Many researchers and entomologists studied the mutualistic behavior of ants and aphids and explored their beneficial association. Ants need food from these insects and eat honeydew to meet their nutritional requirement, while aphids have soft bodies and ants protect them from predators.
On 15 November 2023, Jason Rissanen and a few other researchers from the University of Graz, Austria, published a research article on silky ants, and mentioned that these ants eat more aphids after fungal infections. Aphids produce hydrogen peroxide that kills fungus, but it is harmful when its consumption rate increases to more than 50% of an ant’s diet.
The scientists conducted different research to study their behavior and showed that ants improve the survival rate and reproduction abilities of aphids by providing a safe environment.
In 2000, Thomas Flat published an article after studying the effect of mutualistic ants on aphids’ lives and found that this association improves ants’ survival rate.
This mutualistic association is beneficial for an increase in the population size of both organisms when they fulfill each other’s requirements and live closely.
Ants eat honeydew, obtain nutrition from the sweet secretions released by them, and maintain a healthy lifestyle, but later research also mentioned some other benefits.
Sick silky ants eat more aphids to live longer
A few days ago, an article was written in New Scientist by Chen Ly that was about the fungal infection in silky ants ((Formica fusca) and their behavioral or dietary changes.
It is common for them to get infected with fungus when they live in highly humid places, but this infection can be deadly for them when it grows uncontrollably.
Accordingly, Chen Ly mentioned the research work of Rissanen, which was focused on the changes in the behavior of infected ants to treat fungal growth and ensure survival.
He wrote that the sick silky ants begin to eat more aphids than average and chew their soft bodies to get nutrition and exposure to hydrogen peroxide released by them.
Almost half of the total proportion of their diet consists of aphids after getting severely infected with fungi. This change in dietary habits helps them get rid of fungus and improves their lifespan.
How do aphids treat fungal infections in silky ants?
Jason Rissanen conducted research on silky ants while working as a research assistant at the University of Graz, Austria, and studied their behavior when infected with fungi.
He observed that some species of aphids produce hydrogen peroxide in their saliva that has anti-fungal properties which can kill the fungal growth on the bodies of these ants.
Accordingly, these infected or sick ants get closer to the aphid’s population and begin to eat more of these soft-bodied insects to treat their bodies with hydrogen peroxide.
Rissanen, Torsten Will, Freitakk, and many other researchers from the University conducted an experiment to gain deeper insights into this behavior.
In addition, they collected 30 nests of wild species of silky ants from Hanko, Finland, and stored them in plastic boxes separately.
Talcum powder and ethanol boundaries were created around them to avoid escapes. After that, half of them were infected with Beauveria bassiana.
Both groups were offered a standard food mix containing honey and agar and two other food mixes having small and large numbers of aphids crushed into smaller sizes.
After that, the food preferences of infected and uninfected ants were observed for some time, and a noticeable difference was found in their food choices.
They observed that the infected population of silky ants consumed 50% of their food from a food mix containing a higher percentage of crushed aphids and the remaining 50% from the standard mix.
In contrast, the uninfected group preferred to eat food from the standard mix containing honey and agar and consumed a small number of crushed aphids in the food.
In addition, the researchers found the switching behavior of ants as they began to eat fewer honeydew-secreting insects when they got rid of the fungus.
On 15 November 2023, Jason Rissanen and his colleagues published results in The Royal Society Publishing and mentioned silky ants’ diet when they get severely infected with fungi.
Eating more aphids is deadly for silky ants
Excessive consumption of aphids is bad for silky ants because hydrogen peroxide is harmful to them. It causes instant death when the amount of hydrogen peroxide increases.
However, these are smart enough to adjust the consumption amount up to a safe level. They constitute around 50% of their diet and serve as medication for sick ants.
In addition, they are prone to death when more than 50% of their total diet proportion is based on aphids. Infected ants forage differently than healthy ones, but it can be deadly for them.
So, silky ants are smart enough to eat aphids to treat their fungal infections but keep their amount up to a safe limit.