Dichromothrips smithi (Zimmerman): Bamboo Orchid Thrips

California Pest Rating for
Dichromothrips smithi
Photo Credit: http://keys.lucidcentral.org
Dichromothrips smithi (Zimmerman): Bamboo Orchid Thrips
Thysanoptera: Thripidae
Pest Rating: A

Initiating Event:

In April and May 2015 the thrips Dichromothrips smithi was found on orchids at a nursery in San Luis Obispo County.  A pest rating proposal is required to assign a permanent pest rating.

History & Status:

BackgroundDichromothrips smithi is an important pest in orchid greenhouses in Korea and Hawaii1.  The thrips feed in aggregations on flowers1.  It seems to prefer Bamboo orchids (Arundina graminifolia), but also infests other orchids in the genera Vanilla, Phalaenopsis, Spathoglottis, Dendrobium, Epidendrum, Cattleya, and Cymbidium1.  It is a pest of cultivated Vanilla in India2Dichromothrips smithi may be transported long distances when infested plants or cut flowers are moved.

Worldwide Distribution: Dichromothrips smithi is native to Asia where it is widespread from India to Malaysia, Indonesia, and Japan1.  It was first found in Hawaii in 20071.

Official Control: Dichromothrips smithi is listed as a harmful organism by Japan and the Republic of Korea3.

California DistributionDichromothrips smithi has never been found in the environment of California.

California InterceptionsDichromothrips smithi has been intercepted twice by CDFA on orchids from Hawaii.

The risk Dichromothrips smithi (Bamboo orchid thrips) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Dichromothrips smithi is a tropical thrips that is likely to only establish in the warmest areas of southern and coastal California and in orchid greenhouses. It receives a Low (1) 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: Dichromothrips smithi typically feeds on eight genera of plants in the orchid family.  In China it is reported to have a much broader host range than anywhere else it has been found4.  There it is reported to feed on plants in 10 families including Amaryllidaceae, Leguminosae, Cucurbitaceae, and Solanaceae4.   It 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 or rapid reproduction and local dispersal.  They may be transported long distances when infested plants or cut flowers are moved.  Dichromothrips smithi 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: Dichromothrips smithi is not expected to lower any crop yields.  It is likely to reduce the value or orchid plants by disfiguring them with its presence and feeding.  Since the thrips is not known to be present in North, Central, or South America its presence in California may disrupt markets for orchid plants and cut flowers.  It is not expected to change cultural practices, injure animals, or interfere with water supplies.  Thrips often vector viruses between plants.  Dichromothrips smithi 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: Dichromothrips smithi is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes.  It is not expected to feed on threatened or endangered species or disrupt critical habitats.  It is likely to trigger additional treatment programs in the nursery and cut flower industries and by residents who find infested orchids unacceptable.  The thrips is a significant pest of orchids which are high value ornamental plants.  Dichromothrips smithi 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 Dichromothrips smithi (Bamboo Orchid Thrips): High (13)

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: Dichromothrips smithi has never been found in the environment of 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.

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 (13)


It is unknown why Dichromothrips smithi is reported to have a much greater host range in China than it has elsewhere in its distribution.  This could be due to no-choice lab associations or taxonomic confusion.  It is possible that the thrips will be limited to orchids in California.

Conclusion and Rating Justification:

Dichromothrips smithi has never been found in the environment of California.  If it were to establish in the state it is likely to have significant economic and environmental impacts.  An “A” rating is justified.


1 Hollingsworth, Robert G., Frances Calvert, and Arnold H. Hara. 2012. Dichromothrips smithi (Zimmerman), a New Thrips Species Infesting Bamboo Orchids Arundina graminifolia (D. Don) Hochr. And Commercially Grown Orchids in Hawaii.  Proceedings of the Hawaiian Entomological Society 44:1-9.  http://scholarspace.manoa.hawaii.edu/bitstream/handle/10125/25458/PHES-44_1-9.pdf?sequence=1

2 Hoddle, M.S., Mound, L.A., Paris, D.L. 2012. Thrips of California. CBIT Publishing, Queensland. http://keys.lucidcentral.org/keys/v3/thrips_of_california/identify-thrips/key/california-thysanoptera-2012/Media/Html/browse_species/Dichromothrips_smithi.htm

3 USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD).  https://pcit.aphis.usda.gov/pcit/

4 Liao, Qi-rong and Bo Wang. 2012. Hosts and Occurrence Regularity of Dichromothrips smithi. Guizhou Science. http://en.cnki.com.cn/Article_en/CJFDTOTAL-GZKX201203010.htm

Responsible Party:

Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211, plant.health[@]cdfa.ca.gov.

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Pest Rating: A

Posted by ls