According to a new study, fruit flies get “hungry” and become more combative the longer they have to go without food, similar to humans.
Male fruit fly vials containing varying amounts of food were scanned over different periods of time by experts from the University of East Anglia and Oxford University.
They found that male fruit flies that feed on decaying fruit became more and more combative the longer they were without food, but after 24 hours they reached a plateau.
The team says this aggression could be a strategy to maximize short-term reproductive performance in environments where survival is uncertain.
According to a new study, fruit flies get “hungry” and become more combative the longer they have to go without food, similar to humans. Image from a picture agency
FRUIT FLIES ARE “EXTREME FLYERS”
Although they are best known for moving in circles in search of bananas, scientists show that fruit flies actually have an impressive range.
The species, Drosophila melanogaster, can fly up to 15 km in a single journey, researchers at the California Institute of Technology (Caltech) reported.
This is impressive about 6 million times their average body length, which is only 2.5 millimeters.
This would be like the average person traveling just over 6,200 miles – roughly the distance from the North Pole to the equator – in a single trip.
Read more: Hungry fruit flies can fly up to nine kilometers in a single journey to find food
In nature, the amount of food available increases and decreases, so animals often find themselves in conditions where there isn’t much.
The team behind the study wanted to find out whether animals, in this case fruit flies, have the same “hangry” posture as humans when they are left without food.
They scanned vials containing fruit flies and varying amounts of food to record the number of lunges and fights between the flies. They also investigated the presence of flies that hunt, fence and occupy the food field in the vial.
The vials were scanned 16 or 32 times depending on the treatment, each scan lasting three seconds.
Lead author Dr. Jen Perry of the University of East Anglia said starvation can lead to a debilitated state, making hungry problems less likely to win fights.
“On the flip side, hungry people might be more motivated to fight for food, leading to aggression or hangars,” Perry said.
“We found that hungry male fruit flies show more hostility to one another.”
They attacked each other more aggressively and hit each other with their legs, which they called “fencing behavior”.
The starving fruit flies also spent more time defending limited food fields. The authors found that “the hungrier they get, the more willing they are to fight.”
“In other words, just like humans, fruit flies get hungry,” said Dr. Perry.
Research also suggested that increased aggression in malnourished fruit flies could result from a “desperado” effect.
This is one where people in bad shape get involved in fights even if they are likely to lose, as they cannot gain fitness benefits by not engaging at all.
Both the quantity and quality of nutrients could affect aggression, according to the researchers, who focused on quantity to reflect seasonal variations in nature.
Periods of lack of food are common in natural insect populations, especially since the main diet of fruit flies consists of seasonal and spatially changing fruits.
Male fruit fly vials containing varying amounts of food were scanned over different periods of time by experts from the University of East Anglia and Oxford University. Image from a picture agency
Aggression is costly and carries the risk of physical harm and predation as well as expenditure of time and energy.
Likewise, food deprivation can have a long-term impact on one’s internal state and affect size, physiology, and behavior.
Dr. Danielle Edmunds, who conducted the experiments as part of her PhD at Oxford University, said heightened aggression could be a strategy to maximize short-term reproductive performance in environments where survival is uncertain.
“Our other studies show that poor early life feeding conditions have exactly the opposite effect on aggression,” she said, adding that “Flies that grow up on restricted diets are less aggressive as adults.
“Together, these results show that the effects of food restriction on aggression depend on when it is experienced in the life cycle.”
The study was published in the journal Animal Behavior.
HOW TO NAVIGATE FRUIT FLYING WITH THE SUN?
Almost 40 years ago, scientists first discovered that fruit flies can travel up to nine miles in a single night in search of food and water.
Since then, researchers have not been able to figure out how the small creatures, usually 3 to 4 mm from the wing tips, are able to travel such comparatively long distances without deviating from course or getting lost.
Scientists at the California Institute of Technology (Caltech) have set up a “flight simulator” experiment to solve the mystery behind this ability.
The team created a kind of virtual reality for their fruit fly objects – scientific name Drosophila – that hold them in place but allow them to move their wings in response to visual stimulation.
This was provided through a range of LED lights. When the lights came on, the flies turned their bodies towards them and flapped their wings.
Researchers found that the flies could remember the direction if a certain light was switched on again hours later.
Then they used genetic tools to modify brain cells so that they glow according to the activity of certain neurons.
This indicated that certain cells were responsible for their compass-like ability.
