How do you kill this pest? By importing its natural enemy

August 3, 2024 9:23 AM

How do you kill this pest? By importing its natural enemy. The Commonwealth Scientific and Industrial Research Organisation (CSIRO) introduces a biocontrol fungus in the hope it reduces the spread of African boxthorn weed, but it is not available outside New South Wales due to lack of funding.
posted by chariot pulled by cassowaries (18 comments total)

I’m no scientist (nor Australian) but it seems to me that this has historically not gone well in Australia (cane toads). Like, generally the newly introduced predator discovers there are a whole host of creatures with no defenses that are much easier to prey upon than their traditional prey, and promptly begins eating them, instead.
posted by heyitsgogi at 9:39 AM on August 3 [8 favorites]

They studied using fungus smuts for eradicating invasive cheat grass in the western US, which chokes out the sage brush and other native plants and survives fire, creating dunes. The problem is preventing it from eradicating food crops though evolution of the strains, the so-called "playing God" dilemma.
posted by Brian B. at 10:15 AM on August 3 [2 favorites]

it seems to me that this has historically not gone well

It's all just a slippery slope until someone ends up swallowing a horse.
posted by phunniemee at 10:34 AM on August 3 [4 favorites]

It's all just a slippery slope until someone ends up swallowing a horse.

Actually horses aren't native, and feral horses are out there causing lots of damage. So if you do know something that will swallow a horse . . .
posted by Garm at 10:39 AM on August 3 [4 favorites]

You could hunt them and eat them. Doesn't Australia do this with kangaroos?
posted by ryanrs at 11:34 AM on August 3

It's all just a slippery slope until someone ends up swallowing a horse.

Actually horses aren't native, and feral horses are out there causing lots of damage. So if you do know something that will swallow a horse . . .

*** Looks it up... *** hmmm... nah, that probably won't work
posted by JoeXIII007 at 11:49 AM on August 3 [2 favorites]

this has historically not gone well in Australia (cane toads)

Counterexamples: myxomatosis, calicivirus, cactoblastis.

Cane toads were introduced by a pack of Queensland sugar industry cowboys, not the CSIRO - which as a respectable scientific organization without an industry axe to grind is much more careful about doing quarantined trials first.
posted by flabdablet at 12:38 PM on August 3 [14 favorites]

Isn't this how rabbits got introduced to Australia? How well did that work out for them?
posted by JustSayNoDawg at 12:42 PM on August 3

Counterexamples: myxomatosis, calicivirus, cactoblastis.

Cane toads were introduced by a pack of Queensland sugar industry cowboys, not the CSIRO - which as a respectable scientific organization without an industry axe to grind is much more careful about doing quarantined trials first.

Thanks, flabdablet!

I was just coming back to say something about Cactoblastis! ^_^

p.s. This post was mainly for you, after your comment about box thorn on the Greater Stick Nest Rats post. ^_^
posted by chariot pulled by cassowaries at 12:44 PM on August 3 [5 favorites]

Rabbits were one of the many invasive pests that arrived on the First Fleet, though by no means the most ecologically destructive; that would be the English Officer, for which a workable biological control has yet to be identified.
posted by flabdablet at 12:55 PM on August 3 [12 favorites]

Reminds me of this old woman I heard about. It seems she swallowed a fly.
posted by BCMagee at 2:40 PM on August 3 [2 favorites]

Counterexamples: myxomatosis, calicivirus, cactoblastis.

My takeaway is that it’s tricky to eradicate a naive species using these methods, but when some idiot tries it in a place where rabbits are supposed to be, it works beyond anyone’s imagining. What a world.
posted by GenjiandProust at 3:06 PM on August 3 [1 favorite]

Also, I hope this works in boxthorn. After the previous FPP, that stuff is no good (at least in Australia).
posted by GenjiandProust at 3:08 PM on August 3

if you do know something that will swallow a horse . . .

Surely there’s a fabulous type of gorilla? The beautiful part is, when wintertime rolls around, the gorillas simply freeze to death.
posted by Phanx at 7:05 PM on August 3 [3 favorites]

@flabdablet: The Zulu Warrior might be what you're looking for.
posted by JustSayNoDawg at 7:28 PM on August 3 [3 favorites]

Maybe. All I know is that I'm suddenly filled with a burning desire to acquire a private island, seed it with box thorn, blackberries, prickly pear, boneseed, African lovegrass, rabbits, foxes, sambar deer, horses, rats and cats, and see who wins.

My money's on rabbits, foxes and blackberries.
posted by flabdablet at 3:38 AM on August 4 [2 favorites]

Speaking as someone who has done research on using rust fungi to eradicate invasive weeds, it's difficult to make work. First of all, the weed ought to be a foreign invasive. To use a native rust on an endemic species you need to give the rust a special advantage (formulate and spray it or learn how to pinpoint the key stage in the disease cycle and concentrate on that). That turns out to be expensive and labor-intensive, although it can be done. A colleague of mine developed a program to teach farmers how to grow and collect rust teliospores and wait until the perfect time to place them on the roots of Canada thistle in order to do the most harm.

So, usually you use rusts on foreign invasives and you travel to the weed's place of origin and find a suitable rust. That rust has to be tested to make sure its host range is limited and does not include food plants or rare endemics over here. Doing host range studies takes time and effort: it's hard to get seeds of rare plants in order to test them, just for starters. Back in the olden days I used to use the "centrifugal phylogenetic host range method" to test lots of closely related plants and fewer and fewer plants that were not as closely related, but it was lots of plants. However, with so many genomes available online, one of my colleagues was able to streamline host range testing by using a statistical comparison of genomes that was developed for racehorse breeding to predict what hosts might be susceptible.

You also have to show that the rust is damaging enough on the target. Rusts are biotrophic parasites- they can't live without their host, so they evolve over time to coexist with the plant. You luck out if there is a slight mismatch between your rust and the target- if your weed is from another region or represents a different genotype from the one the rust is adapted to. Often an invasive weed represents a clonal population, so if the rust affects it, it affects ALL of it. Unfortunately, over hundreds of years, often a weed has been imported a number of times and represents several lineages, and if the rust affects one, it might not affect the others.

Then there's the weed's environment: I worked on weeds of pacific arid rangelands, and the rust we had would only infect during the wet rainy winter and go dormant in the hot dry summer, when the weed could grow out of its infection (the situation sounds better for boxthorn). I did testing to show that rusts worked better on annual weeds than on biennial weeds, because in a good year for the rust an annual was out of luck, but the biennial weed had another few years to shake off the rust and recover. A perennial? Whew. Harder still. These researchers are correct to use the rust as only one tool to eradicate the boxthorn. The rust won't do it alone.

Finally, there's the regulatory environment. The rust I worked on took 28 years to get through all the paperwork. Australia has a really fine system in comparison. I wish them good luck with this. They sound like they know what they're doing.
posted by acrasis at 10:21 AM on August 4 [6 favorites]

i mean, what could go wrong?

and, hah! omg phunnieme! (and JoeVIII007 and BCMagee) - first thought! the song was actually running through my head as i read down the thread, hahaha.
posted by lapolla at 9:45 PM on August 4