Comment by JumpCrisscross | Hacker News Reader

Comment by JumpCrisscross | Hacker News Reader

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> Farmers have been increasingly planting corn and soybeans resistant to herbicides, and then applying those herbicides liberally on their fields. That kills off plants between the rows of crops that aren't resistant, such as milkweed... Because milkweed is poisonous to humans and to grazing animals, it's considered a noxious weed in many jurisdictions and is removed as such.

Humans want less milkweed around them. It competes with the crops we want for space and nutrients, or poisons us and our animals. But we also want more monarch butterflies, which need milkweed to reproduce.

We could encourage planting milkweed away from people. Manually this would be challenging. A scalable solution is engineering an ever-so-slightly sturdier variety of milkweed. This could be allowed to grow between rows of corn, or perhaps in arid or rocky habitats people aren't (yet) bothered with. Alternatively, we could encourage monarch butterflies to pick a less troublesome partner.

I grew up on a farm in southern Ontario where, according to the article, little monarch breeding takes place.

Among many features of the farm was pasture thick with milkweed. We did not interfere with it. As a kid, it was trivial during the summer to find monarch caterpillars. Normally, we'd bring one or two into the house each year, put them in a jar that we'd refresh daily with milkweed and watch the process of the caterpillar growing, entering a chrysalis and emerging as a monarch butterfly.

Twenty five years later, when my city kids were the right age, I eagerly took them out to the pasture to find monarch caterpillars. The pasture was just as thick with milkweed as I remembered, but where is was once easy to find monarch caterpillars, year after year there were none to be found. Only one year were we able to find any.

I too mourn the decline of the monarch butterfly, but whatever the cause, it can't be a mere 20% decline in milkweed population. My parents' farm still has the capacity to support the hundreds of monarchs it once did, yet as far as I can tell they are gone.

Monarchs are migratory, so 20% loss of their food source at critical spots in their migration path could be deadly.

Edit: not food source for the adults! Sorry, it's been a long time since I studied Monarchs!

For butterflies, the food source is nectar from flowers. I don't know that flower populations are in decline.

The milk weed dependency is because the butterflies will only lay their eggs on milk weed plants. The caterpillars will only eat milk weed. They tolerate the toxicity, which in turn makes them unpalatable to birds that would otherwise eat them.

callmeed's post gives excellent source material [https://news.ycombinator.com/item?id=7866154]

The butterfly's migratory cycle is longer than its life cycle. The species needs milkweed throughout its migratory path in order to survive.

Crap, my mistake.

So, because we want "easy" farming of monocultures we engineer crops that we can spray with poison and still survive.

Then we determine that we are creating a strain of weeds that is resistant to the current batch of poison, so we engineer crops that are resistant to a stronger poison.

Then we determine that the crops/poisons we've engineered are killing a huge number of butterflies. So, instead of questioning whether or not our first principle, engineering poison resistant crops, you are suggesting we engineer a new poison resistant weed so we don't kill the butterflies?

At what point do we stop trying to engineer ourselves out of a problem that engineering is creating in the first place?

Any question that has its answer somewhere along a line from pure free-market capitalism to pure totalitarian nanny-statism is by definition a political problem and therefore without an easy answer. This is lobbyist territory, through and through.

Those are viable solutions, but unfortunately to a problem that shouldn't be there in the first place? 'Liberally applying' (I take it that actually means misusing) herbicides seems the core problem to me. I might be wrong, but it seems undeniable that without it much more other plants would survive, hence much more animals. There are likely species whos sole habitat is the pieces of free land in between fields. They are just not researched nor in the press.

> Humans want less milkweed around them. It competes with the crops we want for space and nutrients, or poisons us and our animals.

Not only is milkweed not poisonous, it's actually a delicious vegetable. It tastes like a cross between asparagus and broccoli.

This is profoundly untrue, at least for milkweed sensu lato

Most Asclepias species contain cardiac glycosides and can be highly poisonous. Milkweed extracts were spread on arrow tips by some Native American groups to more quickly bring down game when hunting. Some species have also been used as rat poison. Consumption can lead to serious heart problems due to disruption of the calcium gradient across cell membranes.

Fair enough, I only meant common milkweed. But even for the edible species only certain parts are edible, and only at certain times of year anyway. (As with many/most of the plants we eat.)

Aha, but here's the problem: if you live on the east coast (or just east of the Rockies) in the USA, you probably are referring to Asclepias syriaca, but "common milkweed" on the west coast could be a different species, perhaps Asclepias californica. If you live in Asia or South America, it would be other species.

I guess all I'm saying is be careful :) The majority of milkweeds, heck, the majority of "common milkweeds" are poisonous.

Some milkweed is poisonous. This is the problem with using a common name that refers to a genus instead of species.

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