Anoplolepis longipes: long-legged ant

California Pest Rating for

Anoplolepis longipes: long-legged ant

Hymenoptera: Formicidae

Pest Rating: A

PEST RATING PROFILE

Initiating Event:

Anoplolepis longipes was intercepted on a regular basis before 2015 by CDFA. Then, there was a hiatus on interceptions, until it was found in a cut flower shipment from Hawaii on April, 2017. The insect is currently “Q” rated by CDFA, so a pest rating proposal is needed to determine future direction.

History & Status:

Background: Anoplolepis longipes is also known in the literature as Anoplolepis gracilipes and has three common names: long-legged ant, yellow crazy ant, and Maldive ant¹. Anoplolepis longipes workers are typically small to medium-sized, around 4-5 mm long with remarkably long legs and 11 segmented antennae. The antennal scape is 1.5 times longer than the head length; this is a key diagnostic feature for the species³.

The Invasive Species Specialist Group (ISSG) considers it among the top 100 of the world’s worst invaders¹. The native range of these ants is unclear. A recent study by Chen (2008) using ecological niche modelling suggested that Anoplolepis longipes originated in south Asia, expanded into Europe and Afrotropical regions. Then it formed its current distribution. The native range of the species has been obscured by a long history of human-assisted dispersal, as Anoplolepis longipes is readily moved to new areas within sea cargo. To this day, these ants are regularly detected in shipping containers and have been introduced to numerous oceanic islands in the Caribbean, Indian, and Pacific oceans^{3, 4}.

Worldwide Distribution: Anoplolepis longipes has been found widely throughout the moist tropical lowlands of Asia, Africa, Australia, Central and South America. These ants have been introduced to many Pacific, Caribbean and some Indian Ocean islands. Particularly devastating incursions have been reported on Christmas Island. In the United States these ants were introduced to the Hawaii Islands in 1952 ^{3, 5}.

Official Control: Anoplolepis longipes is listed as a harmful organism in French Polynesia and the Republic of Korea⁷. All ants (Formicidae) are listed as harmful organisms by Australia and Nauru⁷.

California Distribution: Anoplolepis longipes has never been found in the environment of California.

California Interceptions: Anoplolepis longipes has been intercepted 259 times since 1990, most recently in April, 2017 by CDFA’s border station and nursery regulatory inspection. Interceptions are typically on plants or plant material imported from Hawaii ⁶.

The risk Anoplolepis longipes (Long-legged ant) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Anoplolepis longipes have a broad diet characteristic of many invasive ants. A generalized feeding regime increases the invasiveness of an ant due to the increased ability to gain nutrition from any available resources including grains, seeds, arthropods, decaying matter and vegetation³. These ants can move into forests, rural areas, and urban environments at the same time because of their ability to gain nutrition from available resources. The California environment is very suitable for these ants and they 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: Score: 3

– 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: Anoplolepis longipes is primarily a species of lowland, tropical forest. Most collection records are below 1200m in elevation and from moist habitats. In Hawaii it is usually found from sea level to about 600 meters in elevation. It is known to invade disturbed habitats such as urban areas, forest edges and agricultural fields. The ability to live in human dwellings made these ants a serious pest in many households and buildings. However, it prefers to live in a moist habitat and does not establish in heated buildings in cities in temperate regions³.

Anoplolepis longipes have been known to successfully colonize a variety of agricultural systems, including cinnamon, citrus, coffee, cocoa, coconut, mango, sugarcane, banana and grape plantations. In agricultural regions they are typically found nesting at the base, or even in the crown, of crop plants. These ants can feed on dead insects, fish scraps, decaying fruits and on live arthropods^{2, 3}. Anoplolepis longipes can reside in urban and forest setting anywhere near the food source. It receives a High (3) in this category.

Evaluate the host range of the pest. Score: 3

– 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: Anoplolepis longipes colonies are polygynous (multi-queened) and generally without intraspecific aggression among workers. The life cycle of Anoplolepis longipes has been estimated to take 76-84 days at 20-22^oC. Workers live approximately 6 months, and the queens for several years. Queens lay about 700 eggs annually throughout their life span. The primary dispersal within the habitat is through budding and rarely via winged female³. Historically, the rate of spread is potentially much larger through human-mediated transportation. These ants can be moved long distances through terrestrial vehicles, infested machinery, boats, cargo ships, and aircraft. They can also be transported in packaging material, timber and in soil. There have been deliberate introductions for biological control of plant pests in coconut, coffee and cacao plantations². It receives at High (3) in this category

Evaluate the natural and artificial dispersal potential of the pest. Score: 3

– 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: Anoplolepis longipes feed and breed on a wide variety of plants, including economically important crops, such as grapes, citrus and many vegetables grown in the moist belt in California. Anoplolepis longipes have the potential to lower yield in these crops by feeding on leaves. These ants may also increase crop production costs by triggering additional management activities. Therefore, it is probable that if Anoplolepis longipes were to establish in California, it would trigger a loss of markets. This would be expected especially for exports of California table grapes. 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: Anoplolepis longipes are aggressive invaders that have the potential to cause slow, long-term ecological changes that have the potential to lower biodiversity, disrupt natural communities, or change ecosystem processes. They may also trigger new treatment programs by residents who find infestations. This may lead to significant impacts on cultural practices. These ants can compete with Argentine ants (Linepithema humile), as well as with native ants by taking over their habitat. On Christmas Island it attacked native crabs and, therefore, could pose a threat to California arthropods, including rare or endangered ones. It receives a High (3) in this category

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

Environmental Impact: A, B, D, E

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: 3

– 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 Anoplolepis longipes (Long-legged ant): High (15)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Anoplolepis longipes 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 (15)

Uncertainty:

There have not been any formal surveys of Anoplolepis longipes 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 California.

Conclusion and Rating Justification:

Anoplolepis longipes is not known to be present in California and would be expected to have a significant economic and environmental impact if it were to establish in the state. An “A” rating is justified.

References:

Encyclopedia of Life. eoL online resources. Accessed June 12, 2017. http://eol.org/pages/470492/overview
Global Invasive spices database. Accessed June 12, 2017. http://www.iucngisd.org/gisd/species.php?sc=110
Invasive Species Compendium: Distribution maps for plant pests. Accessed June 12, 2017. http://www.cabi.org/isc/datasheet/5575
Invasive animal risk assessment Dept. of Agriculture and Fisheries Biosecurity Queensland. Accessed June 12, 2017. https://www.daf.qld.gov.au/__data/assets/pdf_file/0003/63372/IPA-Yellow-Crazy-Ant-Risk-Assessment.pdf
L. H. Himmelstein, 2003. Introduced Species summary project. Accessed June 12, 2017. http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Anoplolepis_gracilipes.html
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). Accessed June 12, 2017. 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

August 25, 2017 – October 9, 2017

NOTE:

You must be registered and logged in to post a comment. If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.

Comment Format:

♦ Comments should refer to the appropriate California Pest Rating Proposal Form subsection(s) being commented on, as shown below.

Example Comment:
Consequences of Introduction: 1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

♦ Posted comments will not be able to be viewed immediately.

♦ Comments may not be posted if they:

Contain inappropriate language which is not germane to the pest rating proposal;

Contains defamatory, false, inaccurate, abusive, obscene, pornographic, sexually oriented, threatening, racially offensive, discriminatory or illegal material;

Violates agency regulations prohibiting sexual harassment or other forms of discrimination;

Violates agency regulations prohibiting workplace violence, including threats.

♦ Comments may be edited prior to posting to ensure they are entirely germane.

♦ Posted comments shall be those which have been approved in content and posted to the website to be viewed, not just submitted.