Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.
If you’ve ever seen a shrubby plant with red leaves, chances are, it’s a Japanese barberry- an invasive plant in Rhode Island. And If you’ve seen a spotted lanternfly, you’ve seen an invasive insect.
It seems like invasive species are all over the place. But what exactly are they, and should we do anything about them?
We had Andrea Li and Leo Nachamie from our Possibly Team look into this.
Andrea Li: Hi, Megan!
Leo Nachamie: Hello!
Megan Hall: So first of all, what exactly is an invasive species?
Andrea Li: That’s a great question. To find out, we talked to Dov Sax, a Professor of Environment and Society at Brown University. He says you first have to understand the difference between native and non-native species.
Dov Sax: A native species is normally defined as something that has historically been found in some part of the world, and a non-native is something that has arrived more recently, often introduced by humans.
Leo Nachamie: Non-native species make up a huge part of our global economy. Cows, for example, are not native to the US. But our lives would be pretty different without them.
Megan Hall: Is invasive species just another name for non-native?
Andrea Li: No. A non-native species becomes invasive when it starts to hurt the other things around it.
Dov Sax: The strict scientific definition for invasive is usually something that is problematic, whether it’s to human health or the economy or to native species.
Leo Nachamie: That’s where an insect like our good friend the spotted lanternfly comes in. They’re considered invasive because they decrease the yield of various crops.
Andrea Li: And L.A’s palm trees are actually not native. Some argue that they’re invasive because they can pose a pretty big fire risk. Whether they’re really invasive is up to debate, though.
Megan Hall: Wait, we don’t know for sure?
Leo Nachamie: Yeah, the definition of “invasive” actually gets pretty hazy. Dov says…
Dov Sax: Invasive is in the eye of the beholder, and any individual non native species will have a multitude of benefits and costs different groups of people might perceive some of those particular benefits or costs as being larger than the others.
Megan Hall: Got it. But let’s suppose almost everyone agrees that a species is invasive. Is there anything we can do about it?
Andrea Li: According to Dov, it might be possible to get rid of that species if it’s in a really small area.
Leo Nachamie: But in the case of bigger areas…
Dov Sax: Once something is spread out far across the landscape, then your only real option is what’s called biological control, or bio control, and that’s usually introducing other non-natives that we want to help us control a particular species.
Megan Hall: How do those other non-natives help?
Andrea Li: Dov says,
Dov Sax: The way that works is you go to the native range of the invasive species in question, and look for some predator that evolved with it that’s good at eating it.
Megan Hall: Woah. Does that work?
Andrea Li: Not exactly.
Dov Sax: It’s not possible to completely remove it. It’s possible to knock back its abundance.
Megan Hall: But if we do choose to use bio controls, do the other nonnative species also become invasive and out of control?
Leo Nachamie: As you might expect, biocontrol caused a lot of unintended damage when it first kicked off in the 1800s.
Andrea Li: For example, the harlequin ladybug was introduced to control aphids. Turns out, it carries a harmful parasite. It also ended up displacing native ladybugs.
Leo Nachamie: But today, the process for introducing a non-native species is a lot more rigorous.
Dov Sax: People that do this, federal and state agencies that are now very careful and do years of testing before they introduce something. I’m unaware of any good examples of bio control done in the last few decades that really backfired in any way.
Andrea Li: Which means that when invasive species are out of control, it’s really the best, and only, tool we have in most cases.
Megan Hall: Got it, Thanks, Andrea and Leo!
That’s it for today. You can find more information, or ask a question about the way your choices affect our planet, at askpossibly.org. You can also subscribe to Possibly wherever you get your podcasts or follow us on Instagram, Facebook, LinkedIn, or Bluesky at “askpossibly”
Possibly is a co-production of Brown University’s Institute for Environment and Society, Brown’s Climate Solutions Initiative, and Ocean State Media.
