Thrips | Indusiothrips seshadrii Priesner

California Pest Rating  for
Indusiothrips seshadrii Priesner: thrips
Thysanoptera: Thripidae
Pest Rating: A


Initiating Event:

A specimen of Indusiothrips seshadrii was recently found on Oahu Island, 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:  Indusiothrips seshadrii is a small (~1 mm in length), whitish-yellow thrips (Priesner, 1952).  It has been reported from unidentified ferns in India and Hawaii (Mound et al., 2017; Priesner, 1952).  This species appears to be rarely collected, and little additional information is available regarding its biology.

Worldwide Distribution:  Indusiothrips seshadrii is known from, and is presumed native to India and Malaysia (Kudô, 1992; Priesner, 1952).  It has been introduced to Oahu, Hawaii (Mound et al., 2017).

Official Control: Indusiothrips seshadrii is not known to be under official control anywhere.

California Distribution:  Indusiothrips seshadrii is not known to occur in California.

California Interceptions:  Indusiothrips seshadrii has not been intercepted in California.

The risk Indusiothrips seshadrii would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Although seshadrii is presumed to feed on ferns, the species it feeds on are not known. California has many species of native ferns, and it is possible that I. seshadrii could find suitable host plants over much of the state.  However, this thrips is currently known to be limited to areas with a tropical climate.  For this reason, I. seshadrii is not expected to be capable of establishing over more than a very limited area.  Therefore, Indusiothrips seshadrii receives a Low (1) 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: Indusiothrips seshadrii may feed on ferns. However, it is not known what species in particular act as hosts.  The fact that it is known from India, Malaysia, and Hawaii suggests that more than a single species of fern is involved.  To incorporate this uncertainty, host range will be considered to be moderate.  Therefore, it 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: This species has wings and presumably flies (Priesner, 1952).  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: Indusiothrips seshadrii is presumed to feed on ferns.  It has not been reported to be a pest, and it does not appear to pose an economic threat to California.  Therefore, it receives a Low (1) in this category.

Economic Impact:

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: Indusiothrips seshadrii is presumed to feed on ferns. No reports were found indicating the extent, if any, of damage inflicted by these thrips on ferns.  However, this could simply be because the host plants are not economically significant.  There are many rare, native ferns in California.  If this thrips became established in California, it could feed on and impact our native ferns.  Therefore, it receives a Medium (2) in this category.

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

Environmental Impact:  B

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 Indusiothrips seshadrii: Low (8)

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: Indusiothrips seshadrii 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: Low (8)


No reports were found indicating that I. seshadrii has any economic or environmental impact, although this could simply reflect a lack of study of the biology of this species because it does not feed on economically-significant plants.  It is possible that I. seshadrii may not be capable of becoming established in California because it requires a tropical climate.

Conclusion and Rating Justification:

Indusiothrips seshadrii is a thrips that apparently feeds on ferns and is not known to be present in California.  It poses a risk to the environment, including rare fern species, of which there are many in California.  For these reasons, an “A” rating is justified.


Kudô, I.  1992.  A new Malaysian thrips with notes on some species of Dendrothripoides and Indusiothrips (Thysanoptera, Thripidae).  Insecta Matsumurana.  47: 91-101.

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.

Priesner, H.  1952.  On some new genera and species of Thysanoptera from the Oriental region.  Indian Journal of Entomology.  13: 183-200.

Symbiota Collections of Arthropods Network.  Accessed 18 December 2017.


Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741;[@]

Responsible Party:

Jason Leathers, 2800 Gateway Oaks, Sacramento CA 95833, (916) 654-1211,[@]

Comment Period:* CLOSED

4/30/18 – 6/14/18


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Pest Rating: A


Posted by ls