Researchers identify new “social” chromosome in the red fire ant.
Nobody wants to be stung by a red fire ant. Fortunately, researchers from the University of London-Queen Mary think that a newly discovered “social” chromosome” in the highly invasive fire ants could offer novel solutions for dealing with this pest. They believe that this social chromosome helps to explain why some colonies allow for more than one queen ant.
According to Invaders of the Sonoran Desert Region (a project of the Arizona-Sonora Desert Museum), there are six known species of fire ants in the United States. These pests are tiny but extremely aggressive. They inject a necrotising, alkaloid venom when they sting. The stings result in painful and itchy pustules.
According to researchers, red fire ants reside in two different types of colonies: Some colonies have a single queen while other colonies have hundreds of queens. They believe that this difference in social organization is determined by a chromosome that carries one of two variants of a “supergene” containing more than 600 genes.
While the two variants, B and b, differ in structure, they have evolved similarly to the X and Y chromosomes that decide the sex of humans. Researchers discovered that if the worker fire ants in a colony carry only the B variant, they will accept a single BB queen, but a colony that has worker fire wants with the b variant will accept multiple Bb queens. Researchers came to this conclusion after analyzing the genomes of more than 500 red fire ants.
According to co-author Dr. Yannick Wurm, from Queen Mary’s School of Biological and Chemical Sciences, this was the first supergene ever identified that determines social behavior. Wurm thinks it is possible that special chromosome in other species also determine basic traits such as behavior.
Researchers also found that young queens destined to create their own single-queen colonies fly off in search of new territories during mating season. However, other young queens join existing multiple-queen colonies. Such colonies are able to generate more workers than are produced in a single-queen colony. Thus, multiple-queen colonies are the more advantageous social form.
This discovery could assist in creating new pest control strategies. For instance, a pesticide could artificially turn off the genes in the social chromosome and create social anarchy within the colony, says Wurm.
The study’s findings were recently published in the journal Nature.