Invasive ants get their genome sequenced

The ants that ruin picnics and infest homes have had their entire genome cracked by an international team of scientists. Assistant Professor of Biology Christopher Smith was part of the research team that sequenced the genomes of three ant species, including the invasive Argentine ant -- a persistent household pest in California and across the world.

photo of an Argentine worker ant with a queen ant of the same species, illustrating that the queen has a much larger body than the worker ant.

An Argentine worker ant (left) with a queen ant of the same species (right). Photo: www.alexanderwild.com

The genomes will help reveal how genetics may determine the very different destinies of queen and worker ants. Similar to bees, ants have highly sophisticated social structures. Queen ants typically have larger bodies, wings and fertile ovaries, and are responsible for reproduction in the colony, while smaller, worker ants are wingless and infertile, and tasked with foraging for food.

The newly sequenced genomes provide clues about how ant embryos with the same genetic code develop into queens or worker ants.

"We now know that ants have the genes and genome signature of DNA methylation -- the same molecular mechanism that published honeybee studies have suggested is responsible for switching whether the genome is read to be a worker or queen," said Smith, who was a lead author on the Argentine ant genome study and the red harvester ant genome study.

photo of a red harvester ant carrying a seed in its mouth

A red harvester ant, one of the species included in the three genomes decoded by scientists. Photo:www.alexanderwild.com

Analysis of the genomes suggests that chemical modification of certain sections of DNA could be responsible for the different developmental paths of queen and worker ants. As an ant larva develops, methylation, which involves methyl chemical groups attaching onto the DNA, may switch off the genes that control reproductive capacity and wing growth.

In the last century, tiny brown Argentine ants have spread from their native South America to nearly every Mediterranean-type climate in the world, where they  plague homeowners, threaten native insects and disrupt agriculture.

More information about the newly published ant genomes:www.sfsu.edu/~news/prsrelea/fy10/013.html

-- Elaine Bible