When establishing a colony, the queen of the black garden ant may consume larvae that show signs of disease to prevent its spread.
According to research published in the journal Current Biology, if a newly emerged black garden ant (Lasius niger) is infected, it is eaten by the queen before it can transmit the disease to others, as reported by Science Alert on September 30.
Black garden ants and larvae. (Photo: Henrik_L).
“The queen starts to build the colony alone and almost starves herself to nourish the first worker ants. The queen that ‘produces’ the most worker ants has the greatest chance of survival, so the ability to consume and ‘recycle’ infected larvae into young ants ensures that precious resources are not wasted,” explained biologist Flynn Bizzell from the University of Oxford, a member of the research team.
Bizzell, along with biologist Christopher Pull at the University of Oxford, discovered that worker ants within colonies do not generally exhibit cannibalistic behavior. However, when the colony is newly established and vulnerable, the queen cannot remove infected larvae from the nest. The queen is trapped inside with the larvae, crowded and without assistance.
The risk of infection in this environment is very high. Therefore, upon detecting pathogens in the nest, they will eliminate infected larvae as quickly as possible. If necessary, the queen will consume up to 92% of infected larvae. Queens that do this can lay 55% more eggs in their next brood.
For the experiment, Bizzell and Pull exposed five larvae from each queen to the spores of a pathogenic fungus. The larvae were then left alone for 24 hours to develop the infection, even though they were not yet capable of spreading it. When returned to the nest, Bizzell and Pull observed the actions of the queen.
Within a few hours, the queen consumed nearly all of the infected larvae, leaving behind the healthy ones. The fungal disease did not seem to affect the queen even after consumption. Bizzell and Pull suggest that this is due to the queens protecting themselves from within. Before and after the queen consumed the infected larvae, the two biologists noticed some ants “caring for” a gland on their abdomen. This gland produces a type of antibacterial acid venom. Ingesting this venom may help the queen neutralize pathogens in her gut.
In a subsequent experiment, when encountering deceased infected larvae that had begun to produce infectious spores, the queen sprayed venom onto the carcasses from her venom gland. However, this stage is very dangerous for the queen. Even after spraying venom on the larvae, she still has an 80% chance of dying from the infectious disease. In cases where the queen survives, her brood may still perish. Therefore, acting quickly to prevent infection is crucial.
The new study provides evidence that queens consume larvae as a response to disease, protecting their own lives as well as those of other young ants.
