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Nigeria needs biotechnology to weather climate change impacts on farming, say West African scientists

BY JOAN CONROW

NOVEMBER 24, 2021

Alliance for Science

Agricultural biotechnology will help Nigeria respond to climate change issues and support food security, asserts a new study by West African researchers.

“Evidence of climate change on agriculture in Nigeria has since been established and increased atmospheric warmness, irregular rainfall, emergent pests, [crop] diseases…and their resultant adverse effect on agricultural productivity are glaring,” the authors write in the November 2021 Handbook of Climate Change Management. “This scenario poses a serious threat to food security in Nigeria and calls for the adoption of innovative biotechnologies to create resilient crops with improved adaptation to the environmental stresses occasioned by the increasing climate change.”

While agricultural production is extremely vulnerable to the impacts of climate change, the higher mean temperatures and longer growing seasons resulting from global warming could favor farming in regions where temperatures are already low, like North America, Europe and Asia, the authors write. But production in already hot regions, like Africa, will possibly suffer greater productivity declines as higher temperatures bring longer periods of excessive heat, which in turn shorten the growing season and eventually reduce crop yields.

Additionally, research and a 2010 global weather forecast assert that climate change will reduce global agricultural production by 6 percent by the year 2080 — a figure that could reach 30 percent or more in warm regions like regions like Africa and India, write the authors, who are affiliated with Ebonyi State University in Nigeria and the Boyce Thompson Institute (BTI) at Cornell University. (Disclaimer: The Alliance for Science is housed at BTI.)

African farmers who have little or no access to irrigation facilities will be hardest hit, they write. “Therefore, farmers in these regions very much need innovative practices and technologies that improve agricultural production under the prevailing climate change scenarios. Current biotechnologies have provided limitless opportunities to expand crop improvement through [their] capacity to source genes for desired traits from distantly related species.”

Agricultural biotechnology has helped to reduce the greenhouse gas emissions (GHG) that contribute to climate change and develop crop cultivars that can tolerate heat, cold, drought, submergence and salinity stress, as well as pests and diseases, the authors write.

However, an assessment of the effects of climate change on agriculture, the anthropogenic causes of climate change and the current biotechnologies employed for climate change mitigation and adaptation in Nigeria “exposed the country’s very low capacity to deal with climate change issues using biotechnology approaches,” the authors conclude.

“In Nigeria, only IITA [International Institute of Tropical Agriculture] has the technical capacity for crop genetic engineering approach,” they note.

Nigerian researchers have developed two biotech crops to help farmers weather these challenges: insect-resistant (Bt) cotton and cowpea. Both have been approved for commercial use. Two other genetically modified crops —Africa bio-fortified sorghum and Nitrogen-Use Efficient, Water-Use Efficient and Salt-Tolerant (NEWEST) rice — are at different stages of field and confined field trials.

“Despite the numerous organizations that should be involved in the development, adoption, promotion and regulation of agricultural biotechnology in Nigeria, a recent comprehensive review of the current status of agricultural biotechnology in Nigeria  showed that the rate of development, adoption and implementation of agricultural biotechnology in Nigeria is still at a low ebb,” the authors assert. “In particular, research and deployment of transgenic technology is still in its embryonic stage in Africa’s most populous country…The slow rate of development and deployment of biotechnology in agriculture in the nation is unequivocally due to ethical, socioeconomic,and political issues, as well as poor knowledge of the technologies.”

The authors warn that “total reliance on conventional breeding methods in developing climate-friendly and resilient crop varieties, without incorporating the more efficient, modern, advanced, precise and reliable biotechnology techniques, will in the long-run deprive the rapidly expanding population access to adequate food provision and threaten food security and economic development.”

Land use change and forestry (LUCF) and the energy sector accounted for up to 70 percent of Nigeria’s GHG emissions in 2014. Agriculture contributes about 13 percent, largely from livestock production and rice cultivation.  In Nigeria, farmers use huge quantities of synthetic (nitrogen) fertilizers annually to boost crop yields, especially rice, which leads to high emission of N2O from this sector, the authors write.

Nigeria’s agricultural sector produces far more GHG emissions than in developed nations due to its use of traditional agricultural practices and overdependence on farming, the authors note.

Climate change has already been triggering drought and flooding scenarios that adversely affected crop production in various parts of Nigeria, the authors write. Reduced rainfall occurred in some northern states in 2010 and reduced millet, sorghum and cowpea production by about 10 percent. Other northern states that do not normally have heavy rainfall have experienced flooding that reduced rice production by as much as 50 percent.

Temperature and rainfall fluctuations are also associated with increases in plant diseases and insect pest pressure that further suppress production and make farming increasingly difficult. “Climate change-induced crop yield losses are forcing existing and potential farmers in Nigeria to abandon farming for nonfarming ventures,” the authors warn.

“As the effects of climate change on agricultural productivity in any region do not depend only on the changing climatic conditions, but even more on the region’s adaptive response capacity, Nigeria is at a high risk of the damaging effects of climate change if effective adaptive and mitigation technologies and strategies remain acutely lacking,” the authors caution.

“However, with the emerging biotechnology landscape in Nigeria, harnessing innovative biotech approaches for effective response to climate change is pivotal, but would require concerted efforts and engagement of all stakeholders including policy makers, scientists, and farmers.”

Image: A drought-ravaged field in Nigeria. Photo: Shutterstock: Paul shuang

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Graduate Students in Nepal Uncover the Impacts of Climate Change and Invasive Species Spread

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Integrated Pest Management Innovation Lab

Jul 27, 2021

Anju Sharma Paudel
Anju Sharma Paudel

This post is written by Sara Hendery, communications coordinator for the Feed the Future Integrated Pest Management (IPM) Innovation Lab

Virginia Tech’s Feed the Future IPM Innovation Lab is celebrating the work of 27 students funded by one of its projects. 

The IPM Innovation Lab collaborates with Tribhuvan University and the University of Virginia’s Biocomplexity Institute to assess the spread of invasive weeds over the last 30 years — based on elevation and under different climate scenarios — in central Nepal. The project has found that as climate change events continue to occur, invasive weeds are spreading faster and higher than ever before. 

Over the course of this six-year project, many research findings have been uncovered by graduate students supported by the project’s funding. Post-graduation, those students are now working at high levels within the Nepal government, universities and the private sector. They have also participated in more than 45 international and national conference presentations and published more than three dozen research papers in national and international scientific journals, with more being developed.

“Student research, with the guidance of experts and advisors, has been at the helm of some of the most exciting research to come out of this project,” said Pramod Jha, professor emeritus at Tribhuvan University and the project lead. “Some have uncovered, for example, incredibly valuable biocontrol options for some of Nepal’s most pressing invasive weed issues as well as assessed the shrinking land availability of critical food crops communities depend on. These students are just at the beginning of recognizing the long-term impacts of climate change and this initial research will propel them into future careers where they can actually see their work come to life.”

Take, for example, soon-to-be graduate Seerjana Maharjan. Maharjan is earning her Ph.D. from Tribhuvan University, researching the ecology and management of the invasive weed Parthenium hysterophorus, which causes human, animal and environmental health issues. Her research considers the possibility of winter rust as a biocontrol agent of parthenium and projects the increased suitable habitat of parthenium under future climate scenarios. Post-graduation, Maharjan will serve as a scientific officer in Nepal’s Department of Plant Resources, Ministry of Forests and Environment

Dol Raj Luitel also works as a senior scientific officer in Nepal’s Department of Plant Resources, Ministry of Forests and Environment. Earning his Ph.D. at Tribhuvan University, Luitel’s research explores the impact of climate change on distribution, production and cropping patterns of finger millet and buckwheat along altitudinal gradients in Nepal. His research assesses the medicinal value of finger millet, the declining habitat of buckwheat under future climate scenarios and the important nutrients that can be found in finger millet and soil at varying elevations.

Ghanshyam Bhandari earned his Ph.D. from the Agriculture and Forestry University, researching insect diversity of maize and eco-friendly management practices of maize stemborers. Bhandari’s research also assesses the performance of traps for capturing maize insects and farmer perception of climate change in relation to maize cultivation. As a current research officer at the Nepal Agricultural Research Council (NARC), Bhandari is assisting the IPM Innovation Lab in developing biological control efforts of the invasive fall armyworm in Nepal. 

Hom Nath Giri earned a Ph.D. from the Agriculture and Forestry University and currently serves as an assistant professor of horticulture at his alma mater. His research explores the growth of cauliflower at different ecological zones in Nepal, the effect of nitrogen on the post-harvest quality of cauliflower, and efficacy testing of pesticides against the cabbage butterfly in Nepal.

Anju Sharma Paudel earned a Ph.D. from Tribhuvan University, her research focusing on the management of the invasive weed Ageratina adenophora. Post-graduation, Paudel is continuing to develop her research, predicting the current and future distribution of Ageratina adenophora in Nepal and whether stem-galling of the invasive weed by the biocontrol agent Procecidochares utilis is elevation dependent.

The IPM Innovation Lab supported Ram Asheswar Mandal, a postdoctoral student at Tribhuvan University, over the course of the program. Mandal’s research assesses the impacts of climate change and biological invasion on livelihoods.

The IPM Innovation Lab has also supported 21 master’s-level students in the same project, many of whom now work as agricultural officers for the Nepal government or as lecturers at local universities.

Muni Muniappan, director of the IPM Innovation Lab, said the involvement of students in this project is a win-win for both students and research.

“Students are eager to address the biggest problems of our time,” he said, “whether it be food insecurity, resource limitations, climate change impacts or other constraints. Students bring to these global challenges new perspectives and out-of-the-box thinking that is exactly what is needed to help move the science forward. In return, they receive real-life, hands-on experience in their own country as well as other countries, which further nurtures their problem-solving abilities.”

Graduating master’s students funded by the project include:

  • Sagar Khadka, Tribhuvan University: Decomposition of Eichhornia crassipes of different fungi in Chitwan Annapurna Landscape, Nepal. 
  • Bidya Shrestha, Tribhuvan University: Impacts of climate change on biodiversity utilization by smallholder farmers. 
  • Pristi Dangol, Tribhuvan University: Changes in the life history traits of the invasive weed Lantana camara in central Nepal.
  • Yashoda Panthi, Tribhuvan University: Diversity of invasive alien plant species and their impacts on provisioning services in a village of Lamjung district. 
  • Ganga Shah, Tribhuvan University: Distribution of vulture species and its nest site from lowland to highland in Chitwan Annapurna Landscape, Nepal.
  • Vishubha Thapa, Tribhuvan University: Food access and threats to vultures in Chitwan Annapurna Landscape, Nepal. 
  • Vivekanand Mahat, Agriculture and Forestry University: Hygiene behavior of the honey bee (Apis cerana. F. and Apis mellifera L.) and diversity of flower visitors in rapeseed (Brassica campestris var. toria). 
  • Sarita Sapkota, Agriculture and Forestry University: Relative abundance of dung beetles and their role in nutrient cycling in Terai and mid hills of Nepal. 
  • Ramesh Upreti, Agriculture and Forestry University: Fruit thinning and defoliation effects on the quality and yield of papaya (Carica papaya) cv. Red Lady under net house conditions at Chitwan. 
  • Madhu Sudan Ghimire, Agriculture and Forestry University: Evaluation of indigenous cultivation of potato against late blight (Phytopthora infestance L.) in Okhaldhunga, Nepal.
  • Pratiksha Sharma, Agriculture and Forestry University: Climate resilient maize production among Chepang and non-Chepang communities in Chitwan, Nepal. 
  • Srijana Paudel, Tribhuvan University: Spatio-temporal distribution of Mikania micrantha in Chitwan Annapurna Landscape, Nepal. 
  • Abhisek Singh, Tribhuvan University: Spatio-temporal distribution of Ipomea carnea ssp fistulosa and spatio-temporal distribution of Lantana camara in Chitwan Annapurna Landscape, Nepal. 
  • Sita Gyawali, Tribhuvan University: Spatio-temporal distribution of Chromolaena odorata in Chitwan Annapurna Landscape, Nepal. 
  • Sandeep Dhakal, Tribhuvan University: Spatio-temporal distribution of Lantana camara in Chitwan Annapurna Landscape, Nepal. 
  • Sanjeev Bhandari, Tribhuvan University: Climate change and its impacts on fodder availability in Puranchaur, Kaski district.
  • Himal Yonjon, Tribhuvan University: Spatio-temporal distribution of Eichhornea crassipes in Chitwan Annapurna Landscape, Nepal. 
  • Chandra Paudel, Tribhuvan University: Impacts of Lantana camara on associated species. 
  • Binod Malla, Tribhuvan University: Impacts of Mikania micrantha on associated species. 
  • Aarati Chand, Tribhuvan University: Impacts of Parthenium hysterophorus on associated species. 
  • Nitu Joshi, Tribhuvan University: Impacts of  Chromolaena odorata on associated species.

This invasive weed modeling project is one of nine projects the IPM Innovation Lab currently manages. Since the program’s inception in 1993, it has funded the research of more than 600 students worldwide.FILED UNDER:AGRICULTURAL PRODUCTIVITYCLIMATE AND NATURAL RESOURCES

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Invasive Species Spread: Mapping the Impacts of Climate Change from Space

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Integrated Pest Management Innovation Lab

Oct 29, 2021

Sita Gyawali
Sita Gyawali

Nepal is considered to be one of the most vulnerable nations to climate change. The country’s unique geographic and topographic variations contribute to its rich biodiversity, which is at great risk from the spread of invasive species. As invasive species are more adaptable to change, they are wiping out critical native species that help communities and ecosystems thrive.  

Using satellite imaging, the Innovation Lab for Integrated Pest Management and Tribhuvan University in Nepal monitor the spread of invasive weeds, tracking species specifically between the period of 1990 to 2018. The programs account for climatic changes that have occurred over the last 30 years – such as fluctuations in rainfall and temperature – to measure how climate change impacts the spread of the invasive weeds over time.

Chromolaena odorata is one such weed, and is considered one of the world’s worst invasive alien species. Native species are greatly impacted by Chromolaena’s spread. The weed alters soil health, and due to the high level of nitrate content in its leaves, it’s poisonous to cattle.

Tribhuvan University graduate student Sita Gyawali utilized multispectral and medium spatial resolution satellite data – using programs such as Landsat, World View 2, and ArcGIS – to show that Chromolaena has significantly increased in spread over the last 30 years. The weed’s expansion in the Chitwan Annapurna Landscape (CHAL) area was 0.62% in 1992, and 0.87%, 1.11%, 1.29% in the years of 2000, 2010, and 2018, respectively. In total, its coverage increased from 201 sq. km to 412 sq. km, indicating that the weed is still invading new areas. The invasion of Chromolaena is expanding mostly in the mid-hill region of Nepal, considered to encompass the country’s most fertile lands.

“Images from such programs as Landsat and World View have become an invaluable source of data for detecting the spatial distribution of Chromolaena in Nepal,” said Gyawali. “Historical time series of remotely sensed data presents opportunities for characterizing habitat preferences of new species. This information provides us the insight we need in order to find management technologies that can combat the weed.”

In addition to Chromolaena, the project is also assessing the distribution expansion of the invasive weed Lantana camara. Lantana can be extremely destructive, as it smothers native vegetation, reducing species diversity and leading to species extinction. Tribhuvan University graduate student Sandeep Dhakal used Landsat images to show that the weed has increased in spread over the last 30 years, progressing from 0.24%, 0.9%, 1.45%, and 2.74 % in area in CHAL in the years 1992, 2000, 2009, and 2018, respectively. The largest area of distribution was found in Middle Mountain, followed by Siwalik and high mountains.

“Effective mapping of invasive species extent and determining the risk they pose for future invasions is incredibly important to Nepal,” said Dhakal. “The food we eat, the land our animals graze on, and more is at risk if we do not continue to utilize these types of programs to understand invasive species impact.”

Tribhuvan University students knew little about remote sensing before the start of the Virginia Tech-managed project. They gained satellite monitoring and modeling expert assistance from collaborators at the University of Virginia’s Biocomplexity Institute, who also operate the IPM Innovation Lab’s monitoring program of the invasive insect pest Tuta absoluta. Through this project alone, the IPM Innovation Lab has supported 27 students for their graduate degrees in Nepal. 

“For students to come into this program and learn a completely new skill – one that they will be able to apply to future careers – is a major contribution to building Nepal’s local research capacity,” said Pramod K. Jha, head of the program. “We know that invasive species respond quickly to change. As climate change persists and globalization continues, we cannot afford to wait to see how our lands are changing over time. Monitoring systems using satellite imaging help give us a bird’s eye view of not only how quickly this change is happening, but how quickly we need to react to ensure no further damage is done.”

Graduate students involved in the invasive weed modeling program in Nepal have already published 42 research publications in international and national journals in the areas of climate change, satellite imaging, biodiversity, and beyond.

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2020 Integrated Pest Management Research, Data and Findings: A Look Back

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Integrated Pest Management Innovation Lab

Feb 09, 2021

Photograph of fall armyworm
Fall Armyworm.

2020 was a year like no other — researchers in search of answers to some of the world’s most pressing questions were forced to think outside the box when trials and experiments were put on hold due to the COVID-19 pandemic. Globally, communities are facing food insecurity challenges more intensely than ever before, emphasizing the ongoing value of research that looks at the sustainable production of crops. Despite a challenging year, Virginia Tech’s Feed the Future Integrated Pest Management Innovation Lab (IPM IL) and its partners aim to highlight some of the 2020 research outputs that will continue to help foster improved livelihoods around the world.

Fall armyworm

Tuta absoluta

Crop protection

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Massimo Pavan

Italy: “The summer season was a disaster due to the high temperatures and diseases”

Table tomatoes represent the most valuable vegetable and are among the most important consumer products. Massimo Pavan, an Italian expert and vice-president of Consorzio di Tutela del Pomodoro di Pachino Igp, explains how the summer was a disaster for growers. 

Now that the summer season has ended, the time has come for a winter season with table tomatoes grown in greenhouses in the Mediterranean areas, with Sicily standing out thanks to its prestigious productions.

“The summer season was a disaster due to the high temperatures and diseases. Although Tuta absoluta did not cause much trouble as it was exterminated by the high temperatures, there were other threats such as the Tomato Brown Rugose Fruit Virus. The drought that hit Sicily caused a 50% drop in production, leading to doubled production costs.”

“Although prices were rather high during the period in question, the favorable quotations were not enough to repay the losses in absolute terms. Cherry tomatoes, with peaks of over €2/kg, settled at an average of €1.50/kg. Thus, we were not pleased with the summer of 2021, especially considering the continuous price increases of the raw materials. Prices have increased so quickly that it is difficult to quantify the actual cost index. In addition, the cost of energy and fuel has also increased in October, which affected November production.”

“The prices are currently low, as is demand in foreign markets such as Germany and Austria. Production prices hover between €0.80 and €1.20/kg with considerable Moroccan competition in the European markets. We know November is traditionally a calmer month, but this month there is a lack of consumer trust, probably due to the uncertainty caused by Covid. In addition, they are starting to be affected by the higher cost of living. Because of that, producers are not seeing increases in sales. We are currently reaching the break-even point at €1.30/kg. We are talking about presumed indexes because the situation is still unclear. After all, assessments must be made at the end of the season. Anyway, we are working at a loss below this threshold, while last year production prices were €1.10/kg.”

“What seems to be happening is a reduction of the cultivation areas destined for tomatoes, which is what occurred in Spain. It will be a physiological consequence of a trend that is difficult to manage. Competition deals with quality, and ours is unbeatable. However, the Maghreb produce has lower prices. The reasons for this difference are well known, starting with the defense tools used in Morocco, which guarantee higher yields. Another determining factor is the cost of labor which, in the north-African country, is 8 times lower than in Italy.”

“Initiatives such as that promoted by Consorzio di Tutela del Pomodoro di Pachino Igp are welcome, as they focus on the sustainability of the product as a promotional strategy. Consumers have the certainty of purchasing a product that is monitored, healthy, and with an excellent flavor, and they can count on a carbon footprint that is exceptionally low, as greenhouses are not heated and do not release CO2 into the atmosphere, unlike what happens in northern Italy and Europe.”

Publication date: Wed 1 Dec 2021

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How do we feed our growing population?

Jacqueline Rowarth05:00, Oct 27 2021

The Detail: The sky-high cost of living in New Zealand

The Detail explores what makes our food so pricey when we produce enough to feed 40 million people.

There are also more than 350 restaurants, cafés and fast-food outlets involved – and the restaurant and ready-to-eat-food prices increased 4.6 per cent. Further, 30 per cent of the food budget is now spent on convenience, despite lockdown and the perceived focus on home cooking.

For the farmer, this means that more of what consumers spend is on processing and preparation, rather than on the basic food they have produced.

Food prices rose 4 per cent in the year ending September 2021 (file photo).
ALDEN WILLIAMS/STUFFFood prices rose 4 per cent in the year ending September 2021 (file photo).

The New Zealand Institute of Economic Research analysed the farm share of retail prices in 2019. Approximately 31 per cent of every dollar spent on meat returned to the farm, 19 per cent of dairy dollars, 22 per cent of grain dollars, 10 per cent of fruit, 16 per cent of vegetables and 2 per cent of the egg dollar.

Not much, really.

And farmers are consumers – so they have been hit by inflation like every other business. In the last quarter, prices paid by farmers have increased 5.9 per cent. Prices received were certainly up 4 per cent, but that hasn’t covered the increase in costs of fertiliser, fuel, electricity and wages.

Even more of a shock might be that what is being experienced in New Zealand in terms of increased food prices is nothing in comparison with that being experienced in the world. The FAO food price index has increased 32.8 per cent from September 2020 – food prices globally have increased by a third in a year.

Dr Jacqueline Rowarth: “Ever-cheaper food ... is likely to be a thing of the past as farmers try to manage improved productivity (more food with reduced inputs) within the uncertainties of a changing environment.”
STUFFDr Jacqueline Rowarth: “Ever-cheaper food … is likely to be a thing of the past as farmers try to manage improved productivity (more food with reduced inputs) within the uncertainties of a changing environment.”

Uncertainty in harvest due to Covid-19, fire, drought and flood, as well as demand, have combined to stimulate inflation not seen since 2011. Food accessibility (available and affordable) is an issue globally.

Ever-cheaper food, though an expectation in developed countries, is likely to be a thing of the past as farmers try to manage improved productivity (more food with reduced inputs) within the uncertainties of a changing environment – due to both the climate and regulation.

The problem with the latter is that regulations are not always made with an understanding of the consequences.View the dashboard Tracking the speed of the economy

On April 29, the Sri Lankan Cabinet approved a ban on importation of chemical fertilisers and other agrochemicals in a bid to become the first country to practise organic-only agriculture. Less than six months later and the government has backed down. Yields and quality of tea crashed.

Despite well-meaning belief, there was insufficient organic fertiliser available for the tea plantations. And with lower yields and quality, tea prices increased, meaning local tea drinkers were as unhappy as the growers.

Sri Lanka wanted to be the first country to practise organic-only agriculture. Less than six months later and the government backed down after yields and quality of tea crashed.
JAROMíR KAVAN/UNSPLASH Sri Lanka wanted to be the first country to practise organic-only agriculture. Less than six months later and the government backed down after yields and quality of tea crashed.

In the European Union, Farm Europe (a think tank) has calculated that the new farm to fork strategy will have significant impact on food supply, and hence food prices. The strategy recommends reducing the use of chemical pesticides by 50 per cent and fertilisers by 20 per cent, setting aside of at least 10 per cent of agricultural area under high-diversity landscape features and putting at least 25 per cent under organic farming.

The estimated result will be a reduction in food supply by 10 to 15 per cent in the key sectors of cereals, oilseeds, beef, dairy cows; over 15 per cent in pork and poultry; and over 5 per cent in vegetables and permanent crops. There will be an increase in prices by 17 per cent and little to no increase in biodiversity or ecological benefits.

Increasingly, research is showing that our best chance of preserving biodiversity and achieving ecological benefits is to ensure productivity gains on existing agricultural area. This will avoid needing more area to compensate – deforestation being the most obvious detrimental effect. The big differences in biodiversity are between natural and managed ecosystems, not within different types of management (organic versus conventional, for instance).Get the latest small business updates, straight to your inboxSubscribe for free 

While the wealthy countries develop new technologies to assist the challenge of meeting the nutritional needs of an ever-increasing global population from current agricultural land, work is vital with the less developed countries to help them achieve higher yields – to overcome what is known as the yield gap.

Better soil management, improved genetics and matching inputs with plant and animal needs (including health and welfare) is key. So is harvesting, processing, storage and distribution to reduce waste.

New Zealand farmers already hold global records in yield (grain) and low GHG (meat and milk). They are also leaders in precision agriculture. Food here is produced without the subsidies common in other countries. Removal of technological tools will increase prices to the consumer as already calculated for the EU.

For good policy to be developed, all the different consequences need evaluation. Research is showing the way.

– Dr Jacqueline Rowarth, Adjunct Professor Lincoln University, is a farmer-elected director of DairyNZ and Ravensdown. The analysis and conclusions above are her own. Contact her at jsrowarth@gmail.com.

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Washington Post

A recipe for fighting climate change and feeding the world

A ladybug rests on a Kernza seed head in one of Sustain-a-Grain's farm fields. The ladybug indicates a healthy and diverse ecosystem. (Chase Castor for The Washington Post)
A ladybug rests on a Kernza seed head in one of Sustain-a-Grain’s farm fields. The ladybug indicates a healthy and diverse ecosystem. (Chase Castor for The Washington Post)

Scientists hope this new kind of perennial
grain offers a taste of what environmentally
friendly farming could look like

By Sarah KaplanUpdated Oct. 12 at 9:01 a.m.Originally published Oct. 12, 2021369

“It’s so different from anything I’ve baked with,” says my baking partner, Jenny Starrs.

We’re standing in the tiny kitchen of my D.C. apartment, examining palmfuls of a dark, coarse, rich-scented flour. It’s unfamiliar because it was milled from Kernza, a grain that is fundamentally unlike all other wheat humans grow.Story continues below advertisement

Most commercial crops are annual. They provide only one harvest and must be replanted every year. Growing these foods on an industrial scale usually takes huge amounts of water, fertilizer and energy, making agriculture a major source of carbon and other pollutants. Scientists say this style of farming has imperiled Earth’s soils, destroyed vital habitats and contributed to the dangerous warming of our world.

But Kernza — a domesticated form of wheatgrass developed by scientists at the nonprofit Land Institute — is perennial. A single seed will grow into a plant that provides grain year after year after year. It forms deep roots that store carbon in the soil and prevent erosion. It can be planted alongside other crops to reduce the need for fertilizer and provide habitat for wildlife.

In short, proponents say, it can mimic the way a natural ecosystem works — potentially transforming farming from a cause of environmental degradation into a solution to the planet’s biggest crises.

[Try the recipe: Kernza sourdough]

This summer I traveled to Kansas, where I met the scientists who are trying to make Kernza as hardy and fertile as traditional wheat. I visited the farmers who must figure out how to grow it effectively. And I invited my friend Jenny, the founder of artisan baking company Starrs Sourdough, to help me make a loaf of Kernza bread.

Kernza has a long road from the laboratory to the kitchen table. It will be even harder to transform the farming practices that humans have relied on for most of history. But if the scientists, farmers and processors are successful, perennial foods might one day be available on grocery store shelves — and the bread that Jenny and I are baking could offer a taste of what’s to come.

The soil

The first step in Jenny’s bread recipe is making the “levain” — a mix of flour, water and yeast that ferments for a long time, producing lots of air bubbles and tasty lactic acid.

While the microbes chow down, Jenny and I compare the whole Kernza to some wheat kernels she has on hand. The Kernza grains are smaller, and they contain less of the gluten protein that makes traditional wheat good for baking bread.

“Obviously, bread flour is awesome,” Jenny says — after all, humans have been perfecting it for nearly 10,000 years.

At the end of the last ice age, in the fertile river valleys of the Middle East, China and Mexico, people found they could sustain themselves more easily by cultivating crops. Three annual grasses — wheat, rice and corn — became the foundation of human diets and human civilization.

[What questions do you have about climate change or extreme weather? Ask The Post.]

Freed from the need to rove the landscape in search of food, people settled down and constructed cities. Religions and school calendars were structured around the rhythms of farming: planting seeds, helping them grow, harvesting grains and then tilling the soil to prepare it for the next round of planting. Generations of careful breeding improved crops’ taste and yield, and ever- stronger fertilizers have made farms still more productive. The population boomed.

But the planet has paid the price. The practice of tillage — churning the ground to destroy weeds and facilitate the planting of next year’s crop — has depleted the very earth from which our food is grown. It breaks up clumps of organic matter and exposes them to the sunlight, releasing carbon into the atmosphere. Tilled soil is less able to hold water, causing nutrients and other particles to run off into rivers, lakes and the sea.

Research suggests that the world’s soils are now eroding 100 times faster than new soil can form, and an estimated 33 percent of soil is so degraded that its ability to grow crops is compromised. Meanwhile, monoculture — the strategy of sowing huge fields with a single crop — achieves higher yields but also puts more pressure on soil and increases the risk that plants will succumb to pests or disease.

Many of humanity’s solutions to these problems also create other issues, Land Institute researchers say. Fertilizer can counter soil degradation, but it pollutes waterways and produces nitrous oxide, a potent greenhouse gas. Pesticides might reduce threats from insects, but they destroy other vital species. Cover crops will curb erosion, but they can be difficult to plant and maintain.

And modern farming is hugely carbon intensive. Factoring in fuel for machinery and food transport, methane produced by belching livestock, and the carbon that’s lost when ecosystems are converted to cropland, agriculture accounts for about a quarter of humanity’s annual planet-warming emissions.

Yet farms are also threatened by climate change, which will increase the risk of prolonged droughts and catastrophic floods.Story continues below advertisement

In Kansas, one of the nation’s leading producers of wheat, these problems are on full display. The state loses an estimated 190 million tons of its rich topsoil each year. Climate change has made Kansas summers hotter and drier, but also makes rainstorms more intense. The state’s farmers are among those most at risk of losing crops as a consequence of human-caused warming.

“It’s a disaster,” Tim Crews, the Land Institute’s lead soil ecologist, tells me one damp day in June. Our shoes squelch in the mud as he leads me around the institute’s Salina, Kan., campus. As we talk, the rain is almost certainly destabilizing soil and washing it into surrounding streams.

Crews sweeps his hand out, as if to indicate not only the farm fields across the road but the entire U.S. agricultural system.

“This is the ecosystem that feeds us, and it has just been nuked,” Crews says. “Is this really the best we can do?”

The seed

Land Institute scientists disagree about how to describe what they’re proposing. Is it a natural evolution from the past 10,000 years of annual agriculture? Or something more like a midcourse correction?

Rachel Stroer, the Land Institute’s president, calls it a “paradigm shift.”

“Instead of an annual monoculture,” she says, “we’re trying to create a perennial polyculture” — cultivating diverse mixes of long-lived plants.

“We want to create an agricultural system to feed humanity that uses nature as the measure of success.”

[Pets can help fight climate change with an insect-based diet. Owners just need to come around to the idea.]

Before people started intensively farming here, Kansas boasted some of the richest soils on Earth. In native prairies, dozens of grass species intermingled with clover, wildflowers, lichens and shrubs, their roots extending as far as 15 feet into the ground. Periodic fires sparked by lightning or set by native people helped clear debris and promote new growth. Insects, birds, prairie dogs and buffalo foraged in the vegetation, while millions of munching microbes buried carbon and other nutrients deep in the earth.

“The ecosystems that built the soils upon which we eat today, and that we have degraded, were perennial and diverse,” Stroer says. “That’s where we get those two characteristics that we’re trying to bring back into agriculture.”

Yet proponents of perennial polyculture have a problem: More than half of all calories consumed by people come from grains, and no one has ever domesticated a grain that lived beyond a year.

That challenge falls to plant biologists such as Lee DeHaan. The son of a Minnesota corn and soy grower, he’d heard family members talk about the Land Institute’s ideas with some skepticism.

“But it captivated me,” he says. “I saw it as solving food for humans, environmental problems and financial security for farmers.”

He began experimenting with a wild grain known as Thinopyrum intermedium, or intermediate wheatgrass. Originally from the steppes of Europe and Asia, it had been brought to North America as forage for cattle, but scientists had a hunch it could also feed people.

In the early 2000s, Land Institute scientists planted their first plots of intermediate wheatgrass. When the plants matured, DeHaan and his colleagues selected the 1,000 top specimens to replant. And when those plants matured, they chose the best among them for further breeding. It was the same process that farmers have been using to domesticate crops for millennia.

To the scientists’ surprise, those early harvests were wildly successful. The new batch of plants had stronger stalks and bigger seeds that didn’t fall out of their husks before they could be harvested.

[Desalination can make saltwater drinkable — but it won’t solve the U.S. water crisis]

“We started to realize we were not that far away from something farmers could actually use,” DeHaan says.

“But the original domestication of crops took hundreds and thousands of years,” he adds. “And with climate change, we don’t have that much time.”

So he turned to tools that were unavailable to his ancient predecessors: gene sequencing, artificial intelligence and advanced supercomputers. Once DeHaan identified the genetic markers associated with the traits he was looking for, he didn’t need to wait for the plants to fully mature before picking the best ones to breed.

After two decades and 11 cycles of this process, the Land Institute has domesticated a form of wheatgrass whose seeds are two to three times bigger than those of its wild ancestor. Under ideal conditions, it can provide as much as 30 percent of the yield of traditional wheat. They call their trademarked creation Kernza — an amalgamation of “kernel” and “Kansas.”Story continues below advertisement

But the plant’s best qualities are below ground. DeHaan shows me a photograph of Kernza’s roots hanging in a Land Institute stairwell — the life-size image is so long, it takes up two stories. In the first four years after planting, Land Institute research suggests, a one-acre plot of Kernza will pull roughly 6.5 tons of carbon dioxide out of the air and into those deep roots.

Kernza can’t completely replace regular wheat — at least, not yet. As Jenny kneads our bread dough, she explains that the weaker gluten proteins in Kernza flour make it harder for loaves to hold their shape. And because Kernza grains are so small, the flour also has proportionally more bran, the hard outer coating of a grain. This isn’t necessarily a bad thing — bran is full of fiber, protein and other nutrients. But it’s not exactly ideal for making angel food cake.

Still, mixed with an equal amount of whole-wheat bread flour, it’s shaping up to make a good-looking loaf. Jenny places the dough inside a cast-iron cooking pot, which will help the bread bake evenly, and slides it into the hot, waiting oven.

The harvest

Before those grains arrived in my kitchen, they were grown by someone like Brandon Kaufman, a fourth-generation Kansas farmer. Kaufman is one of the co-founders of Sustain-a-Grain, a coalition of growers and buyers working to turn the Land Institute’s vision of perennial polyculture into a marketable reality.

That means more than just planting Kernza. Farmers must also figure out how to cultivate it alongside other species, creating fields that are diverse as well as deep-rooted.

[A new report measures the true cost of the American diet]

I visit Kaufman on a sparkling summer morning, driving past endless rows of corn, soy and wheat that blanket central Kansas. The orderly fields belie the tumult facing many small farmers. Net cash income for farms in McPherson County, where Kaufman lives, fell by half between 2012 and 2017, according to the U.S. Department of Agriculture. Buying seeds, fertilizer and equipment can put farmers in the red before a single grain is harvested, and natural disasters — which are growing worse because of climate change — can wipe out a whole year’s work in a single day. The combined debt of all U.S. farmers totals more than $400 billion.

Compared with more-traditional farms, Kaufman’s plots look somewhat scruffy. Tufts of chicory, alfalfa and clover are interspersed with the tall stands of Kernza. Ladybugs dot the greenery, and songbirds twitter in the brush. Kaufman leans down to turn over a dried clump of dung — an offering from the cattle he brings to graze here twice a year. Wriggling in the exposed dirt are several soil-enriching earthworms.Story continues below advertisement

Kaufman’s neighbors would call his fields “dirty.” The mix of crops makes them harder to harvest by machine and less profitable per square foot. His own father, who gave him this land, is skeptical of the whole experiment.

Yet Kaufman says perennial polyculture has been profitable for him. He points out the rich, dark green color of Kernza growing beside patches of alfalfa — a product of the latter plant’s ability to fix nitrogen in the soil. When he brings his cattle to eat the alfalfa, they will spread their waste across the fields and trammel old vegetation into the earth. All this means Kaufman doesn’t have to buy synthetic fertilizers or spend time hauling manure. The ladybugs and birds feed on crop pests, reducing the need for pesticides.

“I don’t need all these inputs and overhead,” Kaufman says. “Diversity is my crop insurance.”

[Why we shouldn’t give in to climate despair]

That’s not to say it’s easy. Kaufman is in a constant battle with weeds, which flourish in his herbicide-free fields. Farm equipment isn’t designed to handle Kernza’s small grains, so harvesting and processing are less efficient. There are scores of kinks to work out in the supply chain connecting farmers to consumers.

But Kaufman thinks about the land he inherited, depleted by a century of intensive farming. He thinks about the state of the planet, battered by climate change and species loss and habitat destruction.

And he thinks about his four children, who he hopes will someday earn their livings from this earth. If his experiments with Kernza are successful, he’ll be able to leave them not just a healthier farm but a healthier world.

“Talk about a legacy,” he says.

The meal

Two decades after the Land Institute planted its first field of intermediate wheatgrass, Kernza can be found in the ingredient lists of cereals, baked goods and beers. For now, most of the products are pricey — the flour that Jenny and I are baking with costs more than $11 per pound, for example, compared with less than $1 per pound for regular all-purpose flour.

Meanwhile, DeHaan and colleagues around the world are working on perennializing other crops: soybeans, sorghum, sunflowers for oil. A form of perennial rice developed at Yunnan University in China has been in commercial production since 2018.

“There’s a lot more belief we can achieve what once seemed unachievable,” DeHaan said.Story continues below advertisement

The proof will be in the eating. Jenny pulls our loaf from the oven, filling the kitchen with a tantalizing, yeasty smell.

“I’m excited that there’s movement in the idea of more sustainable agriculture,” she says. “I hope this can prove there’s a market.”

Finally the bread is cool enough to cut into. Jenny takes a bite, tilts her head and chews. “It tastes like —” she trails off, then tries again.

“Texturally, it’s like rye, but a little spongier,” she says. “And it’s almost like it’s got a hint of herby or spicy-ness.”

She grins. “It’s delicious.”

And we both grab another slice.

About this story

Photo editing by Olivier Laurent. Design and development by Andrew Braford.Sarah KaplanFollowSarah Kaplan is a climate reporter covering humanity’s response to a warming world. She previously reported on Earth science and the universe.

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Rice feeds half the world. Climate change’s droughts and floods put it at risk

Scientists and growers will need to innovate to save the staple crop

an aerial photo of rice fields
In a severe drought, rice farmers in California’s Sacramento Valley have to leave some of their fields unplanted (upper left).CALIFORNIA RICE COMMISSION, BRIAN BAER

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By Nikk Ogasa

SEPTEMBER 24, 2021 AT 6:00 AM

Under a midday summer sun in California’s Sacramento Valley, rice farmer Peter Rystrom walks across a dusty, barren plot of land, parched soil crunching beneath each step.

In a typical year, he’d be sloshing through inches of water amid lush, green rice plants. But today the soil lies naked and baking in the 35˚ Celsius (95˚ Fahrenheit) heat during a devastating drought that has hit most of the western United States. The drought started in early 2020, and conditions have become progressively drier.

Low water levels in reservoirs and rivers have forced farmers like Rystrom, whose family has been growing rice on this land for four generations, to slash their water use.

Rystrom stops and looks around. “We’ve had to cut back between 25 and 50 percent.” He’s relatively lucky. In some parts of the Sacramento Valley, depending on water rights, he says, farmers received no water this season.

California is the second-largest U.S. producer of rice, after Arkansas, and over 95 percent of California’s rice is grown within about 160 kilometers of Sacramento. To the city’s east rise the peaks of the Sierra Nevada, which means “snowy mountains” in Spanish. Rice growers in the valley below count on the range to live up to its name each winter. In spring, melting snowpack flows into rivers and reservoirs, and then through an intricate network of canals and drainages to rice fields that farmers irrigate in a shallow inundation from April or May to September or October.

If too little snow falls in those mountains, farmers like Rystrom are forced to leave fields unplanted. On April 1 this year, the date when California’s snowpack is usually at its deepest, it held about 40 percent less water than average, according to the California Department of Water Resources. On August 4, Lake Oroville, which supplies Rystrom and other local rice farmers with irrigation water, was at its lowest level on record.

a barren muddy field
Drought in the Sacramento Valley has forced Peter Rystrom and other rice farmers to leave swaths of land barren.N. OGASA

Not too long ago, the opposite — too much rain — stopped Rystrom and others from planting. “In 2017 and 2019, we were leaving ground out because of flood. We couldn’t plant,” he says. Tractors couldn’t move through the muddy, clay-rich soil to prepare the fields for seeding.

Climate change is expected to worsen the state’s extreme swings in precipitation, researchers reported in 2018 in Nature Climate Change. This “climate whiplash” looms over Rystrom and the other 2,500 or so rice producers in the Golden State. “They’re talking about less and less snowpack, and more concentrated bursts of rain,” Rystrom says. “It’s really concerning.”

Farmers in China, India, Bangladesh, Indonesia, Vietnam — the biggest rice-growing countries — as well as in Nigeria, Africa’s largest rice producer — also worry about the damage climate change will do to rice production. More than 3.5 billion people get 20 percent or more of their calories from the fluffy grains. And demand is increasing in Asia, Latin America and especially in Africa.

To save and even boost production, rice growers, engineers and researchers have turned to water-saving irrigation routines and rice gene banks that store hundreds of thousands of varieties ready to be distributed or bred into new, climate-resilient forms. With climate change accelerating, and researchers raising the alarm about related threats, such as arsenic contamination and bacterial diseases, the demand for innovation grows.

“If we lose our rice crop, we’re not going to be eating,” says plant geneticist Pamela Ronald of the University of California, Davis. Climate change is already threatening rice-growing regions around the world, says Ronald, who identifies genes in rice that help the plant withstand disease and floods. “This is not a future problem. This is happening now.”

The top rice producers are in Asia

The world’s top rice producer is China, at 214 million metric tons. India, Bangladesh, Indonesia and Vietnam are next. In Africa, Nigeria (6.8 million) is the largest producer. Brazil (11.8 million) and the United States (10.2 million) are also top producers, according to 2018 data from the U.N. Food and Agriculture Organization.

Worldwide rice production, 2018
a map showing where rice is grown around the world
OURWORLDINDATA.ORG

SOURCE: FAO

Saltwater woes

Most rice plants are grown in fields, or paddies, that are typically filled with around 10 centimeters of water. This constant, shallow inundation helps stave off weeds and pests. But if water levels suddenly get too high, such as during a flash flood, the rice plants can die.

Striking the right balance between too much and too little water can be a struggle for many rice farmers, especially in Asia, where over 90 percent of the world’s rice is produced. Large river deltas in South and Southeast Asia, such as the Mekong River Delta in Vietnam, offer flat, fertile land that is ideal for farming rice. But these low-lying areas are sensitive to swings in the water cycle. And because deltas sit on the coast, drought brings another threat: salt.

Salt’s impact is glaringly apparent in the Mekong River Delta. When the river runs low, saltwater from the South China Sea encroaches upstream into the delta, where it can creep into the soils and irrigation canals of the delta’s rice fields.

a farmer's hand holding dead rice plants being pulled from a paddy
In Vietnam’s Mekong River Delta, farmers pull dead rice plants from a paddy that was contaminated by saltwater intrusion from the South China Sea, which can happen during a drought.HOANG DINH NAM/AFP VIA GETTY IMAGES

“If you irrigate rice with water that’s too salty, especially at certain [growing] stages, you are at risk of losing 100 percent of the crop,” says Bjoern Sander, a climate change specialist at the International Rice Research Institute, or IRRI, who is based in Vietnam.

In a 2015 and 2016 drought, saltwater reached up to 90 kilometers inland, destroying 405,000 hectares of rice paddies. In 2019 and 2020, drought and saltwater intrusion returned, damaging 58,000 hectares of rice. With regional temperatures on the rise, these conditions in Southeast Asia are expected to intensify and become more widespread, according to a 2020 report by the Economic and Social Commission for Asia and the Pacific.

Then comes the whiplash: Each year from around April to October, the summer monsoon turns on the faucet over swaths of South and Southeast Asia. About 80 percent of South Asia’s rainfall is dumped during this season and can cause destructive flash floods.

Bangladesh is one of the most flood-prone rice producers in the region, as it sits at the mouths of the Ganges, Brahmaputra and Meghna rivers. In June 2020, monsoon rains flooded about 37 percent of the country, damaging about 83,000 hectares of rice fields, according to Bangladesh’s Ministry of Agriculture. And the future holds little relief; South Asia’s monsoon rainfall is expected to intensify with climate change, researchers reported June 4 in Science Advances.

A hot mess

Water highs and lows aren’t the entire story. Rice generally grows best in places with hot days and cooler nights. But in many rice-growing regions, temperatures are getting too hot. Rice plants become most vulnerable to heat stress during the middle phase of their growth, before they begin building up the meat in their grains. Extreme heat, above 35˚ C, can diminish grain counts in just weeks, or even days. In April in Bangladesh, two consecutive days of 36˚ C destroyed thousands of hectares of rice.

In South and Southeast Asia, such extreme heat events are expected to become common with climate change, researchers reported in July in Earth’s Future. And there are other, less obvious, consequences for rice in a warming world.

One of the greatest threats is bacterial blight, a fatal plant disease caused by the bacterium Xanthomonas oryzae pv. oryzae. The disease, most prevalent in Southeast Asia and rising in Africa, has been reported to have cut rice yields by up to 70 percent in a single season.

“We know that with higher temperature, the disease becomes worse,” says Jan Leach, a plant pathologist at Colorado State University in Fort Collins. Most of the genes that help rice combat bacterial blight seem to become less effective when temperatures rise, she explains.

And as the world warms, new frontiers may open for rice pathogens. An August study in Nature Climate Change suggests that as global temperatures rise, rice plants (and many other crops) at northern latitudes, such as those in China and the United States, will be at higher risk of pathogen infection.

Meanwhile, rising temperatures may bring a double-edged arsenic problem. In a 2019 study in Nature Communications, E. Marie Muehe, a biogeochemist at the Helmholtz Centre for Environmental Research in Leipzig, Germany, who was then at Stanford University, showed that under future climate conditions, more arsenic will infiltrate rice plants. High arsenic levels boost the health risk of eating the rice and impair plant growth.

Leaching in

When grown in a greenhouse at 5 degrees Celsius above preindustrial temperatures with elevated carbon dioxide levels (representing a future climate), California rice varieties absorbed more of a type of highly toxic arsenic from the soil, raising the rice’s arsenic levels above European Union safety thresholds.

Arsenic levels in rice grains
a chart showing arsenic in rice under different climate conditions
CREDIT: E. OTWELL

SOURCE: E.M. MUEHE ET AL/NATURE COMM.2019

Arsenic naturally occurs in soils, though in most regions the toxic element is present at very low levels. Rice, however, is particularly susceptible to arsenic contamination, because it is grown in flooded conditions. Paddy soils lack oxygen, and the microbes that thrive in this anoxic environment liberate arsenic from the soil. Once the arsenic is in the water, rice plants can draw it in through their roots. From there, the element is distributed throughout the plants’ tissues and grains.

Muehe and her team grew a Californian variety of rice in a local low-arsenic soil inside climate-controlled greenhouses. Increasing the temperature and carbon dioxide levels to match future climate scenarios enhanced the activity of the microbes living in the rice paddy soils and increased the amount of arsenic in the grains, Muehe says. And importantly, rice yields diminished. In the low-arsenic Californian soil under future climate conditions, rice yield dropped 16 percent.

According to the researchers, models that forecast the future production of rice don’t account for the impact of arsenic on harvest yields. What that means, Muehe says, is that current projections are overestimating how much rice will be produced in the future.

Managing rice’s thirst

From atop an embankment that edges one of his fields, Rystrom watches water gush from a pipe, flooding a paddy packed with rice plants. “On a year like this, we decided to pump,” he says.

Able to tap into groundwater, Rystrom left only about 10 percent of his fields unplanted this growing season. “If everybody was pumping from the ground to farm rice every year,” he admits, it would be unsustainable.

One widely studied, drought-friendly method is “alternate wetting and drying,” or intermittent flooding, which involves flooding and draining rice paddies on one- to 10-day cycles, as opposed to maintaining a constant inundation. This practice can cut water use by up to 38 percent without sacrificing yields. It also stabilizes the soil for harvesting and lowers arsenic levels in rice by bringing more oxygen into the soils, disrupting the arsenic-releasing microbes. If tuned just right, it may even slightly improve crop yields.

But the water-saving benefits of this method are greatest when it is used on highly permeable soils, such as those in Arkansas and other parts of the U.S. South, which normally require lots of water to keep flooded, says Bruce Linquist, a rice specialist at the University of California Cooperative Extension. The Sacramento Valley’s clay-rich soils don’t drain well, so the water savings where Rystrom farms are minimal; he doesn’t use the method.

Building embankments, canal systems and reservoirs can also help farmers dampen the volatility of the water cycle. But for some, the solution to rice’s climate-related problems lies in enhancing the plant itself.

three men stand next to each other
Fourth-generation rice farmer Peter Rystrom (left) stands with his grandfather Don Rystrom (middle) and his father Steve Rystrom (right).CALIFORNIA RICE COMMISSION, BRIAN BAER

Better breeds

The world’s largest collection of rice is stored near the southern rim of Laguna de Bay in the Philippines, in the city of Los Baños. There, the International Rice Genebank, managed by IRRI, holds over 132,000 varieties of rice seeds from farms around the globe.

Upon arrival in Los Baños, those seeds are dried and processed, placed in paper bags and moved into two storage facilities — one cooled to 2˚ to 4˚ C from which seeds can be readily withdrawn, and another chilled to –20˚ C for long-term storage. To be extra safe, backup seeds are kept at the National Center for Genetic Resources Preservation in Fort Collins, Colo., and the Svalbard Global Seed Vault tucked inside a mountain in Norway.

All this is done to protect the biodiversity of rice and amass a trove of genetic material that can be used to breed future generations of rice. Farmers no longer use many of the stored varieties, instead opting for new higher-yield or sturdier breeds. Nevertheless, solutions to climate-related problems may be hidden in the DNA of those older strains. “Scientists are always looking through that collection to see if genes can be discovered that aren’t being used right now,” says Ronald, of UC Davis. “That’s how Sub1 was discovered.”

two people in blue jumpsuits looking at rice seeds on shelves
Over 132,000 varieties of rice seeds fill the shelves of the climate-controlled International Rice Genebank. Breeders from around the world can use the seeds to develop new climate-resilient rice strains.IRRI/FLICKR (CC BY-NC-SA 2.0)

The Sub1 gene enables rice plants to endure prolonged periods completely submerged underwater. It was discovered in 1996 in a traditional variety of rice grown in the Indian state of Orissa, and through breeding has been incorporated into varieties cultivated in flood-prone regions of South and Southeast Asia. Sub1-wielding varieties, called “scuba rice,” can survive for over two weeks entirely submerged, a boon for farmers whose fields are vulnerable to flash floods.

Some researchers are looking beyond the genetic variability preserved in rice gene banks, searching instead for useful genes from other species, including plants and bacteria. But inserting genes from one species into another, or genetic modification, remains controversial. The most famous example of genetically modified rice is Golden Rice, which was intended as a partial solution to childhood malnutrition. Golden Rice grains are enriched in beta-carotene, a precursor to vitamin A. To create the rice, researchers spliced a gene from a daffodil and another from a bacterium into an Asian variety of rice.

Three decades have passed since its initial development, and only a handful of countries have deemed Golden Rice safe for consumption. On July 23, the Philippines became the first country to approve the commercial production of Golden Rice. Abdelbagi Ismail, principal scientist at IRRI, blames the slow acceptance on public perception and commercial interests opposed to genetically modified organisms, or GMOs (SN: 2/6/16, p. 22).

Looking ahead, it will be crucial for countries to embrace GM rice, Ismail says. Developing nations, particularly those in Africa that are becoming more dependent on the crop, would benefit greatly from the technology, which could produce new varieties faster than breeding and may allow researchers to incorporate traits into rice plants that conventional breeding cannot. If Golden Rice were to gain worldwide acceptance, it could open the door for new genetically modified climate- and disease-resilient varieties, Ismail says. “It will take time,” he says. “But it will happen.”

Climate change is a many-headed beast, and each rice-growing region will face its own particular set of problems. Solving those problems will require collaboration between local farmers, government officials and the international community of researchers.

“I want my kids to be able to have a shot at this,” Rystrom says. “You have to do a lot more than just farm rice. You have to think generations ahead.”

Climate-resilient rice

To keep rice bowls around the world full, researchers breed new varieties of rice that can endure stresses like drought, floods and salt.

Sahbhagi Dhan: Traditional rice varieties take 120 to 150 days to harvest and require four irrigations. Sahbhagi Dhan is a drought-tolerant variety harvested after 105 days and just two irrigations. In normal conditions, it produces about twice as much rice (four to five metric tons per hectare) as other local varieties in India. Under drought conditions, it produces one to two metric tons per hectare; local varieties produce none.

rice paddies
Scuba rice contains a gene that enables the plant to survive several days underwater, important for areas that experience flooding.IRRI/FLICKR (CC BY-NC-SA 2.0)

Scuba riceSub1, a submergence-tolerance gene, has been bred into scuba rice varieties. Rice normally dies after three to four days of total submergence — many varieties will exhaust themselves to death trying to quickly grow to the water’s surface. Sub1 varieties (shown), however, refrain from this frenzied growth spurt, and can withstand over two weeks underwater, able to survive the sudden floods of the summer monsoon.

Salt-tolerant rice: Made by inserting an area of the genome called Saltol, salt-tolerant rice varieties are better able to regulate the amount of sodium ions, toxic in high amounts, in their tissues. Saltol has been incorporated into high-yield varieties throughout the world.

Questions or comments on this article? E-mail us at feedback@sciencenews.org

A version of this article appears in the September 25, 2021 issue of Science News.

CITATIONS

T.M. Chaloner et alPlant pathogen infection risk tracks global crop yields under climate changeNature Climate Change. Vol. 11. Aug. 5, 2021. doi: 10.1038/s41558-021-01104-8

S.C. Clemens et al. Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictionsScience Advances. Vol. 7. June 4, 2021. doi: 10.1126/sciadv.abg3848

A.S. Alisjahbana and D.L. Jock Hoi. Ready for the Dry Years: Building resilience to drought in South-East Asia (2nd edition). United Nations (Economic and Social Commission for Asia and the Pacific) and the Association of Southeast Asian Nations. 2021.

E.M. Muehe et al. Rice production threatened by coupled stresses of climate and soil arsenicNature Communications. Vol. 10. Nov. 1, 2019. doi: 10.1038/s41467-019-12946-4.

D.L. Swain et al. Increasing precipitation volatility in twenty-first-century CaliforniaNature Climate Change. Vol. 8. April 23, 2018. doi: 10.1038/s41558-018-0140-y

Nikk Ogasa

About Nikk Ogasa

Nikk Ogasa was a summer 2021 science writer intern. He has a master’s degree in geology from McGill University, and a master’s degree in science communication from the University of California, Santa Cruz. He lives in Santa Cruz, Calif.

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Nutrition and Climate Change: World Food Prize Laureates on Implications for Feed the Future and Achieving the SDGs

Oct 21, 2021onlineLaureates will share insights and key messages for USAID, Feed the Future, and a wide network of partners. CLIMATE AND NATURAL RESOURCES

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Rice feeds half the world. Climate change’s droughts and floods put it at risk

Scientists and growers will need to innovate to save the staple crop

an aerial photo of rice fields
In a severe drought, rice farmers in California’s Sacramento Valley have to leave some of their fields unplanted (upper left).CALIFORNIA RICE COMMISSION, BRIAN BAER

Share this:

By Nikk Ogasa

SEPTEMBER 24, 2021 AT 6:00 AM

Under a midday summer sun in California’s Sacramento Valley, rice farmer Peter Rystrom walks across a dusty, barren plot of land, parched soil crunching beneath each step.

In a typical year, he’d be sloshing through inches of water amid lush, green rice plants. But today the soil lies naked and baking in the 35˚ Celsius (95˚ Fahrenheit) heat during a devastating drought that has hit most of the western United States. The drought started in early 2020, and conditions have become progressively drier.

Low water levels in reservoirs and rivers have forced farmers like Rystrom, whose family has been growing rice on this land for four generations, to slash their water use.

Rystrom stops and looks around. “We’ve had to cut back between 25 and 50 percent.” He’s relatively lucky. In some parts of the Sacramento Valley, depending on water rights, he says, farmers received no water this season.

California is the second-largest U.S. producer of rice, after Arkansas, and over 95 percent of California’s rice is grown within about 160 kilometers of Sacramento. To the city’s east rise the peaks of the Sierra Nevada, which means “snowy mountains” in Spanish. Rice growers in the valley below count on the range to live up to its name each winter. In spring, melting snowpack flows into rivers and reservoirs, and then through an intricate network of canals and drainages to rice fields that farmers irrigate in a shallow inundation from April or May to September or October.

If too little snow falls in those mountains, farmers like Rystrom are forced to leave fields unplanted. On April 1 this year, the date when California’s snowpack is usually at its deepest, it held about 40 percent less water than average, according to the California Department of Water Resources. On August 4, Lake Oroville, which supplies Rystrom and other local rice farmers with irrigation water, was at its lowest level on record.

a barren muddy field
Drought in the Sacramento Valley has forced Peter Rystrom and other rice farmers to leave swaths of land barren.N. OGASA

Not too long ago, the opposite — too much rain — stopped Rystrom and others from planting. “In 2017 and 2019, we were leaving ground out because of flood. We couldn’t plant,” he says. Tractors couldn’t move through the muddy, clay-rich soil to prepare the fields for seeding.

Climate change is expected to worsen the state’s extreme swings in precipitation, researchers reported in 2018 in Nature Climate Change. This “climate whiplash” looms over Rystrom and the other 2,500 or so rice producers in the Golden State. “They’re talking about less and less snowpack, and more concentrated bursts of rain,” Rystrom says. “It’s really concerning.”

Farmers in China, India, Bangladesh, Indonesia, Vietnam — the biggest rice-growing countries — as well as in Nigeria, Africa’s largest rice producer — also worry about the damage climate change will do to rice production. More than 3.5 billion people get 20 percent or more of their calories from the fluffy grains. And demand is increasing in Asia, Latin America and especially in Africa.

To save and even boost production, rice growers, engineers and researchers have turned to water-saving irrigation routines and rice gene banks that store hundreds of thousands of varieties ready to be distributed or bred into new, climate-resilient forms. With climate change accelerating, and researchers raising the alarm about related threats, such as arsenic contamination and bacterial diseases, the demand for innovation grows.

“If we lose our rice crop, we’re not going to be eating,” says plant geneticist Pamela Ronald of the University of California, Davis. Climate change is already threatening rice-growing regions around the world, says Ronald, who identifies genes in rice that help the plant withstand disease and floods. “This is not a future problem. This is happening now.”

The top rice producers are in Asia

The world’s top rice producer is China, at 214 million metric tons. India, Bangladesh, Indonesia and Vietnam are next. In Africa, Nigeria (6.8 million) is the largest producer. Brazil (11.8 million) and the United States (10.2 million) are also top producers, according to 2018 data from the U.N. Food and Agriculture Organization.

Worldwide rice production, 2018
a map showing where rice is grown around the world
OURWORLDINDATA.ORG

SOURCE: FAO

Saltwater woes

Most rice plants are grown in fields, or paddies, that are typically filled with around 10 centimeters of water. This constant, shallow inundation helps stave off weeds and pests. But if water levels suddenly get too high, such as during a flash flood, the rice plants can die.

Striking the right balance between too much and too little water can be a struggle for many rice farmers, especially in Asia, where over 90 percent of the world’s rice is produced. Large river deltas in South and Southeast Asia, such as the Mekong River Delta in Vietnam, offer flat, fertile land that is ideal for farming rice. But these low-lying areas are sensitive to swings in the water cycle. And because deltas sit on the coast, drought brings another threat: salt.

Salt’s impact is glaringly apparent in the Mekong River Delta. When the river runs low, saltwater from the South China Sea encroaches upstream into the delta, where it can creep into the soils and irrigation canals of the delta’s rice fields.

a farmer's hand holding dead rice plants being pulled from a paddy
In Vietnam’s Mekong River Delta, farmers pull dead rice plants from a paddy that was contaminated by saltwater intrusion from the South China Sea, which can happen during a drought.HOANG DINH NAM/AFP VIA GETTY IMAGES

“If you irrigate rice with water that’s too salty, especially at certain [growing] stages, you are at risk of losing 100 percent of the crop,” says Bjoern Sander, a climate change specialist at the International Rice Research Institute, or IRRI, who is based in Vietnam.

In a 2015 and 2016 drought, saltwater reached up to 90 kilometers inland, destroying 405,000 hectares of rice paddies. In 2019 and 2020, drought and saltwater intrusion returned, damaging 58,000 hectares of rice. With regional temperatures on the rise, these conditions in Southeast Asia are expected to intensify and become more widespread, according to a 2020 report by the Economic and Social Commission for Asia and the Pacific.

Then comes the whiplash: Each year from around April to October, the summer monsoon turns on the faucet over swaths of South and Southeast Asia. About 80 percent of South Asia’s rainfall is dumped during this season and can cause destructive flash floods.

Bangladesh is one of the most flood-prone rice producers in the region, as it sits at the mouths of the Ganges, Brahmaputra and Meghna rivers. In June 2020, monsoon rains flooded about 37 percent of the country, damaging about 83,000 hectares of rice fields, according to Bangladesh’s Ministry of Agriculture. And the future holds little relief; South Asia’s monsoon rainfall is expected to intensify with climate change, researchers reported June 4 in Science Advances.

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A hot mess

Water highs and lows aren’t the entire story. Rice generally grows best in places with hot days and cooler nights. But in many rice-growing regions, temperatures are getting too hot. Rice plants become most vulnerable to heat stress during the middle phase of their growth, before they begin building up the meat in their grains. Extreme heat, above 35˚ C, can diminish grain counts in just weeks, or even days. In April in Bangladesh, two consecutive days of 36˚ C destroyed thousands of hectares of rice.

In South and Southeast Asia, such extreme heat events are expected to become common with climate change, researchers reported in July in Earth’s Future. And there are other, less obvious, consequences for rice in a warming world.

One of the greatest threats is bacterial blight, a fatal plant disease caused by the bacterium Xanthomonas oryzae pv. oryzae. The disease, most prevalent in Southeast Asia and rising in Africa, has been reported to have cut rice yields by up to 70 percent in a single season.

“We know that with higher temperature, the disease becomes worse,” says Jan Leach, a plant pathologist at Colorado State University in Fort Collins. Most of the genes that help rice combat bacterial blight seem to become less effective when temperatures rise, she explains.

And as the world warms, new frontiers may open for rice pathogens. An August study in Nature Climate Change suggests that as global temperatures rise, rice plants (and many other crops) at northern latitudes, such as those in China and the United States, will be at higher risk of pathogen infection.

Meanwhile, rising temperatures may bring a double-edged arsenic problem. In a 2019 study in Nature Communications, E. Marie Muehe, a biogeochemist at the Helmholtz Centre for Environmental Research in Leipzig, Germany, who was then at Stanford University, showed that under future climate conditions, more arsenic will infiltrate rice plants. High arsenic levels boost the health risk of eating the rice and impair plant growth.

Leaching in

When grown in a greenhouse at 5 degrees Celsius above preindustrial temperatures with elevated carbon dioxide levels (representing a future climate), California rice varieties absorbed more of a type of highly toxic arsenic from the soil, raising the rice’s arsenic levels above European Union safety thresholds.

Arsenic levels in rice grains
a chart showing arsenic in rice under different climate conditions
CREDIT: E. OTWELL

SOURCE: E.M. MUEHE ET AL/NATURE COMM.2019

Arsenic naturally occurs in soils, though in most regions the toxic element is present at very low levels. Rice, however, is particularly susceptible to arsenic contamination, because it is grown in flooded conditions. Paddy soils lack oxygen, and the microbes that thrive in this anoxic environment liberate arsenic from the soil. Once the arsenic is in the water, rice plants can draw it in through their roots. From there, the element is distributed throughout the plants’ tissues and grains.

Muehe and her team grew a Californian variety of rice in a local low-arsenic soil inside climate-controlled greenhouses. Increasing the temperature and carbon dioxide levels to match future climate scenarios enhanced the activity of the microbes living in the rice paddy soils and increased the amount of arsenic in the grains, Muehe says. And importantly, rice yields diminished. In the low-arsenic Californian soil under future climate conditions, rice yield dropped 16 percent.

According to the researchers, models that forecast the future production of rice don’t account for the impact of arsenic on harvest yields. What that means, Muehe says, is that current projections are overestimating how much rice will be produced in the future.

Managing rice’s thirst

From atop an embankment that edges one of his fields, Rystrom watches water gush from a pipe, flooding a paddy packed with rice plants. “On a year like this, we decided to pump,” he says.

Able to tap into groundwater, Rystrom left only about 10 percent of his fields unplanted this growing season. “If everybody was pumping from the ground to farm rice every year,” he admits, it would be unsustainable.

One widely studied, drought-friendly method is “alternate wetting and drying,” or intermittent flooding, which involves flooding and draining rice paddies on one- to 10-day cycles, as opposed to maintaining a constant inundation. This practice can cut water use by up to 38 percent without sacrificing yields. It also stabilizes the soil for harvesting and lowers arsenic levels in rice by bringing more oxygen into the soils, disrupting the arsenic-releasing microbes. If tuned just right, it may even slightly improve crop yields.

But the water-saving benefits of this method are greatest when it is used on highly permeable soils, such as those in Arkansas and other parts of the U.S. South, which normally require lots of water to keep flooded, says Bruce Linquist, a rice specialist at the University of California Cooperative Extension. The Sacramento Valley’s clay-rich soils don’t drain well, so the water savings where Rystrom farms are minimal; he doesn’t use the method.

Building embankments, canal systems and reservoirs can also help farmers dampen the volatility of the water cycle. But for some, the solution to rice’s climate-related problems lies in enhancing the plant itself.

three men stand next to each other
Fourth-generation rice farmer Peter Rystrom (left) stands with his grandfather Don Rystrom (middle) and his father Steve Rystrom (right).CALIFORNIA RICE COMMISSION, BRIAN BAER

Better breeds

The world’s largest collection of rice is stored near the southern rim of Laguna de Bay in the Philippines, in the city of Los Baños. There, the International Rice Genebank, managed by IRRI, holds over 132,000 varieties of rice seeds from farms around the globe.

Upon arrival in Los Baños, those seeds are dried and processed, placed in paper bags and moved into two storage facilities — one cooled to 2˚ to 4˚ C from which seeds can be readily withdrawn, and another chilled to –20˚ C for long-term storage. To be extra safe, backup seeds are kept at the National Center for Genetic Resources Preservation in Fort Collins, Colo., and the Svalbard Global Seed Vault tucked inside a mountain in Norway.

All this is done to protect the biodiversity of rice and amass a trove of genetic material that can be used to breed future generations of rice. Farmers no longer use many of the stored varieties, instead opting for new higher-yield or sturdier breeds. Nevertheless, solutions to climate-related problems may be hidden in the DNA of those older strains. “Scientists are always looking through that collection to see if genes can be discovered that aren’t being used right now,” says Ronald, of UC Davis. “That’s how Sub1 was discovered.”

two people in blue jumpsuits looking at rice seeds on shelves
Over 132,000 varieties of rice seeds fill the shelves of the climate-controlled International Rice Genebank. Breeders from around the world can use the seeds to develop new climate-resilient rice strains.IRRI/FLICKR (CC BY-NC-SA 2.0)

The Sub1 gene enables rice plants to endure prolonged periods completely submerged underwater. It was discovered in 1996 in a traditional variety of rice grown in the Indian state of Orissa, and through breeding has been incorporated into varieties cultivated in flood-prone regions of South and Southeast Asia. Sub1-wielding varieties, called “scuba rice,” can survive for over two weeks entirely submerged, a boon for farmers whose fields are vulnerable to flash floods.

Some researchers are looking beyond the genetic variability preserved in rice gene banks, searching instead for useful genes from other species, including plants and bacteria. But inserting genes from one species into another, or genetic modification, remains controversial. The most famous example of genetically modified rice is Golden Rice, which was intended as a partial solution to childhood malnutrition. Golden Rice grains are enriched in beta-carotene, a precursor to vitamin A. To create the rice, researchers spliced a gene from a daffodil and another from a bacterium into an Asian variety of rice.

Three decades have passed since its initial development, and only a handful of countries have deemed Golden Rice safe for consumption. On July 23, the Philippines became the first country to approve the commercial production of Golden Rice. Abdelbagi Ismail, principal scientist at IRRI, blames the slow acceptance on public perception and commercial interests opposed to genetically modified organisms, or GMOs (SN: 2/6/16, p. 22).

Looking ahead, it will be crucial for countries to embrace GM rice, Ismail says. Developing nations, particularly those in Africa that are becoming more dependent on the crop, would benefit greatly from the technology, which could produce new varieties faster than breeding and may allow researchers to incorporate traits into rice plants that conventional breeding cannot. If Golden Rice were to gain worldwide acceptance, it could open the door for new genetically modified climate- and disease-resilient varieties, Ismail says. “It will take time,” he says. “But it will happen.”

Climate change is a many-headed beast, and each rice-growing region will face its own particular set of problems. Solving those problems will require collaboration between local farmers, government officials and the international community of researchers.

“I want my kids to be able to have a shot at this,” Rystrom says. “You have to do a lot more than just farm rice. You have to think generations ahead.”

Climate-resilient rice

To keep rice bowls around the world full, researchers breed new varieties of rice that can endure stresses like drought, floods and salt.

Sahbhagi Dhan: Traditional rice varieties take 120 to 150 days to harvest and require four irrigations. Sahbhagi Dhan is a drought-tolerant variety harvested after 105 days and just two irrigations. In normal conditions, it produces about twice as much rice (four to five metric tons per hectare) as other local varieties in India. Under drought conditions, it produces one to two metric tons per hectare; local varieties produce none.

rice paddies
Scuba rice contains a gene that enables the plant to survive several days underwater, important for areas that experience flooding.IRRI/FLICKR (CC BY-NC-SA 2.0)

Scuba riceSub1, a submergence-tolerance gene, has been bred into scuba rice varieties. Rice normally dies after three to four days of total submergence — many varieties will exhaust themselves to death trying to quickly grow to the water’s surface. Sub1 varieties (shown), however, refrain from this frenzied growth spurt, and can withstand over two weeks underwater, able to survive the sudden floods of the summer monsoon.

Salt-tolerant rice: Made by inserting an area of the genome called Saltol, salt-tolerant rice varieties are better able to regulate the amount of sodium ions, toxic in high amounts, in their tissues. Saltol has been incorporated into high-yield varieties throughout the world.

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What a warmer, wetter world means for insects, and for what they eat

August 30, 2021 11.28am EDT

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  1. Esther Ndumi NgumbiAssistant Professor, Department of Entomology; African-American Studies, University of Illinois at Urbana-Champaign

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Esther Ndumi Ngumbi is a senior Food Security Fellow with the Aspen Institute New Voices.

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new report has been released by the Intergovernmental Panel on Climate Change (IPCC) – the UN’s authority on climate change – which revealed the latest research on how the Earth is changing and what those changes will mean for the future.

The report shows there’s been a dramatic increase in carbon dioxide (CO2) levels and temperatures, stating that Earth is likely to reach the crucial 1.5℃ warming limit in the early 2030s. There are also dramatic changes in precipitation – water that’s released from clouds, such as rain, snow, or hail.

As an entomologist, I study insects and how climate change stressors – such as flooding and drought – affect what insects eat. I’m also a food security advocate.

The report’s projections caused me to reflect on the many direct and indirect impacts that a warmer and wetter world will have on insects, their natural enemies, plants and African food security.


Read more: How changes in weather patterns could lead to more insect invasions


Across the African continent, recent years brought out some of these extremes, showing what a serious issue this is.

For instance, in southern Africa, the 2016 outbreak of the fall armyworm has continued to spread because of increased rainfall and elevated temperatures – perfect conditions for them to breed and grow quickly. These conditions also supported the growth of over 70 host plants that are fed upon by the fall armyworm.

There’s also a major desert locust outbreak in eastern Africa which started in 2019. It spread due to unusually heavy rainfall that created the perfect environment for locusts to breed and increase in numbers and size. The rains also support the growth of vegetation to feed them.

Here I present a closer look at some of the report’s key findings and show how changes could affect insects and, indirectly, us.

Elevated carbon dioxide levels

Global levels of CO₂ are already high, and they’re expected to continue rising. While elevation in CO₂ does not directly impact insects, it can alter plants’ nutritional quality and chemistry. This will indirectly affect insect herbivores.

For instance, according to recent research, elevated CO₂ reduces the nutritional quality of plant tissues by reducing protein concentrations and certain amino acids in the leaves. To compensate, insect herbivores eat more.

Elevated CO₂ levels can also affect an insect’s development, driving down their numbers – as seen in this study of dung beetles.

Rising temperatures

The report says that global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO₂ and other greenhouse gas emissions occur in the coming decades.

Temperature regulates insects’ physiology and metabolism. An increase in temperature increases physiological activity and, therefore, metabolic rates. Insects must eat more to survive and it’s expected that insect herbivores will consume more and grow faster.

This will lead to increases in the population growth rate of certain insects. Because they grow fast they’ll reproduce more. Their numbers will multiply and this will ultimately lead to more crop damage.


Read more: What changes in temperature mean for Africa’s tsetse fly


Previous research projected that with every increase in one degree of global warming, losses of crops to insects will increase from 10% to 25%.

Drought and flooding

The changing climate is expected to change precipitation patterns – such as rainfall. The report anticipates increased and frequent drought and flooding incidences across the world. These environmental stressors will have an impact on plant productivity, plant chemistry, defences, nutritional quality, palatability, and digestibility.

Consequently, insects eat more plants and this can result in more crop damage.

On the other hand, increased precipitation can support fresh vegetation (food for insects) and can facilitate population buildup of insects. As seen with the desert locust, for example, prolonged rain allowed them to have food, multiply in numbers and spread. This was also the case for the fall armyworm; plentiful rains supported the growth of their host plants. When food for the insects is no longer a limiting factor, their populations continue to build up.


Read more: A new model shows where desert locusts will breed next in East Africa


Reducing effectiveness of natural enemies

All insects have natural enemies or predators. For example, the maize stem borer – a significant insect pest of maize across Africa – has several natural enemies, such as Cotesia flavipes. These predators reduce the populations on insects and further reduce the need to use pesticides to control insect pests.

Predators can be affected by climate changes in many ways. For instance, they can be sensitive to increases in temperature and precipitation, ultimately reducing their numbers. Fewer natural enemies could result in more insect pests. One study, which modelled temperature changes on stem borers in East Africa, showed an increase in their numbers and a decrease in impact by natural enemies.

In addition, because of climate change, both crop distribution ranges and insects will shift. As they seek out conditions that suit them, insects move to new areas that lack their natural enemies. This will cause their populations to grow, resulting in more crop damage.

More palatable food

Because of climate change, weather extremes are likely to happen together.

According to researchplants exposed to double stresses may become even more palatable to insects. This is because when two stressors (say drought and insect herbivory, flooding and insect herbivory, or elevated carbon dioxide and elevated heat) happen together, their impact on crops can be additive or synergistic. This would lead to increased crop damage and reduced crop yields.

What can be done?

Climate change will affect agricultural plants and the insects associated with them. These effects are complex, but it is certain pest pressures will increase. There is a need for more insect monitoring and forecasting and modelling so that we can develop adaptation strategies.

In addition, countries should continue to monitor, share information, and use historical data and modelling to predict and prepare for an uncertain future that is expected to have hungrier insect pests, with impacts on crop productivity and food security.

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