Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Water found to be main culprit in Argentine ant invasions


According to a study conducted by two biologists at the University of California, San Diego, Argentine ants in Southern California need wet soil to live and breed. So residents plagued by indoor infestations of the pesky little critters may find relief by simply shutting off or substantially limiting the use of their outdoor irrigation.

The scientists report in the March 30 issue of the Journal of Animal Ecology that they were able within a matter of weeks to increase the abundance and encourage the spread of Argentine ant ants by irrigating normally dry land. Once irrigation ended and soil moisture declined, the researchers found, the number of ants returned to pre-irrigation levels.

Biologists have long suspected that water is critical to the survival of the tiny ants, which thrive in coastal California and invade new subdivisions that have transformed much of Southern California’s arid landscape into a lush oasis. But until now, no one knew for sure.

"This is the first, definitive study that provides unambiguous experimental evidence that soil moisture can control invasions of Argentine ants," says David Holway, an assistant professor of biology who conducted the study with Sean Menke, a graduate student at UCSD.

It also suggests that residents who stringently limit watering their gardens and yards may be able to reduce ant problems without using costly toxic pesticide treatments.

"Our study shows that if you irrigate, you may well have ant problems," says Holway. "And if it’s dry, you’re not going to get Argentine ants. If it’s at all possible to limit your irrigation, you can decrease problems associated with Argentine ants."

The tiny dark-brown ants, which are about three millimeters in length, are thought to have entered the United States aboard ships carrying coffee from Brazil during the 1890s, then expanded throughout California and the southern parts of the United States.

In the Southeast, their proliferation may be now limited to some extent by the introduction of fire ants. But in California, where those competitors are largely absent, the ants thrive, killing and displacing native ants. In Southern California, Argentine ants are second only to termites as household pests.

The UCSD biologists conducted their experiments at five sites San Diego County: two reserves in the University of California Natural Reserve System (the Elliot Chaparral Reserve near the Miramar Naval Air Station and the Dawson-Mono Reserve near Carlsbad), the Los Peñasquitos Canyon Preserve, the Cabrillo National Monument and Tijuana Slough National Wildlife Refuge. At these ecologically different sites, the biologists manipulated soil moisture with drip irrigation for six months during the dry season, from May to October, and observed the effects on the ant populations.

After three months, the Argentine ants had 54 percent more nests in the irrigated sites. And when the water was shut off, the ants gradually retreated, reaching the levels of control sites after another three months.

Because irrigation increased plant growth around the study sites, the scientists also conducted experiments in which they suppressed plant growth with an herbicide. They discovered that the ant populations were 38 percent higher in the irrigated plots with plants than in those without plants, probably because of the presence of aphids, which provide an additional source of food for the ants.

However, the slight increase in the ant populations provided by plants was far less than that provided by water alone, leading the scientists to conclude that water, not plant cover, was the primary attractant for Argentine ants.

"These results are extremely clear," says Holway. "If you have wet soil outside of your home, if you irrigate your yard frequently, you’re providing an environment that is attractive for Argentine ants."

The results also have implications for land-use managers who must deal with streams of irrigated water and other urban runoff from suburban developments year round.

"The extent to which urban runoff can be reduced or contained, problems associated with Argentine ants should diminish," says Holway, adding that he knows first hand how much of a nuisance Argentine ants are for residents in Southern California. "Whenever I’m out in the field and someone asks what I’m doing and I tell them I study Argentine ants, the first thing they want to know is, How do I get rid of the ants from my home?"

Kim McDonald | EurekAlert!
Further information:

More articles from Studies and Analyses:

nachricht Diagnoses: When Are Several Opinions Better Than One?
19.07.2016 | Max-Planck-Institut für Bildungsforschung

nachricht High in calories and low in nutrients when adolescents share pictures of food online
07.04.2016 | University of Gothenburg

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

New method increases energy density in lithium batteries

24.10.2016 | Power and Electrical Engineering

International team discovers novel Alzheimer's disease risk gene among Icelanders

24.10.2016 | Life Sciences

New bacteria groups, and stunning diversity, discovered underground

24.10.2016 | Life Sciences

More VideoLinks >>>