A Thrips | Coremothrips pallidus Hood

California Pest Rating for
Coremothrips pallidus Hood: a thrips
Thysanoptera: Thripidae
Pest Rating: A


Initiating Event:

Coremothrips pallidus was recently reported to be established in Hawaii (Mound et al., 2017).  It is currently Q-rated, and a permanent pest rating proposal is required to support an official pest rating.

History & Status:

Background:  Coremothrips pallidus is a tiny (~1 mm in length), pale yellowish-white thrips (Hood, 1925).  It has been found feeding on avocado leaves in Hawaii (Mound et al., 2017).  Adults and larvae were found on Guettarda scabra (Rubiaceae) in Guadeloupe, which suggests that this plant was being fed upon (Etienne et al., 2015).  It has also been found on leaves of other plants in the families Bixaceae, Combretaceae, Sterculiaceae, and Ulmaceae, but it is not known if these records represent feeding (Cavalleri, 2015; Etienne et al., 2015; Goldarazena et al., 2012; Hood, 1925).

Worldwide Distribution:  Coremothrips pallidus has been reported from Central America (Panama), South America (Brazil), and the Caribbean (Guadeloupe, Saint Vincent, and Trinidad) (Cavalleri, 2005; Etienne et al., 2015; Monteiro, 2002; Symbiota Collections of Arthropods Network).  It was recently reported to be established on the islands of Hawaii and Oahu in Hawaii (Mound et al., 2017).

Official Control: Coremothrips pallidus is not known to be under official control anywhere.

California Distribution:  Coremothrips pallidus is not known to be present in California.

California Interceptions:  Coremothrips pallidus has not been intercepted in California.

The risk Coremothrips pallidus would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Coremothrips pallidus appears to feed on at least two species of plants, including avocado. Avocado is widely planted in southern California.  However, this thrips is apparently restricted to tropical or subtropical areas.  It is possible that it could become established in a limited portion of California.  Therefore, Coremothrips pallidus receives a Medium (2) in this category.

– 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: Although pallidus has been reported from several plants species, only two of these plants are considered verified hosts here: Avocado (because the report specified that feeding had occurred) and Guettarda scabra (because adults and larvae were found on this plant), representing two families. It is likely that some of the other plants in the families listed above (under Background) were also fed upon.  Therefore, C. pallidus receives a Medium (2) in this category.

– 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: Coremothrips pallidus has wings and presumably flies.  It could also be dispersed artificially via transport of infested plant material.  Lastly, it may be capable of wind-aided dispersal.  Therefore, it receives a Medium (2) in this category.

– 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: Coremothrips pallidus has been reported to feed on avocado, which is an important crop in California.  If this species was established in California, it is possible that it could lower the value of avocados.  Therefore, it receives a Low (1) in this category.

Economic Impact: B

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.

Economic Impact Score: 1

– 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: Coremothrips pallidus feeds on plants in at least two families. If this species became established in California, it would encounter plants that are not present in the area of its current distribution.  If it fed on these plants, it is possible that this thrips could have an impact on natural communities.    Therefore, it receives a Medium (2) in this category.

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

Environmental Impact: A

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:

Environmental Impact Score: 2

– 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 Coremothrips pallidus: Medium (9)

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: Coremothrips pallidus is not known to occur in California.  It receives a Not established (0) in this category.

–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:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (9)


Coremothrips pallidus is fairly widely distributed, and yet there do not appear to be any reports of this species being a pest.  It is therefore possible that this proposal is overly pessimistic and this thrips may not become a problem even if it was established in California. Some thrips are vectors of plant viruses, and it is possible (though no reports were found of C. pallidus vectoring diseases) that this species could transmit virus diseases of avocado if it was established in California.

Conclusion and Rating Justification:

Coremothrips pallidus is a plant-feeding thrips that attacks avocado and is not known to be present in California.  If it became established in this state, it could impact avocado cultivation and could also have environmental impacts.  For these reasons, an “A” rating is justified.


Cavalleri, A.  2005.  Comunidades de tripes (Insecta: Thysanoptera) em flores e ramos, com ênfase em Asteraceae, no Parque Estadual de Itapuã, Vlamão, RS.  Ph.D. dissertation.  Instituto de Biociências da Universidade Federal do Rio Grande do Sul, Porto Alegre.

Etienne, J., Ryckewaert, P., and B. Michel.  2015.  Thrips (Insecta: Thysanoptera) of Guadeloupe and Martinique: Updated check-list with new information on their ecology and natural enemies.  Florida Entomologist.  98(1): 298-304.

Goldarazena, A., Gattesco, F., Atencio, R., and C. Korytowski.  2012.  An updated checklist of the Thysanoptera of Panama with comments on host associations.  Check List.  8(6): 1232-1247.

Hood, J.D.  1925.  New neotropical Thysanoptera collected by C.B. Williams.  1925.  Psyche.  32: 48-69.

Monteiro, R.  2002.  The Thysanoptera fauna of Brazil.  Pages 325-340 in R. Marullo and L. Mound, editors.  Thrips and Tospoviruses: Proceedings of the 7th International Symposium on Thysanoptera.  Australian National Insect Collection, Canberra.  390 pp.

Mound, L.A., Matsunaga, J.N., Bushe, B., Hoddle, M.S., and A. Wells.  2017.  Adventive Thysanoptera species in the Hawaiian Islands: New records and putative host associations.  Proceedings of the Hawaiian Entomological Society.  49: 17-28.

Symbiota Collections of Arthropods Network.  Accessed 13 November 2017.  http://scan1.acis.ufl.edu


Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741; plant.health[@]cdfa.ca.gov.

Responsible Party:

Jason Leathers, 2800 Gateway Oaks, Sacramento CA 95833, (916) 654-1211, plant.health[@]cdfa.ca.gov

Comment Period:* CLOSED

4/30/18 – 6/14/18


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Pest Rating: A


Posted by ls