Posts Tagged ‘cassava’


Researchers in Indonesia are releasing the parasitic wasp Anagyrus lopezi in an attempt to save cassava crops from destructive mealybugs.

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Last-ditch effort to aims to save Indonesia’s cassava cash crop.

Originally published: Sep 24 2014 – 9:30am
By: Ker Than, Contributor
(Inside Science) — Scientists today released 2,000 South American parasitic wasps in Indonesia as part of a project aimed at thwarting an invasive insect pest that is devastating the country’s cassava food crop.

The wasps were released into a small, confined field, enabling scientists to assess their performance under local environmental conditions.

“Today’s release constitutes the start of what could eventually become a nationwide release campaign,” said Kris Wyckhuys, an entomologist at the International Center for Tropical Agriculture, a Colombia-based nonprofit that is helping organize the release. The technique has been used, with success, to protect cassava in other countries.

“Once the wasps have completed a couple of generations in the field cages and perform well, the cages could be opened and a full field release can be initiated,” Wyckhuys said.

The use of the parasitic wasps to control cassava mealybugs is a textbook case of classical biological control, in which the natural enemies of a pest are imported from its native country to slow its spread. Edwin Rajotte, an entomologist at Pennsylvania State University in University Park, said that while there are famous situations where classical biological control has not gone according to plan – the introduction of cane toads in Australia is one – the technique’s benefits outweigh its risks.

“A natural enemy has evolved with the pest in its home range, so it is adapted to efficiently seek and parasitize the pest. And they are usually able to move with the pest population as it invades new areas,” said Rajotte, who is not involved in the Indonesia project. “Pests are also not likely to develop resistance to a natural enemy.”

Cassava, also called manioc and yuca, is a bush-like plant that is originally from South America. Its tubers and leaves are now a major food source in many parts of the world, especially Africa and Southeast Asia.

Indonesia is a major cassava producer, and plants roughly one million hectares of the crop every year. In recent years, however, a pill-shaped insect known as the cassava pink mealybug has been ravaging the country’s crops. Also from South America, the mealybug is one of the most destructive cassava pests in the world, capable of reducing cassava yields by up to 84 percent. It kills cassava plants by sucking on their sap, depriving them of vital nutrients and water.

Chemical insecticides have proven ineffective against the mealybug because its body is covered in a protective wax coating. So to slow the mealybug’s spread in Asia, scientists have recruited a natural enemy from its homeland, the tiny Anagyrus lopezi wasp.

“Cassava is originally from South America, so it makes sense that the crop’s pests come from there too,” Wyckhuys said.

About two millimeters long, the parasitic wasp lays its eggs inside the mealybug’s body. When the larvae hatch, they eat their way out of the mealybugs, slowly mummifying and killing them. Scientists estimate that a single female wasp can kill up to 200 mealybugs during the two to three weeks that it lives.

The A. lopezi wasp was first exported to fight mealybug infestations in sub-Saharan Africa in the 1980s, with spectacular results. Scientists estimate the wasps saved about U.S. $20 billion in damages to the cassava industry there.

Since then, however, the mealybug has spread to many parts of Southeast Asia, probably by hitchhiking on infected cassava as it was transported across countries and continents.

“Farmers, traders and middlemen often source planting material from one cassava-growing area to another, and more often than not, they do so without given proper care and attention to mealybug-infestation,” Wyckhuys said.

The Indonesia experiment will mark the second time the wasp has been purposely recruited to fight the mealybugs in Southeast Asia. In 2010, more than a quarter-million wasps were released in Thailand, where they have done a “relatively good job” fighting the mealybug infestation there, Wychkuys said. He noted that occasional outbreaks are reported in large cassava plantations.

Rangaswamy Muniappan, director of the Integrated Pest Management Innovation Lab at Virginia Tech in Blacksburg, which is a key partner in the Indonesia release operation, stressed that before being released, the wasps were kept in quarantine to ensure that they fed only on cassava mealybugs and posed no threat to humans, animals or other insects.

“That has been proven, and the Indonesian government has given permission for this field release,” Muniappan said.

Scientists say that once a full deployment is begun, it should take about a year and a half for the wasps to reduce the mealybug population down to about 15 percent of its current level.

“At that point, they will no longer be of concern,” Muniappan said, “because they won’t be causing much economic damage.”

Ker Than is a freelance writer living in the Bay Area. He tweets at @kerthan.

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PRI’s The World
Reporter Cynthia Graber
July 02, 2014 · 2:15 PM EDT



Thin filaments of fungi form a dense network between the roots of most of the world’s food crops. Some researchers believe that working with such microbes rather than against them, as has often been the case in conventional agriculture, will help the world grow more food with less environmental impact.





Geneticist Ian Sanders and his colleagues grew cassava in this field in Colombia using a fungal gel that he says improved yields by 20 percent. Cassava, which is native to Colombia, is one of the world’s most important food crops, feeding over a billion people.


Thin filaments of fungi form a dense network between the roots of most of the world’s food crops. Some researchers believe that working with such microbes rather than against them, as has often been the case in conventional agriculture, will help the world grow more food with less environmental impact.

Stick a shovel in the ground and you’ll dig up some soil, maybe a few little rocks and, of course, some roots.

Now — take those roots inside for a closer look and you’ll see something else as well.

“When you hold this thing up to the light, what you can see is little tiny filaments,” says geneticist Ian Sanders, holding up a root in his lab at the University of Lausanne in Switzerland.

The filaments look like tiny strands of cotton..

“That’s the fungus,” says Sanders.

Sanders is obsessed with fungi, because he thinks they can play a big role in solving the world’s big food challenges in a time of rapid climate change and population growth.

In particular, Sanders is obsessed with a type of fungi that live on the roots of about 80 percent of the plants on the planet. Their tiny filaments help plants grow by drawing water and nutrients to the plant. In return, the plants feed sugars to the fungi.

It’s a symbiotic relationship that Sanders says is incredibly important.

“Almost all our food plants naturally form this association with these fungi,” he says.

And these species of fungi aren’t alone. There are thousands, maybe millions of kinds of fungi, bacteria and other microbes that help plants in a variety of ways.

But their role has been almost invisible to people. In fact, critics say, modern agriculture actively works against them.

“What we’ve done over the last hundred years in agriculture, is to try to take microorganisms out of the picture,” says Seattle microbiologist Rusty Rodriguez.

“And by doing that, by disrupting the soil with tillage, by using chemical pesticides, we have greatly altered the agricultural microbiome.”

Rodriguez is also obsessed with fungi. And like Sanders, he wants to re-alter the agricultural mircobiome. Both are part of a growing field of researchers and entrepreneurs working to bring microorganisms like fungi back into the agricultural mix, but in a new and targeted way. Sanders is breeding new varieties in the lab, while Rodriguez’s company gathers fungi from extreme environments all over the US and cultivates them in their lab and greenhouse in Seattle.

Right now, Rodriguez is using the fungi to help grow tomatoes, soybeans and corn. His hope is that the microbes will help crops like these survive growing climate stresses like droughts and floods and extreme heat and cold.

Rodriguez is working with different kinds of fungi than Sanders. His grow throughout the plant, not just on roots. But his goal is the same — to find and develop fungi that make agriculture both more productive and more sustainable. And, he says, his first two products using these microbes are just about ready for prime time, with a possible launch later this year.

Sanders’s work isn’t quite there yet. He and his colleagues are still conducting field tests in places like Colombia. But he says the results so far have been very promising.

Columbia is home to cassava, a root crop that feeds more than a billion people around the world. Sanders and a group of Colombian researchers set up experimental plots there to grow cassava using a new fungal gel that they hoped would significant increase yields while significantly reducing fertilizer use.

When they harvested their first crop a year later, Sanders says, they were “delighted” by the results — the plants had grown up to 20 percent more roots.

Sanders says the result actually surprised him, but that it was just the beginning. The research team has since grown cassava with different varieties of lab-bred fungi, and so far, he says, the impact has been even more dramatic.

Rodriguez, in Seattle, shares Sanders’s bullish view of the future of agricultural fungi and bacteria.

“Biologics,” he believes, “are the next paradigm for agriculture.”

Of course we’ve heard talk like that before. Think chemical pesticides, synthetic fertilizers and GMOs, all of which brought big initial benefits, but also big environmental problems, or at least big concerns.

So far, there hasn’t been much push-back on biologics from environmentalists, but just because something’s natural doesn’t mean it’s safe. Which is why both Sanders and Rodriguez say they’re working to make sure the fungi they’re developing won’t bring any unwanted impacts.

“You have to know the organism is safe,” Rodriquez says. “I never want to be in a situation where I stand up in front of an audience and they ask me that question and I say ‘I don’t know.’”

What Rodriguez does know is that lots of tools will be needed to help produce more food, more sustainably.

And Sanders says we’ve been standing on some of those tools all along.

“Sometimes people think you have to go to unexplored wilderness to find something completely new,” Sanders says. “But we just have to look in the soil that’s beneath our feet.”


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JAKARTA] Rapid cropland expansion is the main cause of biodiversity loss in tropical countries, a study by UNEP’s (the UN Environment Programme) World Conservation Monitoring Centre and the Cambridge Conservation Initiative has found.

The study, published in PLOS ONE last month (9 January), highlights maize and soybean as the most expansive crops and as the main drivers of biodiversity loss in tropical regions. Other crops that pose a major threat to habitats and wildlife are beans, cassava, cowpea, groundnut, millet, oil palm, rice, sorghum, sugarcane and wheat, the study says.


  • Rapid expansion of crops such as maize and soybean is leading to biodiversity loss in tropical countries
  • Researchers say pace of expansion could derail progress towards meeting the Aichi Biodiversity Targets
  • A range of sustainability standards and policies are suggested as a way forward

It estimates that cropland in tropical countries expanded by 48,000 square kilometres per year from 1999 to 2008, with Brazil, Ethiopia, Indonesia, Nigeria and Sudan experiencing the greatest expansion.

Stuart H. M. Butchart, a UNEP researcher and one of the authors of the study, tells SciDev.Net: “Unsustainable agriculture is the most significant threat to biodiversity, but conservationists have not previously paid much attention to quantifying which particular crops have caused the greatest problems, nor which ones may do so in the future. This [study] starts to address this issue”.

One example of crop expansion cited in the study that has quickened the rate of species extinction is the Mega Rice Project in Kalimantan, Indonesia. Vast tracts of peat swamps were drained starting from the late 1990s in misguided attempts to turn them into rice plantations.

More than one million hectares, an area about a third the size of Belgium, have been converted for rice production, threatening the survival of Borneo’s last orangutans.

Similarly, peat and forest areas gave way to oil palm in Indonesia and Malaysia while soybean expansion have also replaced habitats of particularly high biodiversity value in the Brazilian Cerrado savanna. Expanding maize cultivation also threatens the dry forests of Madagascar.

Krystof Obidzinski, a scientist at the Centre for International Forestry Research, in Bogor, Indonesia, says that large-scale land acquisition is proceeding apace in countries like Indonesia — with economic benefits dominating the agenda while environmental impacts appear to be underestimated.

If the pace of expansion continues, the report warns, it could derail progress towards meeting the Aichi Biodiversity Targets, a set of 20, time-bound measurable targets aimed at halting global biodiversity loss by the middle of the century.

Butchart believes there should be a system in place so that consumers can make informed choices about the food they buy and how sustainably they have been produced. Such a system could reduce and minimise impacts of agriculture on biodiversity.

Customers can then discern which products are least damaging to the environment and producers have an incentive to minimise their negative impacts.

The study highlights the urgent need for more effective sustainability standards and policies addressing both production and consumption of commodities including robust land-use planning in agricultural frontiers, establishment of new protected areas or REDD+ projects in places agriculture has not yet reached, and reduction or elimination of incentives for land-demanding bioenergy feedstocks.

This article has been produced by SciDev.Net’s South-East Asia & Pacific desk.

Link to full article in PLOS ONE



PLOS ONE doi:10.1371/journal.pone.0051759 (2013)



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April 3, 2014 by acarvajal
El talón de Aquiles de la yuca, una raíz, cultivada ampliamente en África, Asia y América Latina, es la vulnerabilidad a las plagas y enfermedades. Esto debido en parte al método de propagación del cultivo —generalmente mediante la siembra de estacas del tallo— que muchas veces facilita que las plagas y enfermedades pasen de una temporada de cultivo a otra.



Científicos del CIAT, apoyados por la Fundación Bill y Melinda Gates, a través del programa Grand Challenges Explorations (GCE), le apostaron en 2012 a un proyecto de investigación orientado a propagar yuca usando semillas sintéticas producidas por plantas limpias y sanas, para contribuir a romper este ciclo de plagas y enfermedades. “Las semillas se producirían a partir de embriones somáticos in vitro que provienen de plantas libres de enfermedades”, aclara Paul Chavarriaga, biólogo molecular del Área de Investigación en Agrobiodiversidad del CIAT.

Tras casi dos años de investigación en el proyecto “Semillas sintéticas para la propagación clonal de yuca libre de enfermedades”, los resultados son positivos y muy alentadores. Tanto así que dos de los científicos del CIAT involucrados en el proyecto, Paul Chavarriaga y Roosevelt Escobar, han sido invitados a participar en el taller del programa piloto Xcelerator de GCE, que tendrá lugar del 7 al 9 de abril en el campus de la Fundación Bill y Melinda Gates en Seattle, Estados Unidos.

“Para nosotros esta invitación podría significar el respaldo a este proyecto que buscará sacar del laboratorio los buenos resultados alcanzados, para hacerlos útiles a nivel masivo”, así lo percibe Paul Chavarriaga, quien ve cómo el objetivo de la segunda fase está muy sintonizado con el compromiso de la Fundación Gates para reducir de forma muy importante la propagación de plagas y enfermedades de la yuca en África.

Este taller, financiado por la Alianza del Colegiado Nacional de Inventores e Innovadores (NCIIA, por sus siglas en inglés), la Fundación Lemelson y la Fundación Gates, está diseñado para ser una inmersión de tres días en la que los participantes recibirán capacitación y orientación acerca de la comercialización y desarrollo de su innovación. Todo esto con el fin de facilitar su rápido avance y proveer el apoyo necesario para que alcancen mayor impacto y escala.

– See more at: http://ciatblogs.cgiar.org/agrobiodiversidad/semillas-sinteticas-de-yuca-del-laboratorio-al-uso-masivo/#sthash.pfNHU3Sn.dpuf

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