The new study, to be published Wednesday, Oct. 28, in the open-access journal BMC Biology, sheds light on the factors influencing the social behavior of the Argentine ant, Linepithema humile, and provides hope for a new tactic in controlling the spread of this invasive species.
The research was conducted on the highly invasive Argentine ant, but the researchers note that the findings are likely relevant to other types of insects that rely upon chemical signals to identify each other.
"Almost all living organisms use chemical recognition cues to some degree, but it is particularly common among ants and other insects," said evolutionary biologist Neil Tsutsui, UC Berkeley associate professor of environmental science, policy and management and the study's principal investigator. "Surprisingly, it wasn't until this work that the specific chemicals used by Argentine ants to identify each other were isolated and tested."
Native to South America, the Argentine ant has taken hold in numerous countries worldwide, including Australia, Japan and the United States. In California, the ants are pervasive, pushing out native ant species and wreaking ecological havoc along the way. The Argentine ant has been blamed for exacerbating problems with some agricultural crops in the state, and for the decline of the coast horned lizard, which feeds exclusively upon the native ant species decimated by the invader.
In their native habitat, Argentine ants use their aggression to engage in inter-colony warfare with each other as they compete for resources, a behavioral trait that biologists credit for keeping the ants' numbers in check. Colonies tend to be small, typically measuring a few meters to a couple of hundred meters wide.
Biologists say that part of what makes the Argentine ants such successful invaders is that outside their home turf in South America, the fighting among them largely stops, allowing Argentine ant colonies from different regions to band together into a formidable group. Previous research conducted by Tsutsui and others provided evidence that the reason behind this relatively peaceful co-existence is the ants' genetic similarity, suggesting that they are part of the same, vast family. This lack of diversity falls in line with the theory that the invasive ants descended from a few individuals introduced to the new region.
"The striking thing about these Argentine ants in introduced ranges is that – with few exceptions – they are essentially functioning as a single, geographically huge supercolony," said Tsutsui. "If you take ants from San Diego and put them next to those from San Francisco, they'll act like they've known each other all their lives. They are part of a massive supercolony that extends hundreds of miles, nearly the entire length of California."
The UC Berkeley researchers worked with study co-authors Robert Sulc and Kenneth Shea from UC Irvine to narrow down and synthesize seven chemical molecules that trigger aggressive behavior among the Argentine ants. They also used two "control" chemicals not linked to fighting behavior. The "enemy" compounds were similar in that they were all long chains of hydrocarbons with one to three methyl groups attached.
Researchers then coated individual worker ants from the same colony with the purified substance. The researchers matched each of the chemically disguised ants with 10 untreated ants, one by one for five minutes each, in a petri dish.
"The 'enemy' chemicals generated significantly greater instances of flared mandibles, biting and other attacking behavior than did the control chemicals," said study co-lead author Ellen van Wilgenburg, a post-doctoral researcher in Tsutsui's lab at UC Berkeley. "We also saw higher levels of aggression when we increased the concentration of the chemicals and when we combined some of the chemicals together."
Despite this finding, Tsutsui cautions that significant barriers must be overcome before a pest-control substance based upon these chemicals is ready for the market. "We are still in the process of understanding how these chemicals control social behaviors in ants," he said. "These are custom chemicals that are very costly to synthesize at this stage. We are still a long way off from having large enough quantities to deploy in the field, or even knowing if these chemicals can control populations in the field."
The other co-lead author of the study is Miriam Brandt, a former post-doctoral researcher from Tsutsui's lab.
The U.S. Department of Agriculture, the California Structural Pest Control Board, the Defining Wisdom Program of the University of Chicago and the National Science Foundation helped support this research.
Sarah Yang | EurekAlert!
Newly designed molecule binds nitrogen
23.02.2018 | Julius-Maximilians-Universität Würzburg
Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy