Aggie entomologists show how ant colonies are adapting to urbanization

Research focused on changes in the physiology and behavior of ants based on their environment hopes to shed light on other species of ants and animals that are changing amid urbanization.


Texas A&M AgriLife photo by Michael Miller

Search by Texas A&M AgriLife Research scientists in the Texas A&M Department of Entomology showed that a common ant species undergoes physiological and behavioral changes in unnatural environments.

Consistent signatures of urban adaptation in a native, urban invasive Tapinoma sessile ant,” Posted in Molecular Ecology, works included by lead author Alexander Blumenfeld, a former graduate research assistant; Ed Vargo, Principal Investigator and President Endowed with Urban and structural entomology; Anjel Helms, chemical ecologist and assistant professor; and Pierre-André Eyer, postdoctoral research associate, all in the Department of Entomology.

“Urbanization is a growing habitat all over the world, and it’s becoming increasingly important for organisms to develop ways of living when their natural environments are disturbed,” Vargo said. “Studies like this address important questions about this change, ‘Can they adapt to urban environments and how?'”

The environment influences the behavior of ants, chemical changes

The study focused on Tapinoma sessile, a relatively small species of ant commonly known as the house ant or sugar ant. It is the most common invasive ant in the United States.

In its native environment, the house ant creates small, single-queen colonies typically found under fallen leaves, rocks and logs, Vargo said. But in suburban/urban settings, these house ants build ever-expanding multi-queen colonies around man-made structures such as sidewalks, plant containers, and landscape mulching.

Vargo said the study provides a wide range of scientific applications related to biological and behavioral changes stimulated by environmental conditions throughout the animal kingdom. It could also provide information on how invasive species interact with environments new to them.

“The change is very similar to invasive ants once they move from their original range to an invasive range,” he said. “The idea is to better understand this syndrome in an ant species that can take on a small, inconspicuous colony that then becomes an economic and ecological problem as the harmful colonies get bigger and bigger.”

Answer questions about adaptive evolution

a close-up shot of two ants on a leaf, one walking on top, the other clinging to the side

Researchers continue to study how and why environmental changes like urbanization lead to behavioral and physiological adaptations in ants.


Texas A&M AgriLife photo by Michael Miller

The researchers used a large genetic database to identify chemical and behavioral changes that influenced the social organization of ants, Vargo said. They explored and compared population genetics and reproductive structure within and between ants in several urban and undisturbed natural sites within their range.

Scent house ants have been observed and analyzed in natural and disturbed locations across the country, including Indiana, Arkansas, Colorado, and California.

The team analyzed the ant’s chemistry, such as hydrocarbons, the genetic constitutions of the colonies and behaviors, such as aggression towards family and foreign ants, and found marked differences depending on the environment, said Vargo.

The study found that domestic ants in both urban and natural areas showed adaptations that resulted in genetic concentration. Vargo said that queens of house ants in their natural habitat usually leave the colony they were born in, fly to another suitable location, and attempt to establish a new colony. Queens of urban colonies stay in the nest and expand the colony rather than leaving.

As a result, urban queens were closely related and less aggressive towards ants with a genetic relationship. Behavioral analyzes showed that ants in supercolonies were aggressive towards ants with outside genetics.

Additionally, polydomous colonies, which are spatially separate but socially connected colonies of ants, were only present in urban habitats, Vargo said. This suggests that house ants only create super colonies in developed areas. Ants from different urban areas shared some genetic similarities, suggesting that they adapt to common characteristics in the urban environment.

As a next step, the researchers plan to compare stable isotopes in ants to examine dietary changes and their connection to natural and urban environments and possible contributing factors such as temperature and the urban heat island effect.

Vargo said researchers have hypotheses but no data yet linking how and why the changes occurred.

The research was initiated by Blumenfeld, who was a doctoral student in Vargo’s lab and is now a post-doctoral researcher at Yale University. He said he wanted to answer questions related to the adaptive evolution of animals, regardless of classification or species, and whether they are invasive or adapt to human-caused disturbances, including cities. .

“The study highlights the influence of urbanization on the evolutionary course of species,” he said. “It is important for us to answer questions related to adaptive evolution, whether it is an invasive species or a forest species adapting to urban environments.