Solenopsis richteri

Forel, 1909

Black Imported Fire Ant, BIFA

Solenopsis richteri, the black imported fire , is a South American native fire ant that has been introduced to North America. Once considered a or color variant of , it is now recognized as a distinct species with demonstrably different range and ecological preferences. It appears more cold-tolerant and less than the . In its native Argentina, it is attacked by six species of Pseudacteon phorid flies that significantly reduce its foraging activity. The species hybridizes with S. invicta where their ranges overlap, particularly in Tennessee. In Eritrea, it has been documented as a serious agricultural pest of crops and grazing areas.

Solenopsis richteri by (c) aacocucci, some rights reserved (CC BY), uploaded by aacocucci. Used under a CC-BY license.

Solenopsis richteri by (c) Joseph McPhail, some rights reserved (CC BY), uploaded by Joseph McPhail. Used under a CC-BY license.

Pronunciation

How to pronounce Solenopsis richteri: //səˈliːnəpˌsɪs ˈrɪktəraɪ//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Dark blackish coloration distinguishes S. richteri from the reddish-brown S. invicta. are variable in size, ranging from very small to moderately sized (approximately 1/16 to 1/4 inch). Nests are constructed underground with bare soil areas of 30–60 m² surrounding the mound entrance. In areas of sympatry with S. invicta, hybrid identification requires molecular or biochemical analysis due to introgressive hybridization producing intermediate phenotypes.

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Habitat

Constructs underground nests in open grassland and agricultural fields devoid of trees and shrubs. In its native South American range, found in Argentina. In introduced North American range, occurs in Tennessee and potentially other southeastern states. In Eritrea, occupies crop fields and grazing areas with nests distributed approximately 25 meters apart.

Distribution

Native to South America: Argentina (Las Flores and other regions), with records from Brazil (Mato Grosso do Sul, Paraná, Rondônia, Rio Grande do Sul) and Paraguay. Introduced to North America: Tennessee (documented co-occurrence and hybridization with S. invicta), with potential broader distribution in southeastern United States. Also present in Eritrea (Hamelmalo sub-zone) where it is an established pest.

Diet

In Eritrea, preferred are grass seeds and crops, followed by small animals including , , worms, and seeds of some weed . Specific dietary details from native South American range are not documented in available sources.

Life Cycle

Exhibits typical fire colony structure with multiple queens in mature colonies. Virgin queens are capable of in queenless colonies. Winged reproductive males and females participate in mating ; males aggregate at mating sites.

Behavior

Forages primarily during cold periods of the day and at night when temperatures are cool. Exhibits risk-adjusted foraging in response to phorid pressure, reducing activity proportionally regardless of food resource size. engage in nest cleaning and patrolling behaviors. When attacked by Pseudacteon phorid flies, foraging activity is significantly reduced and worker size distribution of foragers shifts downward. Males aggregate at specific locations for mating.

Ecological Role

In native Argentina, serves as for six Pseudacteon phorid that regulate . In introduced Eritrea, acts as a significant agricultural pest causing yield losses of 24–32 quintals per hectare and reducing livestock forage availability. Hybridizes with S. invicta in zones of co-occurrence, potentially affecting dynamics.

Human Relevance

Serious agricultural pest in Eritrea, causing substantial crop yield losses and reducing grazing capacity. Subject to research using phorid flies in Argentina. Hybridizes with the more widespread S. invicta, complicating management efforts. Less and potentially more cold-tolerant than S. invicta, which may influence future range expansion under climate change.

Similar Taxa

Solenopsis invictaOverlaps in distribution and hybridizes with S. richteri; distinguished by reddish-brown versus black coloration, with S. invicta being more and aggressive. Molecular analysis often required for definitive identification in hybrid zones.
Solenopsis geminataShares fire characteristics and geographic range in some areas; distinguished by morphological and behavioral differences, though specific distinguishing features not detailed in available sources.