Image: Alex Wild / © AntWeb.org / CC-BY-SA-3.0
-
What a Plant Knows
How does a Venus flytrap know when to snap shut? Can it actually feel an insect’s tiny, spindly legs? And how do cherry blossoms know when to bloom? Can they...
Read More »
In 1907 Argentine ants (Linepithema humile) arrived in Los Angeles via a cargo ship. Within just a few years of their arrival the six-legged stowaways formed a single, massive colony—known as a supercolony—that stretched through California from south of the Mexico border to San Francisco
A liberal spraying of pesticides in the past century has done nothing to diminish the ants' numbers—L. humile infestations are the most common cause of pest control calls in southern California. The Argentine ant's takeover of coastal California is marked by small shifts in the local, native ecosystem. Populations of the coast horned lizard (Phrynosoma coronatum) have declined sharply in recent years due to the displacement of native ants the lizard depends on for food. Citrus farmers have required increasing quantities of pesticides to cope with rising numbers of aphids, scale insects and other pests that the Argentines actively protect in exchange for the sweet honeydew they produce.
In an effort to better understand and help combat the ants, a group of researchers led by Neil Tsutsui at the University of California, Berkeley, sequenced the genome of L. humile. The results were published January 31 in Proceedings of the National Academy of Sciences.
"An increasingly large number of research groups are focusing on Argentine ants because of their agricultural problems," Tsutsui says. "One of our main goals was just to provide a large resource for the community of scientists that study Argentine ant biology."
Tsutsui and colleagues found an unusually large number of chemical receptor genes that allow the ants to recognize and process different environmental chemical cues. The Argentines have 367 of these genes, compared with 174 in honeybees and 79 in mosquitoes. All ants communicate largely by "smelling" different chemicals in the environment with their antennae. Tsutsui said that identifying both the chemicals and the messages they send, researchers might be able to disrupt the Argentines' normal behavior.
"We know a lot about the behavioral processes that are regulated by these chemicals, and we know a lot about the chemicals themselves, but we don't know much about the missing links in between those two things," Tsutsui says.
Sequencing DNA is one thing; figuring out how to use that knowledge to halt the ants' spread is another. A 2009 paper in Insectes Sociaux found that Argentine ants from California, Europe and Japan formed a global supercolony. Argentines are very territorial in their South American homeland. Neighboring colonies fight each other regularly for food and nest space. These frequent brawls help keep ant numbers in check. But neighboring Argentine ant colonies that invade new locations often live side by side with nary a scuffle, so there is no in-species mechanism to keep populations down.
"If you take ants from any of those locations, they don't fight. They interact as if they are nest mates," says David Holway, an ecologist at the University of California, San Diego. "If you take Argentine ants from some other supercolony, they will fight very aggressively."
Highly adaptable street toughs
These supercolonies, however, are only one aspect of L. humile's success. Tsutsui and colleagues found a cluster of genes that allow the ants to eat a variety of foods. These genes allow the ant to metabolize the toxins frequently found in unfamiliar food. Years of evolution have honed this invader's skill at making itself at home in habitats ranging from Argentina's La Plata Basin to the cement jungles of Los Angeles to the green pastures of California's San Joaquin Valley. Frequent flooding of their native Paraná River selected for ants over time that were adapted to invading disturbed habitat and to easily moving their nests.
See what we're tweeting about
8 Comments
Add CommentIt seems that importing more ants from many different colonies might help. The problem seems to be due to a single intoduction from one colony.
Reply | Report Abuse | Link to thisIt seems pretty simple,you blind the ants by covering the chemical that creates the path they follow.They get lost and the colony dies.And or create a path to death trap,and you do so without a pesticide.
Reply | Report Abuse | Link to thisHere in San Diego County's oak woodland I've witnessed an accidental elimination of the Argentine ant. Arriving at this ranch 28 years ago, I witnessed the full vigor of the species as it invaded kitchens and bathrooms. Any attempts at blockage were soon thwarted. Outside, they systematically devastated our native California Harvester ant which is the preferred prey of the endangered Coast Horned Lizard. The property owner died and I was left to determine the extent of irrigation. Having learned that summer watering encourages the oak fungus [Armillaria mellea] resulting in root or crown rot, I drastically cut back on watering. Before long it became apparent that the Argentine ant was dwindling. Each subsequent year saw more mounds of the native California Harvester ant. Today it takes a diligent search to find any Argentines. We see a few more Coast Horned Lizards now.
Reply | Report Abuse | Link to thisI did conduct one experiment on an Argentine that bears reporting. A lone ant appeared years ago on a counter top [a scout perhaps; aren't they all?]. I opened a can of sardines [before the BPA revealations] and smeared a line of the oil where the ant would find it. I had it leading to a bit of sardine. The ant found my pathway, followed it to the sardine and briefly examined the food. Then, in seconds, it lowered its abdomen to the countertop surface. Walking away, it held the abdomen pressed against the surface all the while. In those few minutes I had been shown the altruism of the species. It could have eaten its fill and then made the return trail for its mates. But instead it thought only of the colony.
Davidino...excellent observation...I hope you can get others to follow your lead....
Reply | Report Abuse | Link to thisPlease someone post something about the fireants in Florida like this...only being wishful;-)
My home was infested with these ants. If food got left on the kitchen counter overnight, in the morning it would have a column of ants leading to it from some crack in the wall.
Reply | Report Abuse | Link to thisI used a spray solution of 1 tsp. liquid dish soap per quart of water to kill the ants with easy clean up. (I believe the soap bubbles immediately suffocate the ants)
But this did not get rid of the problem.
After putting up with that for two years, I got a pack of poison bait stakes and put them all around the perimeter.
This is slow-acting poison bait that the workers carry back to the nest. It kills them all including the queens.
I haven't seen an ant here for eight years.
Unfortunately this is evolution at its finest. The more adaptable ant is crowding out the less adaptable ant. When Argentine ants meet Fire ants, I wonder which will prevail.
Reply | Report Abuse | Link to thisFood for thought:
Reply | Report Abuse | Link to thisThey want to kill the ants? Why? Is not this the age of "SAVE EVERYTHING"? Save the ants, anyone?
these ants compete locally against each other but not in a new territory.
Reply | Report Abuse | Link to thisIn a new territory there's only one gene set regardless of the size of the area so the individuals recognize each other as mates. In the "old" territory gene variants settle and procreate within the monogenomic territory and are not recognized by the original gene set. War follows and consequently the whole population is kept in check. With time there are more mutations so the original gene set becomes marginal. So introduce other argentine ants queens from somewhere else and the problem will take care of itself faster than just letting time take care of it.
As a closing note: ants make good study because they are the components of super-organisms, they can teach us a lot about robotics, networks, traffic and logisitcs. For instance how to get energy reloads in real time with no down time using each individual as a reservoir for the other. Imagine electric cars or robots getting their energy like this.