Retithrips syriacus (Mayet): Black vine thrips

Black Vine ThripsCalifornia Pest Rating for
Retithrips syriacus (Mayet): Black vine thrips
Thysanoptera: Thripidae
Pest Rating: A

Initiating Event:

February 26, 2014, USDA distributed a Deregulation Evaluation of Established Pests (DEEP) report proposing to change the status of Retithrips syriacus, black vine thrips, from actionable to non-actionable for the continental United States.  The thrips would remain actionable for Hawaii, Guam, and the Virgin Islands.  The insect is currently unrated by CDFA, so a pest rating proposal is needed to determine future direction.

History & Status:

Background:  Retithrips syriacus breeds on the leaves of a variety of plants in 29 plant families including grapes, roses, cotton, and castor oil2.  It may spread through trade on leaves where it has been intercepted (rarely) on various species1.

Worldwide Distribution: Retithrips syriacus is widespread in Africa and western Asia1.  It has also been found in Brazil, Venezuela, and Puerto Rico1.  It was first detected in southern Florida in 19931.

Official Control: Costa Rica, Ecuador, Japan, Jordan, the Republic of Korea, Panama, and Peru list Retithrips syriacus on their harmful organism lists1.

California Distribution:  Retithrips syriacus has never been found in the environment of California.

California Interceptions:  Retithrips syriacus has never been intercepted in California.

The risk Retithrips syriacus (black vine thrips) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: The present distribution of Retithrips syriacus corresponds to USDA plant hardiness zones 9-13, indicating that it may establish in much of California. The thrips receives a High (3) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California.  Score:

Low (1) Not likely to establish in California; or likely to establish in very limited areas.

Medium (2) may be able to establish in a larger but limited part of California.

High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: Retithrips syriacus feeds and breeds on a variety of plants in at least 29 plant families.  The thrips receives a High (3) in this category.

Evaluate the host range of the pest. Score:

Low (1) has a very limited host range.

Medium (2) has a moderate host range.

High (3) has a wide host range.

3) Pest Dispersal Potential: Thrips are capable of rapid reproduction.  Retithrips syriacus may move long distances in trade on nursery stock or leaves, and may be spread by wind.  One of the hosts of Retithrips syriacus is castor oil plant.  Castor oil plant is common and very abundant in riparian areas of Southern California.  If the thrips were to enter this part of the state it is likely to spread rapidly throughout the region on this host.  The thrips receives a High (3) in this category.

Evaluate the natural and artificial dispersal potential of the pest. Score:

Low (1) does not have high reproductive or dispersal potential.

Medium (2) has either high reproductive or dispersal potential.

High (3) has both high reproduction and dispersal potential.

4) Economic Impact: Retithrips syriacus feeds and breeds on a wide variety of plants including economically important crops such grapes, cotton, and roses.  Although the thrips has not yet caused economic damage in tropical southern Florida1, the native distribution of the thrips tends more toward a Mediterranean climate more typical of California and the thrips may be predicted to be more damaging here. Retithrips syriacus has the potential to lower yield in these crops by feeding on leaves.  The thrips may also increase crop production costs by triggering additional management activities.  Retithrips syriacus is listed as a quarantine pest by multiple countries and USDA has proposed to keep the thrips actionable in Hawaii, Guam, and the Virgin Islands.  Therefore it is probable that if Retithrips syriacus were to establish in California, it would trigger a loss of markets. This would be expected especially for exports of California table grapes.  Retithrips syriacus receives a High (3) in this category.

Evaluate the economic impact of the pest to California using the criteria below. Score:

A. The pest could lower crop yield.

B. The pest could lower crop value (includes increasing crop production costs).

C. The pest could trigger the loss of markets (includes quarantines).

D. The pest could negatively change normal cultural practices.

E. The pest can vector, or is vectored, by another pestiferous organism.

F. The organism is injurious or poisonous to agriculturally important animals.

G. The organism can interfere with the delivery or supply of water for agricultural uses.

Low (1) causes 0 or 1 of these impacts.

Medium (2) causes 2 of these impacts.

High (3) causes 3 or more of these impacts.

5) Environmental Impact: Rosa is considered a host of Retithrips syriacus.  Small-leaved rose (Rosa minutifolia) is listed as an endangered species by California and could be directly affected by the thrips.  The presence of Retithrips syriacus may also trigger additional chemical treatments in agricultural production.  The thrips receives a High (3) in this category.

Evaluate the environmental impact of the pest on California using the criteria below.

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.

B. The pest could directly affect threatened or endangered species.

C. The pest could impact threatened or endangered species by disrupting critical habitats.

D. The pest could trigger additional official or private treatment programs.

E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. Score:

Low (1) causes none of the above to occur.

Medium (2) causes one of the above to occur.

High (3) causes two or more of the above to occur.

Consequences of Introduction to California for Retithrips syriacus (Black vine thrips):  High (15)

Add up the total score and include it here.

 –Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Retithrips syriacus has never been found in California and receives a Not established (0) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included. (Score)

Not established (0) Pest never detected in California, or known only from incursions.

Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).

Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.

High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (15)


It is possible that Retithrips syriacus may be managed by existing IPM practices in agriculture.

Conclusion and Rating Justification:

Retithrips syriacus is expected to find favorable conditions in California where it may have significant economic and environmental impacts.  An A-rating is justified.


1Baez, Ignacio.  2014.  Deregulation Evaluation of Established Pests (DEEP); DEEP Report on Retithrips syriacus (Mayet): Black vine thrips.

2Thrips of California

Responsible Party:

Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211,[@]

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Pest Rating: A

Posted by ls