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|Female (left) and male (right) cochineals|
|Female (left) and male (right) cochineals|
The cochineal (// koch-i-NEEL or // KOCH-i-neel; Dactylopius coccus) is a scale insect in the suborder Sternorrhyncha, from which the crimson-coloured natural dye carmine is derived. A primarily sessile parasite native to tropical and subtropical South America and Mexico, this insect lives on cacti in the genus Opuntia, feeding on plant moisture and nutrients.
The insect produces carminic acid that deters predation by other insects. Carminic acid, typically 17–24% of dried insects' weight, can be extracted from the body and eggs, then mixed with aluminium or calcium salts to make carmine dye, also known as cochineal. Carmine is today primarily used as a food colouring and for cosmetics, especially as a lipstick colouring.
The carmine dye was used in Central America in the 15th century for colouring fabrics and became an important export good during the colonial period. After synthetic pigments and dyes such as alizarin were invented in the late 19th century, natural-dye production gradually diminished. Health fears over artificial food additives, however, have renewed the popularity of cochineal dyes, and the increased demand has made cultivation of the insect profitable again, with Peru being the largest exporter. In Mexico, some towns in the state of Oaxaca are still working in handmade textiles.
Other species in the genus Dactylopius can be used to produce cochineal extract, but they are extremely difficult to distinguish from D. coccus, even for expert taxonomists, and the latter scientific name (and the vernacular "cochineal insect") is therefore commonly used when one is actually referring to other biological species. The primary biological distinctions between species are minor differences in host plant preferences, in addition to very different geographic distributions.
Cochineal is probably from French cochenille, Spanish cochinilla, Latin coccinus, meaning "scarlet-colored", and Latin coccum, meaning "berry (actually an insect) yielding scarlet dye". See also the related word kermes which is the source of a similar but weaker Mediterranean dye also called crimson, which was used to color cloth red before discovery of cochineal in the New World. Some sources identify the Spanish source word for cochineal as cochinilla "wood louse" (a diminutive form related to Spanish, cerdo and chancho, ultimately from French cochon, meaning "pig")."
Cochineal dye was used by the Aztec and Maya peoples of Central and North America. Eleven cities conquered by Montezuma in the 15th century paid a yearly tribute of 2000 decorated cotton blankets and 40 bags of cochineal dye each. Production of cochineal is depicted in Codex Osuna. During the colonial period, the production of cochineal (grana fina) grew rapidly. Produced almost exclusively in Oaxaca by indigenous producers, cochineal became Mexico's second-most valued export after silver. Soon after the Spanish conquest of the Aztec Empire, it began to be exported to Spain, and by the 17th century was a commodity traded as far away as India. The dyestuff was consumed throughout Europe and was so highly prized, its price was regularly quoted on the London and Amsterdam Commodity Exchanges. In 1777, French botanist Nicolas-Joseph Thiéry de Menonville, presenting himself as a botanizing physician, smuggled the insects and pads of the Opuntia cactus to Saint Domingue. This particular collection failed to thrive and ultimately died out, leaving the Mexican monopoly intact. After the Mexican War of Independence in 1810–1821, the Mexican monopoly on cochineal came to an end. Large-scale production of cochineal emerged, especially in Guatemala and the Canary Islands; it was also cultivated in Spain and North Africa.
The demand for cochineal fell sharply with the appearance on the market of alizarin crimson and many other artificial dyes discovered in Europe in the middle of the 19th century, causing a significant financial shock in Spain as a major industry almost ceased to exist. The delicate manual labour required for the breeding of the insect could not compete with the modern methods of the new industry, and even less so with the lowering of production costs. The "tuna blood" dye (from the Mexican name for the Opuntia fruit) stopped being used and trade in cochineal almost totally disappeared in the course of the 20th century. The breeding of the cochineal insect has been done mainly for the purposes of maintaining the tradition rather than to satisfy any sort of demand.
It has become commercially valuable again, although most consumers are unaware that the phrases "cochineal extract", "carmine", "crimson lake", "natural red 4", "C.I. 75470", "E120", or even "natural colouring" refer to a dye derived from an insect. One reason for its popularity is many commercial synthetic red dyes were found to be carcinogenic. The dye can, however, induce an anaphylactic shock reaction in rare cases.
The carmine of antiquity also contains carminic acid, and was extracted from a similar insect, Kermes vermilio, which lives on Quercus coccifera oaks native to the Near East and the European side of the Mediterranean Basin. Kermes carmine was used as a dye and a laked pigment in ancient Egypt, Greece, and the Near East and is one of the oldest organic pigments. Recipes for artists' use of carmine appear in many early painting and alchemical handbooks throughout the Middle Ages; the laking process for both pigments was improved in the 19th century. Carmine was not light-fast and was largely abandoned in art.
Deep brownish-red [Indian lake or lac (NR25)] is made from the blood-red secretion of female scale insects (Laccifer lacca) that feed on the twigs of various trees native to India, including Butea frondosa and Ficus religiosa. The twigs become encrusted with a reddish, bumpy, and glossy resin that is processed to extract the red colourant; lighter grades of the resin are used as the basis for shellac, and was used as a silk dye in India and imported to Spain since the early 13th century. In chemical terms, lac is closely related to carmine, and is equally fugitive.
Cochineal insects are soft-bodied, flat, oval-shaped scale insects. The females, wingless and about 5 mm (0.20 in) long, cluster on cactus pads. They penetrate the cactus with their beak-like mouthparts and feed on its juices, remaining immobile unless alarmed. After mating, the fertilised female increases in size and gives birth to tiny nymphs. The nymphs secrete a waxy white substance over their bodies for protection from water loss and excessive sun. This substance makes the cochineal insect appear white or grey from the outside, though the body of the insect and its nymphs produces the red pigment, which makes the insides of the insect look dark purple. Adult males can be distinguished from females in that males have wings, and are much smaller.
The cochineal disperses in the first nymph stage, called the "crawler" stage. The juveniles move to a feeding spot and produce long wax filaments. Later, they move to the edge of the cactus pad, where the wind catches the wax filaments and carries the insects to a new host. These individuals establish feeding sites on the new host and produce a new generation of cochineals. Male nymphs feed on the cactus until they reach sexual maturity. At this time, they can no longer feed at all and live only long enough to fertilise the eggs. They are, therefore, seldom observed. In addition, females typically outnumber males due to environmental factors.
D. coccus is native to tropical and subtropical South America and Mexico, where their host cacti grow natively. They have been widely introduced to many regions where their host cacti also grow. About 200 species of Opuntia cacti are known, and while it is possible to cultivate cochineal on almost all of them, the most common is Opuntia ficus-indica. D. coccus has only been noted on Opuntia species, including O. amyclaea, O. atropes, O. cantabrigiensis, O. brasilienis, O. ficus-indica, O. fuliginosa, O. jaliscana, O. leucotricha, O. lindheimeri, O. microdasys, O. megacantha, O. pilifera, O. robusta, O. sarca, O. schikendantzii, O. stricta, O. streptacantha, and O. tomentosa. Feeding cochineals can damage and kill the plant. Other cochineal species feed on many of the same Opuntia, and the wide range of hosts reported for D. coccus likely is because of the difficulty in distinguishing it from other Dactylopius species.
A nopal cactus farm for the production of cochineal is traditionally known as a nopalry. The two methods of farming cochineal are traditional and controlled. Cochineals are farmed in the traditional method by planting infected cactus pads or infesting existing cacti with cochineals and harvesting the insects by hand. The controlled method uses small baskets called Zapotec nests placed on host cacti. The baskets contain clean, fertile females that leave the nests and settle on the cactus to await fertilization by the males. In both cases, the cochineals must be protected from predation, cold, and rain. The complete cycle lasts three months, during which time the cacti are kept at a constant temperature of 27 °C (81 °F). At the end of the cycle, the new cochineals are left to reproduce or are collected and dried for dye production.
To produce dye from cochineals, the insects are collected when they are around 90 days old. Harvesting the insects is labour-intensive, as they must be individually knocked, brushed, or picked from the cacti and placed into bags. The insects are gathered by small groups of collectors who sell them to local processors or exporters.
Several natural enemies can reduce the population of the insects on hosts. Of all the predators, insects seem to be the most important group. Insects and their larvae such as pyralid moths (order Lepidoptera), which destroy the cactus, and predators such as lady bugs (Coleoptera), various Diptera (such as Syrphidae and Chamaemyiidae), lacewings (Neuroptera), and ants (Hymenoptera) have been identified, as well as numerous parasitic wasps. Many birds, human-commensal rodents (especially rats) and reptiles also prey on cochineal insects. In regions dependent on cochineal production, pest control measures are taken seriously. For small-scale cultivation, manual methods of control have proved to be the safest and most effective. For large-scale cultivation, advanced pest control methods have to be developed, including alternative bioinsecticides or traps with pheromones.
Opuntia species, known commonly as prickly pears, were first brought to Australia in an attempt to start a cochineal dye industry in 1788. Captain Arthur Phillip collected a number of cochineal-infested plants from Brazil on his way to establish the first European settlement at Botany Bay, part of which is now Sydney, New South Wales. At that time, Spain and Portugal had a worldwide cochineal dye monopoly via their New World colonial sources, and the British desired a source under their own control, as the dye was important to their clothing and garment industries; it was used to colour the British soldiers' red coats, for example. The attempt was a failure in two ways: the Brazilian cochineal insects soon died off, but the cactus thrived, eventually overrunning about 100,000 sq mi (259,000 km2) of eastern Australia. The cacti were eventually brought under control in the 1920s by the deliberate introduction of a South American moth, Cactoblastis cactorum, the larvae of which feed on the cactus.
Carminic acid is extracted from the female cochineal insects and is treated to produce carmine, which can yield shades of red such as crimson and scarlet. The body of the insect is 19–22% carminic acid. The insects are processed by immersion in hot water or exposure to sunlight, steam, or the heat of an oven. Each method produces a different colour that results in the varied appearance of commercial cochineal. The insects must be dried to about 30% of their original body weight before they can be stored without decaying. It takes about 80,000 to 100,000 insects to make one kilogram of cochineal dye.
The two principal forms of cochineal dye are cochineal extract, a colouring made from the raw dried and pulverised bodies of insects, and carmine, a more purified colouring made from the cochineal. To prepare carmine, the powdered insect bodies are boiled in ammonia or a sodium carbonate solution, the insoluble matter is removed by filtering, and alum is added to the clear salt solution of carminic acid to precipitate the red aluminium salt. Purity of colour is ensured by the absence of iron. Stannous chloride, citric acid, borax, or gelatin may be added to regulate the formation of the precipitate. For shades of purple, lime is added to the alum.
As of 2005, Peru produced 200 tons of cochineal dye per year and the Canary Islands produced 20 tons per year. Chile and Mexico have also recently begun to export cochineal. France is believed to be the world's largest importer, and Japan and Italy also import the insect. Much of these imports are processed and re-exported to other developed economies. As of 2005, the market price of cochineal was between US$50 and 80 per kilogram, while synthetic raw food dyes are available at prices as low as $10–20 per kilogram.
Traditionally, cochineal was used for colouring fabrics. During the colonial period, with the introduction of sheep to Latin America, the use of cochineal increased, as it provided the most intense colour and it set more firmly on woolen garments than on clothes made of materials of pre-Hispanic origin such as cotton or agave and yucca fibers. In general, cochineal is more successful on protein-based animal fibres (including silk) than plant-based material. Once the European market discovered the qualities of this product, the demand for it increased dramatically. By the beginning of the 17th century, it was traded internationally. Carmine became strong competition for other colourants such as madder root, kermes, Polish cochineal, brazilwood, and Tyrian purple, as they were used for dyeing the clothes of kings, nobles, and the clergy. For the past several centuries, it was the most important insect dye used in the production of hand-woven oriental rugs, almost completely displacing lac. It was also used for painting, handicrafts, and tapestries. Cochineal-coloured wool and cotton are still important materials for Mexican folk art and crafts.
Today, it is used as a fabric and cosmetics dye and as a natural food colouring. It is also used in histology. In artists' paints, it has been replaced by synthetic reds and is largely unavailable for purchase due to poor lightfastness. When used as a food additive, the dye must be named on packaging labels. Sometimes carmine is labelled as E120. A small number of people have been found to have allergies to carmine, ranging from mild cases of hives to atrial fibrillation and anaphylactic shock, with 32 cases documented to date. Carmine has been found to cause asthma in some people. Natural carmine dye used in food and cosmetics can render the product unacceptable to vegetarian or vegan consumers. Many Muslims consider carmine-containing food forbidden (haraam) because the dye is extracted from insects and all insects except the locust are haraam in Islam. Jews also avoid food containing this additive, though it is not treif, and some authorities allow its use because the insect is dried and reduced to powder.
Cochineal is one of the few water-soluble colourants to resist degradation with time. It is one of the most light- and heat-stable and oxidation-resistant of all the natural organic colourants and is even more stable than many synthetic food colours. The water-soluble form is used in alcoholic drinks with calcium carmine; the insoluble form is used in a wide variety of products. Together with ammonium carmine, they can be found in meat, sausages, processed poultry products (meat products cannot be coloured in the United States unless they are labeled as such), surimi, marinades, alcoholic drinks, bakery products and toppings, cookies, desserts, icings, pie fillings, jams, preserves, gelatin desserts, juice beverages, varieties of cheddar cheese and other dairy products, sauces, and sweets.
Carmine is considered safe enough for use in eye cosmetics. A significant proportion of the insoluble carmine pigment produced is used in the cosmetics industry for hair- and skin-care products, lipsticks, face powders, rouges, and blushes. A bright red dye and the stain carmine used in microbiology is often made from the carmine extract, too. The pharmaceutical industry uses cochineal to colour pills and ointments.
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