Colonies treated with dopamine were more likely to forage on wet, muggy days, scientists found. Photo by Becca Nelson/Cell Press
Sept. 27 (UPI) -- New research suggests the neurotransmitter dopamine encourages ant foraging.
Scientists were inspired to study the effects of brain chemistry on ant behavior after noticing differences in the foraging patterns of different ant colonies in the Arizona desert.
Some red harvester ant colonies, scientists observed, send their foragers in search of food on dry days, while others kept their foragers at home. When scientists dissected and analyzed the brains of ants from each colony, they found coding differences among the genes responsible for neurotransmitter signaling and metabolism.
To better understand the role of neurotransmitters in dictating foraging behavior, scientists studied a new set of ant colonies, treating some with dopamine and others with a control solution.
In some colonies, scientists applied the solutions to entire ant populations. In other colonies, researchers dosed individual foragers with one of the two solutions and observed changes in their behavior.
"I would go out to a colony and collect foraging ants just after they had left the nest," Daniel Friedman, a doctoral biology candidate at Stanford University, said in a news release. "Then I would drive them back to the lab, put them on ice to slow them down, and paint their heads so I would know to which group they belonged. Then I would drop the dopamine or control solution into their mouths and take them back to their colonies."
The day after treatment, scientists observed ants dosed with dopamine took more foraging trips than their nest-mates treated with the control solution. Scientists also found dopamine-treated colonies foraged on muggier days and stayed inside their nests on drier days.
In a follow up test, scientists treated ants with a dopamine-blocker. The effect was the opposite -- treated ants were less likely to forage.
"The increases in forager brain dopamine seemed to increase individual ant foraging. That supports the idea that behavioral differences between nest-mates might be related to differences in brain dopamine levels," said Friedman. "We know that the individual risk that the foragers take relates to the collective decision-making of the colony, but there's a lot more to learn there."
Friedman and his research partners published their findings this week in the journal iScience. In future tests, researchers hope to test the impacts of other related neurotransmitters, as well as measure the effects of dopamine under a variety of environmental conditions.