Idea on how to help natives compete with exotic invasives

[biwa]

I know a lot of people are concerned that our land is being taken over by exotic plants, and as a result, people try to plant natives when possible. But from a Darwinian point of view, it seems like the invasives will inevitably win out, because they grow better. I suspect the reason the invasive plants do so well is because they are not bothered by the same bugs and diseases that the native plants have to deal with.

So here's an idea: Let's breed bugs to eat the invasives.

There is a moth here called a [url=https://en.wikipedia.org/wiki/Hemaris_thysbe]Hummingbird Clearwing[/url] that I think is raising its young in my viburnum bush. Literature on them says they can also be found eating honeysuckle. I could breed some, selecting for the ones that find Japanese Honeysuckle the tastiest. For the first few generations, I may need to start them on a native plant that is closely related to the exotic one.

I suspect that after a few (10-15) generations of selective breeding, I will have a caterpillar that eats Japanese Honeysuckle. If this works, we may be able to use similar breeding programs to help with other invasive plants.

[Kisal]

JMO, but I don't think that's a good idea. Too often, when an alien animal species is introduced into an ecosystem, it does not perform as expected. As often as not, the species will find some native plant that it likes ... or will adapt to one or more ... and the plant species have no defenses against the introduced animal. Usually, this happens because the introduced animal species has no predators, and the population rapidly grows beyond the ability of the available food source to support it. Again, JMO.

[rainbowgardener]

Agree with Kisal...

biwa is right that exotics like the Japanese honeysuckle shrub tend to thrive because, being exotic, they don't have any native diseases/ predators that are adapted to attack them. However, trying to breed such sounds very tricky and there's something called the law of unintended consequences.

By breeding something to attack the honeysuckle (or whatever), you are just introducing a NEW alien exotic species into the system, that also doesn't have any built in biological controls. Even if you could breed something so selectively that it ONLY ate Japanese honeysuckle and ate massive quantities of that, once the amount of JH in the environment was reduced and your new organism was facing starvation, I guarantee you, the new organism would adapt to eat something else that was readily available. Nature works that way.

So then you have a big population of mutant hummingbird clearwings attacking your native viburnums and other stuff... what will you do about that? ("I know an old lady who swallowed a cat...She swallowed the cat to catch the bird; she swallowed the bird, to catch the spider, she swallowed the spider to catch the fly....")

[Pineville]

So many of the nasty insects that destroy our native plants were imported from other countries- either accidentally or on purpose. Emerald Ash Borer and Japanese Beetle are two that come to mind.

Controlling the spread of existing invasive plants may be impossible, short of using chemicals and physical removal. We can however, prevent the additional spreading of these plants by educating gardeners and through legislation. Here in Pennsylvania, for example, it is illegal for a garden center to sell Purple Loosestrife. I try my best to remove the invasive plants on my property, but at times it is a losing battle. Japanese Stilt Grass and Multi-flora Rose are the toughest. I take great joy in ripping these plants out of the ground. I also love cutting down the Norway Maples that are spreading through the woods. I know the organic gardeners may cringe, but if you really want to get rid of exotics, Roundup may be your best friend.

[rainbowgardener]

Yup. I did a week long service project with the Sierra Club in Joshua Tree Natl Park, CA a few years ago, doing eradication of invasive exotic species (gardeners usually call it weeding ) It was mostly something in the mustard family we were pulling and we pulled tons of it. Hopefully with ten volunteers working for a week, we pulled enough to slow it down. So that's the Sierra Club approved method of dealing with invasives -- hand pulling.

Here at home, the Japanese honeysuckle shrub is my number one foe, but we also have tree of heaven, garlic mustard, English ivy.... I do sometimes put Roundup on the honeysuckle (cut the shrub down to ground level, dab Round up on all the cut stem stubs, and repeat once or twice a year for a few years until the gosh-darn thing is finally dead). But I'm using the Roundup less since I discovered the honeysuckle popper (wonderful tool invented by a guy who lives just a few miles from me: https://www.misterhoneysuckle.com/pages/content/benefits.html )

[biwa]

I forgot to mention: the hummingbird clearwing is a native species of moth. I'm not introducing a new alien species, just thinking of breeding a native moth to eat the alien honeysuckle.

Weeding is a fine in suburbs, but I think developing a predator would be an easier control method in the long run. Here, the Japanese Honeysuckle can be found in wild areas, not just gardened ones.

[Kisal]

Once it is altered, whether through selective breeding or genetic engineering, it will no longer be a "native species."

[rainbowgardener]

Even if we grant that your selectively bred clearwings are still the same species and still have bio controls around, it still sounds like an iffy kind of interference. In order to make any dent in the honeysuckle population, you would require a massive clearwing population. Once you have achieved this massive population, what happens to them when the honeysuckle is gone?

I think the best bio interventions are done on the species themselves not by introducing outside ones. For example in the insect world there's been work done on reducing fly/ mosquito populations with by releasing hormones that are specific to the species that induce sterilization of the females or species specific pheromones which confuse the males so they can't find the females. No new species involved and all very specific to the target pest, so no effect on other beings.

So some genius needs to figure out what the plant equivalent would be -- how do you prevent a plant from setting seed? But then the honeysuckle also spreads from the roots. Still no seed would slow it down a lot.

[a0c8c]

You'd have to create a sinlge plant specific disease to erradicate them, and that disease will eventually cross oceans and kill of the plant in it's native habitat.

Also, if we could design and create diseases like that, we'd have cured all disease by now(retroviruses are the future of medicine, and also our biggest concern).

[biwa]

Once it is altered, whether through selective breeding or genetic engineering, it will no longer be a "native species."

Okay, I understand this. Thank you for clarifying. I wonder if I could control the amount of deviation from the native species to minimize this problem. Perhaps some percentage of each generation should be freshly caught? It would help prevent inbreeding as well.

Even if we grant that your selectively bred clearwings are still the same species and still have bio controls around, it still sounds like an iffy kind of interference. In order to make any dent in the honeysuckle population, you would require a massive clearwing population. Once you have achieved this massive population, what happens to them when the honeysuckle is gone?

I was thinking more long term. I don't want to get rid of all the Japanese Honeysuckle within the next 10 years or anything. I just want to even the score a little bit so the native honeysuckles have a better chance. For this, I really only need to make a few of the modified moths. If I breed them right, they should multiply on their own because they've got ample food source for the caterpillars.

[Kisal]

Presuming you were successful in your efforts to breed a clearwing moth population that only and exclusively laid its eggs on Japanese honeysuckle, and never any type of native honeysuckle or other desirable plant, it would still be necessary to ensure that your moths bred true after release. I think it would be critical that the altered moths not be able to interbreed with non-altered clearwing moths. Such interbreeding could conceivably produce a mix of genetic material which would lead to mutations in the offspring, resulting in their laying their eggs on some desirable plant totally unrelated to Japanese honeysuckle. Just another point to consider, I think.

[The Helpful Gardener]

The answer to damaging an environs should not include more damage. Similarly diluting existing genetic pools with out-of town genotypes is not optimal, to be sure, but neither is inbreeding (not so much an RNA issue as a DNA issue, so less important in plants than animals, at least how I understand it). Might be that intercession is necessary. And beneficial, even.

I just fed my sourdough starter, and sat down to type only after petting the cat for a bit. Seems these organisms have figured out a very interesting survival trait; by glomming onto humans, the dominant species, cats, dogs, yeasts, and any number of other creatures have figured out a symbiotic relationship that works for the betterment and increase of their species. All this talk of man domesticating the wolf is hubris. The wolf selected us just as much if not more so!

So if a certain trait in a plant makes it more attractive to humans, is that a natural selection? Doesn't the furtherment of that trait mean that that selection is beneficial to the plant?

What about 'Red Sprite' winterberry? The increased size of the berry and 'persistance of fruit" through winter make it a valued plant with many designers and architects, but what good are persistant fruit to a bird? The crossing of the native I. verticillata with the Asian I. serrata has made a berry too large to be useful to many of our native bird species. Great selection for humans; lousy selection for birds. And who knows about insects or reseeding or any of the other things that add value to an ecosystem? Our "natural" selection as humans can be far too biased from a biotic viewpoint...

My state is a few years down the road in a [url=https://www.ipm.uconn.edu/cipwg/art_pubs/GUIDE/x03purple.html]beetle release to stop Lythrum salicaria[/url]; seems like we already have plenty of Euro-bird population for control and it seems to be working. One invasive on the way down and we didn't add to the problem. Whew!

But what a roll of the dice; what if it all went wrong? What if they turned into the next Asian longhorn beetle, a menace just over the border in Worcester MA? This beetle is causing the deforestation of that city as they cut trees to try and stop the outbreak; it literally threatens the continual belt of maple forest all the way to Canada and beyond. No more Vermont syrup; and maybe they need to pick a new leaf for the Canadian flag, eh?

So should we be playing God with the greater ecosystem? Are human interests best ecological interests, like James Trefil and others have postulated? Maybe yes, maybe no, but it needs a case by case judgement rather than shotgun pronouncements...

HG