Mushroom from ‘The Last of Us’ is used as a natural pesticide

Not that they need any help, but HBO’s “The Last of Us” has made the mushrooms cooler than ever, thanks to the starring role a parasitic fungus plays in societal collapse. The creators of the TV show and the video game series it’s based on were inspired by an actual mushroom that turns insects into zombies, which in many ways is more fascinating than fiction.

The fungus, called cordyceps, doesn’t make undead zombies, but it hijacks the biology of its hosts, forcing the victim to do what it wants, then ultimately kills it. The fungus grows inside the exhaled insect corpse, consuming its tissues until it bursts open and releasing more spores to start the cycle again.

Obviously, that’s a horrible way to die, but it’s a fairly common tactic in the Mushroom Kingdom. About 700 different species of the genus cordyceps are scattered throughout the world, many of which have developed specialized relationships with their hosts.

For years, scientists have explored the use of this fungus as an all-natural pesticide, providing a potent alternative to some of the more toxic chemicals commonly sprayed on crops. Not only could cordyceps be a fantastic insect killer, but it could help protect many agricultural industries that are currently threatened by major invasive species.

Take the cotton insect (Phenacoccus solenopsis) For example. It looks more like an alien crustacean than an insect, its grey-yellow body obscured by the crispy white down it wraps around its body. Cotton mealybugs are scale insects that feed on fruits, vegetables and ornamental plants, but true to its name, it Really likes to suck the sap of the cotton plants. Unfortunately, it also injects toxic saliva into its meal, which causes the leaves to wither and eventually kills the plant.

Cotton mealybugs have spread across the world and in most places farmers’ response is to drown their plants in chemical pesticides, which have a nasty habit of maiming or killing other non-target plants and animals. . This can eventually backfire, as the insects develop resistance to common pesticides. What if there was something to kill scale insects that wasn’t so harmful and they couldn’t fight off?

Enter Cordyceps fumosorosea, a species of fungus that produces many different toxic chemicals to attack insects and arthropods. When a C. fumosorosea spore lands on an insect, it begins to produce an enzyme that dissolves the hard outer shell of the insect’s body, slipping inside. Once it enters the victim, it begins sucking in nutrients until it develops tendrils throughout the insect’s body, rupturing it and spitting out more spores for the next poor insect.

In a study published in January in the journal Biocontrol Science and Technology, researchers from Bahauddin Zakariya University in Multan, Pakistan found that C. fumosorosea is a very effective pesticide against cotton mealybugs, with a mortality rate of 87.5%. Other studies with different insects have reported a mortality rate of 100%. But even when it didn’t completely kill hosts, it stunted their growth and inhibited their ability to reproduce. The fungus appears to raise the body temperature of its prey, which leads to loss of appetite and may even disrupt its ability to mount an immune defense.

Previous research has shown that other insects are equally susceptible to Cordyceps fumosoroseaincluding diamondback moth (Plutella xylostelle), a rice-shaped insect with three cream-colored diamonds imprinted on its back. Unfortunately, this butterfly is a big fan of “cabbage crops,” which include broccoli, cabbage, cauliflower, Brussels sprouts, and kale.

But C. fumosorosea dispatches the moth just as effectively, sometimes in as little as 72 hours, according to a 2021 study in the journal Insects. And other insects also need to be careful, including termites, red palm weevils, whiteflies and other agricultural pests. It’s unlikely that any of these parasites could develop defenses against fungi, since they are so versatile in controlling their hosts.

Despite its widespread use against insect pests, cordyceps did not evolve to attack plants. This means that farmers can potentially spray as much of this fungus as they want on their crops without having to worry about it killing their plants or damaging other plants in the environment. It could be an extremely effective alternative to pesticides, which are often toxic chemicals that don’t discriminate when damaging living things.

Using nature like this is called integrated pest management, a more comprehensive approach to pest management that doesn’t involve toxic chemicals or genetically engineered crops to resist pathogens. Besides the weaponization of mushrooms, there are other examples, such as disturbing noises to prevent certain insects from communicating.

And even, Cordyceps fumosorosea is just one of hundreds of these types of mushrooms. We need much more research on the effectiveness of this tactic using different cordyceps strains, while ruling out any potential off-target effects. We wouldn’t want to accidentally spray a field with this product and wipe out a rare species of butterfly, for example.

Want a daily recap of all the news and commentary Salon has to offer? Subscribe to our morning newsletter, Crash Course.

So when can we see these mushrooms hitting store shelves? Some fungal pesticide products exist, including a kind of vaccine for elm trees called DutchTrig. Scientists are actively working to get this research out of the lab, but there are a lot of important steps to take before making this ADM mushroom public. However, some entomologists like those at the University of Florida are experimenting with spore-spreaders that look like yellow sponges, which are hooked into citrus trees to send out Asian citrus psyllids, a really nasty insect that likes to attack oranges. The products therefore exist, but bringing them to market requires additional steps.

While “The Last of Us” is a fantastic and groundbreaking franchise, the mushrooms in it are purely fictional. They don’t have much in common with real-world cordyceps except the name and humans, who regularly eat these mushrooms with no problem, don’t have to worry about them hurting us. It would take much, much more complex biological warfare for such a pathogen to control the minds of humans, but luckily there is more interest in entertainment for these solutions, which could improve our relationship with nature and the environment. agriculture.

Learn more

about this topic

Leave a Comment