Formica francoeuri Bolton: Native Ant

California Pest Rating for

Formica francoeuri Bolton: Native Ant

Hymenoptera: Formicidae

Pest Rating: C

PEST RATING PROFILE

Initiating Event:

On September 25, 2015 it was found that a resident of Orange County is selling queen ant starter colonies for Formica francoeuri. An internet search reveals that this ant is commonly kept by hobbyists. A pest rating proposal is required to determine future direction on this pest.

History & Status:

Background: Formica francoeuri nests in soil and forages for honeydew from aphids and mealybugs¹. It is known to tend the larvae of at least six species of lycaenid butterflies in California². It is not known to have been inadvertently spread via any human assisted pathways.

Worldwide Distribution: Formica francoeuri is native to California and Baja California³. It is not known to have invaded any other states or nations.

Official Control: Formica francoeuri is not known to be under official control in any other states or nations. However, all ants are considered harmful organisms by Australia and Nauru⁴.

California Distribution: Formica francoeuri is native to and widespread in California.

California Interceptions: Formica francoeuri has not been reported in any regulatory situations in California.

The risk Formica francoeuri would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Formica francoeuri is native to and widespread in California and is not likely to establish in parts of the state where it does not already occur. It receives a Low (1) 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: Formica francoeuri is a generalist feeder on honeydew and has never been documented as a plant pest. It receives a Low (1) 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 typically have high reproductive rates. Formica francoeuri has not been reported to move long distances in commerce. It receives a Medium (2) 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: Formica francoeuri is already widespread in California and it has not lowered any crop yields or reduced crop values. Its presence has not disrupted any markets. It has not changed cultural practices or vectored other organisms. It is not known to have injured any animals or interfered with any water supplies. Formica francoeuri 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: Formica francoeuri is native to and widespread in California and it has not been found to lower biodiversity, disrupt natural communities, or change ecosystem processes. It has not affected any threatened or endangered species or disrupted critical habitats. The ant is not known to have triggered any treatment programs or impacted cultural practices, home/urban gardening, or ornamental plantings. Formica francoeuri receives a Low (1) 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 Formica francoeuri (native ant): Low (6).**

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: Formica francoeuri is widespread in California and receives a High (-3) 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: Low (3)

Uncertainty:

There is low uncertainty with this ant.

Conclusion and Rating Justification:

Formica francoeuri is a native ant that is widespread in California and is not known to have ever had any negative economic or environmental impacts. No significant impacts are expected from hobbyists trading colonies of this ant within the state. A “C” rating is justified.