stunted and galled, and appear dusted with faecal pellets. Young leaves, especially, may be yellow. The presence of small pit galls on young leaves can indicate T. erytreae (USDA, 2012).
List of Symptoms/Signs
Top of pageSign | Life Stages | Type |
---|---|---|
Leaves / abnormal colours | ||
Leaves / abnormal forms | ||
Leaves / external feeding | ||
Leaves / frass visible | ||
Leaves / leaves rolled or folded | ||
Leaves / yellowed or dead | ||
Whole plant / external feeding |
Species Vectored
Top of page citrus huanglongbing (greening) disease (citrus greening)Liberibacter africanus (African greening)
Biology and Ecology
Top of page
A bibliography of T. erytreae up to 1987 has been compiled by Van den Berg and Fletcher (1988) and a general review has been presented by Van den Berg (1990). T. erytreae has a temperature sensitivity similar to that of Liberibacter africanus (the agent of citrus huanglongbing (greening) in Africa; Schwarz and Green, 1970; Catling, 1973). It is very sensitive to hot, dry weather (the eggs and first-instar nymphs being particularly vulnerable). It is favoured by cooler, moist areas above 500-600 m altitude, where citrus growth flushes tend to be prolonged. Green and Catling (1971) used maximum saturation deficit as an accurate predictor of the geographical distribution of T. erytreae.
Sex ratios fluctuate in the field, but females always predominate. There is a pre-oviposition period of 3-7 days, but this is considerably extended in the absence of young foliage; longevity is also prolonged under such conditions. Mating occurs 2-4 times a day and eggs may be laid immediately. Eggs are supplied with a sharp point that is driven through the leaf epidermis and is thought to be responsible for maintaining a favourable internal water relationship. Females remain fertile for 11-16 days in the absence of males, and maximum egg production occurs towards the middle of their life span, which normally lasts 17-50 days; up to 2000 eggs may be laid per female. There is an incubation period of 6-15 days and nymphal development (five instars) takes 17-43 days, both periods being inversely related to mean temperature and directly related to nutritional value of the leaves. The temperature threshold for nymphal development is around 10-12°C. There is no diapause. Van den Berg et al. (1990) have studied the daily activities and habits of adults, and egg hatching and moulting in T. erytreae, while Van den Berg et al. (1991a) have studied mating, fertility and oviposition.
T. erytreae transmits the causal agent of the African form of citrus huanglongbing (greening) disease, Liberibacter africanus, under natural conditions in Africa and the Middle East (McClean and Oberholzer, 1965). It has been shown experimentally that T. erytreae is also able to transmit the Asian form, Liberibacter asiaticus (Massonie et al., 1976). In Mauritius and Reunion, where both forms occur, T. erytreae probably transmits both.
Natural enemies
Top of pageNatural enemy | Type | Life stages | Specificity | References | Biological control in | Biological control on |
---|---|---|---|---|---|---|
Acantholepis spinosior | Predator | Adults/Nymphs | South Africa | Citrus | ||
Allograpta pfeiferi | Predator | Adults/Nymphs | South Africa | Citrus | ||
Amblyseius degenerans | Predator | Adults/Nymphs | South Africa | Citrus | ||
Anisochrysa burgeonina | Predator | Adults/Nymphs | South Africa | Citrus; Rutaceae | ||
Anisochrysa handschini | Predator | Adults/Nymphs | South Africa | Citrus | ||
Anystis baccarum | Predator | |||||
Aphanogmus incredibilis | Parasite | |||||
Aphanogmus triozae | Parasite | |||||
Aphidencyrtus cassatus | Parasite | |||||
Camponotus grandidieri | Predator | Adults/Nymphs | South Africa | Citrus | ||
Camponotus rufoglaucus | Predator | Adults/Nymphs | South Africa | Citrus | ||
Cheilomenes lunata | Predator | Adults/Nymphs | ||||
Cheilomenes propinqua | Predator | Adults/Nymphs | South Africa | Citrus; Rutaceae | ||
Cheiloneurus cyanonotus | Parasite | |||||
Chrysoperla pudica | Predator | Adults/Nymphs | South Africa | Citrus | ||
Cladosporium oxysporum | Pathogen | Adults/Nymphs | ||||
Coccophagus pulvinariae | Parasite | Adults/Nymphs | ||||
Diaphorencyrtus aligarhensis | Parasite | |||||
Hyperaspis senegalensis | Predator | Adults/Nymphs | ||||
Lepisiota capensis | Predator | Adults/Nymphs | South Africa | Citrus | ||
Leucauge medjensis | Predator | Adults/Nymphs | South Africa | Citrus | ||
Menida lythrodes | Predator | Adults/Nymphs | South Africa | Citrus; Rutaceae | ||
Micromus sjostedti | Predator | Adults/Nymphs | South Africa | Citrus | ||
Myrmicaria natalensis | Predator | Adults/Nymphs | South Africa | Citrus | ||
Nectria flammea | Pathogen | |||||
Pheidole megacephala | Predator | Adults/Nymphs | South Africa | Citrus; Rutaceae | ||
Psyllaephagus pulvinatus | Parasite | Nymphs | South Africa | Citrus | ||
Suarius aquamosa | Predator | Adults/Nymphs | South Africa | Citrus | ||
Tamarixia dryi | Parasite | Nymphs | Reunion | Citrus |
Means of Movement and Dispersal
Top of pageT. erytreae is only likely to spread locally by natural dispersal, up to distances of 1.5 km (Van den Berg and Deacon, 1988). Citrus material (budwood, grafted trees, rootstock seedlings) from infected areas can carry eggs and/or nymphs over longer distances. Such fifth- or sixth-instar nymphs, as well as the adults derived from these nymphs, are capable of transmitting L. africanum to citrus. International movement on citrus fruits is extremely unlikely.
Impact
Top of pageThe main economic importance of T. erytreae is as the vector of the very serious citrus huanglongbing (greening) disease caused by Liberibacter species (EPPO/CABI, 1997). Heavy infestations of T. erytreae also cause severe leaf distortion and the development of conspicuous pits on the leaf surface.
Risk and Impact Factors
Top of page Invasiveness- Invasive in its native range
- Proved invasive outside its native range
- Abundant in its native range
- Highly mobile locally
- Fast growing
- Has high reproductive potential
- Host damage
- Increases vulnerability to invasions
- Negatively impacts agriculture
- Negatively impacts livelihoods
- Reduced native biodiversity
- Threat to/ loss of native species
- Damages animal/plant products
- Negatively impacts trade/international relations
- Pest and disease transmission
- Highly likely to be transported internationally accidentally
- Highly likely to be transported internationally illegally
Detection and Inspection
Top of pageThe presence of small pit galls on young leaves may indicate African citrus psyllid (USDA, 2012).
Similarities to Other Species/Conditions
Top of pageT. erytreae is similar to Diaphorina citri, the Asian citrus psyllid, which is the vector of citrus huanglongbing (greening) in Asia. The geographical range of the two species did not originally overlap, but they now occur together in Mauritius, Reunion and Saudi Arabia.
Prevention and Control
Top of pageChemical Control
Insecticides such as dimethoate can be used against T. erytreae, for which there is an active monitoring programme in orchards in South Africa.
Biological Control
In Reunion, T. erytreae has been successfully controlled by the introduction of a parasite, Tamarixia dryi, from South Africa (Aubert et al., 1980). Research on the biological control of the vectors has also been carried out in Mauritius. Aubert (1987) and Van den Berg (1990) report the results for Mauritius and also Reunion. In South Africa, numerous predators occur but have not been found to reduce populations to economically acceptable levels (Van den Berg et al., 1987).
Cultural Practices
T. erytreae enters orchards from indigenous hosts in the surrounding vegetation (Van den Berg et al., 1991b), so it is recommended that these hosts are removed.
Phytosanitary Measures
Because of the difficulty of ensuring freedom from eggs or nymphs, importation of plants for planting and cut branches of citrus from countries where Liberibacter africanum and its vector occur should be prohibited (OEPP/EPPO, 1990). It is possible to fumigate citrus budwood material against T. erytreae (FAO, l983).
References
Top of pageAubert B; Bové JM; Etienne J, 1980. La lutte contre la maladie du greening des agrumes à l'ile de la Réunion. Résultats et perspectives. Fruits, 35:605-624.
Berg MA van den; Fletcher CD, 1988. A bibliography of the citrus psylla, Trioza erytrep (Del Guercio) (Hemiptera: Triozidae), up to 1987. Phytoparasitica, 16(1):47-61
Bohlen E, 1973. Crop pests in Tanzania and their control. Berlin, Germany: Verlag Paul Parey.
EPPO, 1990. Specific quarantine requirements. EPPO Technical Documents, No. 1008. Paris, France: European and Mediterranean Plant Protection Organization.
EPPO, 2011. EPPO Reporting Service. EPPO Reporting Service. Paris, France: EPPO. http://archives.eppo.org/EPPOReporting/Reporting_Archives.htm
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
FAO, 1983. International plant quarantine treatment manual. FAO Plant Production and Protection Paper No. 50. Rome, Italy: FAO.
Green GC; Catling HD, 1971. Weather-induced mortality of the citrus psylla Trioza erytreae, a vector of greening virus, in some citrus-producing areas of South Africa. Agricultural Meteorology, 8:305-317.
McClean APD; Oberholzer PCJ, 1965. Citrus psylla, a vector of the greening disease of sweet orange. South African Journal of Agricultural Science, 8:297-298.
Schwarz RE; Green GC, 1970. Citrus-greening and the citrus Psyllid Trioza erytreae - a temperature-dependent agent-vector complex. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz, 77(9):490-493
USDA, 2012. .
Van den Berg MA; Deacon VE; Jager K de, 1990. Ecology of the citrus psylla, Trioza erytreae. 1. Daily activities and habits of adults. 2. Egg hatching and moulting. Phytophylactica, 22:323-328, 329-333.
Contributors
Top of page27/03/13 Updated by:
Esther Arengo, National Agricultural Research Laboratories, Uganda
Distribution Maps
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