Scientists have found that fire ants from colonies with multiple queens have more viruses than fire ants from colonies with just one queen.
Workers of the red fire ant on a sequencing chip. Credit: Yannick Wurm & Emeline Favreau.
Animals that live in larger societies are typically better able to compete for food and resources than animals living in smaller societies. New research, led by Queen Mary University of London and published in Molecular Ecology highlights a difficult-to-measure cost of living in larger societies.
The researchers applied a highly sensitive biomedical approach to count and catalogue thousands of fragments of viruses infecting the red fire ants. They found that those ants that live in multiple-queen colonies are infected by more viruses and have stronger viral infections than the fire ants that live in single-queen colonies.
Lead author of this study Dr. Yannick Wurm, from the School of Biological and Behavioural Sciences at Queen Mary University of London said “Typically, animal societies that include more individuals are highly successful. We found that many more viruses infect the larger multiple-queen ant colonies than the smaller single-queen colonies. This shows that the benefits of living in larger societies come with a cost of higher pathogen exposure.”
The authors of the study argue this could be because multiple-queen colonies include more ants and that these ants behave in manners likely to lead to having more interactions with the outside world where they could be infected. Furthermore, the immune defenses of ants in multiple-queen colonies are more variable than in single-queen colonies, thus these colonies are more likely to include susceptible individuals.
The red fire ants are highly invasive pests in many parts of the world, living up to their Latin name Solenopsis invicta, meaning “the invincible”. These ants can live in colonies with a single queen, or in colonies that contain dozens of queens. Because each queen lays many eggs every day, the multiple-queen colonies grow to be larger than the single-queen colonies. Dr Anindita Brahma, first author of this study and also from Queen Mary University of London said, “The multiple-queen fire ant colonies carry many viruses in regions where these ants are invasive. This creates a risk that the invasive fire ants could host and transmit viruses to native species.”
Dr. Wurm added “Carrying many viruses could increase the damage caused by the most invasive ant species, all of which include multiple-queen societies”.
Previous research has shown that other invasive ant species can carry and pass on viruses that reduce the lifespan of honeybees. The new knowledge can help scientists predict the impacts of the spread of invasive ant species on pollinators and other beneficial insects.
To identify which viruses were present, the researchers used a cutting-edge molecular approach. After RNA from the queens from each colony had been extracted and sequenced, the researchers analysed the RNA sequence data and compared this to the sequences of known viruses in a database of all known viruses.
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