Nav: Home

Ants maintain essential interactions despite environmental flux

June 12, 2019

UNIVERSITY PARK, Pa. -- Ants adjust their social interactions to accommodate changes in population density, according to researchers at Penn State and Georgetown University. The findings suggest that ant colonies are capable of maintaining their sophisticated social organization despite potentially drastic changes in their environments.

"Ants are among the most ecologically successful groups in nature due to their complex social organization, particularly their division of labor, including food acquisition," said David Hughes, associate professor of entomology and biology. "The survival of ant colonies depends on their ability to maintain this organization. In our study, we saw remarkable resilience of ant colonies to changes in population density. This finding helps to explain ants' evolutionary success."

According to Hughes, changes in ant colony size and population density are natural occurrences. They can increase as the queen reproduces and the colony grows, and they can decrease when the colony decides to split into multiple nest sites.

"To minimize potentially adverse effects due to changes in density and to maintain social balance, ant colonies should try to actively manage the rates of their interactions," said Hughes. " Until now, however, few studies have investigated these phenomena."

The researchers manipulated the population densities of three colonies of carpenter ants by quadrupling the sizes of their nest spaces. They placed the colonies inside wooden camera boxes fitted with infrared lights so they could film the ants under natural dark nesting conditions. The ants were able to leave the nests at any time to enter foraging areas.

The team manually identified the position in the nest of each ant at every point in time -- equivalent to more than 6.9 million data points -- to investigate whether the increased nest space influenced the spatial organization of the insects. The researchers found that the ants' positions relative to the others was similar regardless of the population density. When population density was lower, ants simply were separated further in space from each other.

Next, the researchers examined 3,200 ant interactions to analyze whether the increase in nest space influenced their task performance -- especially related to trophallaxis, or the transfer of foods from ant to ant. The team's results appeared May 2, 2019, in eLife.

"As a statistician, I built statistical models that captured how individual ants move within their nests, and how and when they chose to engage in important social behaviors like trophallaxis," said Ephraim Hanks, associate professor of statistics, Penn State. "These analyses helped to explain how ant populations maintained high levels of community interactions even after their spatial environment was changed."

Indeed, the team found that -- contrary to its expectations, which were that ant interactions would decrease with decreasing population -- ant interactions actually did not change with decreased density.

"Our results showcase the kinds of behavioral mechanisms ant colonies apply to achieve social homeostasis in the face of disturbance," said Hughes. "Specifically, ants actively regulate their spatial distribution and interaction behaviors in a way that allows them to maintain critical elements of their social interaction patterns -- such as food and information exchange -- in spite of drastic changes in their environment."

"This work shows that social species like ants can maintain levels of social connection and interaction even when their environment changes drastically," said Hanks. "As social interactions are a critical driver of the spread of infectious disease, our work shows that changing spatial environments, such as how cities or businesses are laid out, may have little or no effect on the spread of infectious disease, as social species may change their movement patterns to conserve community interactions."
Andreas Modlmeier, former postdoctoral fellow and a leader of the study, and Ryan Bringenberg, former undergraduate student, Penn State; Ewan Colman, postdoctoral fellow, Georgetown University; and Shweta Bansal, assistant professor of biology, Georgetown University.

The National Science Foundation supported this research.

Penn State

Related Infectious Disease Articles:

A new treatment for antibiotic resistant bacteria and infectious disease
A study, published in the American Journal of Respiratory and Critical Care Medicine, describes a new treatment pathway for antibiotic resistant bacteria and infectious diseases with benefits for patients and health care providers.
$2.35 million grant enables better prediction of infectious disease outbreaks
Researchers at Penn State have received $2.35 million from the National Science Foundation to study disease transmission among animals with a goal of better predicting outbreaks of infectious diseases within humans.
UA infectious disease researcher receives prestigious fellowship
The American Association for the Advancement of Science (AAAS) has selected Kacey Ernst, Ph.D., M.P.H., associate professor of epidemiology in the University of Arizona Mel and Enid Zuckerman College of Public Health, as a 2017-2018 Public Engagement Fellow.
World still 'grossly underprepared' for infectious disease outbreaks
The world remains 'grossly underprepared' for outbreaks of infectious disease, which are likely to become more frequent in the coming decades, warn a team of international experts in The BMJ today.
Study examines trends in infectious disease mortality in US
In a study appearing in the Nov. 22/29 issue of JAMA, Heidi E.
New study explains factors that influence the timing of infectious disease outbreaks
The delay between the time when a disease outbreak becomes possible and when it actually happens depends chiefly on how frequently infection is introduced to the population and how quickly the number of cases caused by a single individual increases, according to new research from the University of Georgia.
Remote and poor Australians at greater risk of infectious disease
A unique 21-year study of more than 2.4 million cases of infectious disease across Australia reveals a major social divide where being poorer, living remotely or being an Indigenous Australian means having an increased risk of sexually transmissible infections.
Fifth Annual IDWeek brings together internationally-recognized infectious disease experts
Infectious disease experts nationwide will gather in New Orleans for the 5th annual IDWeek Oct.
In sub-Saharan Africa, cancer can be an infectious disease
University of Colorado Cancer Center researcher shows that mothers who contract malaria during pregnancy may have children with increased risk of Burkitt's lymphoma.
Infectious and non-infectious etiologies of cardiovascular disease in human immunodeficiency virus i
Less than fifty percent of HIV-infected patients achieve viral suppression in medically underserved areas.

Related Infectious Disease Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...