Thrips | Trichromothrips priesneri (Bhatti) | Pest Rating Proposals and Final Ratings

California Pest Rating for

Thrips | Trichromothrips priesneri (Bhatti)

Thysanoptera: Thripidae

Pest Rating: A

PEST RATING PROFILE

Initiating Event:

Trichromothrips priesneri was tentatively reported to be established on the island of Maui, 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: Adult T. priesneri are bicolored, with a dark brown abdomen and wings and white (with brown markings) thorax and head (Mound et al., 2017). The size is probably similar to that of other Trichromothrips species: 1-1.5 mm (Nakahara, 1993). Very little information is available on this species. In Taiwan, T. priesneri has been collected from unidentified grass and Ipomoea nil (Wang, 2008). In Hawaii, it was found in a coastal, wetland area with dodder and Cyperaceae (Mound et al., 2017). It is not known if these plants are fed upon by the thrips. Other species of Trichromothrips have been reported to feed on ferns, bamboo, orchids, and other plants (Goldarazena et al., 2012; Mound and Masumoto, 2004; Ng and Mound, 2015), although again, it is possible that some of these records do not represent feeding but rather plants that the thrips happened to be resting on. One species of Trichromothrips was reported to be a pest on orchids and various greenhouse plants, but no further information was found to support this (Mound et al., 2016).

Worldwide Distribution: Trichromothrips priesneri is found in, and is presumably native to India (Karnataka, Madhya Pradesh, Tamil Nadu, and Uttar Pradesh states) (Rachana and Varatharaja, 2017; Tyagi and Kumar, 2016). It is also reported from Taiwan and Hawaii; these reports are presumed to represent introductions, although the identification of the Hawaii specimens appears to have been tentative (Mound et al., 2017; Wang, 2008).

Official Control: Trichromothrips priesneri is not known to be under official control anywhere.

California Distribution: Trichromothrips priesneri is not known to be present in California (Symbiota Collections of Arthropods Network).

California Interceptions: Trichromothrips priesneri has not been intercepted in California (CDFA Pest and Damage Report Database, 2017).

The risk Trichromothrips priesneri would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: The areas that priesneri occurs in have a tropical or subtropical climate, suggesting that this species requires such climates. This is expected to limit the potential distribution of this species in California to a limited area. Not enough is known about the feeding habits of T. priesneri to consider the presence of host plants in the potential distribution of this species in California. Therefore, T. priesneri 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 the collection of specimens in Taiwan from grass and Ipomoea nil suggests that these may be host plants, too little is known about the biology of priesneri to assess its host range. To account for uncertainty, the host range will be assumed to be moderate. Therefore, T. priesneri 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 Reproductive and Dispersal Potential: Trichromothrips priesneri has wings and presumably flies. 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: Little is known about the biology of priesneri, but it presumably feeds on living plants. At least one species of Trichromothrips is reported to be a pest. It is possible that T. priesneri could become a pest if it became established in California. If this happened, lower crop yields and increased crop production costs could result. Therefore, it receives a Medium (2) in this category.

Economic Impact: A, 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: 2

– 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: If priesneri became established in California and it became a pest, this could result in official or private treatment programs. Therefore, it receives a Medium (2) in this category.

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

Environmental Impact: D

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.

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 Trichromothrips priesneri: Medium (10)**

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: Trichromothrips priesneri is not known to be present 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 (10)

Uncertainty:

There is a great deal of uncertainty in this proposal. The biology of T. priesneri is poorly known. It is not known for certain what plants it feeds on. The potential of this thrips to cause damage to the plants it feeds on is also not known. Finally, it is not known how large of an area in California this species could become established in. It appears to require a tropical or subtropical climate, and this could prevent its establishment in California or limit establishment to a very small area.

Conclusion and Rating Justification:

Trichromothrips priesneri is a thrips that apparently feeds on living plants. It is not known to occur in California, and it may pose an economic and environmental threat to the state. For these reasons, a “A” rating is justified.

References:

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

Mound, L. and Masumoto, M. 2004. Trichromothrips veversae sp. n. (Insecta, Thysanoptera), and the Botanical Significance of Insects Host-specific to Austral Bracken Fern (Pteridium esculentum). Proceedings of the Linnaean Society of New South Wales 125:67-71.

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

Mound, L., Nakahara, S., and Tsuda, D. M. 2016. Thysanoptera-Terebrantia of the Hawaiian Islands: an identification manual. ZooKeys 549:71-126.

Nakahara, S. 1993. The genus Dorcadothrips (Thysanoptera: Thripidae) in Hawaii and North America with a description of a new species. Journal of the New York Entomological Society 101:399-409.

Ng, Y. F., and Mound, L. A. 2015. Species of Thripinae (Thysanoptera) from bamboo in Malaysia, with one new species and six new records. Zootaxa 3918:492-502.

Rachana, R. and Varatharaja, R. 2017. Checklist of terebrantian thrips (Insecta: Thysanoptera) recorded from India. Journal of Threatened Taxa 9:9748-9755.

Symbiota Collections of Arthropods Network. Accessed March 27, 2017: http://scan1.acis.ufl.edu

Tyagi, K. and Kumar, V. 2016. Thrips (Insecta: Thysanoptera) of India – An updated checklist. Halteres 7:64-98.

Wang, C -L. 2008. A new synonym and two new records for Taiwan of Thripidae related to Trichromatothrips (Thysanoptera). Zootaxa 1941:67-68.

Author:

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

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6/26/18 – 8/10/18

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