Buy Tobacco Leaf Online | Whole Leaf Tobacco

Can an Artificial Sweetener Kill Hornworms?

Status
Not open for further replies.

deluxestogie

Administrator
Staff member
Joined
May 25, 2011
Messages
23,931
Points
113
Location
near Blacksburg, VA
Stevia (Stevia rebaudiana) is a naturally sweet herb that has become a popular sugar substitute among the "natural foods" crowd. An extract of it (vastly diluted with erythritol--a "sugar alcohol") is widely sold under the brand name, Truvia. Of course sugar, which comes from sugar cane, is also a natural sweetener. One significant difference between the two is that the "sugar alcohols" of Truvia can not be digested. They are absorbed, broken down in the liver, and excreted by the kidneys.

Erythritol is not a fermentable sugar.

A curious study published this week in the Journal of Applied Entomology reports the effects of feeding fruit flies erythritol.

https://phys.org/news/2017-05-common-artificial-sweetener-safe-effective.html

While adult flies that consumed erythritol dramatically reduced their egg laying, larvae were killed by consuming it.

Fruit flies (Drosophila melanogaster) are not closely related to the hornworm moth (Manduca sexta), but consumption of erythritol may have a similar effect. That is to say, larvae (the hornworms) may be metabolically poisoned by consuming erythritol. That question is not answered by the current paper, but is just my conjecture.

It may be that fruit fly larvae dine entirely on the available sweet material, whereas hornworm larvae would be consuming mostly tobacco leaf lamina, and not at risk from erythritol. Who knows if misting a tobacco leaf with a solution of Truvia might have a larvicidal effect.

I may test the idea this season. Even if it kills hookworms, would the erythritol residue on tobacco leaf affect the finished tobacco? Does it breakdown on the leaf surface in sunlight and rain? What chemical byproducts might be created by kilning leaf that has been treated with erythritol.

The fruit fly study used 1 molar erythritol. That is, one molecular weight (in grams) of erythritol, diluted into one liter of water. This computes to 122 grams of erythritol per liter of water, or roughly 1/4 pound of Truvia per liter.

Bob
 

ChinaVoodoo

Moderator
Joined
Sep 1, 2014
Messages
7,166
Points
113
Location
Edmonton, AB, CA
Very interesting, Bob.
I think it would wash away in the rain. I think you should try it, even if it does produce a residue. I have once made a blend with xylitol. I noticed no adverse flavors.
 

Jitterbugdude

Moderator
Founding Member
Joined
May 22, 2011
Messages
4,266
Points
113
Location
Northeast Maryland
Interesting hypothesis. Too much Erythritol will give you the shits. Your experiment may succeed if the end point is elimination of hornworms but your tobacco might taste a little crappy..:)

Erythritol can be bought in bulk for cheap. If you use Truvia and it works you won't know if it was the Stevia, the Erythritol or the combination of the two that worked.
 

deluxestogie

Administrator
Staff member
Joined
May 25, 2011
Messages
23,931
Points
113
Location
near Blacksburg, VA
I think it would wash away in the rain.
BT preparations also wash away in the rain.

Erythritol can be bought in bulk for cheap. If you use Truvia and it works you won't know if it was the Stevia, the Erythritol or the combination of the two that worked.
That is certainly a valid point. The research explicitly used erythritol, and it worked on fruit flies. Since the major "sweet" component of Stevia (rebaudioside) is 200 times sweeter than table sugar, the Truvia folks dilute it with pure erythritol, which would presumably result in the ballpark of ~0.5% rebaudioside, and ~99.5% erythritol.

So, I'll give it a try with Truvia (which I can pick up at Walmart, while buying groceries). If it works, then further testing might be in order. Somehow, every year, I manage to find a little extra work for myself.

Bob

EDIT: I wonder what new pests would be attracted to the tobacco that's coated with sweetener.
 

DistillingJim

Well-Known Member
Joined
May 23, 2016
Messages
357
Points
28
Location
UK
Such a study reinforces my position to steer clear of artificial sweetener
 

deluxestogie

Administrator
Staff member
Joined
May 25, 2011
Messages
23,931
Points
113
Location
near Blacksburg, VA
I theorize that any insect that digests cellulose would be capable of digesting erythritol.
Cellulose is a high order polymer of simple glucose. We lack the enzyme required to separate the polymer into its glucose components.

Erythritol itself is already a simple 4-carbon molecule.

Bob
 

ChinaVoodoo

Moderator
Joined
Sep 1, 2014
Messages
7,166
Points
113
Location
Edmonton, AB, CA
Cellulose is a high order polymer of simple glucose. We lack the enzyme required to separate the polymer into its glucose components.

Erythritol itself is already a simple 4-carbon molecule.

Bob

If there's something about the chemical bonds which allows it to pass through our digestive system, with only a proportion broken down, I just thought that an animal who's digestive system had already proven to be able to digest carbohydrates we cannot, might have the apparatus to break those bonds as well. Just a pessimistic thought.
 

deluxestogie

Administrator
Staff member
Joined
May 25, 2011
Messages
23,931
Points
113
Location
near Blacksburg, VA
For most creatures that digest cellulose, the initial breakdown of cellulose into simple sugars and small-chain polysaccharides is carried out by the cellulase enzymes produced by gut microbes (in the rumin or hindgut). Cows and horses, for example, can't digest cellulose without the microbes providing that first step.

What happens to the sugars after that is what is important. Glucose and many other simple sugars are fed into the Kerbs Cycle of intermediary metabolism, to produce energy, or are polymerized into storage carbohydrates (i.e. glycogen). There is simply no biochemical mechanism to utilize erythritol in the same manner, so it is cleared from the body.

Apparently fruit flies don't have an adequate mechanism for removing the unusable erythritol.

Bob

EDIT: More to the point of hornworms, they generally avoid the veins of the leaves that they eat. And their poop comes out in BB-sized pellets or larger. So they may not digest cellulose, but instead pass it through the gut (like we do when we eat leafy greens). In our diets, we call it "crude fiber."
 

ChinaVoodoo

Moderator
Joined
Sep 1, 2014
Messages
7,166
Points
113
Location
Edmonton, AB, CA
For most creatures that digest cellulose, the initial breakdown of cellulose into simple sugars and small-chain polysaccharides is carried out by the cellulase enzymes produced by gut microbes (in the rumin or hindgut). Cows and horses, for example, can't digest cellulose without the microbes providing that first step.

What happens to the sugars after that is what is important. Glucose and many other simple sugars are fed into the Kerbs Cycle of intermediary metabolism, to produce energy, or are polymerized into storage carbohydrates (i.e. glycogen). There is simply no biochemical mechanism to utilize erythritol in the same manner, so it is cleared from the body.

Apparently fruit flies don't have an adequate mechanism for removing the unusable erythritol.

Bob

EDIT: More to the point of hornworms, they generally avoid the veins of the leaves that they eat. And their poop comes out in BB-sized pellets or larger. So they may not digest cellulose, but instead pass it through the gut (like we do when we eat leafy greens). In our diets, we call it "crude fiber."

Yes, I've discovered a seemingly exhaustive scholarly list of insects which digest cellulose. Manduca was not on it.

This is curious research:
https://www.ncbi.nlm.nih.gov/pubmed/17704080

They imply that hornworm appetite control is unlike many other insects. Instead of requiring a single polysaccharide to stimulate biting, they require multiple classes. Maybe this allows a creature with such a tiny brain to know which plant is tobacco and that they should eat it. Maybe spraying it with erythritol would camouflage the tobacco.
 

deluxestogie

Administrator
Staff member
Joined
May 25, 2011
Messages
23,931
Points
113
Location
near Blacksburg, VA
That was an interesting article. I have wondered in the past if certain classes of tobacco (which have different ratios of various carbohydrates) are more appealing to hornworms than other classes of tobacco. I've assumed that their eggs are laid by luck of the draw, and they just eat the plant of their birth. Which specific plants are chosen by the moth for egg laying may depend on the character of the blossom nectar (which is the only tobacco material they feed on). But then, the first wave of hornworm eggs seems to appear prior to blossoming, and certainly occurs on topped plants. All of this is mysterious. Somehow, the moth figures out what plant is a tobacco plant, even without feeding on its nectar. So they must be tasting or at least "smelling" the leaf surface, which is covered in secretions from the leaf trichomes (hairs).

Several consecutive wet and windy nights often result in many eggs being laid on lower than typical stalk position leaves, with multiple eggs per leaf (which is otherwise unusual). Such weather conditions alter the moth's normal egg laying behavior.

Bob
 

ChinaVoodoo

Moderator
Joined
Sep 1, 2014
Messages
7,166
Points
113
Location
Edmonton, AB, CA
That was an interesting article. I have wondered in the past if certain classes of tobacco (which have different ratios of various carbohydrates) are more appealing to hornworms than other classes of tobacco. I've assumed that their eggs are laid by luck of the draw, and they just eat the plant of their birth. Which specific plants are chosen by the moth for egg laying may depend on the character of the blossom nectar (which is the only tobacco material they feed on). But then, the first wave of hornworm eggs seems to appear prior to blossoming, and certainly occurs on topped plants. All of this is mysterious. Somehow, the moth figures out what plant is a tobacco plant, even without feeding on its nectar. So they must be tasting or at least "smelling" the leaf surface, which is covered in secretions from the leaf trichomes (hairs).

Several consecutive wet and windy nights often result in many eggs being laid on lower than typical stalk position leaves, with multiple eggs per leaf (which is otherwise unusual). Such weather conditions alter the moth's normal egg laying behavior.

Bob

Wild. It's a puzzle without the box to tell you what it is supposed to look like.

So if they are being born there, but are selective in when to engage in biting/eating, the sense of taste might relate to programming that tells them not which plant to eat, but which tissue to eat, (and when). This could coincide exactly with the mother's discretion for egg laying location.
 

Jitterbugdude

Moderator
Founding Member
Joined
May 22, 2011
Messages
4,266
Points
113
Location
Northeast Maryland
A long time ago I read of a scientist's research saying that plants vibrate at certain frequencies and that insects can pick up these frequencies. It makes sense from casual observation. Go out and scout an area for any insect you want, in this case lets say Mexican Bean Beetles. You most likely will not find a single one but plant a patch of green beans and you have them all over the place.
 

Hasse SWE

Well-Known Member
Founding Member
Joined
Jul 25, 2013
Messages
1,315
Points
63
Location
Sweden (Värnamo)
A long time ago I read of a scientist's research saying that plants vibrate at certain frequencies and that insects can pick up these frequencies. It makes sense from casual observation. Go out and scout an area for any insect you want, in this case lets say Mexican Bean Beetles. You most likely will not find a single one but plant a patch of green beans and you have them all over the place.
Absolutely true Jitterbugdude, I guess all of us hobby grower have noted that.
 

BigBonner

Moderator
Founding Member
Joined
May 22, 2011
Messages
1,671
Points
63
Location
Kentucky
This info makes person wonder if that might have something to do with our declining Honeybee problem . Old soda cans with soda left inside , candy tossed , food with sweetener discarded

When I was helping my son build his high tunnel , we would have a soda while we eat lunch . His bee hives are about 40' from the high tunnel . I told my son to watch his pop as bees could get in and if he drank it , it could kill him from throat swelling . It was not but a minute after I said that that bees started to land on the top of his can . I had poured mine in a cup . They had found the sodas really quick .
 

deluxestogie

Administrator
Staff member
Joined
May 25, 2011
Messages
23,931
Points
113
Location
near Blacksburg, VA
Details

I purchased this at Walmart last night. I don't recall the price, but do recall that it was way more than I wanted to spend, but way less than the brand name product, Truvia.

Garden20170528_2669_Stevia_Walmart_500.jpg


This is somewhat more than 1/2 pound of "mixture." So, what percentage of this mix is actually erythritol? There's no way to know, and no way to compare its blend to that of Truvia. Although the ingredients are listed in order of descending proportion, the actual numbers are proprietary--secret.

What's worse, you will notice in the image below that the font weight of the ingredients is MUCH lighter than everything else on the package label. In the store, I was simply unable to read it at all, even with my reading glasses. I had to ask a young employee (I actually found one!) to tell me if the first ingredient was erythritol. He squinted, stared for a moment, then affirmed that it was.

Garden20170528_2670_Stevia_Walmart_deceptiveIngredients_500.jpg


This photo was processed in Photoshop to amplify the text, and is larger than real life, which is why you can read it. Should we really need photo processing to be able to read ingredients? At home, in bright light, and with a magnifying glass, I was able to read it.

How much insecticidal potion will this amount of sweetener make? In my initial post in this thread, I estimated that 122 grams of erythritol were needed per liter of water. This container holds 280 grams. If we assume that most, but not all, of its weight is erythritol, then this 1/2 pound+ container of sweetener will make up about 2 liters of the desired solution. We're talking about 40 servings of sweetener per liter! (This estimate may err in providing a little more erythritol than planned, since the second listed ingredient is dextrose with maltodextrin, yet the nutrition label lists zero calories. So there can't be very much of it in there.)

I'm unable to estimate how many plants this will treat, or how many times the same plants will need to be sprayed with it, in order to see some effect.

Given all the sweetener to be used, I will test this on my 8 VA Bright Leaf plants--4 treated, 4 not treated. I intend to flue-cure all of them. Keeping track of which leaves are treated, all the way to coming out of the flue-cure chamber will be a challenge. And yet, given the variability of hornworm distribution in a bed of tobacco, this is probably too few plants to provide any conclusive results.

Probably the worst part of this experiment is that hornworm eggs and even actively feeding hornworms that are found on treated plants will have to be allowed to do whatever damage they can bring about, without interference from a distressed tobacco grower.

Bob

EDIT: Experimental Goals: 1) does this stuff suppress hornworms? 2) does this stuff ruin the finished tobacco?
 

Charly

Moderator
Joined
May 1, 2016
Messages
2,209
Points
113
Location
France
Thank you Bob for experimenting for us ;)
I will follow this experimentation with pleasure.
 
Status
Not open for further replies.
Top