California Pest Rating for
Hercinothrips bicinctus (Bagnall): Banana-silvering Thrips
Pest Rating: B
PEST RATING PROFILE
In April 2016 the Banana-silvering thrips Hercinothrips bicinctus was found by a dog-team on a shipment of Passiflora leaves from San Diego County. A trace-back survey found that the thrips were infesting passion flower vines in an outdoor garden at a residence. A pest rating proposal is required to assign a permanent pest rating.
History & Status:
Background: Hercinothrips bicinctus is considered to be a polyphagous thrips that breeds on the leaves of a variety of plants, often in greenhouses1. Nymphs and adults live on leaves, stems, and fruit. Eggs are inserted into plant tissue2. Primary hosts include banana, passion fruit, choko, and some weeds3. Feeding causes leaf damage2 and silvery or brown patches on fruit2. Infested fruit may crack, allowing decay organisms to enter2. Hercinothrips bicinctus may be transported long distances when infested plants or fresh plant parts are moved.
Worldwide Distribution: Hercinothrips bicinctus is thought to be native to Africa1. From there it has invaded Australia, New Zealand, Bermuda, Mexico, and Hawaii. There is also an unconfirmed record from Brazil4.
Official Control: Hercinothrips bicinctus is listed as a harmful organism by Colombia, Costa Rica, Indonesia, Israel, Jamaica, Japan, the Republic of Korea, and Timor-Leste5.
California Distribution: Hercinothrips bicinctus has only been found at a single residential property in San Diego County.
California Interceptions: Hercinothrips bicinctus has only been intercepted twice in California, in June 2009 on various leis from HI, and in April 2016 on a mailed shipment of Passiflora and Persea sp. leaves from the infested property.
The risk Hercinothrips bicinctus (Banana-silvering thrips) would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: Based on its present tropical and subtropical distribution, Hercinothrips bicinctus is expected to establish throughout the warmer parts of coastal and southern California. It receives a Medium (2) 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: Hercinothrips bicinctus is polyphagous. 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 have high reproductive rates and can rapidly spread long distances when infested plants or fresh plant parts are moved. Hercinothrips bicinctus 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: Most of the damage caused by Hercinothrips bicinctus is limited to disfigured leaves and blemished fruit. This type of damage could potentially lower the yield of production nurseries and fruit crops or increase production costs. However, other thrips with similar biologies such as Hercinothrips femoralis (banded greenhouse thrips) are already widespread in California. Existing management techniques for these thrips that are already present are likely to limit economic impacts from this new thrips. However, Hercinothrips bicinctus is listed as a harmful organism by many nations and has not yet been found anywhere else in the continental United States. It is possible that its presence in California could disrupt markets. Hercinothrips bicinctus receives a Low (1) 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: If it becomes established in California, Hercinothrips bicinctus is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. However, this thrips colonized native plants as it invaded Australia and it might do the same thing in California. Due to the polyphagous nature of the thrips this could include threatened or endangered species. Fortunately, Hercinothrips bicinctus is not expected to disrupt critical habitats. It could trigger new treatment programs by residents who find infested plants unsightly. Banana plants are common ornamentals in California and will likely be significantly impacted by this pest. Herciniothrips bicinctus 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 Hercinothrips bicinctus (Banana-silvering Thrips): Medium (12)
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: Hercinothrips bicinctus is only known from a single residential property in San Diego County. It receives a Low (-1) 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (11)
It is possible that Hercinothrips bicinctus is more widespread in southern California.
Conclusion and Rating Justification:
Existing management practices for other thrips are likely to limit economic damage from the establishment of Hercinothrips bicinctus in California. However, its establishment could disrupt markets and have significant environmental impacts. A “B”-rating is justified.
1 Hoddle MS, Mound LA, Paris DL. 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/Hercinothrips_bicinctus.htm
2 Hill, Dennis S. 2008. Pests of Crops in Warmer Climates and Their Control. Skegness Lincs: Springer. https://books.google.com/books?id=U5dezH9_eEMC&pg=PA261&lpg=PA261&dq=Hercinothrips+bicinctus+pest&source=bl&ots=wP_kfwwlIV&sig=-XAxXb2RsC1KJE8vYQnHWgypTR8&hl=en&sa=X&ved=0ahUKEwiEoqXI1K_NAhUU-2MKHfoVDkoQ6AEISTAL#v=onepage&q=Hercinothrips%20bicinctus%20pest&f=false
3 Treverrow, N.L. 1987. Banana rust thrips and banana silvering thrips. NSW Agriculture AGFACTS. http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0015/120039/banana-rust-silvering-thrips.pdf
4 Mound, L.A. & R. Marullo. 1996. The Thrips of Central and South America: An Introduction: (Insecta: Thysanoptera). Memoirs on Entomology, International, 6: 1- 487.
5 USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). https://pcit.aphis.usda.gov/pcit/
Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211, plant.health[@]cdfa.ca.gov.
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Pest Rating: B
Posted by ls