Untold Stories, Beyond Methyl Bromide

January 17, 2018

“THE IDEA TO write this book came to me after I retired in 2005 and was cleaning out, re-reading, and reorganizing 40 years of files…in spite of three books and more than 200 journal publications and book chapters, my files filled with history and unpublished data were headed for the trash bin…the greater my urge to somehow pull the stories together into a single read-through description of my career…unique, it is the approach I took and the philosophy behind my approach to do hypothesis-driven research starting in the field, followed by the laboratory,” writes R. James Cook in the “Preface” to his book, Untold Stories (APS Press, 2017).

In 1974, Cook and Kenneth F. Baker co-authored a landmark book, Biological Control of Plant Pathogens. That book, which in some ways is a precursor to Untold Stories, summarized scientific evidence relevant to creating ecological balances favoring beneficial organisms (e.g. biocontrol agents, antagonists, competitors) as pesticide alternatives to control pathogens capable of weakening and destroying plants, including major food crops such as potato and wheat. Human medicine has at various times in various places employed a similar biological approach, such as using bacteriophages to fight diseases such as cholera, but for an array of reasons biological control has found more fertile ground in agriculture. Ecological balances can be tilted or nudged from pathogens to beneficial organisms in various ways, including via soil pH adjustments, tillage systems, cropping sequences, fallows, composts, amendments, nutrients, etc. The specifics can vary widely among crops, individual fields, regions, soil types, etc. Dr. Cook, as the Untold Stories subtitle, “Forty Years of Field Research on Root Diseases of Wheat,” hints, found wheat a fertile microcosm for exploring the phenomena of naturally disease suppressive soils for producing healthy crops.

Cook’s job when he joined the USDA Agricultural Research Service included soil diseases afflicting wheat, one of humanity’s most ancient crops and a worldwide dietary staple. The USA grew 45.7 million acres of wheat in 2017, most of it winter planted varieties, the lowest acreage since record keeping began in 1919. USA farmers grow twice as much corn and soybean, roughly 90 million acres of each. Wheat exports earn the USA roughly $6 billion a year, out of $140 billion in total agricultural exports. Though wheat helps the USA balance of trade, family farms growing wheat are not sustainable or economically viable if soil pesticides are used. Dr. Cook’s challenge was curing wheat soil diseases without costly pesticides. In the 1970s, the mainstream view was that solving pest problems without pesticides was drug-induced organic hippie crazy talk, a near impossible task with low probability of success.

Fortunately Dr. Cook possessed sound inner instincts complemented by scientific understanding of ecology and microbiology, with an emphasis on biological control of plant diseases absorbed working alongside Kenneth Baker and others at the University of California, Berkeley where biological control was still honored and respected despite falling from its early 20th century heights during the synthetic pesticide era. Cook briefly acknowledges Louis Pasteur, the famous French freelance microbiologist, chemist and entomologist who developed modern medical germ theory and laid the foundations for modern epidemiology while alleviating a mysterious silkworm colony collapse (disease epidemic) depressing the mid-19th century French economy.

On page 236 of Untold Stories, Cook quotes Pasteur: “In the field of observation, chance favors the prepared mind.” I would go back one step more to Pasteur’s mentor, chemist Jean Baptiste Dumas, who according to French-borne microbiologist René Dubos, persuaded a reluctant Pasteur to tackle the silkworm problem despite an insect ignorance for which he was widely ridiculed: “To Pasteur’s remark that he was totally unfamiliar with the subject, Dumas had replied one day: ‘So much the better! For ideas, you will have only those which shall come to you as a result of your observations!’” Microbiologist Alexander Fleming, famous for the fungal antibiotic penicillin, noted another important factor: “Louis Pasteur in his youth and throughout his life believed in hard work. He lived for his work and put his whole heart and soul into it. His was not a 40-hour week. He worked so constantly in his laboratory that it was inevitable that he became a beautiful technician…”

Another message embedded in Cook’s Untold Stories: Successfully tackle hard problems that appear insoluble to everyone else, and the probability of job security and life success increase. Cook developed an expertise in finding cooperative wheat farmers and locating fields where natural biological controls seemed to be working on their own. Then did a laboratory form of reverse ecological process engineering to find out why these fields developed a disease immunity or natural suppression of wheat soil pathogens. When you can replicate or duplicate the phenomena experimentally, then a degree of understanding can be claimed.

 

Untold Stories feels like the real nitty-gritty, with behind-the-scenes stories about how research projects are accomplished. The type of details typically omitted from science journals, by design. If anyone dared put into their journal article the details of how they obtained funding, navigated the bureaucracy to win support, or cleverly acquired a piece of new equipment, it would no doubt get edited out. This is a reason Roald Hoffmann in his book, The Philosophy, Art, and Science of Chemistry (Oxford University Press, 2012), suggested a new kind of science journal allowing first person “voice” and personal experience. Actually, it would only be “new” in the “retro” sense that “everything old is new again.” In the early days of modern science, personal autobiographical expression, musings and miscellany were common. These early science articles could be confusingly messy and hard to decipher, perhaps harking back to the deliberately obscure days of alchemy. However, personal observation and experience was handled well by agricultural researchers in the early 20th century. Which is not meant to denigrate the utility and immense value of standardized journal formats with introduction, methodology, results, discussion, etc. There is room in the world for both.

Untold Stories embeds science in a wider human context, beyond what is possible in the modern journal format, which necessarily excludes the human dimension, but leaves behind an unintended residue, a subjective impression of a science rendered lifeless by the invisibility of its practitioners. Cook family members pitched in to write the forward, edit, design and deliver their father’s book ready for printing by the American Phytopathological Society (APS) Press. Cook’s attitude towards public service is refreshing, and clearly extended into his so-called retirement. Judging from the 2005 start date and the 2017 book publication date, Dr. Cook put over a decade into this “Magnum Opus” book project. Wife and family were promised this would absolutely be his last book. One might lament, but I have to believe Dr. Cook mined his past experiences so thoroughly as to be able to rest on his laurels and not feel that much was left out that could not be remedied in a few journal articles.

A mathematical ratio of untold stories to published stories would be interesting, and Dr. Cook is in a position to be the expert. Let’s say the Untold Stories:Published Stories ratio was 1:1 and had a certain “volume.” Then the “volume” (e.g. measured in pages, articles/books, person-years of work, or whatever) of untold stories could be multiplied by the number of scientists or the amount published in a given time period to yield an estimate of how much scientific research ends up in the proverbial trash bin.

The Untold Stories photo caption on page 52 brought to mind a much maligned molecule, methyl bromide, a research tool and experimental control integral to scientific investigation of naturally disease suppressive wheat soils. Salt marsh microbes naturally produce methyl bromide as an antibiotic type weapon in waging ecological warfare for survival against competitors and antagonists. The caption: “A discussion session in progress at a Pacific Coast Research Conference on Soil Fungi with Professor S.D. Garrett, Cambridge University, as the discussion leader…Steve Wilhelm from UC Berkeley, credited with the introduction of soil fumigation to the California strawberry industry, is in the front row…”

Dr. Wilhelm, who I knew to also be interested in promising methyl bromide alternatives such as steam, marigold cover crops and green manures, crops up again on page 186 of Cook’s book: “it was not until the middle of the twentieth century that soil fumigation was used on a large scale…Steve Wilhelm at UC Berkeley…together with Albert Paulus at UC Riverside, did the pioneering work on the use of mixtures of chloropicrin and methyl bromide to control soil-borne pathogens and weeds before planting strawberries in California starting in the late 1950s. Strawberry yields were roughly 5 tons per acre in fields not fumigated and up to 25 tons per acre in fields that were fumigated.”

Soil fumigation with methyl bromide and chloropicrin worked so well that California had near zero untreated strawberry fields available to investigate for naturally suppressive soils, which is unfortunate, as methyl bromide use is being phased out under the Montreal Protocol as an ozone depleting substance. Something I learned about in more depth working with the late Jamie Liebman, a plant pathologist at BIRC (Bio-Integral Research Center), where as subcontractors we helped develop a Montreal Protocol methyl bromide alternative research agenda for funding by the U.S. EPA and United Nations. I wrote a short chapter on this period in history titled “Rowland’s Recipe for Climate Treaty Success” in an ABC-CLIO book titled Science and Political Controversy, edited by David E. Newton in 2014. In 2015, attending agricultural, soil and entomological science meetings in Minneapolis, not far from APS headquarters, I was pleased to find that research agenda still extant and going deeper. Funny what a mere photo caption can trigger in human memory. No doubt Untold Stories will have similar effects on readers whose interests and paths intersected with those of Dr. Cook.

California’s $2 billion strawberry industry, which produces about 90% of the USA crop, an awesome 1.7 billion pounds on about 40,000 acres (43,000 pounds of strawberries per acre), was for all practical purposes birthed into existence by injecting chloropicrin and methyl bromide into soils under plastic tarps. California’s hyper-productive strawberry growers, like Florida tomato and inland Pacific Northwest potato growers, can earn back methyl bromide soil fumigation costs. Family wheat farms would be bankrupted and abandoned to tumbleweed and erosion by soil fumigation costs. Scientifically, the less prosperous economics of wheat growing were fortuitous, as Dr. Cook was precluded from earning a living testing and recommending soil pesticides. Instead, as Dr. Cook’s book rigorously details, applied science became indistinguishable from pure science (much as it did for Pasteur) as it delved into the microbiology, ecology and non-chemical remedies for soil pathogens causing unhealthy plants and crop failures.

A key scientific discovery was that growing wheat in the same field again and again, year after year without interruption or rotation, can result in soils becoming naturally suppressive or functionally immune to disease pathogens. But this goes against centuries of accumulated wisdom arguing that toxic root secretions (allelopathy) poison the soil, and are best alleviated by crop rotations. Cook’s objection on page 227: “this makes no mention of a role for root diseases and ignores one of the most fundamental principles of plant pathology taught to beginning students in plant pathology, that growing the same crop in the same soil increases the populations of pathogens of the roots of that crop…It takes a long time to replace the first explanation with the correct explanation for almost any phenomenon in nature.” It also takes time, as those who have studied ecology know, for pathogen, prey or pest populations to build up to peaks before predator and natural enemy populations reduce or crash them down to low levels. Dr. Cook’s mission was to shorten that time.

One set of wheat experiments described in the “Take-All Decline” chapter 7, owed inspiration to 1950s’ potato scab disease research in Washington State, where small amounts (10%) of suppressive soil (presumably containing beneficial microbes) were added to disease-susceptible soils. Within 2-3 years, wheat soils were growing healthy plants. “Although I never repeated this experiment (nor did it need to be repeated), it would turn out to be the most influential experiment of my career,” wrote Dr. Cook on page 144. “It led to my award of a Guggenheim Fellowship…to my first competitive grant awarded by the USDA Competitive Grants Research Office (CARGO) in 1978…to the USDA ARS approving the formation of the Root Disease and Biological Control Research Unit in 1984; and to the USDA ARS providing permanent funds for me to hire…”

This only scratches the surface of a truly remarkable book likely to become a classic of science.

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Natural Nicotine Heals Honey Bees

January 23, 2017

NEONICOTINOID INSECTICIDES (e.g. thiamethoxam, imidacloprid, clothianidin) developed at Bayer Japan as safer alternatives (e.g. to human spray applicators) to the natural nicotine once widely used by farmers and gardeners, is now suspected of contributing to honey bee health problems like learning disorders and colony collapse. In contrast, natural nicotine, found in honey produced by bees working tobacco fields, as well as in pollen, nectar, leaves and other plant parts, is a nutrient and medicine helping to heal weak honey bee colonies, said Susan Nicolson of South Africa’s University of Pretoria at “Entomology Without Borders,” a joint meeting of the International Congress of Entomology (ICE) and the Entomological Society of America (ESA) in Orlando, FL.

Natural nicotine, even if produced organically in a sustainable recycling sort of way from tobacco waste products, is mostly shunned in organic farming and gardening. “Over 120 million sites will be returned on a web search on tobacco, but most will not be associated with plant science,” wrote USDA-ARS researcher T.C. Tso in Tobacco Research and Its Relevance to Science, Medicine and Industry. “Many plant scientists in academic institutions cannot obtain grant support for projects using tobacco as a research tool. Some even have to avoid tobacco because of the applying of ‘political correctness’ to academic research. The tobacco plant has served as a valuable tool since the dawn of plant and biological sciences, so it is indeed a great loss to scientific progress that a research tool already invested with so many resources and about which there is such abundant knowledge and such great potential for new advancement is now being wasted.”

Honey bees readily consume bitter alkaloids such as nicotine mixed in sugary plant nectars. Adult honey bees excel at detoxifying alkaloids such as nicotine, which should not be surprising, as survival depends on it. Younger, larval honey bees have fewer enzymes to detoxify nicotine, but also survive quite well even when their royal jelly contains high levels of nicotine. Honey bees and insects immune to nicotine, such as green peach (peach-potato) aphids, transform nicotine into less toxic butanoic acid. A knotty question naturally arises: If natural nicotine heals honey bees, why are synthetic neonicotinoids so terribly different? Are natural compounds like nicotine inherently more beneficial and their synthetic analogs (e.g. neonicotinoids) inherently bad, perhaps due to subtle differences in molecular structure? If bees and other pollinators are a major concern, perhaps natural product restrictions on nicotine need to be relaxed to provide competition to the synthetic neonicotinoids.

“Alkaloids, especially in the nicotine family, have been the main focus of tobacco research because alkaloids are the characteristic product of tobacco,” writes Tso. Dozens of other tobacco molecules are relatively overlooked, including sugar compounds providing least-toxic botanical insect and mite control. Anabasine (neonicotine), an alkaloid found in tobacco and other plants, has also been widely used as a natural insecticide. Strangely enough, anabasine is also an insect attractant and a poison gland product of Aphaenogaster ants. In a strange urban twist to the wild bird practice of lining nests with medicinal herbs emitting essential oils counteracting parasites: Researchers in Mexico discovered urban birds lining nests with cigarette butts to similar advantage. In times past, organic gardeners soaked cigarette butts in water to get a nicotine spray brew. Historically, most commercial nicotine insecticide used on farms and gardens was a sustainable tobacco waste extract.

There are 60-80 described tobacco or Nicotiana species, some available in seed catalogs and grown as ornamentals. Most Nicotiana species grow wild in the Americas, with some in Australia and Africa. “Tobacco plants are easy to grow and have a short growing period,” writes Tso. “Each tobacco plant may produce 14 g or about 150,000 seeds which may provide seedlings for 2 to 5 acres (1–3 ha) of field tobacco, depending on the type.” In Europe, oil extracted from tobacco seeds is being explored for an alternative bio-diesel fuel industry, with dry leftovers as animal feed.

Native American Nicotiana species are being integrated into China’s ancient agricultural interplanting tradition. When tobacco is interplanted in vineyard rows, tobacco roots and grape roots intermingle. Perhaps some sort of biological soil fumigation occurs. Whatever the mechanism, vineyards are cleansed of soil-dwelling phylloxera aphids, a pest that almost destroyed wine grape growing in France in the 1800s and is still a worldwide problem. According to the journal Chinese Tobacco Science, intercropping tobacco with sweet potato also alleviates soil and other pest problems, maximizing profits per unit area of land. Burley tobacco is intercropped with cabbage and other vegetable crops, according to the Journal of Yangtze University (Natural Science Edition).

Neonicotinoids are soluble in water and absorbed systemically by plants, and some are sprayed on urban lawns and landscapes. However, over 80% of synthetic neonicotinoids are applied to seeds prior to planting hundreds of millions of acres of corn, soybean, sunflowers and other crops. In Canada’s Ontario and Quebec provinces, 100% of corn seed is treated with neonicotinoids, said Nadejda Tsvetkov of Toronto’s York University at “Entomology Without Borders.” Though neonicotinoids were seldom found in corn pollen samples, somehow, perhaps by water transport, neonicotinoids are finding their way into clover and willow tree pollen far from corn fields.

“For a lot of farmers it is hard to get seeds untreated, especially corn,” as commercial seed is routinely treated with neonicotinoids regardless of need, said the University of Maryland’s Aditi Dubey at “Entomology Without Borders. In Maryland and other mid-Atlantic USA states where low pest pressures are the norm, neonicotinoid seed treatments are both unneeded and counterproductive. In 3-year Maryland rotations with double-cropped soybeans, winter wheat and corn, sowing seeds treated with thiamethoxam or imidacloprid reduced beneficial predatory ground beetles and increased slug damage to crops. Mid-Atlantic USA farmers typically apply 4 unnecessary prophylactic seed treatments every 3 years. Besides reduced biocontrol and more pest damage, soil accumulation over time is a disturbing agro-ecosystem possibility.

Alternative seed treatments include natural plant hormones such as salicylic acid and methyl jasmonate, which induce a natural immunity called induced systemic acquired resistance (SAR). Crops such as lettuce and argula (rocket) grown from seed treated with salicylic acid and methyl jasmonate also release volatile gases repelling pests such as sweet potato whitefly, a major worldwide pest, said Ben-Gurion University’s Mengqi Zhang at “Entomology Without Borders,” a gathering of 6,682 delegates from 102 countries. Numerous botanical materials and microbes have also been investigated around the world as alternative seed treatments.

A proactive approach to honey bee and bumble bee health includes a diversified landscape sown with herbs and medicinal botanicals for self-medication, not just natural nicotine from tobacco nectar or other sources. Thymol, an essential oil found in thyme and many other plants, is already sprayed in hives by beekeepers to combat Varroa mites. At “Entomology Without Borders,” North Carolina State University’s Rebecca Irwin reported laboratory choice tests where bumble bees rejected nicotine. In field tests, bumble bees were given a choice of different colored flowers each with a different botanical such as thymol, nicotine, anabasine and caffeine. Bumble bees only selected flowers with thymol to self-medicate. Interestingly, thymol and other herbal essential oils also synergize nicotine, boosting effectiveness against disease pathogens and perhaps also minimizing the likelihood of colony collapse.

Landscapes and hedgerows sown with medicinal plants such as thyme, sunflower and foxglove minimize bumble bee disease transmission, said Lynn Adler of the University of Massachusetts, Amherst. The current USA farm bill will actually pay farmers to plant bee-friendly sunflower edges or hedgerows around canola fields. Antimicrobial and medicinal honeys derived from sunflower, bay laurel (Laurus nobilis), black locust, etc., also effectively combat bee diseases like chalkbrood and foulbrood, said Silvio Erler of Martin-Luther-Universität in Halle, Germany at “Entomology Without Borders.”

Bee pharmacology is also useful in human medicine. In Oaxaca, Mexico gangrene is stopped and wounds are healed by combining maggot therapy and honey, reported Alicia Munoz. Maggot therapy uses sterilized (germ-free) green bottle fly maggots to disinfect and cleanse wounds by eating unhealthy tissues and secreting antibiotics, allowing healthy pink tissue to grow back under honey-soaked gauze. This cost-effective approach reduces hospital stays, lowers morbidity and can eliminate the need for surgery. It may sound yucky, but for diabetics and patients with bed sores or wounds where surgery is medically impossible, a few maggots and a little honey is preferable to amputating wounded or infected limbs.

Cancer-fighting bee propolis products were touched upon at “Entomology Without Borders” by Chanpen Chanchao of Chulalongkorn University in Bangkok, Thailand, where hives of stingless bees are reared like conventional honey bees. Cardol, a major component of propolis from the Indonesian stingless bee, Trigona incisa, causes early cancer cell death by disrupting mitochondrial membranes and “producing intracellular reactive oxygen species (ROS).” ROS are essential to energy, immunity, detoxification, chemical signaling, fighting chronic and degenerative diseases, etc. Cardol “had a strong antiproliferative activity against SW620 colorectal adenocarcinoma,” killing colon cancer cells within 2 hours, followed by complete cell necrosis within 24 hours. Thus, cardol is an “alternative antiproliferative agent against colon cancer.”


Pigments of the Imagination: Cochineal’s Renaissance

June 22, 2016

SAP-SUCKING SCALE INSECTS, such as cochineal, kermes and lac, are sometimes sprayed with pesticides as landscape and crop pests, and other times cultivated as beneficial insects. For example, cochineal secals have provided biological weed control in India, Australia and South Africa where imported prickly pear cactus (Opuntia spp.) hedges have escaped and become rangeland weeds. Cochineal scale insects, bred in ancient Mexico to yield 15%-30% color pigment content, have been grown in the Americas for many centuries on prickly pear cactus as a sustainable, biodegradable colorant crop yielding dyes ranging from red, yellow, orange and brown to pink, lavender and purple (depending on mordant, pH, etc.). Intensely red cochineal has a long and famous history in painter’s palettes, tapestry and fabrics, and has been used for centuries to color or stain tissues red or purple for microscope visibility in biology and microbiology labs, medicine and dentistry. Cochineal scale pigments also color selected beverages, foods (on labels as E-120 & carmine) and cosmetics like lipstick, rouge and nail polish. Biochemistry labs like the cochineal red molecule’s ability to bind or bond with proteins, nucleic acids and fats (lipids). Analytic chemists use cochineal “for photometric determination of boron, beryllium, uranium, thorium, and osmium.” At the cutting edge frontier of science, cochineal pigments are being adapted to “molecular information processing” and computing. The red pigment’s “strong photosensitization and photocurrent switching effects” are being designed into next generation optoelectronic (i.e. light, photon) devices like semiconductors, fuel cells, sensors and photovoltaic solar energy systems.

“In Latin-the indispensable language of Renaissance medical professionals—the word pigmentum signified both a pigment and a drug,” writes Amy Butler Greenfield on page 83 of the paperback edition of her meticulously researched book, A Perfect Red, which follows the parallel rise and fall of the Spanish Empire and the secretive cochineal red export trade. “Artists who made their own paints were often advised to procure cochineal from their local “Drugist” or pharmacy, advice that highlights the fact that Europeans also used cochineal as a medicine,” a practice “at least partly borrowed from ancient Mexico,” where cochineal was used to clean teeth and also dissolved in vinegar and applied as a poultice to cure wounds and strengthen bodily organs. Spain profited more from importing cochineal into Europe than from all its plundered and mined New World gold. When ancient alchemy’s metamorphosis into modern chemistry advanced to synthesizing a less expensive, wider range of brighter dye pigments, the Spanish red dye monopoly was obsoleted and the financial collapse of the steadily weakening empire allowed for a global power shift; the USA, fresh from coast to coast expansion and hot for global colonial-style conquests, easily knocked off the remnant hollow shell of the Spanish Armada in the Caribbean and Philippines in 1898.

Let’s start with cochineal and scale insects as pests, and organic control alternatives, as that is how most people encounter and view scale insects. Parasitoid wasps, lady beetles, birds and many other natural enemies provide biological control of scale insects, but not always enough at the right time. Highly refined petroleum oils, vegetable oils and high-pressure water sprays (with or without soap or surfactants) are among the often used remedies. High pressure water sprays, from a nozzle or heavy overhead rainfall, wash off or injure cochineal scales; and this remedy is sometimes used post-harvest by packing houses to clean fruit prior to shipping. Laboratory studies indicate that epazote (Chenopodium ambrosioides), mint (Mentha spp.) and marigold (Tagetes spp.) extracts applied with emulsifiers are potential organic or environmentally friendly synthetic pesticide alternatives.

At the Entomological Society of America (ESA) annual meeting in Minneapolis I talked with Colorado State University extension entomologist Whitney Cranshaw, whose special spiked shoes for killing white grub beetle larvae beneath the soil surface while walking golf course turf and lawns achieved notoriety in Smithsonian magazine many moons ago. This time he was a lonely entomologist, as out of hundreds of passersby no one was stopping at the poster of graduate student Rachael Sitz reporting on a kermes scale vectoring a bacteria causing drippy blight of red oaks in Colorado. Cranshaw was ecstatic having a customer, and figured I was studying the poster display because the kermes scale was also found in California locales such as San Jose, Mammoth Lakes and Monticello Dam on blue oaks and chinquapin bushes. Actually, I was wondering if this particular kermes scale, which went by the scientific name Allokermes rattani, was related to Old World kermes scales used for centuries by pigment artists in Europe and Asia. According to Cranshaw, workers handling the Colorado kermes scale came away with hands dyed a deep brown. So, perhaps this “pest” scale insect is indeed an untapped resource, similar to cochineal, waiting to be discovered by textile artists, painters and photographers looking for natural organic pigments.

My own interest in these insect pigments is a bit abstract, how to incorporate these pigments into the photographic printing process, inspired in part by viewing Robert Rauschenberg’s vegetable pigment prints with photo images from Indonesia. Cochineal was apparently on occasion used in early color photography printing, dating back to the 1800s and heliochromes, which I surmise are solar prints that also use silver as a light-sensitive pigment. Some modern authors talk of a “green synthesis,” fusing conventional silver nanoparticle photography with cochineal red pigments; but I have not found much on the subject. “Color photography,” U.S. Patent No. 923,019 from 25 May 1909 reads: “To all whom it may concern: Be it known that I, EDGAR CLIFTON, a subject of His Majesty the King of the United Kingdom of Great Britain and Ireland, residing at 3 BeaufortVillas, London Road, Enfield, in the county of Middlesex, England, have invented certain new and useful Improvements in Color Photography…known as the two color process; the three color process; and the four plate process…so that the assemblage gives more or less natural color effects…As the red dye: alizarin (with alumed reliefs), cochineal red (or carmin with ammonia), or magdala red…”

SCALING UP PRODUCTION of pigment scales, versus natural harvest, is often surprisingly difficult. For one thing, about 14,000 individual scale insects are needed to obtain 100 grams of raw cochineal pigment. Far from being dumb savages, ancient Mexico’s New World cochineal growers were superb insect breeders. The best cochineal “breeds” contain 18%-30% pigment by dry weight. Spaniards settling in the New World never mastered the delicate art of cultivating cochineal scale on prickly pear cactus, and instead relied on the indigenous los indios de Mexico, some of whom grew rich on the cochineal trade in what was essentially a free market. Many Spanish colonists found it intolerable that the natives were becoming the richest citizens, and this led to all kinds of frictions and conflicts aimed at turning the natives into poorer, more docile (less uppity) and easier to control colonial subjects. The Spanish were remarkably successful at keeping curious outsiders out of the cochineal production areas for centuries, making the cochineal red dye one of the world’s all-time best kept trade secrets. Most Europeans assumed the grana or granules of cochineal were seeds or plant material, like indigo or madder. On those rare occasions when the secret was revealed, the public refused to believe that cochineal red was literally dried insects. This combination of secrecy and worldwide ignorance allowed the Spanish cochineal monopoly to persist for several centuries and be more lucrative than precious metals.

As any entomology grad student can tell you, the same insect that is an abundant pest can often be impossibly hard to grow when you want it for experiments or as a thesis subject. For one thing, the “insect crop” usually has its own set of pests (called natural enemies), which for cochineal scales includes bacteria, lady beetles, syrphid or hover flies, predatory caterpillars, rodents, reptiles and birds. To prevent “crop failure,” cochineal scales need pampering and protection: 1) from natural enemies; 2) shade to protect from direct sunlight; 3) shelter from heavy rains that wash off and injure the scales. Raising cochineal scales as “farm animals” or “livestock” on prickly pear cactus was often a family enterprise in Old Mexico, an art or skill passed down from generation to generation. The prickly pear cactus itself is still also food, animal fodder and medicine in Mexico. But cochineal grana are no longer treated like money or currency, as it was in Aztec Mexico when cochineal was used in payment of tribute or taxes. In that sense, in contrast to a modern dollar, euro, yen, peso, pound, rupee or digital currency, which cannot be directly used as dyes or medicines, the grana possessed an exquisite versatility and flexibility in ancient times.

CARMINIC ACID, a MEDICINAL CHEMICAL pigment compound extracted from cochineal and first synthesized in 1998, belongs to a class of anti-tumor and antibiotic compounds called anthracycline derivatives, which “are believed to develop their cytotoxic effect by penetrating into the tumor cell nucleus and interacting there with DNA,” write chemists at Gazi University in Ankara, Turkey. Combined with other compounds, cochineal is also active against viruses and other microbes. In Tamil Nadu, India cochineal scale insects collected from cacti are crushed, boiled in water and dried to a powder used against whooping cough and as a sedative. Other traditional uses likely abound.

In nature, cochineal functions as an insect repellent. One theory is that cochineal repels ants, protecting young scale insects before their protective waxy outer covering forms. A carnivorous caterpillar eating the scales incorporates the cochineal dye into its own bodily defenses. A study in the Journal of Polymer Science concluded that cochineal and other natural dyes (madder, walnut, chestnut, fustic, logwood) and mordants (aluminum, chrome, copper, iron, and tin) increased the insect resistance of the wool fabric to attack by black carpet beetles.” Indigo was least effective, and cochineal and madder were most effective except when used with tin and chrome as the mordant or binding agent. I only remember one ESA presentation investigating cochineal as a natural insecticide, and that was back in 2004; the idea was that since carminic acid was already approved as safe for food by the FDA, cochineal could be formulated as an organic bait spray to stop fruit flies without losing organic certification. The researcher theorized that cochineal needs sunlight to be activated as an insecticide, and would thus be ideal for organic agriculture. But as far as I know, the idea was never adapted as an agricultural or quarantine practice.

COMBINING COLOR and HEALING is, however, an idea gaining traction. Carminic acid, a brilliant red compound constituting about 10% of cochineal8, “is one of the most light and heat stable of all the colorants and is more stable than many synthetic food colors,” write Khadijah Kashkar and Heba Mansour in the Department of Fashion Design at King Abdul Aziz University, Saudi Arabia. “Besides the color attributes, recently, also has been reported to beneficial to health with potential antibiotic and antitumor properties. At the beginning of the 21st century it is predicted that many colors will be used for both their additional beneficial functions in the body, as well as, coloring effect.” Whether color and healing were also linked in ancient or Aztec times with cochineal is an intriguing question. Perhaps everything old is indeed new again, but who knows what the ancient New World healers or shaman thought when applying bright red or purple cochineal poultices.

PREVENTIVE MEDICINE might be what to call the combination of organic cotton and natural cochineal dyes to block ultraviolet light from skin contact. Ajoy Sarkar of Colorado State University, writing in the journal BMC dermatology: “The ultraviolet radiation (UVR) band consists of three regions: UV-A (320 to 400 nm), UV-B (290 to 320 nm), and UV-C (200 to 290 nm). UV-C is totally absorbed by the atmosphere and does not reach the earth. UV-A causes little visible reaction on the skin but has been shown to decrease the immunological response of skin cells. UV-B is most responsible for the development of skin cancers…Other than drastically reducing exposure to the sun, the most frequently recommended form of UV protection is the use of sunscreens, hats, and proper selection of clothing. Unfortunately, one cannot hold up a textile material to sunlight and determine how susceptible a textile is to UV rays.” Heavy concentrations of synthetic dyes in synthetic fabrics generally provide good UVR protection, but are not as comfortable as cotton fabrics for warm, humid climates. Generally, the darker the color and the thicker the weave or denser the fabric, the better to protect against UVR. Depending upon the weave (e.g. twill vs sateen), Sarkar reported good to excellent UVR protection with natural dyes such as madder, indigo and cochineal.

COCHINEAL’S 21ST CENTURY RENAISSANCE and resurgence includes harnessing cochineal’s ability to capture (harvest) or route light (photons) and electrons in advanced or next generation optoelectronic devices such as semiconductors, light harvesting antennae, sensors, fuel and solar cells, and molecular information and logic gates for computing devices. I was surprised to learn that natural pigments have a long history in advanced electronics: “As early as the birth stage of lasers, coumarin, which is found naturally in high concentration in the tonka bean (Dipteryx odorata), was used in dye lasers” and “coumarin dye is still the basic active medium for many tunable dye laser sources,” writes M. Maaza (2014) of the University of South Africa. “Extracts from Hibiscus sabdariffa, commonly known as Roselle, carminic acid of the cochineal scale and saffron exhibit exceptional nonlinear optical (NLO) properties of a prime importance in optics.”

THE “NEXT GENERATION” SOLAR CELL replacement for today’s silicon-based solar cells will probably be a dye-sensitized solar cell (DSSC) based on titanium dioxide (TiO2), a semiconductor material that is fused with color pigments analogous to those used in conventional color photography (e.g. silver halide emulsions sensitized by dyes). TiO2 and other metal oxides are widely used in medicine, food preservation, cosmetics, sunscreens, paints, inks and a wide range of electronic devices for sensing, imaging, optics, etc. TiO2 is relatively inexpensive, and deemed low toxicity. Interestingly, TiO2 nanoparticles for solar cells can be produced from cultures of bacterial cells, such as the Lactobacillus sp. found in yogurt or curd, which means an even “greener” solar cell fabrication process.

The scientific roots of the modern solar cell go back to French physicist Edmond Becquel’s discovery of the photovoltaic effect in 1839; and prototype solar cells with efficiencies of 1% or less also date back to the 1800s. Though Albert Einstein explained the photovoltaic effect in 1904, the development of lightweight solar energy cells to power spacecraft in the 1950s. But the DSSC or Grätzel cell is a 1990s’ innovation attributed to Mr. O’Regan and Michael Grätzel. “This new device was based on the use of semiconductor films consisting of nanometer-sized TiO2 particles, together with newly developed charge-transfer dyes,” and had “an astonishing efficiency of more than 7%,” write Agnes Mbonyiryivuze et al. (2015) in the journal Physics and Materials Chemistry.

Next generation DSSCs or photovoltaic cells are currently undergoing a major design transition using natural color pigments like those found in cochineal scale insects. DSSCs with efficiencies in the 10% to 15% range can be manufactured with titanium dioxide (TiO2) nanoparticles bonded on a thin film with a light-sensitive dye utilizing a rare and expensive platinum group heavy metal, ruthenium (Ru; named after Russia). Ruthenium’s relatively high cost and environmental and toxicology concerns are a barrier to commercialization that is spurring the search for substitutes; namely cheaper and more environmentally friendly natural pigment. Companies working “to bring DSSC technology ‘from the lab to the fab’” include “Dyesol, G24i, Sony, Sharp, and Toyota, among others,” write Mbonyiryivuze et al. (2015). “Functional cells sensitized with berry juice can be assembled by children within fifteen minutes, the large choice of colors, the option of transparency and mechanical flexibility, and the parallels to natural photosynthesis all contribute to the widespread fascination. In 2013, the drastic improvement in the performance of DSSC has been made by Professor Michael Grätzel and co-workers at the Swiss Federal Institute of Technology (EPFL). They have developed a state solid version of DSSC called perovskite-sensitized solar cells that is fabricated by a sequential deposition leading to the high performance of the DSSC. This deposition raised their efficiency up to a record 15% without sacrificing stability…this will open a new era…even surpass today’s best thin-film photovoltaic devices.”

“PIGMENTS MAKE NATURE COLORFUL and LIKABLE,” writes Chunxian Chen, a researcher at the University of Florida’s Citrus Research and Education Center and the editor of a 277-page book published by Springer in 2015, Pigments in Fruits and Vegetables: Genomics and Dietetics, which places a heavy emphasis on the nutritional and medicinal benefits of colorful natural pigments like those coloring crops of carrots and sweet potatoes orange and radishes and tomatoes red. “Plant pigments usually refer to four major well-known classes: chlorophylls, carotenoids, flavonoids, and betalains…Chlorophylls are the primary green pigments for photosynthesis. The latter three are complementary nongreen pigments with diverse functions…The importance of colors in living organisms cannot be overstated…they are biosynthesized behind the scenes in living organisms and ultimately ingested in daily diet.” Presumably this daily consumption and medicinal benefits makes natural pigments in general logical and sustainable alternatives to expensive heavy metals in “green” electronic, computer and solar energy cell designs.

Agnes Mbonyiryivuze, in her 2014 dissertation titled “Indigenous natural dyes for Gratzel solar cells: sepia melanin,” provides a readable overview of solar energy cells utilizing natural pigments. The list of natural pigments fabricated into solar cells is long, and the sources range from cochineal scale insects, green algae, baker’s yeast, fungi and bacteria to bougainvillea flowers, Chinese medicinal plants (e.g. tea, pomegranate leaves, wormwood, mulberry fruit) and food crops like beets, parsnip, purple cabbage, blackberry and black grapes. The black pigments are of particular interest, including skin melanins providing UV protection and the black powder from cuttlefish (Sepia officinalis) ink sacks. “To maximize the absorption of more photons from the sun light for DSSC,” writes Mbonyiryivuze, “it is better to have a black dye sensitizer having extremely high broadband absorption. It should absorb not only in visible range but also in ultraviolet and near-infrared regions. This challenge can be handled by using natural dyes from other sources such as fauna from which sepia melanin was obtained. Melanins are well-known natural pigments used for the photoprotective role as a skin protector because of their strong UV absorbance and antioxidant properties. Melanin possesses a broad band absorbance in UV and visible range up to infrared.” Sepia melanin “can also conduct electricity and is thus considered a semiconductor material.”

“There are numerous trials of solar cell construction which are based on biomolecules and supramolecular systems, for instance, chlorophylls, porphyrins, phtalocyanines, and other natural or bioinspired dyes,” write researchers in Poland constructing double layer solar cells with cochineal red and gardenia yellow pigments bonded to TiO2 nano-surfaces. “Hybrid materials incorporating biomolecules immobilized on conducting or semiconducting surfaces are unique systems combining collective properties of solids with structural diversity of molecules, which besides photosensitization show other unique electrochemical and catalytical properties.”

According to Mousavi-Kamazani et al. in Material Letters (2015), quantum dots composed of cochineal and copper offer the economically attractive “possibility of single step production of three-layered solar cells.” Clearly, though the distance might be measured in years or decades, we are getting closer to a cochineal and natural pigment renaissance that transcends traditional fabric dyes and artist’s pigments and extends into medicine and the heart of modern computers, lasers and electronic and optical devices of all sorts.