How chemicals cues can make friendly ants turn against each other

Washington, October 28 (ANI): Experiments led by researchers at the University of California, Berkeley, have demonstrated that normally friendly ants can turn against each other by exploiting the chemical cues they use to distinguish colony-mates from rivals.

The new study 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.

Native to South America, the Argentine ant has taken hold in numerous countries worldwide, including Australia, Japan and the United States.

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.

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," she added. (ANI)