Biltothrips minutus (Bhatti)

California Pest Rating for

Biltothrips minutus (Bhatti)

Thysanoptera: Thripidae

Pest Rating: A

PEST RATING PROFILE

Initiating Event:

Biltothrips minutus was collected on December 8, 2016 from the head of a cabbage (Brassica oleracea) in Hawaii. This was the first interception of this species in the United States. The insect is currently unrated by CDFA, so a pest rating proposal is needed to determine future direction.

History & Status:

Background: Biltothrips minutus is a member of the Scirtothrips genus-group and it was originally described within the genus Sericothrips. The Scirtothrips genus-group lineage is comprised of 11 genera. Only two (Scirtothrips and Anascirtothrips) are widespread globally, whereas the remaining nine genera are restricted in their distributions. The members of this group breed on a wide range of plants, but they appear to prefer tissues of the youngest leaves and fruitlets. Some species of this lineage are considered major pests¹.

Biltothrips minutus was described from West Bengal in India and has subsequently been reported from Thailand, Malaysia and the Society Islands in the Pacific Ocean. Biltothrips minutus lacks ocellar setae pair I, which is unique within this genus². No literature is available concerning its biology and host plants.

Worldwide Distribution: Biltothrips minutus was described from India and has been reported in Malaysia and Thailand¹. It was recently intercepted in Hawaii.

Official Control: Biltothrips minutus is not known to be under official control by any state or nation except for Japan where all Thripidae are listed as harmful organisms⁴.

California Distribution: Biltothrips minutus has never been found in the environment of California³.

California Interceptions: Biltothrips minutus has not been intercepted in any regulatory situation in California³.

The risk Biltothrips minutus would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Biltothrips minutus is reported in areas with climate similar to California and is expected to encounter suitable host material throughout much of state. It receives a High (3) in this category.

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

– 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: The host range for Biltothrips minutus is unknown, but being the members of Scirtothrips lineage they probably can feed on a variety of plants growing throughout. It receives a High (3) in this category.

Evaluate the host range of the pest:

– 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 famous for their high reproductive rates. They may spread long distances when infested plants are moved. It receives a High (3) in this category.

Evaluate the natural and artificial dispersal potential of the pest:

– 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: Although there is no information available about Biltothrips minutus species as a significant economic pest, it could feed on young growth and lower crop yields. This species may lower the quality and value of nursery plants. It may also increase crop production costs by triggering additional management activities. It receives a High (3) in this category

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

Economic Impact: A B, C

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: 3

– 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 Biltothrips minutus were to become established in California it is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. The presence of Biltothrips minutus in California may trigger additional chemical treatments in nurseries and agricultural production. It receives a Medium (2) in this category.

Evaluate the Environmental impact of the pest to 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 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 Biltothrips minutus: High (14)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Biltothrips minutus 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 -0

–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 (14)

Uncertainty:

Biltothrips minutus was recently intercepted in the United States for the first time and nothing much is known about its habitat and host range. Nevertheless, the environment of California is highly favorable for thrips species. Therefore, the uncertainty about this species is high.

Conclusion and Rating Justification:

Biltothrips minutus has never been found in the environment of California and its entry to the State has potentially significant economic and environmental impacts. An “A” rating is justified.

References:

Ng, Y.F. and Mound, L.A. 2015. Genera of the Scirtothrips genus-group (Thysanoptera, Thripidae) with a new species of Siamothrips from Malaysia. Zootaxa 4021 (2): 387-394. Accessed on 1-13 2017. https://www.researchgate.net/publication/283194234_Genera_of_the_Scirtothrips_genus-group_Thysanoptera_Thripidae_with_a_new_species_of_Siamothrips_from_Malaysia
Ng, Y.F. and Mound, L.A. 2016. Two new species of Scirtothrips genus-group (Thripidae) of Northern Peninsular Malaysia. Zootaxa 4088 (1): 141-145.
Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services. http://phpps.cdfa.ca.gov/user/frmLogon2.asp
USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). https://pcit.aphis.usda.gov/pcit/

Responsible Party:

Javaid Iqbal, California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6695; plant.health[@]cdfa.ca.gov.

Comment Format:

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