The Missing Insect Pests of 2022

[deluxestogie]

My usual insect pests (flea beetles, aphids, hornworms, etc.) were nearly absent from my tobacco during the 2022 growing season. (Crickets and grasshoppers were out in force. A few budworms showed up.) It was beyond the bounds of what I have experienced over the past decade and more. A newly published study from the University of Bristol hints at what may be at work in a warming environment. You can read the entire (brief) article, or just go with the punchline:

"Acclimation of both upper and lower critical thermal limits was weak—for each 1°C shift in exposure, limits were adjusted by only 0.092°C and 0.147°C respectively (i.e. only a small compensation of 10 or 15%)."​

Insects struggle to adjust to extreme temperatures making them vulnerable to climate change, study finds

Insects have weak ability to adjust their thermal limits to high temperatures and are thus more susceptible to global warming than previously thought.

phys.org

The implication is that many insects cannot keep up with the current rate of temperature change. They will either perish or move to a cooler locale.

Bob

 

[GreenDragon]

Didn't seem to affect the Japanese Beetles this year! I did have fewer hornworms in my 'maters and tobacco though.

 

[deluxestogie]

I did see Japanese Beetles this year, but many fewer than usual. I saw hardly any June bugs.

Bob

 

[HillDweller]

Plenty of aphids here, but no hornworms.

 

[LeftyRighty]

I'm even seeing fewer moths on my porch lights at night, and spider webs nearby.
But I find it difficult to believe that 'climate change or global warming' is responsible. Being an old geezer, I've experienced too many extremely hotter summers and colder winters, wetter and drier seasons. Mother Nature is too finicky and unpredictable, and insects are more adaptive than other critters.
I'll venture that 'chemicals' are more responsible, as more agricultural usage, wildfires, urban expansion & pollution, etc.

 

[deluxestogie]

Meta-analysis reveals weak but pervasive plasticity in insect thermal limits
Hester Weaving, John S. Terblanche, Patrice Pottier, Sinead English
Nature Communications

Extreme temperature events are increasing in frequency and intensity due to climate change. Such events threaten insects, including pollinators, pests and disease vectors. Insect critical thermal limits can be enhanced through acclimation, yet evidence that plasticity aids survival at extreme temperatures is limited. Here, using meta-analyses across 1374 effect sizes, 74 studies and 102 species, we show that thermal limit plasticity is pervasive but generally weak: per 1 °C rise in acclimation temperature, critical thermal maximum increases by 0.09 °C; and per 1 °C decline, critical thermal minimum decreases by 0.15 °C. Moreover, small but significant publication bias suggests that the magnitude of plasticity is marginally overestimated. We find juvenile insects are more plastic than adults, highlighting that physiological responses of insects vary through ontogeny. Overall, we show critical thermal limit plasticity is likely of limited benefit to insects during extreme climatic events, yet we need more studies in under-represented taxa and geographic regions.​

https://www.nature.com/articles/s41467-022-32953-2.pdf

 

[deluxestogie]

Research demonstrates effects of hotter fall temperatures on insects

Climate change has wreaked havoc with many species' life cycles and now a pair of Western students is shedding light on how it's affecting the survival of two high-profile insects.

phys.org

 

[Wolffman]

I live in hot TX and we have all the usual bugs. Nothing is missing here.