The parasitic space worms are coming, and they’re ready to kill.
No, it’s not the tagline for some Tremors in Space B-movie monster flick. Instead, it’s the result of some research recently published in the journal npj Microgravity. And despite how it sounds, it’s actually good news. (Spoiler: it’s not us that they’re killing.)
Here’s the issue: One of the many, many problems that need to be solved before space colonization can take place is what people are going to eat. Right now, astronauts rely on packets of dehydrated food that are launched into space either on their original journey or on top-up resupply missions. However, this isn’t a viable solution when, for instance, colonists arrive on Mars. As Andy Weir’s The Martian suggested, space agriculture is a distinct possibility for providing a continuous supply of sustenance.
But — and this is getting ahead of ourselves — it seems likely that crops in space could face the same problem of insect pests as crops on Earth. That’s not to suggest that they’ll be fending off alien insects (at least, not aliens in the traditional sense), but that a steady stream of colonists from Earth could bring with them some of the same insects that already feed on our crops on terra firma.
No crop dusting in space
Without proper pest control, farmers on Earth risk losing up to 80 percent of their crops. Needless to say, that kind of bad harvest could prove devastating for a developing space colony. Clearly some form of pest control is sensible to investigate. Since air quality is critical in space (being a limited resource, and it not being quite so easy to open a window to get clean air), it would also make sense if pest control methods were biological, non-toxic ones.
That’s where the worms enter, stage left. These tiny worms are what researchers from the U.S. Department of Agriculture and the biotech company Pheronym refer to as “biocontrol organisms.” Already widespread on Earth, these parasitic roundworms, called entomopathogenic nematodes, are not harmful to humans, but are great at controlling a wide variety of insect pests. This makes them a perfect natural bio-pesticide, midway between microbial pathogens and predators. They kill insects using a naturally occurring bacteria in their gut.
“When humans are traveling in space and growing crops to sustain themselves, it may be inevitable that there will be pests attacking those crops,” David Shapiro-Ilan, a research entomologist at the Southeastern Fruit and Tree Nut Research Station in Byron, Georgia, told Digital Trends. “[We] wanted to determine if beneficial nematodes could be used as natural bio-pesticides to protect crops in space the same way they are used on Earth.”
For this reason, the researchers delivered samples of the entomopathogenic nematodes to the International Space Station to see how they would fare. They were flown up to the ISS last year with the express goal of seeing whether they would survive and thrive in the space environment, principally in microgravity.
Killing insects in microgravity: Not straightforward
“Killing insects in microgravity may sound like a straightforward question, but it is not a simple task,” Fatma Kaplan, CEO of Pheronym, told Digital Trends. “It seems like we are comparing one condition: gravity versus microgravity. However, microgravity changes several factors.”
It turns out that microgravity does a lot more than simply make things float around in space. Water, for example, behaves very differently in microgravity, compared to how it does on Earth. Predicting how an agricultural biocontrol agent will behave in microgravity is tough because so many environmental factors are (no pun intended) up in the air — from the behavior of water to the lack of buoyancy-driven convection to, as the researchers write, “the required cooperation of two organisms to execute a multistep infection.”
All of these could matter when it comes to entomopathogenic nematodes’ ability to do their job. If adapting to space is tough for humans, why wouldn’t it be the same for tiny roundworms?
“One part of the experiment was to see whether they could emerge out of the insect once they consumed the host,” Kaplan said. “One of the factors that control emergence is a pheromone signal. We did not know whether they could produce dispersal pheromone to emerge. The pheromone composition from this experiment will be compared to our product development on Earth.”
Signs are promising
Fortunately, it turns out that things are looking good. The samples taken to space were then frozen and returned to Earth for analysis. (Intriguingly, it seems that worms born on Earth could return unfazed, but worms that were hatched in space died when re-entry took place.)
“As far as we can tell the nematodes performed in excellent fashion and were able to find, infect, and reproduce in insect pest hosts,” Shapiro said. “There may be other biological control tactics that could be used in space, but this was the first test of a natural enemy being used as a pest control agent in space. We think beneficial nematodes are a good candidate for space travel because they have wide host ranges — [meaning that they] can kill lots of different pest species.”
In the future, Shapiro continued, the researchers would like to “delve further into the impact of microgravity, and the return to gravity on nematode physiology.” The ultimate goal is to better understand how to protect crops in space. Our ancestors will thank them.