Research on northern-range leafcutter ants (Atta texana) in Louisiana indicates that established colonies experience markedly lower annual mortality than tropical Atta species. The authors estimate a life expectancy of approximately 65–75 years for A. texana colonies in this region and report that maximum colony lifespans can exceed 100 years. These estimates contrast strongly with the typical maximum lifespans of 15–20 years attributed to tropical Atta colonies.
The study is presented as a preprint and has not undergone peer review. Funding sources reported include U.S. National Science Foundation grants DEB-1911443 and DEB-2239483. The authors declare no competing interests.
Measured or inferred annual mortality for established A. texana colonies in Louisiana is reported at about 1–2%. By comparison, annual mortality rates for tropical Atta species fall in the range of 10–25%, consistent with much shorter colony life expectancies (15–20 years). Using the observed low annual mortality, the authors derive a median life expectancy estimate of roughly 65–75 years and infer that some colonies can survive past 100 years.
The authors identify three main factors that together explain the exceptional longevity of A. texana colonies at the northern range limit:
Absence of Nomamyrmex army-ant predators that specialize in raiding Atta colonies. The lack of this specialized predator presumably reduces externally driven colony mortality.
Polygyny of A. texana colonies. Unlike the single-queen (monogynous) organization typical for most Atta species, A. texana colonies commonly host multiple reproductive queens. Polygyny alters social structure and reproductive dynamics in ways that can stabilize and prolong colony persistence after individual-queen death.
Adoption of young queens by established colonies. The combination of polygyny and the practice of adopting incoming queens can rejuvenate aging colonies and maintain or restore reproductive capacity at the colony level.
The authors further suggest that low genetic diversity in range-limit populations of A. texana may facilitate queen adoption, although detailed genetic data are not provided in the abstract.
Centenarian A. texana colonies were not recognized previously in part because mid-20th-century research prioritized eradication of A. texana as a forestry pest. Large-scale, landscape-wide pesticide application — including aerial spraying — removed many old colonies from the landscape from the 1930s through the turn of the century. After restrictions and bans on the most harmful pesticides 30–50 years ago, A. texana populations began to recover. However, recovery of their former ecological niche and the re-establishment of long-lived colonies required additional decades.
The historical pesticide era therefore biased earlier empirical observations toward younger colony ages and masked the capacity of A. texana to form long-lived, centenarian colonies in undisturbed habitat.
In intact habitats, large and well-established A. texana colonies with extensive territories appear especially adept at recruiting and adopting young queens. The authors argue that, in this system, colony age does not necessarily translate into increased mortality via senescence. Instead, a different causal pathway is proposed: well-established residency (a correlate of colony age) increases the probability of rejuvenation through queen adoption, which reduces reproductive senescence at the colony level and thereby extends colony lifespan. In other words, older colonies that attain large size and territorial control can persist and self-renew, creating a feedback that supports potentially unending life.
This shift from an age-driven senescence model (old age → mortality) to a residency-driven rejuvenation model (well-established residency → rejuvenation → long life) is central to the authors’ interpretation of how A. texana colonies can reach centenarian ages.
The account and numerical estimates are taken from the preprint abstract. Details of methods, sample sizes, geographic scope, direct measurements versus modeled inferences, and genetic data referenced are not reported in the abstract text provided here. The authors emphasize this work as a preprint; it has not been certified by peer review.
Readers seeking full methodological detail, data, and analyses should consult the complete preprint and supplementary materials referenced by the authors.