A multifaceted strategy combining genetically engineered cotton with classical pest control tactics eradicated the pink bollworm from cotton-producing areas of the continental U.S. and Mexico, according to a new study to be published in Proceedings of the National Academy of Sciences.

“Although pink bollworm remains a daunting pest in over 100 countries, our strategic coalition rid the U.S. and Mexico of this invasive insect,” said lead study author Bruce Tabashnik, a Regents Professor in the University of Arizona Department of Entomology.

“By analyzing computer simulations and 21 years of field data from Arizona, we discovered that genetically engineered cotton and the release of billions of sterile pink bollworm moths acted synergistically to suppress this pest,” said Jeffrey Fabrick, a co-author of the study and a research entomologist with the U.S. Department of Agriculture’s Agricultural Research Service.

According to the study, the eradication program saved U.S. cotton growers $192 million from 2014 to 2019. It also helped to reduce insecticides sprayed against all cotton pests by 82%, preventing the application of over a million pounds of insecticides per year in Arizona.

A Long Road to Suppression

Native to Australasia — a region that comprises Australia, New Zealand and some neighboring islands — the pink bollworm is one of the world’s most invasive insects. After female moths lay their eggs on cotton plants, the caterpillars hatch, bore into cotton bolls and devour the seeds within. Their feasting disrupts production of cotton lint.

This voracious pest was first detected in the U.S. in 1917. Using field data from 1969, the new study estimates that over 200 billion pink bollworm caterpillars infested cotton fields in Arizona that year. In 1990, the pest cost Arizona cotton growers $32 million in damages, despite $16 million invested in insecticides to control it.

The tide began to turn in 1996, with the introduction of cotton genetically engineered to produce proteins from the bacterium Bacillus thuringiensis. The proteins in Bt cotton kill pink bollworm and other caterpillar pests but are harmless to people and most beneficial insects.

Although Bt cotton kills essentially 100% of susceptible pink bollworm caterpillars, the pest rapidly evolved resistance to Bt proteins in laboratory experiments at the University of Arizona and in Bt cotton fields in India.

To delay pest resistance, UArizona scientists worked with farmers to develop and implement a strategy of planting non-Bt cotton refuges to allow survival of susceptible insects. Tabashnik’s team also determined the mutations that cause resistance in the lab and used DNA screening to monitor for those adaptations in the field.

Within 10 years, the use of Bt cotton reduced pink bollworm populations by 90%. For the first time since the pest’s arrival, eradication seemed within grasp.

‘Everything but the Kitchen Sink’

“In contrast with the rapid evolution of pest resistance to genetically engineered crops elsewhere, Bt cotton was suppressing this pest in Arizona for 10 years,” Tabashnik explained. “We said, ‘Let’s take this a step further. Let’s throw everything but the kitchen sink at it and get rid of it. If not forever, for as long as we can sustain it.'”

In a concerted, binational effort, University of Arizona Cooperative Extension and research scientists joined forces with cotton growers, the biotech industry and government partners to devise the first program of its kind to eradicate the invasive pest.

In addition to traditional pest control tactics, such as plowing cotton fields after harvest to reduce the pest’s overwintering survival, a novel strategy largely replacing refuges of non-Bt cotton with mass releases of sterile pink bollworm moths was initiated in Arizona in 2006.

The sterile moths were released from airplanes by the billions to overwhelm field populations of the pest. In concert, the U.S. Environmental Protection Agency waived the requirement for planting refuges, allowing farmers in Arizona to plant up to 100% Bt cotton.

To test the success of this multipronged attack, scientists with the University of Arizona College of Agriculture and Life Sciences conducted computer simulations and analyzed field data collected in Arizona from 1998 to 2018. Their results show neither of the two tactics would have worked alone.

“In this era plagued by invasive organisms, as well as doubts about the power of science and controversy about genetic engineering, the study exemplifies the tremendous benefits of collaboration and synergy between biotechnology and classical tactics,” Tabashnik said. “We hope the concepts illustrated here will inspire integrated approaches to combat other invasive life forms.”

“Photosynthesis is the entry point for carbon dioxide to become all the things that allow plants to grow, but measuring canopy photosynthesis is really difficult,” said Carl Bernacchi, a Research Plant Physiologist for the U.S. Department of Agriculture, Agricultural Research Service, who is based at Illinois’ Carl R. Woese Institute for Genomic Biology. “Most methods are time-consuming and only measure a single leaf when it’s the function of all leaves on all plants that really matters in agriculture.”

Bernacchi’s team uses two spectral instruments simultaneously — a hyperspectral camera for scanning crops and a spectrometer used to record very detailed information about sunlight — to quickly measure a signal called Solar Induced Fluorescence (SIF) that is emitted by plants when they become ‘energy-excited’ during photosynthesis.

With this SIF signal, the team gains critical insights about photosynthesis that could ultimately lead to improving crop yields.

They discovered that a key part of the SIF signal better correlates with photosynthetic capacity. This ‘SIF yield’ accounts for only a fraction of the energy emitted as SIF by plants to the energy captured by plants in total, but it carries important information.

“With this insight, we can use a couple of instruments in a synergistic way to make more accurate estimates, and we can make these tools and pipelines more accessible to people who are interested in advancing the translation of photosynthesis,” said Peng Fu, a postdoctoral researcher who led this work at Illinois.

In this study, they picked out specific bands of light that are known to be linked to SIF (and are already well understood physiologically) to better understand what hyperspectral data is actually needed to make these estimates.

In the past, they relied on expensive hyperspectral cameras that captured thousands of bands of light. “However, this study suggests that much cheaper cameras could be used instead now that we know what bands of light are needed,” said Matthew Siebers, a postdoctoral researcher at Illinois.

These tools could speed up progress by orders of magnitude, said Katherine Meacham-Hensold, also a postdoctoral researcher at Illinois. “This technology is game-changing for researchers who are refining photosynthesis as a means to help realize the yields that we will need to feed humanity this century.”

Realizing Increased Photosynthetic Efficiency (RIPE) is an international research project that is improving photosynthesis to equip farmers worldwide with higher-yielding crops to ensure everyone has enough food to lead a healthy and productive life. RIPE is supported by the Bill & Melinda Gates Foundation, the U.S. Foundation for Food and Agriculture Research, and the U.K. Foreign, Commonwealth & Development Office, who are committed to ensuring Global Access and making the project’s technologies available to the farmers who need them the most.

Such superpositions are hard to create, as they are destroyed if any kind of information about the place and time of the event leaks into the surrounding — and even if nobody actually records this information. But when superpositions do occur, they lead to observations that are very different from that of classical physics, questioning down to our very understanding of space and time.

Scientists from EPFL, MIT, and CEA Saclay, publishing in Science Advances, demonstrate a state of vibration that exists simultaneously at two different times, and evidence this quantum superposition by measuring the strongest class of quantum correlations between light beams that interact with the vibration.

The researchers used a very short laser-pulse to trigger a specific pattern of vibration inside a diamond crystal. Each pair of neighboring atoms oscillated like two masses linked by a spring, and this oscillation was synchronous across the entire illuminated region. To conserve energy during this process, a light of a new color is emitted, shifted toward the red of the spectrum.

This classical picture, however, is inconsistent with the experiments. Instead, both light and vibration should be described as particles, or quanta: light energy is quantized into discrete photons while vibrational energy is quantized into discrete phonons (named after the ancient Greek “photo = light” and “phono = sound”).

The process described above should therefore be seen as the fission of an incoming photon from the laser into a pair of photon and phonon — akin to nuclear fission of an atom into two smaller pieces.

But it is not the only shortcoming of classical physics. In quantum mechanics, particles can exist in a superposition state, like the famous Schrödinger cat being alive and dead at the same time.

Even more counterintuitive: two particles can become entangled, losing their individuality. The only information that can be collected about them concerns their common correlations. Because both particles are described by a common state (the wavefunction), these correlations are stronger than what is possible in classical physics. It can be demonstrated by performing appropriate measurements on the two particles. If the results violate a classical limit, one can be sure they were entangled.

In the new study, EPFL researchers managed to entangle the photon and the phonon (i.e., light and vibration) produced in the fission of an incoming laser photon inside the crystal. To do so, the scientists designed an experiment in which the photon-phonon pair could be created at two different instants. Classically, it would result in a situation where the pair is created at time t1 with 50% probability, or at a later time t2 with 50% probability.

But here comes the “trick” played by the researchers to generate an entangled state. By a precise arrangement of the experiment, they ensured that not even the faintest trace of the light-vibration pair creation time (t1 vs. t2) was left in the universe. In other words, they erased information about t1 and t2. Quantum mechanics then predicts that the phonon-photon pair becomes entangled, and exists in a superposition of time t1 and t2. This prediction was beautifully confirmed by the measurements, which yielded results incompatible with the classical probabilistic theory.

By showing entanglement between light and vibration in a crystal that one could hold in their finger during the experiment, the new study creates a bridge between our daily experience and the fascinating realm of quantum mechanics.

“Quantum technologies are heralded as the next technological revolution in computing, communication, sensing, says Christophe Galland, head of the Laboratory for Quantum and Nano-Optics at EPFL and one of the study’s main authors. “They are currently being developed by top universities and large companies worldwide, but the challenge is daunting. Such technologies rely on very fragile quantum effects surviving only at extremely cold temperatures or under high vacuum. Our study demonstrates that even a common material at ambient conditions can sustain the delicate quantum properties required for quantum technologies. There is a price to pay, though: the quantum correlations sustained by atomic vibrations in the crystal are lost after only 4 picoseconds — i.e., 0.000000000004 of a second! This short time scale is, however, also an opportunity for developing ultrafast quantum technologies. But much research lies ahead to transform our experiment into a useful device — a job for future quantum engineers.”

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Materials provided by Ecole Polytechnique Fédérale de Lausanne. Original written by Christophe Galland, Nik Papageorgiou. Note: Content may be edited for style and length.

The research shows a single letter change in their DNA code can potentially decide whether a plant is a lark or a night owl. The findings may help farmers and crop breeders to select plants with clocks that are best suited to their location, helping to boost yield and even the ability to withstand climate change.

The circadian clock is the molecular metronome which guides organisms through day and night — cockadoodledooing the arrival of morning and drawing the curtains closed at night. In plants, it regulates a wide range of processes, from priming photosynthesis at dawn through to regulating flowering time.

These rhythmic patterns can vary depending on geography, latitude, climate and seasons — with plant clocks having to adapt to cope best with the local conditions.

Researchers at the Earlham Institute and John Innes Centre in Norwich wanted to better understand how much circadian variation exists naturally, with the ultimate goal of breeding crops that are more resilient to local changes in the environment — a pressing threat with climate change.

To investigate the genetic basis of these local differences, the team examined varying circadian rhythms in Swedish Arabidopsis plants to identify and validate genes linked to the changing tick of the clock.

Dr Hannah Rees, a postdoctoral researcher at the Earlham Institute and author of the paper, said: “A plant’s overall health is heavily influenced by how closely its circadian clock is synchronised to the length of each day and the passing of seasons. An accurate body clock can give it an edge over competitors, predators and pathogens.

“We were interested to see how plant circadian clocks would be affected in Sweden; a country that experiences extreme variations in daylight hours and climate. Understanding the genetics behind body clock variation and adaptation could help us breed more climate-resilient crops in other regions.”

The team studied the genes in 191 different varieties of Arabidopsis obtained from across the whole of Sweden. They were looking for tiny differences in genes between these plants which might explain the differences in circadian function.

Their analysis revealed that a single DNA base-pair change in a specific gene — COR28 — was more likely to be found in plants that flowered late and had a longer period length. COR28 is a known coordinator of flowering time, freezing tolerance and the circadian clock; all of which may influence local adaptation in Sweden.

“It’s amazing that just one base-pair change within the sequence of a single gene can influence how quickly the clock ticks,” explained Dr Rees.

The scientists also used a pioneering delayed fluorescence imaging method to screen plants with differently-tuned circadian clocks. They showed there was over 10 hours difference between the clocks of the earliest risers and latest phased plants — akin to the plants working opposite shift patterns. Both geography and the genetic ancestry of the plant appeared to have an influence.

“Arabidopsis thaliana is a model plant system,” said Dr Rees. “It was the first plant to have its genome sequenced and it’s been extensively studied in circadian biology, but this is the first time anyone has performed this type of association study to find the genes responsible for different clock types.

“Our findings highlight some interesting genes that might present targets for crop breeders, and provide a platform for future research. Our delayed fluorescence imaging system can be used on any green photosynthetic material, making it applicable to a wide range of plants. The next step will be to apply these findings to key agricultural crops, including brassicas and wheat.”

The results of the study have been published in the journal Plant, Cell and Environment.

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Materials provided by Earlham Institute. Note: Content may be edited for style and length.