From the “Why do we care that agricultural pests can’t lay eggs properly? – Oh wait, we don’t!” department…and Eurekalert.
Rising carbon dioxide level disrupts insects’ ability to choose optimal egg-laying sites
Climate change is rapidly reshaping ecosystems across the globe, and new research has identified a previously unrecognized consequence: disrupted insect reproductive behavior. A recent study published in National Science Review reveals that rising atmospheric carbon dioxide (CO2) levels are interfering with how agricultural pests choose egg-laying sites—posing significant risks to biodiversity, food security, and pest management strategies.
Insects, despite their adaptability, are especially sensitive to shifts in environmental conditions. As global temperatures rise and atmospheric composition changes, their behavior is changing in ways that ripple through ecosystems. CO2, the primary greenhouse gas driving global warming, has increased from 278 ppm in 1750 to approximately 420 ppm in 2023. Emerging evidence shows that elevated CO2 levels—alongside pollutants such as ozone and nitrogen oxides—are disrupting insects’ ability to detect chemical cues essential for reproduction and survival. Until now, the underlying mechanisms remained poorly understood.
Now, an international collaborative study by scientists from the Chinese Academy of Agricultural Sciences, the Norwegian University of Science and Technology, and the Max Planck Institute has provided key insights. Focusing on Helicoverpa armigera—the cotton bollworm, a major global crop pest—the team discovered that females normally use plant-emitted CO2 to locate suitable egg-laying sites, particularly favoring younger leaves that emit higher CO2 gradients. These sites are critical for larval survival and development. However, under elevated atmospheric CO2 concentrations, this behavior is significantly disrupted. The study found that moths’ CO2-sensing ability is impaired, causing them to lay eggs in less suitable locations. “This disruption is akin to confusing a key olfactory cue from a GPS system,” said Prof. Guirong Wang, lead author of the study. “Without accurate CO2 signals, the insects struggle to find ideal egg-laying sites, which could affect pest population dynamics and agricultural damage.”
To understand the biological basis for this disruption, the researchers identified three CO2-detecting gustatory receptors—HarmGR1, HarmGR2, and HarmGR3. When any of these receptors were genetically deleted, the moths’ ability to detect CO2 impaired, resulting in disoriented egg-laying behavior.
The study’s simulations paint a worrying future: if atmospheric CO2 reaches 1000 ppm by 2100, moths’ preference for optimal egg-laying sites could drop by up to 75%. This would likely reduce larval survival, destabilize pest populations, and alter biodiversity and ecological balance.
Beyond the alarming ecological implications, these findings point to new opportunities. “By targeting the CO2 receptors, we can explore novel, eco-friendly pest control strategies,” said Dr. Qiuyan Cheng, first author of the paper. One promising approach is RNA interference (RNAi), a gene-silencing technique already used in mosquito control, which could disrupt pest reproduction without harmful chemicals.
The study adds to growing evidence that climate change is influencing insect behavior in complex and unexpected ways—not only through temperature shifts but also via direct changes to atmospheric chemistry. With global CO2 levels on track to exceed 1000 ppm by the end of the century, researchers stress the urgent need for both emissions reductions and innovative agricultural adaptation.
Journal
National Science Review DOI 10.1093/nsr/nwaf270
“Insects, despite their adaptability, are especially sensitive to shifts in environmental conditions.”
Yuh, but… with a short reproductive cycle, they can evolve very quickly to adjust. I’ve seen few insects this year due to this relentless drought. But if next summer is a wet one- we’ll all be screaming about the mosquitoes and other insects. It doesn’t take many to survive a bad period to produce plenty the next time the weather improves. I’ve spent much of the summer gardening and so far I’ve seen ONE mosquito and ONE tick. Not complaining. 🙂
This only exposes the “hallucinations” of the AI(s ?) being used by the staff at Eurekalert.
From “Page 4 of 21” of the PDF file of the actual paper :
In the “References” section, on “Page 12 of 21 :
Ref. 42 is paywalled … but is 15 years old, and the title (and abstract) show its primary focus is definitely not on “projections of atmospheric CO2 levels in 2100”.
The very first sentence of the abstract to Ref. 43 :
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RCP 8.5 ~= 935 ppm in 2100 … 935, 950, close enough for government work …
IPCC AR6, WG-III (Three !) assessment report, FAQ 3.3, “How plausible are high emissions scenarios, and how do they inform policy?”, on page 386 :
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OK, what does the IPCC consider to be “business as usual / in the absence of additional climate policies” emissions pathways ?
AR6 WG-I assessment report, section 1.6.1.4, “The likelihood of reference scenarios, scenario uncertainty and storylines”, on page 239 :
CMIP5 emissions pathway, atmospheric greenhouse gas (especially CO2) concentrations URL :
https://www.pik-potsdam.de/~mmalte/rcps/
NB (1) : The “Global Annual Mean Mixing Ratios” column has data from 1765 to 2500 (!) for each pathway.
NB (2) :”RCP3-PD” (Peak then-Decline) is now usually called “RCP 2.6” (2.6 W/m² in 2100).
CMIP6 emissions pathway, atmospheric CO2 levels URL :
https://greenhousegases.science.unimelb.edu.au/#!/ghg?mode=downloads
NB (i) : “Historical –> Yearly –> Global mean, northern hemisphere, southern hemisphere” data goes from “Year 0” (actually 1 BC, if you’re as pedantic as I am …) to 2014.
NB (ii) :You have to cycle through the “Choose a scenario” option and download each “Future” (from 2015 to 2500) data file separately.
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Summary of levels in 2100, rounded to the nearest ppm.
Pathway :: CO2 in 2100
SSP5-8.5 : 1135 [ “Counterfactual” set ]
RCP 8.5 :: 936
SSP3-7.0 : 867
RCP 6.0 :: 670 [ “BaU / No additional climate policies” set ]
SSP4-6.0 : 668
SSP2-4.5 : 603
RCP 4.5 :: 538
SSP4-3.4 : 473 [ Roger Pielke Jr’s “most likely” option (?) ]
SSP1-2.6 : 446 [ “Hopelessly optimistic” set ]
RCP 2.6 :: 421
SSP1-1.9 : 394
Only SSP5-8.5 exceeds 1000 ppm (in 2100).
If SSP3-7.0 is above the IPCC’s “counterfactual” threshold, then so is RCP 8.5.
The “Business-as-Usual (BaU)” pathways are in the 600 +/- 70 ppm range, which is most definitely not “on track to exceed 1000 ppm”.
If you have a mothball in one hand and a mothball in the other, what do you have?
A damn big moth!
“Emerging evidence shows that elevated CO2 levels—alongside pollutants such as ozone and nitrogen oxides—are disrupting insects’ ability to detect chemical cues essential for reproduction and survival.”
It could not possibly be due to nitrogen based fertilizers?
It could not possibly be due to modern agriculture technologies that address such infestations?
Has to be CO2.
It must have been CO2 that caused my FIOS internet disruption. CO2 is the evil that keeps on giving, everywhere, everything, every time.
/sarc
U-Reek Alert…figures.
Aside from the “what was the bad news again?” element, somebody in the know about how to sift through the climate research (propaganda), because I’m SURE there has to be some “study(ies)” telling us how insect “pests” were going to thrive as the climate warmed.
Debunked!
That is a point indeed. If they cannot lay eggs, how can they thrive?