Crops Could Face Double Trouble From Insects And A Warming Climate

Crops Could Face Double Trouble From Insects And A Warming Climate In the heat, tomato plants can’t fight off the hungry tobacco hornworm, Manduca sexta. From

For millennia, insects and the plants they feed on have been engaged in a co-evolutionary battle: to eat or not be eaten. Until recently, the two antagonistic sides have maintained a stalemate of sorts. With climate change, however, warmer temperatures could tip the balance in favor of the insects and spell danger for crops and the farmers that tend to them.

Our research team at Michigan State University’s Plant Resilience Institute watched what happened in hotter weather when hornworm caterpillars attacked a tomato plant. The tomato lost. We saw a surprising trade-off by the plant during the heat wave: It defended itself against the caterpillars but this effort prevented it from dealing with the harmful effects of heat. This caused the plant to overheat, which strengthened the caterpillars’ hand.

A study by researchers in 2018 predicted that each degree of global warming will increase crop loss from insects by 10% to 25% because insect populations and their appetites surge in warm temperatures. Other climate-related variables, including prolonged droughts or floods, are likely to compound those losses.

But although scientists have identified these varied challenges to food production, they still don’t know much about how the combination of heat and insects will affect the plants’ built-in defense systems.

Plants constantly sense and respond to changes in their environments, including the presence of plant-eating insects.

How plants fight off insect pests

Unlike animals, plants cannot run or hide from predators. Instead, plants produce an arsenal of toxic chemicals that repel attack by insects and other plant consumers.

Producing these compounds is costly and often stunts their growth, so plants deploy this chemical defense arsenal only when damaged by a chewing insect. This process is triggered by the plant wound hormone, jasmonate, which tightly controls the biosynthesis, distribution and storage of chemical defense compounds that repel insects.

For more than 20 years, we have studied how jasmonate protects plants from insect herbivores. Only recently have we begun to think about how rising global temperatures influence this common plant defense mechanism.

Heat and the hungry caterpillar

In our study we challenged tomato plants with hornworm caterpillars under either normal temperature conditions: 82 degree F days (about 28 degrees C) and 64 degree F nights (about 18 degrees C). We also simulated heat waves, with temperatures rising to 100 F (38 C) in the daytime and falling to 82 F (28 C) at night for several days.

The plants responded to the hotter temperatures by intensifying production of jasmonate and, as a consequence, increasing the output of various defense compounds. Even so, insects ate the plants relentlessly in the heat.

Meanwhile, a parallel study by our team found that moderate increases in temperature speeded up the insects’ metabolism so that they ate faster and did more damage to the plants. Although tomato plants fought hard with their chemical response, they couldn’t neutralize the insects’ powerful heat-triggered eating stimulus.

Models may underestimate crop losses due to climate change because they don’t consider how infested plants react to rising temperatures.

Insects + heat = double trouble

Plants use two strategies to cool down when temperatures get too high. They will open their tiny leaf pores, which are called stomata, releasing water that cools them much as sweating cools humans. Plants also combat heat stress by lifting their leaves away from the hot soil, perhaps in search of a cool breeze.

We unexpectedly discovered in our work that tomato plants challenged by caterpillars at the warmer temperature didn’t do these things, and thus failed to cool their leaves.

In our follow-up experiments, we found that when caterpillars ate its leaves and the plant activated the hormone jasmonate, this blocked the opening of the tiny stomata, and also prevented leaves from lifting up to cool. The plant couldn’t deploy its cooling response, and at the same time photosynthesis (making food from sunlight and carbon dioxide) was reduced.

These circumstances effectively slow the growth of the plant. Thus, although tomato plants can cope well with insect attacks or elevated temperature, if those two stresses come at the same time, that spells double trouble. The result is rapid defoliation by hungry caterpillars plus leaf overheating.

Studying plants in real environments

Why insect attack keeps the plants from cooling themselves remains a mystery. However, when plants close their stomata during an insect attack, they conserve water by preventing it from evaporating from wounded leaves. We think this response may benefit the plant when water is in short supply, which is often the case during heat waves.

We plan to address this question by studying plants grown in the rough-and-tumble of natural environments, rather than under highly controlled laboratory conditions. We believe such studies are necessary to develop crops that can withstand both heat and wound stress.

Making more resilient plants

Many experts estimate that agricultural productivity must double in the next 30 years to meet the demands of a rapidly growing population. Current yield trajectories for major crops, combined with the uncertain impacts of a changing global environment, suggest that the world will fall well short of this demand using conventional agricultural practices.

The United Kingdom’s Royal Society and other scientific organizations have called for a Second Green Revolution that will permit the sustainable intensification of agriculture through development of crops that are more resilient in face of increasingly harsh environmental conditions.

Recent technological advances, from genomics and gene editing to computational and data science approaches, provide researchers with unprecedented opportunities to work toward this goal. In achieving a better understanding of the complex interactions of heat and insect attacks, we hope that our research may inform new strategies to increase plant resilience in a warming world.

About The Author

Gregg Howe, Professor of Biochemistry and Molecular Biology, Michigan State University and Nathan Havko, Postdoctoral Fellow in Plant Research, Michigan State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

Life After Carbon: The Next Global Transformation of Cities

by Peter Plastrik , John Cleveland
1610918495The future of our cities is not what it used to be. The modern-city model that took hold globally in the twentieth century has outlived its usefulness. It cannot solve the problems it helped to create—especially global warming. Fortunately, a new model for urban development is emerging in cities to aggressively tackle the realities of climate change. It transforms the way cities design and use physical space, generate economic wealth, consume and dispose of resources, exploit and sustain the natural ecosystems, and prepare for the future. Available On Amazon

The Sixth Extinction: An Unnatural History

by Elizabeth Kolbert
1250062187Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world are currently monitoring the sixth extinction, predicted to be the most devastating extinction event since the asteroid impact that wiped out the dinosaurs. This time around, the cataclysm is us. In prose that is at once frank, entertaining, and deeply informed, New Yorker writer Elizabeth Kolbert tells us why and how human beings have altered life on the planet in a way no species has before. Interweaving research in half a dozen disciplines, descriptions of the fascinating species that have already been lost, and the history of extinction as a concept, Kolbert provides a moving and comprehensive account of the disappearances occurring before our very eyes. She shows that the sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human. Available On Amazon

Climate Wars: The Fight for Survival as the World Overheats

by Gwynne Dyer
1851687181Waves of climate refugees. Dozens of failed states. All-out war. From one of the world’s great geopolitical analysts comes a terrifying glimpse of the strategic realities of the near future, when climate change drives the world’s powers towards the cut-throat politics of survival. Prescient and unflinching, Climate Wars will be one of the most important books of the coming years. Read it and find out what we’re heading for. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you,, and at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.



follow InnerSelf on

facebook icontwitter iconyoutube iconinstagram iconpintrest iconrss icon

 Get The Latest By Email

Weekly Magazine Daily Inspiration


The Great Climate Migration Has Begun
The Great Climate Migration Has Begun
by Super User
The climate crisis is forcing thousands around the world to flee as their homes become increasingly uninhabitable.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
Earth Has Stayed Habitable For Billions Of Years – Exactly How Lucky Did We Get?
by Toby Tyrrell
It took evolution 3 or 4 billion years to produce Homo sapiens. If the climate had completely failed just once in that…
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
How Mapping The Weather 12,000 Years Ago Can Help Predict Future Climate Change
by Brice Rea
The end of the last ice age, around 12,000 years ago, was characterised by a final cold phase called the Younger Dryas.…
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
by Frank Wesselingh and Matteo Lattuada
Imagine you are on the coast, looking out to sea. In front of you lies 100 metres of barren sand that looks like a…
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
Venus Was Once More Earth-like, But Climate Change Made It Uninhabitable
by Richard Ernst
We can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of…
Five Climate Disbeliefs: A Crash Course In Climate Misinformation
The Five Climate Disbeliefs: A Crash Course In Climate Misinformation
by John Cook
This video is a crash course in climate misinformation, summarizing the key arguments used to cast doubt on the reality…
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
by Julie Brigham-Grette and Steve Petsch
Every year, sea ice cover in the Arctic Ocean shrinks to a low point in mid-September. This year it measures just 1.44…


green energy2 3
Four Green Hydrogen Opportunities for the Midwest
by Christian Tae
To avert a climate crisis, the Midwest, like the rest of the country, will need to fully decarbonize its economy by…
Major Barrier to Demand Response Needs to End
by John Moore, On Earth
If federal regulators do the right thing, electricity customers across the Midwest may soon be able to earn money while…
trees to plant for climate2
Plant These Trees To Improve City Life
by Mike Williams-Rice
A new study establishes live oaks and American sycamores as champions among 17 “super trees” that will help make cities…
north sea sea bed
Why We Must Understand Seabed Geology To Harness The Winds
by Natasha Barlow, Associate Professor of Quaternary Environmental Change, University of Leeds
For any country blessed with easy access to the shallow and windy North Sea, offshore wind will be key to meeting net…
3 wildfire lessons for forest towns as Dixie Fire destroys historic Greenville, California
3 wildfire lessons for forest towns as Dixie Fire destroys historic Greenville, California
by Bart Johnson, Professor of Landscape Architecture, University of Oregon
A wildfire burning in hot, dry mountain forest swept through the Gold Rush town of Greenville, California, on Aug. 4,…
China Can Meet Energy and Climate Goals Capping Coal Power
China Can Meet Energy and Climate Goals Capping Coal Power
by Alvin Lin
At the Leader’s Climate Summit in April, Xi Jinping pledged that China will “strictly control coal-fired power…
Blue water surrounded by dead white grass
Map tracks 30 years of extreme snowmelt across US
by Mikayla Mace-Arizona
A new map of extreme snowmelt events over the last 30 years clarifies the processes that drive rapid melting.
A plane drops red fire retardant on to a forest fire as firefighters parked along a road look up into the orange sky
Model predicts 10-year burst of wildfire, then gradual decline
by Hannah Hickey-U. Washington
A look at the long-term future of wildfires predicts an initial roughly decade-long burst of wildfire activity,…

 Get The Latest By Email

Weekly Magazine Daily Inspiration

New Attitudes - New Possibilities | | | InnerSelf Market
Copyright ©1985 - 2021 InnerSelf Publications. All Rights Reserved.