Scirtothrips perseae (avocado thrips)
- Summary of Invasiveness
- Taxonomic Tree
- Distribution Table
- History of Introduction and Spread
- 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
- Means of Movement and Dispersal
- Pathway Vectors
- Plant Trade
- Wood Packaging
- Impact Summary
- Environmental Impact
- 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
- Scirtothrips perseae Nakahara, 1997
Preferred Common Name
- avocado thrips
- SCITPE (Scirtothrips perseae)
Summary of InvasivenessTop of page
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Uniramia
- Class: Insecta
- Order: Thysanoptera
- Family: Thripidae
- Genus: Scirtothrips
- Species: Scirtothrips perseae
DescriptionTop of page
The males are similar to the females but are smaller. Tergite IX posterior angles with a pair of stout, curved processes (drepanae) extending around segment X. The sternites lack glandular areas.
The second-instar larvae are white; the antennal segments are grey; the tergites are covered in an irregularly arranged dot-like sculpture; the pronotum has a similar marking near the posterior margin; the setae are bluntly capitate on the head and posterior angles of pronotum, remaining setae finely acute; abdominal spiracles small.
DistributionTop of page
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|
|United States||Present, Localized|
History of Introduction and SpreadTop of page
Risk of IntroductionTop of page
HabitatTop of page
Hosts/Species AffectedTop of page
Host Plants and Other Plants AffectedTop of page
|Persea americana (avocado)||Lauraceae||Main|
Growth StagesTop of page
SymptomsTop of page
List of Symptoms/SignsTop of page
|Fruit / malformed skin|
|Leaves / abnormal leaf fall|
Biology and EcologyTop of page
S. perseae is haplodiploid; unfertilized eggs produce males and fertilized eggs result in female progeny. Molecular work on S. perseae is currently underway in California, USA to examine the genetic constitution of this pest for comparison with conspecifics in Latin America.
S. perseae is multivoltine in California and there appears to be no overwintering stage or diapause. Population levels typically peak in late spring/early summer and hot summer temperatures can cause abrupt population crashes (Hoddle et al., 2002a).
S. perseae has six distinct life stages. The females lay eggs inside young leaves or fruit (Hoddle, 2002a). Two larval stages subsequently develop and feed on young leaves or fruit. The two pupal stages are non-feeding and pupation occurs either in cracks or crevices on branches, or in leaf duff (litter) below the trees. The adults that emerge from the pupal stage feed on leaves and fruit. Because they can fly, they can disperse to adjacent trees to search for young, tender leaves in which to lay eggs.
Laboratory studies have indicated that the avocado thrips larvae and adults exhibit the highest survivorship, longevity and fecundity at moderately cool temperatures (20-25°C). Moderately hot temperatures (30°C), cause high larval mortality and reduced adult longevity when the thrips are confined in small cages under constant laboratory conditions (Hoddle, 2002b).
Preferences for low temperatures may optimally co-ordinate avocado thrips development and reproduction with avocado phenology over the spring, when the plants are producing young leaves and fruit, which are ideally suitable for thrips feeding and oviposition.
The cool temperatures in late winter to early summer, which favour avocado leaf flush and fruit initiation, are most preferred by S. perseae. The pest populations typically build rapidly under these climatic conditions and this pest is most severe in orchards that are in close proximity to the coast. The marine influence has a moderating effect on hot summer temperatures (Hoddle et al., 2002a).
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Notes on Natural EnemiesTop of page
Two releases of Franklinothrips at a rate of 218 adults per tree failed to control avocado thrips at densities of 12 larvae per leaf. In this study, a major problem was the poor quality of the predator after shipping from Europe to California. After transit over 50% of the adults had died and the survivors were probably of marginal health. In two later studies, weekly releases of Franklinothrips at a rate of approximately 50 adults per tree failed to control avocado thrips at initially low (1 thrips per leaf) and high densities (25 thrips per leaf) at sites in Escondido and Ventura, USA respectively. In these studies, a major problem was a lack of consistent thrips populations at densities that could support predator population growth. The low-density populations did not develop and the high-density populations crashed soon after the trial started.
Laboratory work on Franklinothrips has identified the optimal temperatures (Hoddle et al., 2000), diets (Hoddle et al., 2001a), harvesting of pupae (Hoddle et al., 2001b) and automated sorting of pupae; techniques that are applicable to the cost-effective mass rearing of this predator. Adult Franklinothrips females can eat approximately 14 to 20 second-instar avocado thrips larvae in a 24-hour period (Hoddle, 2003a). This predator does not show a feeding preference for first- or second-instar avocado thrips larvae. Both life stages are equally likely to be attacked after the predator encounters them. On average, Franklinothrips spends 7 to 13 seconds probing avocado leaves with its mouthparts and such activity occupies around 2 to 5% of its time (Hoddle, 2003b). This observation may explain, in part, why Franklinothrips populations decline following applications of insecticides that exhibit translaminar activity [Agri-Mek (abamectin) and Success (spinosad)]. Leaf feeding in this manner may expose Franklinothrips to insecticides that have moved into the leaf material, thereby killing them (Hoddle, 2003b).
Means of Movement and DispersalTop of page
Avocado thrips appear to be poor fliers and most likely fly under conditions which allow them to regulate their flight direction (Hoddle et al., 2002c). As with most thrips, strong winds can probably transport S. perseae long distances.
In California, USA, S. perseae does not appear to spread any viral diseases.
The movement of infested harvesting bins has been implicated in the rapid long-range movement of adult S. perseae during fruit harvest. Bin disinfestations are recommended when moving them between infested and uninfested regions.
Movement in Trade
S. perseae is most likely to be spread on plants and not shipments of mature fruit. Mature harvested fruit are unsuitable feeding substrates for larval and adult S. perseae.
Pathway VectorsTop of page
|Land vehicles||Road, rail, sea and air||Yes|
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Flowers/Inflorescences/Cones/Calyx||adults; larvae||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Fruits (inc. pods)||adults; eggs; larvae||Yes||Yes||Pest or symptoms usually invisible|
|Leaves||adults; eggs; larvae||Yes||Yes||Pest or symptoms usually invisible|
|Seedlings/Micropropagated plants||adults; eggs; larvae||Yes||Yes||Pest or symptoms usually invisible|
|Plant parts not known to carry the pest in trade/transport|
|Growing medium accompanying plants|
|Stems (above ground)/Shoots/Trunks/Branches|
|True seeds (inc. grain)|
Wood PackagingTop of page
|Wood Packaging not known to carry the pest in trade/transport|
|Loose wood packing material|
|Processed or treated wood|
|Solid wood packing material with bark|
|Solid wood packing material without bark|
Impact SummaryTop of page
ImpactTop of page
Environmental ImpactTop of page
DiagnosisTop of page
Detection and InspectionTop of page
Similarities to Other Species/ConditionsTop of page
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.Cultural Control
A novel method of controlling avocado thrips pupating in the soil beneath host trees (approximately 78% of second-instar larvae drop from the trees to pupate in the soil) is the use of coarse composted organic yard waste. Composted material that is prepared correctly is devoid of pathogenic diseases and pestiferous arthropods. Small field trials have demonstrated that 50% fewer thrips adults emerge from mulch laid under avocado trees in comparison to non-mulched trees that have leaf duff (litter) and branches under them. It is probable that the mulch suppresses the pupation of avocado thrips because it harbours a more diverse fauna of natural enemies (including entompathogenic fungi, nematodes and generalist arthropod predators) that opportunistically feed on microarthropods living in the mulch. This diverse fauna is lacking in avocado leaf duff in California, USA. Consequently, these generalist natural enemies attack avocado thrips larvae that fall from the trees to pupate. Interestingly, about 98% of Franklinothrips orizabensis (a common predatory thrips in avocado orchards) larvae drop from the trees to pupate in the soil. The organisms living in the mulch do not adversely affect F. orizabensis, probably because they pupate within protective silk cocoons, something avocado thrips does not do. It is unknown if the mulch can provide orchard-wide suppression of avocado thrips; if the reduction of thrips emergence is great enough to prevent economic damage to fruit; if the level of suppression seen is consistent year to year; or how regularly the mulch needs to be reapplied as it decomposes (Hoddle et al., 2002a).
This area has not been studied for S. perseae.
In developing a strategy for managing avocado thrips, a grower should consider a large number of interrelated factors including tree size and vigour (which may affect the amount and timing of leaf flushes that avocado thrips prefer), the past history of avocado thrips population dynamics, and fruit scarring experienced in the grove and surrounding regions. Also the amount of leaf flush and/or small fruit present; whether these fruit are the major set or additional fruit sets are expected; avocado thrips levels; natural enemy levels; grove topography; spray equipment availability; the grower's tolerance for fruit scarring; and an interest in preserving avocado thrips pesticide susceptibility. One should also consider that the weather, and the timing and amount of leaf flushes and avocado fruit sets, can vary tremendously from year to year. Just because avocado thrips caused significant fruit scarring one year or in a particular grove, does not mean that this or other nearby groves will have economic avocado thrips levels in subsequent years. Many groves do not need to be treated for avocado thrips and as a general principle, if practical, it is best to withhold treatments as long as possible to maximize the negative impact of the weather and natural enemies on avocado thrips levels. Under ideal circumstances and if practical, treatments should not be applied until it is clear that economic levels of avocado thrips (approximately three to ten immature thrips per fruit depending on the threshold for treatment) are present on a significant fruit set and are likely to cause economically significant damage (i.e. withhold treatments on off-bloom fruit, if hot weather is imminent, if natural enemy levels are high, or if the grower has a high tolerance for fruit scarring).
Because making decisions on the need for and timing of avocado thrips treatments can be difficult, it is important that the grower becomes as familiar as possible with avocado thrips and natural enemy biology, possible control options, and/or employs a knowledgeable pest control advisor to assist with scouting and decision-making.
There are three major options for the chemical control of avocado thrips as listed below and the materials are listed from least to most persistent in the control of avocado thrips.
- Veratran D plus sugar - this material is a botanical pesticide made from the ground seeds of a lily-like plant, Schoenocaulon officinale. The spray tank should be acidified to pH 4.5 prior to adding the Veratran D to the tank because acidification helps to maximize treatment efficacy. Veratran D residues are not persistent on leaves and are reduced to 50% of the initial level approximately 4 days after treatment. This results in perhaps 1-3 weeks of control depending on weather, application method, and thrips levels. Additives should not be added to a Veratran D treatment unless experience has shown that efficacy is not compromised. Veratran D is a stomach poison, thus it is relatively innocuous to most natural enemies.
- Success 2 SC plus Narrow Range 415 Spray Oil - Success (spinosad) is in the macrocyclic lactone class of chemistry, is unstable in sunlight (most surface residues are degraded within a day), and exhibits translaminar activity (it moves into the upper cell layers of leaves or fruit where it is toxic to avocado thrips when they feed). Success is relatively innocuous to natural enemies and treatments normally last for 2-4 weeks.
- Agri-Mek 0.15 EC plus Narrow Range 415 Spray Oil - Agri-Mek (abamectin) is also a macrocylic lactone, is unstable in sunlight, exhibits translaminar activity and should be used with oil. Thrips poisoned by Agri-Mek take 3-5 days to die and thus, control can be somewhat slower than with faster acting insecticides. This material is quite persistent in leaves and treatments can last for 6-10 weeks or more. Agri-Mek is also fairly innocuous to natural enemies.
Six applications of Veratran D in a single orchard over 2 years, resulted in the development of an 11-fold resistance by avocado thrips to this material. The development of avocado thrips resistance is a real concern and unnecessary treatments should be avoided. If Veratran D is being used for avocado thrips control, a maximum of two to three applications per year should be applied and this material should be rotated with either Agri-Mek or Success to reduce the rate at which insecticide resistance can develop. Avocado thrips have the potential to develop a resistance to Agri-Mek and Success. Because Agri-Mek and Success are of similar chemistry, there is a concern that cross-resistance might appear (i.e. if thrips develop resistance to one material, they might become resistant to the other). For these reasons, growers should only apply a single treatment of Agri-Mek per year, up to a maximum of two applications of Success per year (it is less persistent in leaves and fruit than Agri-Mek is), or up to a total of one Agri-Mek and one Success treatment per year (Yee et al., 1999, 2001a, b).
Early Warning Systems
None are used for S. perseae.
Field Monitoring/Economic Threshold Levels
At present the economic injury level used for avocado thrips ranges from three to five larvae and adults per three-quarters of expanded avocado leaf during bloom and when the fruit are still less than 3 cm long.
These are still under development for S. perseae.
ReferencesTop of page
EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm
Hoddle MS, 2003. Predation behaviors of Franklinothrips orizabensis (Thysanoptera: Aeolothripidae) towards Scirtothrips perseae and Heliothrips haemorrhoidalis (Thysanoptera: Thripidae). Biological Control, 27(3):323-328; 19 ref.
Hoddle MS, 2003. The effect of prey species and environmental complexity on the functional response of Franklinothrips orizabensis: a test of the fractal foraging model. Ecological Entomology, 28(3):309-318; 40 ref.
Hoddle MS; Jones J; Oishi K; Morgan D; Robinson L, 2001. Evaluation of diets for the development and reproduction of Franklinothrips orizabensis (Thysanoptera: Aeolothripidae). Bulletin of Entomological Research, 91(4):273-280; 33 ref.
Hoddle MS; Nakahara S; Phillips PA, 2002. Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller). Biological Control, 24(3):251-265; 40 ref.
Hoddle MS; Oishi K; Morgan D, 2001. Pupation biology of Franklinothrips orizabensis (Thysanoptera: Aeolothripidae) and harvesting and shipping of this predator. Florida Entomologist, 84(2):272-281; 33 ref.
Hoddle MS; Robinson L; Drescher K; Jones J, 2000. Developmental and reproductive biology of a predatory Franklinothrips n. sp. (Thysanoptera: Aeolothripidae). Biological Control, 18(1):27-38; 34 ref.
Hoddle MS; Robinson L; Morgan D, 2002. Attraction of thrips (Thysanoptera: Thripidae and Aeolothripidae) to colored sticky cards in a California avocado orchard. Crop Protection, 21(5):383-388; 33 ref.
Silvers C, 2000. Biological control of Scirtothrips perseae Nakahara in California avocados: assessment of two generalist predators. MS Thesis, University of California, Riverside, USA, 103pp.
Yee W; Phillips PA; Faber BA, 2001. Effects of aerial spray volume, coverage, and sabadilla on Scirtothrips perseae (Thysanoptera: Thripidae). Journal of Economic Entomology, 94:1085-1089.
Yee WL; Phillips PA; Faber BA, 2001. Effects of aerial spray volume, coverage, and abamectin on Scirtothrips perseae (Thysanoptera: Thripidae). Journal of Economic Entomology, 94(5):1090-1096; [Available online at http://www.entsoc.org/pubs/jee/jeetocs/].
Yee WL; Phillips PA; Faber BA; Morse JG; Hoddle MS, 1999. Control of avocado thrips using aerial applications of insecticides. California Avocado Society Yearbook, 83:141-162; 17 ref.
CABI, Undated. Compendium record. Wallingford, UK: CABI
CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI
Distribution MapsTop of page
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