Brachyponera chinensis: Asian needle ant

California Pest Rating
Brachyponera chinensis:  Asian needle ant
Hymenoptera: Formicidae
Former Pest Rating: Q
Current Pest Rating: A
Initiating Event:

Brachyponera chinensis was frequently intercepted in 2016 by CDFA and requires a pest rating proposal to support its pest rating.

History & Status:

Background: Brachyponera chinensis is commonly known as Asian needle ant, in the past this species has also been called the Chinese needle ant1. Until 2014 the species was also known as Pachycondyla chinensis, this name was used in lot of older publications. Asian needle ant is native to Japan and it was first detected in the United States in Georgia in approximately 1932 (Smith, 1934). Since then, populations have spread throughout large areas along the east coast and into other regions. It is an average size dark brownish-black ant with a conspicuous sting. Asian needle ant generally nests in the soil in somewhat damp areas, especially below stones, in rotting logs and stumps, or other debris. In urban settings it may also be found under mulch, railroad ties, bricks and pavers. Colony size ranges from fewer than 100 individuals to several thousand and multiple queens may be present. Unlike many introduced, invasive ant species, it can also nest in natural wooded habitats. Asian needle ant prefers termites as a food source. It poses medical risks for humans from anaphylaxis resulting from stings. Typically, stings are a result of an individual disturbing a colony or having a winged female land on the body and become trapped between the skin and clothing layer. Stings are painful and persist for up to 30 minutes or more1, 2.

Worldwide Distribution: Brachyponera chinensis is native to Japan and is also found in China1.It has spread to New Zealand, Cambodia, Philippines, Taiwan, Thailand, Vietnam and Republic of Korea1. The Asian needle ant has been in the U.S. since the 1930s, but their population has exploded in the past 8 years2.  Now it is found in AL, CT, FL, GA, MS, NC, NY, SC, TN, TX, VA, WA, and WI1.

Official Control: Brachyponera chinensis is not known to be under official control in any other states or nations5.

California Distribution:  Brachyponera chinensis has never been found in the environment of California.

California Interceptions: Brachyponera chinensis was intercepted 6 times in 2016 by CDFA’s border stations and nursery regulatory inspections. Interceptions were typically on plants or plant material imported from eastern infested States4.

The risk Brachyponera chinensis (Asian needle ant) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Asian needle ant can move into forests, rural areas, and urban environments at the same time because it can tolerate cooler temperatures, it could spread into a broad range of territory3.California environment is very suitable for this ant and it could establish throughout California. 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: Asian needle ants build nests in both disturbed areas and natural habitats. They are a temperate species, found in deciduous forests, hardwood forests, agricultural land, and in urban and suburban areas, such as office parks and backyards2. Asian needle ants feed on dead insects, fish scraps, and decaying fruit. They prey on live arthropods, especially termites. It can reside in urban and forest setting anywhere near the food source3. 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: Asian needle ants are holometabolous, undergoing complete metamorphosis. Their first batch of eggs is laid in early spring, and egg laying continues throughout the summer. Colony size ranges from fewer than 100 individuals to several thousand, and multiple queens may be present. Asian needle ant is capable of rapid reproduction and can disperse long distances when colonies or queens are moved. It receives at 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: Asian needle ant is not expected to lower crop yields or increase crop production costs.  It is not expected to vector other pestiferous organisms. Asian needle ants are active predators of many live arthropods which may consume parasitoids, disrupting biological control of pests. Asian needle ants are an emerging health threat because their sting is painful and venomous, resulting changes in cultural practices in livestock production. The ants are not expected to interfere with water supplies.

It receives a Medium (2) in this category.

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

Economic Impact: D, F

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.

4) Environmental Impact: As an invasive species in the eastern United States, Asian needle ants are displacing native ants and arthropod species, such as native ants like Aphaenogaster rudis. Moreover, it can compete with Argentine ants (Linepithema humile) by making nests earlier in the year, when temperatures are too cold for Argentine ants, taking control of areas before Argentine ants have the opportunity2. It is not known to affect any threatened or endangered species or disrupted critical habitats. The ant is not known to trigger any treatment programs or impact cultural practices, home/urban gardening, or ornamental plantings 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.

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 Brachyponera chinensis (Asian needle ant): High (13)

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: Brachyponera chinensis has never been found in natural environment 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 (13)

Uncertainty:

There have not been any formal surveys of Brachyponera chinensis in California. This species has been intercepted through regulatory pathways by CDFA but it is possible that it might be present in certain areas of the California.

Conclusion and Rating Justification:

Brachyponera chinensis is not known to be present in California and is expected to have significant economic and environmental impacts if it were to establish in the state.  An “A” rating is justified.

References:
  1.  Ants (Formicidae) of the Southeastern United states by Joe A. McGowan, updated   23 March 2016  Accessed December 23, 2016 http://www.mississippientomologicalmuseum.org.msstate.edu/Researchtaxapages/Formicidaepages/genericpages/Pachycondyla.chinensis.htm#.WFlxjFMrI2w
  1.  Animal Diversity Web.  Accessed December 23, 2016     http://animaldiversity.org/accounts/Pachycondyla_chinensis/
  1.  American Association for the Advancement of Science. Article by Mary Bates, Ph.D.   Accessed December 23, 2016 https://www.aaas.org/blog/qualia/invasive-asian-needle-ants-thriving-spreading-us
  1. 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
  1. USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed December 23, 2016 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 Period: CLOSED

1/17/2017 – 3/3/2017

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Pest Rating: A