“Controlled study” infects butterfly larva with parasites then feeds them lab-grown CO2 enhanced milkweed. Result is sub-par science.
Rising carbon dioxide levels pose a previously unrecognized threat to monarch butterflies
ANN ARBOR–A new study conducted at the University of Michigan reveals a previously unrecognized threat to monarch butterflies: Mounting levels of atmospheric carbon dioxide reduce the medicinal properties of milkweed plants that protect the iconic insects from disease.
Milkweed leaves contain bitter toxins that help monarchs ward off predators and parasites, and the plant is the sole food of monarch caterpillars. In a multi-year experiment at the U-M Biological Station, researchers grew four milkweed species with varying levels of those protective compounds, which are called cardenolides.
Half the plants were grown under normal carbon dioxide levels, and half of them were bathed, from dawn to dusk, in nearly twice that amount. Then the plants were fed to hundreds of monarch caterpillars.
The study showed that the most protective of the four milkweed species lost its medicinal properties when grown under elevated CO2, resulting in a steep decline in the monarch’s ability to tolerate a common parasite, as well as a lifespan reduction of one week.
The study looked solely at how elevated carbon dioxide levels alter plant chemistry and how those changes, in turn, affect interactions between monarchs and their parasites. It did not examine the climate-altering effects of the heat-trapping gas emitted when fossil fuels are burned.
“We discovered a previously unrecognized, indirect mechanism by which ongoing environmental change–in this case, rising levels of atmospheric CO2–can act on disease in monarch butterflies,” said Leslie Decker, first author of the study, which is scheduled for publication July 10 in the journal Ecology Letters.
“Our results emphasize that global environmental change may influence parasite-host interactions through changes in the medicinal properties of plants,” said Decker, who conducted the research for her doctoral dissertation in the U-M Department of Ecology and Evolutionary Biology. She is now a postdoctoral researcher at Stanford University.
U-M ecologist Mark Hunter, Decker’s dissertation adviser and co-author of the Ecology Letterspaper, said findings of the monarch study have broad implications. Many animals, including humans, use chemicals in the environment to help them control parasites and diseases. Aspirin, digitalis, Taxol and many other drugs originally came from plants.
“If elevated carbon dioxide reduces the concentration of medicines in plants that monarchs use, it could be changing the concentration of drugs for all animals that self-medicate, including humans,” said Hunter, who has studied monarchs at the U-M Biological Station, at the northern tip of Michigan’s Lower Peninsula, for more than a decade.
“When we play Russian roulette with the concentration of atmospheric gases, we are playing Russian roulette with our ability to find new medicines in nature,” he said.
Earlier work in Hunter’s lab had shown that some species of milkweed produce lower cardenolide levels when grown under elevated carbon dioxide. That finding caught the attention of Decker, who with Hunter designed a follow-up study to look at the potential impact of rising CO2 on the disease susceptibility of monarchs in the future.
They created an experimental system that allowed them to manipulate and measure all the key links in the chain: carbon dioxide levels, toxin concentrations in milkweed leaves, infection by parasites, and monarch susceptibility to those parasites. The fieldwork was conducted in 2014 and 2015.
Inside 40 growth chambers on a hilltop at the Biological Station, they exposed milkweed plants to two different carbon dioxide levels. Twenty chambers were maintained at current global CO2 concentrations of around 400 parts per million, and 20 chambers received 760 ppm of CO2, a level that could be reached well before the end of the century if the burning of fossil fuels continues unabated.
The four milkweed species differed in their levels of protective cardenolide compounds. The most protective species was Asclepias curassavica, commonly known as tropical milkweed. The chamber-raised plants were fed to monarch caterpillars, and each caterpillar got a steady diet of a single milkweed species with known carbon dioxide exposure.
Three-day-old caterpillars were also infected with carefully controlled doses of a common monarch parasite that is distantly related to the malaria pathogen. Ophryocystis elektroscirrhais a protozoan that shortens adult monarch lifespan, impedes its ability to fly and reduces the number of offspring it produces.
Over about two weeks’ time, the infected caterpillars grew to a length of about 2 inches, with striking yellow, white and black bands. Then they pupated inside a hard-shelled chrysalis for about 10 days before emerging as orange-and-black butterflies.
At their Biological Station lab, Decker and Hunter raised hundreds of adult monarchs. The lifespan of each individual–in Michigan, monarch butterflies typically live for about a month–was recorded, and the number of parasitic spores on each carcass was counted.
Piecing together all this data, the researchers were able to determine how changes in atmospheric carbon dioxide levels altered toxin concentrations in the four milkweed species and, in turn, how exposure to those plants affected the monarch’s lifespan and disease susceptibility.
The largest declines in parasite tolerance and butterfly lifespan occurred in monarchs that fed on A. curassavica, a milkweed species in which cardenolide production declined by nearly 25 percent when grown under elevated CO2.
In caterpillars that fed on A. curassavica milkweed grown under elevated CO2, tolerance to the parasite declined by a whopping 77 percent when compared to caterpillars that fed on A. curassavica grown under ambient-level CO2.
Monarchs that fed on A. curassavica grown under elevated CO2 suffered a reduction in lifespan of seven days due to parasitic infection. Parasites reduced mean lifespan by only two days for monarchs that ate A. curassavica grown under ambient CO2 levels.
“We’ve been able to show that a medicinal milkweed species loses its protective abilities under elevated carbon dioxide,” Decker said. “Our results suggest that rising CO2 will reduce the tolerance of monarch butterflies to their common parasite and will increase parasite virulence.”
In recent years, monarch populations have been declining rapidly. Most discussions of the monarch butterfly’s plight focus on habitat loss: logging of trees in the Mexican forest where monarchs spend the winter, as well as the loss of wild milkweed plants that sustain them during their annual migration across North America.
“Habitat loss, problems during migration and climate change all contribute to monarch declines,” Hunter said. “Unfortunately, our results add to that list and suggest that parasite-infected monarchs will become steadily sicker if atmospheric concentrations of CO2 continue to rise.”
###
Why this study is ridiculous.
- It’s not done in a natural setting, thus excluding all other natural environmental effects.
- The butterflies are purposely infected, rather than taking their chances in nature.
- The milkweed is subjected to an instant increase in CO2, instead of a process that would take decades. There’s no chance for adaptation.
- Like #3, no chance for adaptation of the butterflies
- Where’s the OTHER control group? No mention of one. Did they infect butterfly larva and NOT feed them milkweed and count the deaths. No. One wonders if the mortality rate of 77% might be similar in that scenario.
- Given the lack of a control group, it seems the results were pre-determined.
In my opinion, this is sub-par science. I’ve seen better science at high-school science fairs.
The study:
https://onlinelibrary.wiley.com/doi/full/10.1111/ele.13101
Elevated atmospheric concentrations of carbon dioxide reduce monarch tolerance and increase parasite virulence by altering the medicinal properties of milkweeds
Leslie E. Decker Jacobus C. de Roode Mark D. Hunter
Abstract
Hosts combat their parasites using mechanisms of resistance and tolerance, which together determine parasite virulence. Environmental factors, including diet, mediate the impact of parasites on hosts, with diet providing nutritional and medicinal properties. Here, we present the first evidence that ongoing environmental change decreases host tolerance and increases parasite virulence through a loss of dietary medicinal quality. Monarch butterflies use dietary toxins (cardenolides) to reduce the deleterious impacts of a protozoan parasite. We fed monarch larvae foliage from four milkweed species grown under either elevated or ambient CO2, and measured changes in resistance, tolerance, and virulence. The most high‐cardenolide milkweed species lost its medicinal properties under elevated CO2; monarch tolerance to infection decreased, and parasite virulence increased. Declines in medicinal quality were associated with declines in foliar concentrations of lipophilic cardenolides. Our results emphasize that global environmental change may influence parasite–host interactions through changes in the medicinal properties of plants.
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“we are playing Russian roulette with our ability to find new medicines in nature,”
This “study” only showed a drop in concentration for the first generation.
1) We don’t know what will happen in future generations.
2) A drop in concentration does not mean the “medicine” is gone, so we aren’t playing Russian roulette with anything.
3) An emotion laden term like “Russian roulette” has no place in a paper claiming to do science.
Consumption of cardenolides (a toxin, as noted) has negative effects on growth and fecundity of the uninfected butterflies. Healthy female butterflies eating too much of the high cardenolide Milkweeds have lower survival rates. It is only in the infected butterfly setting that there is a threshold between too little and too much. The milkweeds produce the toxin to prevent themselves from being over-consumed. It is an evolved struggle between the plant and the herbivores that would eat it to the roots without defenses.
https://www.thoughtco.com/monarchs-dont-get-sick-eating-milkweed-1968216
This is common in nature. For example, Arsenic was used going back to the time of Hippocrates to treat all sorts of ailments with varying degrees of success. Before the era of effective antibiotics arrived in the 20th Century, arsenic compounds were known as the “Savior from Syphillis.”
There is a threshold though that can be quickly crossed with Arsenic compounds to chronic toxicity to the patient. Even today, Arsenic is used to treat and cure otherwise un-treatable trypanosomiasis. But using arsenic as a medicinal must be carefully monitored.
Another toxic compound noted in the Press Release, taxol, is used as a naturally found chemotherapeutic agent for certain cancers. But make no mistake, taxol is toxic. Healthy people should not take taxol. It has severe side-effects.
Belladona nightshadeis also very toxic. But at low doses can have medicinal effects because of its atropine-like effects to reduce spasmotic bowel episodes.
https://www.homeremediess.com/belladonna-deadly-nightshade-atropa-belladonna-medicinal-uses-images/
“Rising carbon dioxide levels pose a previously unrecognized threat to monarch butterflies”
TRANSLATION: “The polar bear thing still doesn’t seem to be working.”
The milkweed should switch to boxers.
Hopelessly inadequate experimental design because of lack of appropriate control groups. Any insect toxicologist peer reviewing the MSS or mentoring the student would have shredded it on that shortcoming alone. (retired insect toxicologist)
I call bullsh!t and I will not waste any more time on this ridiculous paper.
Here is my recommended approach to global warming alarmist nonsense:
https://wattsupwiththat.com/2018/07/05/scott-pruitt-out-at-epa/#comment-2401030
My rejection of warmist propaganda is a practical accommodation of Brandolini’s Law, which states that:
“THE AMOUNT OF ENERGY NEEDED TO REFUTE BULLSH!T IS AN ORDER OF MAGNITUDE BIGGER THAN TO PRODUCE IT.”
– Alberto Brandolini, 11 January 2013
One year earlier, I published the following statement [Note that it is still true, after more than two decades of warmist propaganda]:
“After more than a decade, NONE of the scary predictions of the global warming alarmists have materialized. The warmists’ predictive track record is one of absolute failure.”
…
“BASED ON THE WARMISTS’ DISMAL TRACK RECORD, ONE CAN SAFELY ASSUME THAT EVERYTHING THEY PREDICT IS HIGHLY LIKELY TO BE FALSE.”
– Allan M.R. MacRae, January 15, 2012
https://wattsupwiththat.com/2012/01/14/tisdale-on-foster-and-rahmstorf-take-2/#comment-748715
Notwithstanding their reverse order of occurrence, you can call my above statement “MacRae’s Corollary to Brandolini’s Law”.
“MacRae’s Corollary” is designed to save you countless hours of toil, as evidenced by the ~decade of diligent work and remarkable mathematical competence that Steve McIntyre expended to disprove Mann’s “hockey stick” (aka “hokey stick”).
Just assume that the warmists are hopeless pathological liars, and that all their very-scary predictions of runaway global warming, wilder weather, etc are false. You will have a very high probability of being correct.
Regards, Allan 🙂
“You will have a very high probability of being correct.”
6 σ ?
Thank you John H for your question; here is my answer:
BACKGROUND INFORMATION:
BRANDOLINI’S LAW states:
“THE AMOUNT OF ENERGY NEEDED TO REFUTE BULLSH!T IS AN ORDER OF MAGNITUDE BIGGER THAN TO PRODUCE IT.”
– Alberto Brandolini, 11 January 2013
MACRAE’S COROLLARY TO BRANDOLINI’S LAW states:
“BASED ON THE WARMISTS’ DISMAL TRACK RECORD, ONE CAN SAFELY ASSUME THAT EVERYTHING THEY PREDICT IS HIGHLY LIKELY TO BE FALSE.”
– Allan M.R. MacRae, January 15, 2012
THE STATISTICAL BASIS FOR MACRAE’S COROLLARY TO BRANDOLINI’S LAW:
First, assume that warmist bullsh!t is normally distributed. This is risky, because warmists are not normal, and neither is their bullsh!t.
To date, the warmists have been wrong about every very-scary prediction of runaway global warming and wilder weather, etc, and are operating at more than +/-3σ, or 3 standard deviations from the mean. such that warmists are at least 99.7% full of bullsh!t.
Recognizing that the warmists might actually want to slip-in a bit of truth as a tactical measure to improve their shattered credibility, conservatively assume +/-2σ, or 2 standard deviations from the mean. such that they are at least 95% full of bullsh!t.
In conclusion, +/-3σ is accurate to date, but +/-2σ is more charitable.
Thoroughly absurd!
1) Three species of milkweed are grown under two conditions of CO₂
2) Milkweed plants are harvested, separated by species and fed to monarch caterpillars.
3) The monarch caterpillars are “inoculated” with spores of “parasites”. I must admit to being puzzled by what parasites, except fungi or viruses, are transmitted via spores.
4) Then these characters chart caterpillar response to their parasites.
5) From these charts the alleged researchers assume milkweed medicinal loads based on caterpillar parasite loads/survival.
6) From their caterpillar measurements, statistical analyses are performed and p values calculated.
A) Whatever happened to direct qualitative and quantitative testing of the milkweed plant toxins?
B) Whatever happened to monarch caterpillars living on and eating milkweed directly?
* a) Eliminating issues with delays or hazards between harvesting milkweed and feeding caterpillars.
* b) Eliminating issues with harvested plants left in sunlight, rinsed by rain, kept in hot locations.
C) Isn’t it amazing that these researchers fail to validate or verify their inoculation procedures and success, before jumping to assuming parasite effects?
etc. etc. It’s just another Sophomoric High School level pretense research pretense.
3) The monarch caterpillars are “inoculated” with spores of “parasites”. I must admit to being puzzled by what parasites, except fungi or viruses, are transmitted via spores.
Perhaps you should read the paper? It’s a protozoan parasite, Ophryocystis elektroscirrha.”
A) Whatever happened to direct qualitative and quantitative testing of the milkweed plant toxins?
They did it: “On the same day as inoculations, we sampled milkweed cardenolide and nutrient concentrations using established methods (Zehnder & Hunter 2009; Tao & Hunter 2012).”
C) Isn’t it amazing that these researchers fail to validate or verify their inoculation procedures and success, before jumping to assuming parasite effects?
Really, what makes you think that they didn’t do so? Perhaps you should have read the paper?
“After death, infection success and spore loads were measured from adults following established methods (de Roode et al. 2008a,”
This would appear to be a sophomoric level attack on the study by someone who didn’t actually read it!
They also present their data very poorly. Of the nine files of supporting information the one graphical representation had error bars like a wizards sleeve. I can hardly type for laughing.
“…and 20 chambers received 760 ppm of CO2, a level that could be reached well before the end of the century if the burning of fossil fuels continues unabated.”
There is no evidence to support that at all. The study is complete rubbish!
There’s a different flaw that I didn’t notice anyone mentioning. The whole “more CO2 makes less nutritious plants” thing is always reported as strictly a matter of percentage. With more CO2, plants grow much larger, and presumably have more total nutrition.
But put in the total size as a denominator and you might be able to say that some vitamins and other chemicals are less “concentrated.” That’s not surprising. Still, reporting only the concentration while being careful to avoid mentioning that the total vitamins (or whatever chemicals) has increased is a bit disingenuous.
So, how does this relate to the monarch study? They had an environment where all the monarchs were perfectly well fed. There were no food shortages or limitations of any kind. This is where the extra CO2 would have helped the real world Monarch population a lot more than any lowered concentrations might have hurt.
Poorly designed experiments seem to be standard fare now days. That they get published at all is a mystery but in a peer reviewed journal is a bit bizarre.
I live on the migratory flyway for monarchs, though we have some monarchs from spring through winter. We also plant milkweed specifically for monarchs. One of the things we have noted is that not only do monarchs feed on milkweed but so do several other specific insect species, a bug, a beetle, and an aphid. Those insect often show up earlier than monarch larvae on the plant. We know from published research that when a plant is attacked by pests they increase their chemical defenses. In other words a plant where insect pests are excluded may not produce the same level of chemical protection as one being bombarded by pest.
I didn’t read the entire paper but what is the mechanism by which milkweed does not produce as much chemical protection at higher levels of CO2 in a closed environment?
Not having a control is never a good thing.
Anthony Watts : “sub-par science “………………..,WHY are you being so kind ?
This was absolutely NOT science……..NO CONTROL GROUP !
Automatic FAIL !!
This was just inhuman treatment of butterflies…….where are the ANIMAL RIGHTS ACTIVISTS
PROTESTING THIS ACTION ??????
IF DECKER WAS AWARDED A DOCTORATE BASED ON THIS “STUFF-UP” THEN
” Decker, who conducted the research for her doctoral dissertation in the U-M Department of Ecology and Evolutionary Biology. She is now a postdoctoral researcher at Stanford University.”
SHOULD BE STRIPPED OF THE DOCTORATE on the basis that it devalues ALL the
other doctorates they have awarded !
This “evidence” is about as substantial as the Feminist-Movements “Lived Experience ” malarkey !
Rocket scientist identified the main problem with the study, that “Tropical Milkweed,” A. curassavica, does not occur where the study was conducted or in most of the United States and is just one of 4 species of milkweed that are host plants for Monarch caterpillars. It also has other problems as a Monarch host plant- https://monarchbutterflygarden.net/is-tropical-milkweed-killing-monarch-butterflies/ Common Milkweed, both A. exaltata (in the east) and A. speciosa (in the west). are the host plant for most Monarch cats in the U.S. Because of modern farming with genetically modified crops immune to herbicides, both Common milkweed and nectaring flowers for bees. butterflies and other insects are reducing the range and populations of these important pollinators. Almost everything except the genetically modified crop is killed. That is a known problem.
The study, as noted, also needs a control before any conclusions can be inferred. I do butterfly studies and have online butterfly field guides to South Carolina and the Yucatan Peninsula that you can find by clicking on my website- https://sites.google.com/site/southcarolinauplandbutterflies/
“1. It’s not done in a natural setting, thus excluding all other natural environmental effects.”
Exactly. This is to study a particular effect. It’s extremely hard indeed to find milkweed growing naturally at 760 ppm CO2.
“2. The butterflies are purposely infected, rather than taking their chances in nature.”
The researchers have to infect every monarch with a known, realistic quantity of parasite, since it’s the effect of increased CO2 on milkweed cardenolides and how that in turn affects the parasite-mediated longevity of the monarchs, not the effect of initial parasite load or how many butterflies have the parasite in nature or predation rates, etc.
“3. The milkweed is subjected to an instant increase in CO2, instead of a process that would take decades. There’s no chance for adaptation. (and point 4)”
True. This is a limitation to the study. Unfortunately, there are always going to be limited opportunities to study what organisms might be like 80 years from now. For the same reason, we can’t be sure that increased CO2 levels will always increase growth and water use efficiency of most plants.
‘”5. Where’s the OTHER control group? No mention of one. Did they infect butterfly larva and NOT feed them milkweed and count the deaths. No. One wonders if the mortality rate of 77% might be similar in that scenario.”
Given that milkweed is the sole food of monarchs (2nd paragraph), it’s pretty likely the outcome would be a 100% mortality rate.
“Given the lack of a control group, it seems the results were pre-determined.”
The control groups are monarchs fed the milkweed grown at 400 ppm. Apart from other research, there is no a priori reason to expect the plant grown at higher levels to influence monarch mortality.
Based on the PR and abstract, I see no problems with the study design. There are caveats such as evolutionary potential, but that is not a problem with experimental design but with the fact that we can’t see the future. It’s normal for scientific research to have caveats and limitations; that doesn’t mean it’s sub-par. This is evidence, not “proof.”