Ochetellus glaber (Mayr): An Ant

California Pest Rating for

Ochetellus glaber (Mayr): An Ant

Hymenoptera: Formicidae

Pest Rating: A

PEST RATING PROFILE

Initiating Event:

Ochetellus glaber is frequently intercepted by CDFA and presently has a temporary rating of “Q”. A pest rating proposal is required to establish a permanent pest rating.

History & Status:

Background: Ochetellus glaber is a species of ant that is adapted for living around the interface of open and scrub habitat¹. It often nests arboreally, under stones, or in dry fallen logs¹. The ants are generalist foragers that may feed on honeydew, insects, or worms. They sometimes forage in houses for fluids or sweets but are not considered a major house pest¹. Colonies have multiple queens and colonies may reproduce by budding when a queen and some workers move to a new area. This allows the ants to be transported long distances when nests or queens are moved as contaminating pests in commerce.

Worldwide Distribution: Ochetellus glaber is probably native to Australia. It was first found in New Zealand in 1927¹ and Hawaii in 1977². It has also invaded Japan and parts of Asia. It recently spread to Florida³.

Official Control: Ochetellus glaber is not known to be under official control in any other states or nations⁴.

California Distribution: Ochetellus glaber has never been found in the environment of California.

California Interceptions: Between January 1, 2000 and December 31, 2014 Ochetellus glaber was intercepted 199 times by CDFA’s high risk programs and dog teams. These interceptions have been on nursery stock and fresh plant parts from Hawaii. The ant was also intercepted once at a border station on beehives from Florida.

The risk Ochetellus glaber would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Ochetellus glaber is found in regions with similar climates to California. The ant can be expected to establish a widespread distribution in the state and receives a High (3) 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: Ochetellus glaber is a generalist forager that can feed on a wide variety of sources. 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: Ants are capable of rapid reproduction and can disperse long distances when colonies or queens are moved. Ochetellus glaber 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: Ochetellus glaber is not expected to lower crop yields or increase crop production costs. It is not expected to disrupt any markets for Californian agricultural commodities. It is not expected to change cultural practices or vector other pestiferous organisms. Ochetellus glaber is known to tend honeydew producing insects and may consume parasitoids, disrupting biological control of pests such as pink hibiscus mealybug⁵. The ants are not expected to interfere with water supplies. Ochetellus glaber 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: Invasive ants such as Ochetellus glaber may cause slow, long-term ecological changes that have potential to lower biodiversity, disrupt natural communities, or change ecosystem processes. They may also trigger new private treatment programs by residents who find infestations unacceptable and in the nursery industry. Ochetellus glaber 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 Ochetellus glaber: High (13)

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: Ochetellus glaber 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.

–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:

Invasive ants such as argentine ant (Linepithema humile) are already widespread in California and occupy many of the niches that Ochetellus glaber might be expected to colonize. It is possible that competition from argentine ant may help preclude establishment of other invasive species such as Ochetellus glaber. There is some evidence that Ochetellus glaber is a species complex and should be considered two or more distinct species⁶.

Conclusion and Rating Justification:

Ochetellus glaber has never been found in California and is expected to have limited economic and significant environmental impacts if it were to establish here. An “A” rating is justified.

References:

¹ Landcare Research Manaaki Whenua. Ochetellus glaber fact sheet. http://www.landcareresearch.co.nz/publications/factsheets/Factsheets/ochetellus-glaber

²Kirschenbaum, Ranit and J. Kenneth Grace. 2008. Agonistic Interactions Among Invasive Ant Species (Hymenoptera: Formicidae) from Two Habitats on Oahu, Hawaii. Sociobiology 51(3): 543-553. http://manoa.hawaii.edu/ctahr/termite/aboutcontact/grace/pdfs/241.pdf

³ Deyrup, M. 2003. An updated list of Florida ants (Hymeoptera: Formicidae). Florida Entomologist 86:43-48. http://antkey.org/content/updated-list-florida-ants-hymenoptera-formicidae

⁴ USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). https://pcit.aphis.usda.gov/pcit/

⁵ González-Hernández, Héctor, Neil J. Reimer, and Marshall W. Johnson. 1999. Survey of the natural enemies of Dysmicoccus mealybugs on pineapple in Hawaii. BioControl 44: 47-58. http://link.springer.com/article/10.1023/A:1009954625169#page-2

⁶Hoffman, Benjamin D., Alan N. Andersen, and Xiang Zhang. 2011. Taxonomic confusion of two tramp ant species: Iridomyrmex anceps and Ochetellus glaber are really species complexes. Current Zoology. http://www.actazool.org/site_media/onlinefirst/downloadable_file/2011/06/30/11.1_incomplete_taxonomy_hinders_invasion_research.pdf