While flies are often thought of as pests, a new study might make you think twice about killing them.
Researchers at Queen Mary University of London claim that insects feel pain “most likely” because they have central nervous system control over nociception (the recognition of painful stimuli) just like humans.
Based on the results, the researchers say insects should be included in animal welfare — especially as insect farming ramps up.
While flies are often thought of as pests, a new study might make you think twice before killing them. Researchers at Queen Mary University of London claim that insects feel pain “most likely” because they have central nervous system control over nociception (the recognition of painful stimuli) just like humans
Fruit flies feel “chronic pain” like humans
Chronic pain is defined as pain that persists after an original injury has healed, researchers from the University of Sydney said.
Like humans, fruit flies experience a specific type of neuropathic pain that occurs after damage to the nervous system.
People can experience this type of pain after suffering from sciatica, spinal cord injuries, or a pinched nerve.
When a fruit fly damaged a nerve in one of its legs, its other legs responded by becoming “oversensitive” to dangerous stimuli.
The fly receives “pain” messages that travel through sensory neurons to its ventral nerve cord.
After that, its pain threshold changes permanently and they become “hyper alert” when trying to detect potentially harmful stimuli.
Nociception is the recognition of painful stimuli and is usually accompanied by the sensation of pain.
Modulation of nociception allows animals to adapt their behavior in different contexts.
In mammals, this is done by neurons from the brain and is called the descending control of nociception.
‘For example, if an animal is injured during a fight, dampening its nociceptive processing can increase the animal’s combat performance by ensuring that it does not waste time or energy responding to the injury,’ the researchers explained.
‘Once the animal has returned to safety, the descending controls may also facilitate nociceptive processing and encourage the animal to protect the injured area to promote healing.’
To date, few studies have examined whether insects have such control.
In the new study, the researchers analyzed previous behavioral, molecular and anatomical neuroscientific evidence on pain in insects.
Their analysis indicates that insects, like mammals, are likely to have descending controls for nociception.
“Behaviourally, changes in the insect brain can alter their nocifensive behavior, whether that change involves physical manipulation or the processing of motivational stimuli,” the researchers write.
“At the molecular level, insects have molecular signaling pathways that can inhibit nocifensive behavior peripherally and centrally.
“Insects have anatomically descending neuronal projections from the brain to the ventral nerve cord, where nocifensive behavior is carried out.”
Based on the findings, the researchers call for further research into pain and insects to “clarify whether we should provide ethical protections to insects in potentially harmful environments such as agriculture and research.”
With the world population set to reach 10 billion by 2050, the United Nations has recommended mass-producing insects for food.
With the world population set to reach 10 billion by 2050, the United Nations has recommended mass-producing insects for food (stock image)
The UN recommends mass production of insects for food
With the world population set to reach 10 billion by 2050, the United Nations has recommended mass-producing insects for food.
“Edible insects can diversify diets, improve livelihoods, contribute to food and nutrition security, and have a smaller ecological footprint compared to other protein sources,” the UN said in a 2021 report.
“These potential benefits, combined with an increased interest in exploring alternative food sources that are both nutritious and environmentally benign, are driving the commercial production of insects for food and animal feed.”
“Edible insects can diversify diets, improve livelihoods, contribute to food and nutrition security, and have a smaller ecological footprint compared to other protein sources,” the UN said in a 2021 report.
“These potential benefits, combined with an increased interest in exploring alternative food sources that are both nutritious and environmentally benign, are driving the commercial production of insects for food and animal feed.”
However, if the researchers are right and that insects can feel pain, it raises ethical concerns about breeding them for food.
Last year, scientists called for the world’s first squid farm to be shut down over concerns the animals could feel pain and emotion.
About 350,000 tonnes of octopus are caught each year – more than 10 times the figure in 1950 – with the animal being a particularly popular delicacy throughout Asia and the Mediterranean.
Such is the demand that companies worldwide have spent decades trying to unravel the mystery of how to raise the squid in captivity, as its larvae only eat live food and require a carefully controlled environment.
Spanish multinational Nueva Pescanova announced that it will start marketing farmed octopus next summer, with plans for sale in 2023.
However, Nueva Pescanova declined to disclose this what conditions the squid are kept in, including the size of the tanks, the food they eat and how they are killed.
Many scientists have reacted with dismay to the news, saying that squid should never be raised commercially for food.
In a study by the London School of Economics and Political Science, experts said they were “convinced that high welfare octopus farming is impossible” and that the government “may consider a ban on imported farmed octopuses”.
SHOULD YOU RESTRICT RED MEAT? WHAT THE EVIDENCE SAYS
Meat is a good source of protein, vitamins and minerals in the diet.
The Department of Health advises that we eat no more than 70g (cooked weight) of red and processed meat per day, which is the average daily consumption in the UK.
This is mainly because there is a link between colon cancer and red meats like beef and lamb, as well as processed meats like sausage and bacon.
A 2011 report titled Iron and Health by the Scientific Advisory Committee on Nutrition (SACN) reviewed evidence linking colon cancer to iron — meat being the main source of iron.
SACN concluded that eating lots of red and processed meat likely increases the risk of colon cancer and advised accordingly.
The American Institute for Cancer Research advises us to eat no more than three servings of red meat a week and urges us to “avoid” processed meats.
Processed meat often contains nitrogen-based preservatives that prevent it from spoiling during shipping or storage.
These preservatives have been linked to both colon and stomach cancer.
When red meat is digested, the pigment heme is broken down in our gut to form chemicals called N-nitroso compounds.
These compounds have been found to damage the DNA of cells lining our digestive tract, which could lead to cancer.
Our bodies can also respond to this damage by causing cells to divide more quickly to replace those that are lost.
This “extra” cell division can increase the risk of cancer.
Cancer Research UK says three chemicals in meat are linked to colon cancer because they damage cells in the gut.
Red and processed meats have also been linked to type 2 diabetes.
This may be due to the preservatives used or the meat’s higher saturated fat content than chicken and fish.
However, researchers in Canada, Spain and Poland are casting a shadow over the dietary advice adopted by health organizations around the world in November 2019.
In a landmark paper, the scientists analyzed previous studies on how eating meat affects the health of more than four million people.
The study, published in the journal Annals of Internal Medicine, found no evidence that eating beef, pork, and lamb could increase rates of heart disease, cancer, stroke, or type 2 diabetes — despite fears.
