WHO WE ARE SERVICES RESOURCES




Most recent stories ›
AgroInsight RSS feed
Blog

Community and microbes December 5th, 2021 by

Vea la versión en español a continuación

“In grad school they taught us budding plant pathologists that the objective of agriculture was to ’feed the plants and kill the bugs,” my old friend Steve Sherwood explained to me on a visit to his family farm near Quito, Ecuador. “But we should have been feeding the microbes in the soil, so they could take care of the plants,”

When Steve and his wife, Myriam Paredes, bought their five-hectare farm, Granja Urkuwayku, in 2000, it was a moonscape on the flanks of the highly eroded Ilaló Volcano. The trees had been burned for charcoal and the soil had been stripped down to the bedrock, a hardened volcanic ash locally called cangahua that looked and felt like concrete. A deep erosion gulley was gouging a wound through the middle of the farm. It was a fixer-upper, which was why Steve and Myriam could afford it.

Now, twenty years later, the land is covered in rich, black soil, with green vegetable beds surrounded by fruit trees and native vegetation.

The first step to this rebirth was to take a tractor to the cangahua, to break up the bedrock so that water and compost could penetrate it. This was the only time Steve plowed the farm.

To build the broken stone into soil, Steve and Myriam added manure, much of it coming from some 100 chickens and 300 guinea pigs – what they describe as the “sparkplugs of the farm’s biological motor.”

By 2015, Urkuwayku seemed to be doing well. The farm has attracted over 300 partners, families that regularly buy a produce basket from the farm, plus extras like bread, eggs, mushrooms, honey, and firewood, in total bringing in about $1,000 a week. Besides their four family members, the farm also employs four people from the neighborhood, bringing in enough money to pay for itself, so Steve and Myriam don’t have to subsidize the farm with their salaries, from teaching. The nasty gulley is now filled in with grass-covered soil, backed up behind erosion dams. Runoff water collects into a 500,000-liter pond, used to irrigate the crops during the dry season.

But in 2015 Myriam and Steve tested the soil and were surprised to see that it was slowly losing its fertility.

They think that the problem was too much tillage and not enough soil cover. Hoeing manure into the vegetable beds was breaking down the soil structure and drying out the beds, killing the beneficial fungi. As Steve explains, “the fungi are largely responsible for building soil particles through their mycelia and sweat, also known as glomalin, a carbon-rich glue that is important for mitigating climate change.” The glomalin help to remove carbon from the air, and store it in the soil.

Then Steve befriended the administrator of a local plywood factory. The mill had collected a mountain of bark that the owner couldn’t get rid of. Steve volunteered to take it off their hands. The two top advantages of peri-urban farming are greater access to customers, and some remarkable sources of organic matter.

So the plywood factory started sending Steve dump-truck loads of bark (mostly eucalyptus). To get the microbes to decompose the bark, Steve composts sawdust with some organic matter from the floor of a local native forest. The microbe-rich sawdust is then mixed with the bark and carefully spread in deep layers between the rows of vegetables, which were now tilled as little as possible. The vegetables are planted in trays, and then transplanted to the open beds.

No matter how much bark and sawdust Steve and his team lay down, the soil always absorbs it. The soil seems to eat the bark, just as in a forest. The soil microbes thrive on the bark to create living structures, like mycelia: fungal threads that reach all the way through the vegetable beds, in between the bark-filled paths. Steve and Myriam have learned that the microbes have a symbiotic relationship with plants; microbes help a plant’s roots find moisture and nutrients, and in turn, the plant gives about a third of all of its energy from photosynthesis back to the microbes.

Myriam and Steve have seen that as the soil becomes healthier, their crops have fewer problems from insect pests and diseases. In large part, this is because of the successful marriage between plants and the ever-growing population of soil microbes. Urkuwayku is greener every year. It produces enough to feed a family and employ four people, while regularly supplying 300 families with top-notch vegetables, fruits, and other produce. A community of consumers supports the farm with income, while a community of microorganisms builds the soil and feeds the plants.

Previous Agro-Insight blog stories

Reviving soils

A revolution for our soil

Enlightened agroecology, about Pacho Gangotena, ecological farmer in Ecuador who influenced Steve and Myriam

The guinea pig solution

Living Soil: A film review

Dung talk

A market to nurture local food culture

Experiments with trees

Related training videos on the Access Agriculture platform

Good microbes for plants and soil

Turning fish waste into fertiliser

Organic biofertilizer in liquid and solid form

Mulch for a better soil and crop

COMUNIDAD Y MICROBIOS

“En la escuela de posgrado nos enseñaron a los futuros fitopatólogos que el objetivo de la agricultura era ‘alimentar a las plantas y matar a los bichos’”, me explicó mi viejo amigo Steve Sherwood durante una visita a su granja familiar cerca de Quito, Ecuador. “Pero deberíamos haber alimentado a los microbios del suelo, para que ellos cuidaran a las plantas”.

Cuando Steve y su esposa, Myriam Paredes, compraron su finca de cinco hectáreas, Granja Urkuwayku, en el año 2000, era un paisaje lunar en las faldas del erosionado volcán Ilaló. Los árboles habían sido quemados para hacer carbón y del suelo no quedaba más que la roca madre, una dura ceniza volcánica llamada “cangahua” que parecía hormigón. Una profunda cárcava erosionaba un gran hueco en el centro de la granja. La propiedad necesitaba mucho trabajo, y por eso Steve y Myriam podían acceder a comprarla.

Ahora, veinte años después, el terreno está cubierto de una rica tierra negra, con camellones verdes rodeados de árboles frutales y nativos.

El primer paso de este renacimiento fue meter un tractor a la cangahua, para romper la roca para que el agua y el abono pudieran penetrarla. Esta fue la única vez que Steve aró la finca.

Para convertir la piedra rota en suelo, Steve y Myriam añadieron estiércol; mucho venía de unas 100 gallinas y 300 cuyes, lo que la pareja describe como las “bujías del motor biológico de la granja.”

En 2015, Urkuwayku parecía ir bien. La granja ha atraído a más de 300 socios, familias que compran regularmente una canasta de productos de la granja, además de extras como pan, huevos, champiñones, miel y leña, en total aportando unos 1.000 dólares a la semana. Además de los cuatro miembros de su familia, la granja también da trabajo a cuatro personas locales. Ya que los ingresos a la granja pagan sus gastos, Steve y Myriam no tienen que subvencionarla con los sueldos que ganan como docentes. Barreras de conservación han llenado el barranco con tierra, ahora cubierta de pasto. El agua de escorrentía se acumula en un estanque de 500.000 litros, usado para regar los cultivos durante la época seca.

Pero en 2015 Myriam y Steve analizaron el suelo y se sorprendieron al ver que lentamente perdía su fertilidad.

Creen que el problema era el exceso de labranza y la falta de cobertura del suelo. La introducción de estiércol en los camellones hortalizas estaba rompiendo la estructura del suelo y secando el suelo, matando los hongos beneficiosos. Como explica Steve, “los hongos se encargan en gran medida de construir las partículas del suelo a través de sus micelios y su sudor, también conocido como glomalina, un pegamento rico en carbono que es importante para mitigar el cambio climático”. La glomalina ayuda a eliminar el carbono del aire y a almacenarlo en el suelo.

Entonces Steve se hizo amigo del administrador de una fábrica local de madera contrachapada (plywood). La fábrica había acumulado un montonazo de corteza y el dueño no sabía cómo deshacerse de ello. Steve se ofreció a quitárselo de encima. Las dos grandes ventajas de la agricultura periurbana son un mayor acceso a los clientes y algunas fuentes fabulosas de materia orgánica.

Así que la fábrica de contrachapados empezó a enviar a Steve volquetadas de corteza (sobre todo de eucalipto). Para hacer que los microbios descompongan la corteza, primero Steve descompone aserrín con un poco de materia orgánica del suelo de un bosque nativo local. Luego, el aserrín rico en microbios se mezcla con la corteza y se esparce cuidadosamente en capas profundas entre los camellones de hortalizas, donde ahora se mueve el suelo lo menos posible. Las hortalizas se siembran en bandejas y luego se trasplantan al campo abierto.

No importa cuánta corteza y aserrín que Steve y su equipo pongan, la tierra siempre la absorbe. El suelo parece comerse la corteza, como en un bosque. Los microbios del suelo se alimentan de la corteza para crear estructuras vivas, como micelios: hilos de hongos que llegan hasta los camellones, entre los senderos llenos de corteza. Steve y Myriam han aprendido que los microbios tienen una relación simbiótica con las plantas; los microbios ayudan a las raíces de las plantas a encontrar humedad y nutrientes y, a su vez, la planta devuelve a los microbios la tercera parte de toda la energía que obtiene de la fotosíntesis.

Myriam y Steve han comprobado que a medida que el suelo se vuelve más sano, sus cultivos tienen menos problemas de plagas de insectos y enfermedades. En gran parte, esto se debe al exitoso matrimonio entre las plantas y la creciente población de microbios del suelo. Urkuwayku es más verde cada año. Produce lo suficiente para alimentar a una familia y emplear a cuatro personas, al tiempo que provee regularmente verduras, frutas y otros productos de primera calidad a 300 familias. Una comunidad de consumidores apoya a la granja con ingresos, mientras que una comunidad de microorganismos construye el suelo y alimenta a las plantas.

Previos blogs de Agro-Insight

Una revolución para nuestro suelo

La luz de la agroecología, acerca de Pacho Gangotena, agricultor ecológico en el Ecuador quien ha sido una influencia para Steve y Myriam

Experimentos con árboles

Reviving soils

The guinea pig solution

Living Soil: A film review

Dung talk

A market to nurture local food culture

Videos sobre temas relacionados en la plataforma de Access Agriculture

Buenos microbios para plantas y suelo

El mulch mejora el suelo y la cosecha

Turning fish waste into fertiliser

Organic biofertilizer in liquid and solid form

 

Different ways to learn November 21st, 2021 by

Vea la versión en español a continuación

In June I wrote a story about a virtual meeting with some farmers in Iquicachi, on the shores of Lake Titicaca (Zoom to Titicaca), where they discussed how to manage what was (for them) a new pest: the potato tuber moth. Later, several people wrote to me to say that they hoped these farmers could solve their problem. So I’m writing an update.

I went to Lake Titicaca on 16 November to meet the farmers in person, and they’re doing well.

The agronomists they work with taught them to use ground chalk from a building supply shop to coat the seed potatoes. The chalk discourages the tiny larva of the moth from burrowing into the potato. This and some other techniques are helping to keep the tuber moth down.

At our recent meeting, I was impressed (as I often am) how scientists and farmers have different ways of seeing the world. There’s nothing mystical about his. It’s because they use different methods of observation.

An entomologist sees an insect by killing some specimens and looking at them under the microscope. It is an excellent way to see the details of nature that cannot be readily seen with the naked eye. For example, one of the three species of tuber moths has triangular markings on its wings.

But the farmers of Titicaca were less interested in comparing each species of moth, and more intent on comparing them to another pest, one they have had for ages: the Andean potato weevil.

These Yapuchiris (expert farmers) and their neighbors noticed that the moths’ larvae are much smaller than the worms that hatch from weevil eggs. Second, the weevil only eats a part of the tuber, while the larvae of the moth “have no respect for the potato” and destroy the whole thing. Third, the weevil can’t fly, but the moth “flies in jumps” (it takes short flights).

In all fairness, entomologists have also noticed these behaviors, and the Yapuchiris have recently observed that one species of moth is darker than the other. But the farmers emphasize behavior more, and have their own rhetoric for discussing it (e.g. as jumping). Note that this is not ancestral knowledge, because this pest is new on the Altiplano. These Yapuchiris only noticed the moth 10 years ago, and they have been observing it since then. The farmers learn about insects while farming and processing food. They watch while they work. They don’t set up lab experiments.

The Yapuchiris have strengthened their observations by interacting with agronomists. In this case the extensionists explained that the moths are the adults of the worms, so the farmers then began to pay more attention to the moths.

These improved observations have paid off.

While I was in Iquicachi, one of the Yapuchiris, Martín Condori, suggested that since the tuber moth does not fly very far, it could be kept out of potatoes by planting a row of broad beans or lupin beans between every three rows of potatoes. It’s a new idea, that only occurred to don Martín while we were meeting.

His fellow Yapuchiri, Paulino Pari, immediately warmed to don Martín’s suggestion for an intercropping experiment. Don Paulino said that a row of lupin beans might help to stop the moth from spreading into the potatoes, because the lupin plants are toxic to the moths.

This is the value of farmer-scientist collaboration. The farmers learn that the worms in their potatoes have hatched from the eggs laid by moths. Farmers then pay more attention to the moths, and create new ideas for keeping the moths out of the potato field.

Intercropping may or may not help to manage the moth, but it is an idea that farmers and agronomists can try together.

Years ago in Honduras, Keith Andrews, an entomologist, first told me that farmers identify insects more by their behavior and ecology than by their morphology. I’ve spent many years noticing that he was right.

Acknowledgements

A special thanks to Ing. Roly Cota, who works at PROSUCO, for taking me to Iquicachi and introducing me to the Yapuchiris, so we could validate three new fact sheets for farmers on the potato tuber moth. Our work was supported by the  Collaborative Crop Research Program (CCRP) of the McKnight Foundation.

Photo credit

Photo courtesy of Roly Cota.

Further reading

There is some excellent research on the potato tuber moth. For example, see this paper and references cited.

Olivier Dangles, Mario Herrera, Charlotte Mazoyer and Jean-François Silvain 2013 Temperature-dependent shifts in herbivore performance and interactions drive nonlinear changes in crop damages. Global Change Biology 19, 1056–1063, doi: 10.1111/gcb.12104.

Scientific names

There are two native tuber moths in Bolivia: Symmetrischema tangolias, and Phthorimaea operculella. There is also a Guatemalan tuber moth, Tecia solanivora, but it has not been reported in Bolivia. All three of these moths belong to the Gelechiidae family. They are about a centimeter long, about as long as your smallest fingernail. Many Gelechiidae attack stored cereal products, and so you may have been alarmed to find them in your cupboard.

Video on the fascinating lupin bean

Growing lupin without disease

APRENDIENDO CON OTROS OJOS

Por Jeff Bentley, 21 de noviembre del 2021

En junio escribí un relato sobre una reunión virtual con los agricultores de Iquicachi, a orillas del lago Titicaca (Zoom al Titicaca), en la que se discutía cómo gestionar lo que era (para ellos) una nueva plaga: la polilla de la papa. Más tarde, varias personas me escribieron para decirme que esperaban que estos agricultores pudieran resolver su problema. Así que escribo una actualización.

El 16 de noviembre fui al Lago Titicaca para conocer a los agricultores en persona, y están bien.

Los agrónomos con los que trabajan les enseñaron a usar tiza molida de una tienda de materiales de construcción para recubrir la papa semilla. La tiza no deja que la pequeña larva de la polilla penetre a la papa. Esta y otras técnicas están ayudando a reducir la polilla de la papa.

En esta última reunión, me impresionó (como en muchas veces) cómo los científicos y los agricultores tienen formas diferentes de ver el mundo. No tiene nada de místico. Es porque usan distinto métodos de observación.

Un entomólogo observa un insecto al matar algunos ejemplares y mirándolos al microscopio. Es una forma excelente de ver los detalles que no se pueden ver fácilmente a simple vista. Por ejemplo, una de las tres especies de polillas de la papa tiene marcas triangulares en las alas.

Pero los campesinos del Titicaca estaban menos interesados en comparar cada especie de polilla, y más en compararlas con otra plaga, una que tienen desde hace mucho tiempo: el gorgojo de los Andes.

Estos Yapuchiris (agricultores expertos) y sus vecinos se dieron cuenta de que las larvas de las polillas son mucho más pequeñas que los gusanos que nacen de los huevos del gorgojo. En segundo lugar, el gorgojo sólo se come una parte del tubérculo, mientras que las larvas de la polilla “no respetan la papa” y la destruyen completamente. En tercer lugar, el gorgojo no puede volar, pero la polilla “vuela a saltos” (have vuelos cortos).

En realidad, los entomólogos también se han dado cuenta de estos comportamientos, y los Yapuchiris han observado recientemente que una especie de polilla es más oscura que la otra. Pero los campesinos enfatizan más el comportamiento, y tienen su propia retórica para discutirlo (los saltos, por ejemplo). Fíjese que no se trata de un conocimiento ancestral, porque esta plaga es nueva en el Altiplano. Estos Yapuchiris sólo se dieron cuenta de la polilla hace 10 años, y desde entonces la observan. Los campesinos aprenden sobre los insectos mientras cultivan y procesan los alimentos. Observan mientras trabajan. No hacen experimentos de laboratorio.

Los Yapuchiris han reforzado sus observaciones interactuando con los agrónomos. En este caso, los extensionistas les explicaron que las polillas son los adultos de los gusanos, por lo que los agricultores comenzaron a prestar más atención a las polillas.

Estas observaciones mejoradas han dado sus frutos.

Durante mi visita a Iquicachi, uno de los Yapuchiris, Martín Condori, sugirió que, como la polilla de la papa no vuela muy lejos, se podría sembrar un surco de tarwi (lupino) entre cada tres surcos de papa, para que no entre la polilla. Es una idea nueva, que sólo se le ocurrió a don Martín mientras nos reuníamos.

Otro Yapuchiri, don Paulino Pari, aceptó inmediatamente la sugerencia de don Martín de hacer un experimento de cultivo intercalado. Don Paulino dijo que un surco de tarwi podría ser una barrera para la polilla, porque las plantas de tarwi son tóxicas para las polillas.

Este es el valor de la colaboración entre agricultores y científicos. Los agricultores se enteran de que los gusanos de sus papas han nacido de los huevos puestos por las polillas. Los agricultores prestan entonces más atención a las polillas y crean nuevas ideas para mantener las polillas fuera del campo de papas.

Los cultivos intercalados pueden ayudar o no a controlar la polilla, pero es una idea que los agricultores y los agrónomos pueden probar juntos.

Hace años, en Honduras, Keith Andrews, un entomólogo, me explicó por primera vez que los agricultores identifican a los insectos más por su comportamiento y ecología que por su morfología. Llevo muchos años comprobando que tenía razón.

Agradecimientos

Muchas gracias al Ing. Roly Cota, quien trabaja en PROSUCO, por llevarme a Iquicachi y convocar una reunión con los Yapuchiris, donde pudimos validad tres nuevas hojas volantes para agricultores sobre la polilla de la papa. Nuestro trabajo ha sido auspiciado por el Programa Colaborativo de Investigación sobre Cultivos (CCRP) de la Fundación McKnight.

Foto

Foto cortesía de Roly Cota.

Lectura adicional

Hay varios excelentes trabajos de investigación sobre la polilla de la papa. Por ejemplo, vea este artículo y los otros en las referencias citadas.

Olivier Dangles, Mario Herrera, Charlotte Mazoyer and Jean-François Silvain 2013 Temperature-dependent shifts in herbivore performance and interactions drive nonlinear changes in crop damages. Global Change Biology 19, 1056–1063, doi: 10.1111/gcb.12104.

Nombres científicos

Hay dos polillas de la papa nativas en Bolivia: Symmetrischema tangolias, y Phthorimaea operculella. Además, hay una polilla guatemalteca de la papa, Tecia solanivora, pero no ha sido reportada en Bolivia. Las tres polillas pertenecen a la familia Gelechiidae. Miden más o menos un centímetro, más o menos lo largo de su uña meñique. Muchos Gelechiidae atacan cereales almacenados, y es posible que le hayan sorprendido en su dispensa.

Video sobre el fascinante tarwi

Producir tarwi sin enfermedad

El mismo video, en el idioma aymara

Black fire ants July 11th, 2021 by

The surest way to tell if you have black fire ants in your garden is to accidentally stand on or near their nest. The ants will crawl through your clothes first and then start stinging you all at once. You may have to go inside and take off your trousers to find all of the ants in your pants. A second diagnostic test of black fire ants is to plant a vegetable seedbed, and wait for it to come up, but it never does. The ants have eaten all your seeds.

These ants love seeds and they will dig up every one you plant in their foraging area.

You can try dousing their nest with boiling water, insecticide or gasoline (and then lighting it). I’m just kidding, but it may not even work; these ants are pretty tough. Or you can take Rachel Carson’s suggestion, and fight pests with biology, not chemistry.

Years ago, while working with my student Eloy González on his entomology thesis at El Zamorano, Honduras, by total serendipity we learned that fire ants can be perfectly controlled with raw grains of rice.

Here’s how it works. Plant your vegetable seedbed any way you like. Then sprinkle a handful of raw rice over the surface. The black fire ants are omnivorous, but they prefer dense food packages like seeds or other insects. The ants also know a bargain when they see one. The ants will haul off your rice grains and ignore your smaller, harder-to reach soil-covered vegetable seeds.

Once your vegetables come up, the black fire ants will lose interest in them. However, the ants will continue to patrol your vegetable patch, looking for insect pests to drag back to their nest, to eat.

If you don’t want to use rice, try bread crumbs, bits of stale tortillas or other food scraps.

In our garden, we have had no insect pests, except for the Mediterranean fruit flies. Our patchwork of many species of trees and vegetables confuses most insect pests. And because we have never applied insecticides, we have many beneficial insects that kill most of the herbivorous ones before they can become pests. We manage our black fire ants with the rice trick, and by not standing on their nests. They repay us by helping to keep our vegetables pest-free.

If you live outside of tropical Central or South America, you may never have to deal with black fire ants. But wherever you live, you can always look for ways to live with insects, with biology, not chemistry.

Further reading

Paul has his own story about Vietnamese farmers who educate weaver ants, to protect their orchards from insect pests.

Ants as friends.

Related Agro-Insight blog stories

Ants in the kitchen

Sugar sweet ants

The smell of ants

When ants and microbes join hands

Videos about insects that hunt and control insect pests, from Access Agriculture

The wasp that protects our crops

Promoting weaver ants in your orchard

Weaver ants against fruit flies

Scientific names

The black fire ant, also called the tropical fire ant, is Solenopsis genimata. The red fire ant, the so-called “imported” one is Solenopsis invicta. The red fire ant is native to Argentina, and slipped into the USA, possibly as a stowaway on a ship, after 1933. in Silent Spring, Rachel Carson tells the story of how the US Department of Agriculture lost its chemical war against the red fire ant. That red ant is still thriving in North America. Unlike the black fire ant, which builds discrete, ground-level nests, the red one builds, a tall, conspicuous entrance to its burrow.

Silent Spring, better living through biology June 13th, 2021 by

Hey farmer, farmer

Put away that DDT now

Give me spots on my apples

But leave me the birds and the bees

Please!

“Big Yellow Taxi,” by Joni Mitchell

It’s possible that Joni Mitchell’s 1970 lyrics owe a debt to Rachel Carson’s (1962) book Silent Spring. Why not? The book was a major influence on the environmental movement, inspiring Earth Day, the Environmental Protection Agency (EPA), and the US ban on DDT, besides. Less often mentioned, the book also touched off integrated pest management (IPM).

For all that, Carson makes few mentions of farmers in her book. Many of the cases she meticulously described are of the US and Canadian governments arrogantly dropping insecticide from airplanes, blanketing forest, field, stream, pasture, and even suburban communities.

DDT and other noxious organophosphate insecticides were applied in each case to kill some specific pest: The Japanese beetle, the spruce budworm, and the fire ant, for example.

In every case, the results were disastrous. Dead livestock, and cancer in humans, but the birds were decimated. The bald eagle, national bird of the USA, was nearly exterminated by DDT. The bald eagle has since made a comeback, but many other bird species are on the decline.

The chemical companies that sold these pesticides to the government had the audacity (or the stupidity) to claim that insects would not be able to evolve resistance to the toxins. The pests would be eradicated!

But they weren’t. The bugs won the war. In every single case, the target pest species was more numerous a few years after the spraying started.

To explain this, Carson coined the analogy of the pesticide treadmill. Before a pesticide is used, an insect’s population is controlled by its natural enemies, such as spiders, wasps, ants, and birds. Insecticide kills the pest, and its natural enemies, too. The pest evolves resistance to the pesticide, much quicker than do its natural enemies (which often reproduce more slowly and absorb more of the poison). Once freed from its natural enemies, the pest population explodes. Now it has to be managed by pesticides.

In 1962, Carson mused that Darwin would have been pleased to see how well his theories were proven, as insect pests had quickly evolved resistance to pesticides. If Carson were here today, she might not be so happy to see how the chemical companies have also evolved. They have engineered maize and soy varieties that can withstand herbicides, so fields can be sprayed with glyphosate that kills all the plants, except for the ones with designer genes. The corporations that sell the seed conveniently sell the herbicide as well. Companies like Monsanto once claimed that the weeds would not be able to evolve resistance to the genetically modified crops.

But they did. At least 38 species of weeds are now resistant to glyphosate.

As Carson said nearly 60 years ago (and it’s still true), farms and forests are biological systems. Their pest problems have to be solved with biology, not with chemistry. In Rachel Carson’s day, only 2% of economic entomologists were working on biological pest control. Most of the other 98% were studying chemicals. Funding for chemicals breeds contempt for biological alternatives.

Biological pest control uses natural enemies to control pests. Carson cites the famous case of the cottony cushion scale, a citrus pest in California. The pest was controlled in 1872, long before DDT was available, by importing a lady bird beetle from Australia that ate the scale insects. The scale insects then became rare in California orchards until the 1940s, when insecticides killed the lady bird beetles and the pests exploded.

A recent book by Biovision and IPES Food suggests that many big donors still fund conventional research in pesticides. Perhaps it’s time to invest in scientists who can pick up Rachel Carson’s challenge, and solve biological problems with biology.

Further reading

Carson, Rachel 1962 (1987 edition). Silent Spring. Boston: Houghton Mifflin.

Heap, Ian, and Stephen O. Duke 2018 “Overview of glyphosate‐resistant weeds worldwide.” Pest Management Science 4(5): 1040-1049.

On chemical companies denying that weeds would develop resistance to their herbicides see chapter 5 in:

Philpott, Tom 2020 Perilous Bounty: The Looming Collapse of American Farming and How we can Prevent It. New York: Bloomsbury Publishing. 246 pp. (See also a review of this book in Our threatened farmers).

Biovision Foundation for Ecological Development & IPES-Food. 2020. Money Flows: What Is Holding Back Investment in Agroecological Research for Africa? Biovision Foundation for Ecological Development & International Panel of Experts on Sustainable Food Systems

Videos on natural, biological pest control

The wasp that protects our crops

Killing fall armyworms naturally

Weaver ants against fruit flies

Zoom to Titicaca June 6th, 2021 by

Vea la versión en español a continuación

Covid may be the world’s most spectacular emerging disease, but agriculture has its own new pests and diseases. Fortunately, collaboration between agronomists and farmers can offer solutions, as I saw in a recent meeting on the shores of Lake Titicaca.

This is 2021, so we met on Zoom, but I was struck by how much the meeting resembled others I have attended in person with farmers and agronomists.

Ing. Sonia Laura, a researcher from Prosuco who works closely with farmers, had driven out to the village of Iquichachi, a couple of hours from La Paz. Sonia set up the call on her laptop, and the farmers (Sra. Cristina, Sra. Arminda, Sr. Juan, Sr. Paulino, Sr. Zenobio, and Sr. Fidel) all managed to squeeze onto the screen. Bundled up in coats and hats against the high Andean cold, they explained how several years ago, they noticed a new worm eating the potatoes they store at home.

The moth lays its eggs on stored potatoes, and on potato plants in the field. The eggs hatch into caterpillars that go back and forth: from field to home in the harvest, and from storage to field with the seed.

The farmers showed some graphs of data they had been collecting with Sonia, under advice from Ing. Reinaldo Quispe, an agronomist from Proinpa, who joined the call from his office in La Paz. Reinaldo and the farmers had been using the sex scent (pheromone) of female moths to attract and trap the male moths. Each moth species has its own unique sex pheromone. Reinaldo had identified the pests, two related species of tuber moths, native to the Andes, but usually found in the lower, warmer valleys. Both species belong to a moth family that specializes in infesting stored foods.

The agronomist Raúl Ccanto joined us from Peru, from the NGO Yanapai. Raúl explained that Peruvian farmers had suffered from these two moths for many years. Over the years of working with the farmers, Yanapai and others had developed some practical solutions.

As Raúl explained, select the seed carefully. When you take seed from the house to plant in the field, make sure that you only plant healthy tubers, not the ones full of worms.

Also rotate your crops. “This is something you farmers have always done, but it’s important to say that it is a good thing.” Growing potatoes one year, followed by other roots and tubers (such as oca and papalisa, which are not of the potato family), and then other legumes and cereals, helps to keep the soil free of potato pests.

Raúl’s PowerPoint included the results of experiments, done in collaboration with Peruvian farmers, where they tried various ways to manage the moths in stored seed potato. One idea that worked well, and was also cheap, was to dust healthy seed potatoes with talc, which keeps the moths from laying their eggs in potatoes. The talc worked almost as well as malathion, the insecticide.

Raúl skipped lightly over the malathion, barely mentioning it, and for good reason. He had included the chemical treatment in the experiment as a comparison, but he was not promoting it. As Reinaldo explained, farmers often prefer insecticides and use them even in stored potatoes, which one should not do.

In fact, medical schools in Bolivia teach their third-year students to diagnose and treat malathion poisoning, because it is common. “This is something you’ll see,” the older doctors tell their students.

With any new pest or disease, it’s important to know where it came from. Raúl explained that the moths may have recently colonized the cold Altiplano, not just because of climate change, but also because people are bringing wormy seed in from fairs in distant parts of the country. And they are growing more potatoes. As more of the land is planted more often and over larger areas, to meet market demand, a more attractive environment is created for potato pests.

Yes, the farmers agreed, potatoes are being grown more often. And that is why it is crucial for scientists and farmers to put their heads together, to confirm useful ideas, from different perspectives.

The farmers wanted to know if there was something they could apply to their potatoes, to kill the moth. Raúl and Reinaldo both explained that there is no one thing that will manage the pest. It will have to be managed by rotating crops, and by selecting healthy seed. Other ideas like dusting the potatoes with talc will also help. The good news is that the moths can be managed.

It may be in human nature to yearn for simple solutions. Many of us have simply wished that Covid would go away, and that things would go back to normal. Like Covid, managing the tuber moth will require several good ideas, well explained, widely shared and applied.

In this case, the new information motivated the farmers to set up their own experiments. Sonia told me that after our call, the farmers met to reflect and take action. They decided that each one of them would select their seed, clean their potato storeroom, and sprinkle talc on the selected seed. They will keep using the pheromone traps, among other things. Later, they will explain these practices to their other community members, to take action as a group.

Scientific names

The tuber moths are Phthorimaea operculella and Symmetrischema tangolias (Lepidoptea: Gelechiidae).

Oca (Oxalis tuberosa) and papalisa (Ullucus tuberosus) are native Andean crops, not widely grown outside the region. The papalisa is also called “olluco” in Peru.

Talc is a clay mineral, magnesium silicate, a natural stone that is ground to make a powder.

Acknowledgements

Sonia Laura works with María Quispe at Prosuco (Promoción de la Sustentabilidad y Conocimientos Compartidos) in La Paz.

Raúl Ccanto works at Grupo Yanapai (meaning “to help” in Quechua), in Peru.

Reinaldo Quispe works at Proinpa (Fundación para la Promoción e Investigación de Productos Andinos), Bolivia.

The work with the Andean tuber moths is supported by the McKnight Foundation’s CCRP (Collaborative Crop Research Program).

Thanks to Sonia Laura and to Paul Van Mele for reading a previous version of this story.

Photos

Thanks also to Sonia Laura for her beautiful photographs.

ZOOM AL TITICACA

Por Jeff Bentley, 6 de junio del 2021

El Covid-19 podría ser la enfermedad nueva más espectacular del mundo, pero la agricultura tiene sus propias plagas y enfermedades emergentes. Afortunadamente, la colaboración entre agrónomos y agricultores puede ofrecer soluciones, como vi en una reciente reunión a orillas del Lago Titicaca.

Estamos en el 2021, así que nos reunimos por Zoom, pero me sorprendió lo mucho que se parecía la reunión a otras a las que he asistido en persona con agricultores y agrónomos.

La Ing. Sonia Laura, una investigadora de Prosuco, que trabaja estrechamente con los agricultores, había ido en camioneta hasta la comunidad rural de Iquicachi, a un par de horas de La Paz. Sonia organizó la llamada en su laptop, y los agricultores (las y los señores Cristina, Arminda y Juan, Paulino, Zenobio, Fidel,) se hicieron entrar todos en la pantalla. Abrigados con chompas y gorros contra el frío altoandino, explicaron que hace pocos años se dieron cuenta de que un nuevo gusano se comía las papas que almacenaban en sus casas.

La polilla de papa pone sus huevos en las papas almacenadas y en las plantas de papas en el campo. De los huevos nacen gusanos del campo, que van a casa en la cosecha, y del almacén regresan a la chacra con la semilla.

Los agricultores mostraron algunos gráficos de datos que habían estado recopilando con Sonia, bajo la orientación del Ing. Reinaldo Quispe, de Proinpa, quien se unió a la llamada desde su oficina en La Paz. Sonia y los agricultores habían estado usando el olor sexual (feromona) de las polillas hembras para atraer y atrapar a las polillas macho. Cada especie de polilla tiene su propia feromona sexual. Reinaldo había identificado las plagas, dos especies relacionadas de polillas del tubérculo, nativas de los Andes, pero que suelen encontrarse en los valles más bajos y cálidos. Ambas especies pertenecen a una familia de polillas especializada en infestar alimentos almacenados.

Desde Perú nos acompañó el agrónomo Raúl Ccanto, de la ONG Yanapai. Raúl explicó que los agricultores peruanos habían sufrido estas dos polillas durante muchos años. A lo largo de sus años de trabajo con los agricultores, Yanapai y otros han desarrollado algunas soluciones prácticas.

Como explicó Raúl, hay que seleccionar la semilla con cuidado. Cuando saques la semilla de la casa para sembrarla, asegúrate de plantar sólo los tubérculos sanos, no los que están llenos de gusanos.

También hay que rotar los cultivos. “Esto es algo que ustedes los agricultores siempre han hecho, pero es importante decir que es bueno que lo hagan”. Lo que ayuda a mantener el suelo libre de plagas de la papa es cultivarlas solo un año, seguido de otras raíces y tubérculos (como la oca y la papalisa, que no son de la familia de la papa), y luego sembrar leguminosas y cereales.

La presentación de Raúl incluyó los resultados de los experimentos, realizados en colaboración con agricultores peruanos, en los que se probaron varias formas de controlar las polillas en los almacenes de semillas de papa. Una idea que funcionó bien, y que además era barata, fue rociar la papa seleccionada con talco, que impide que las polillas pongan sus huevos en las papas. El talco funcionaba casi tan bien como el malatión, el insecticida.

Raúl pasó por alto el malatión; apenas lo mencionó, y con razón. Había incluido el tratamiento químico en el experimento como comparación, pero no lo promovía. Como explicó Reinaldo, los agricultores suelen preferir los insecticidas y los usan incluso en las papas almacenadas, lo cual no se debe hacer.

De hecho, las facultades de medicina de Bolivia enseñan a sus estudiantes de tercer año a diagnosticar y tratar la intoxicación por malatión, porque es algo común. “Esto es algo que van a ver”, dicen los doctores a sus alumnos.

Con cualquier plaga o enfermedad nueva, es importante saber de dónde viene. Raúl explicó que las polillas pueden haber colonizado recientemente el frío Altiplano, no sólo por el cambio climático, sino también porque la gente está trayendo semillas agusanadas de ferias en otras partes del país. Y están cultivando más papas sobre mayor superficie. A medida que se siembra más seguido y en más área, para satisfacer la demanda del mercado, se crea un ambiente más atractivo para las plagas de la papa.

Sí, los agricultores reconocieron que hoy en día las papas se cultivan más seguido. Y por eso es crucial que científicos y agricultores compartan sus ideas, para confirmar las que son útiles.

Los agricultores querían saber si había algo que pudieran aplicar a sus papas para matar la polilla. Raúl y Reinaldo explicaron que no hay una sola cosa que la pueda manejar. Habrá que controlar la plaga mediante la rotación de cultivos y la buena selección de semillas. Otras ideas, como aplicar talco a las papas, también ayudarán. La buena noticia es que las polillas sí tienen solución.

Tal vez algo en la naturaleza humana anhela las soluciones sencillas. Muchos hemos deseado que el Covid desaparezca de una sola vez, y que las cosas vuelvan a la normalidad. Al igual que el Covid, el manejo de la polilla de la papa requerirá varias buenas ideas, bien explicadas, ampliamente compartidas y competentemente aplicadas.

En este caso, la nueva información motivó la gente a armar sus propios experimentos. Sonia me informa que se reunieron para reflexionar y tomar acuerdos. Decidieron que cada persona del grupo haría la selección de semilla. Limpiaría su almacén de papas, y pondría talco en las papas seleccionadas. Seguirán con las trampas con feromonas, entre otras cosas. Luego comunicarán estas prácticas en una reunión con toda la comunidad para tener un trabajo comunal en el control de esta plaga.

Nombres científicos

Las polillas de la papa son Phthorimaea operculella y Symmetrischema tangolias (Lepidoptea: Gelechiidae).

La oca (Oxalis tuberosa) y la papalisa (Ullucus tuberosus) son cultivos nativos andinos, poco cultivados fuera de la región. La papalisa también se llama “olluco” en el Perú.

El talco es silicato de magnesio. Es una piedra natural que se muele para obtener el polvo. Como explica Raúl Ccanto, es un “mineral no metálico”.

Agradecimientos

Sonia Laura trabaja con María Quispe en Prosuco (Promoción de la Sustentabilidad y Conocimientos Compartidos) en La Paz.

Raúl Ccanto trabaja en el Grupo Yanapai (que significa “ayudar” en quechua), en el Perú.

Reinaldo Quispe trabaja en Proinpa (Fundación para la Promoción e Investigación de Productos Andinos), en Bolivia.

El trabajo con las polillas de la papa está apoyado por el CCRP (Programa Colaborativo de Investigación de Cultivos) de la Fundación McKnight.

Gracias a Sonia Laura y a Paul Van Mele por leer una versión previa de este relato.

Fotos

Gracias también a Sonia Laura por sus hermosas fotos.

Design by Olean webdesign