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Cochineal (Coccus cacti or Dactylopius coccus) is a scale insect in the order of Homoptera, native to tropical and subtropical South America and Mexico. A parasite, it lives primarily on the prickly pear cactus Napalea cochinillifera by feeding on moisture in its leaves. The dried bodies of the females or eggs are the main source of expensive crimson or carmine red coloured dye primarily used as an food artificial colouring or for cosmetics named after the insect.

After synthetic pigments have been invented in late [19th century]], the booming natural dye producing industry has gradually diminished. However, current health concerns over artificial food additives caused a return of cochineal dyes; increased demand made cultivation of this insect again profitable ^[1].

The Insect

Cochineals are soft-bodied, flat, oval-shaped scale insects that cluster on cacti plants. The cacti pads are colonised by female wingless insects which are about 5 mm long. After fertilised, female increases in size and gives a birth to tiny nymphs. They secrete a waxy white substance over their bodies and their nymphs for protection from water and excessive sun. This substance makes cochineal insect appear white or grey from the outside. The body of the insect and its nymphs produces a red pigment, which makes the inners of the insect look dark purple. Initially nymphs are white. The pigment is based on carminic acid and its purpose is to protect from predators. When adult, tiny, comparing to females, males have wings and they only live long enough to fertilise the eggs.^[2]

Habitat

Native to tropical and subtropical South America and Mexico. Later cochineal have been introduced to Spain, Canary Island, Algiers and Australia.

The Host Cacti

All of the host plants of the cochineal colonies were identified as species of Opuntia and Nopalea (Opuntia amyclaea Tenore, O. atropes Bravo, O. cantabrigiensis Lynch, O. brasilienis (Willd.) Haworth, O. ficus-indica (L.) Mill., O. fuliginosa Griffiths, O. jaliscana Bravo, O. leucotricha De Candolle, O. lindheimeri Engelmann, O. microdasys (Lehmann) Pfeiffer, O. megacantha Salm-Dyck, O. pilifera Weber, O. robusta Wendland, O. sarca Griff. ex Scheinv. O. schikendantzii Weber, O. stricta Haworth, O. streptacantha Lem., O. tomentosa Salm-Dyck) ^[3].

The feeding of the female cochineal often causes damage and sometimes kills the host cactus plant. Immature males while being nymphs feed on a cactus for a short time, and when adult, males cannot feed at all.

Cochineal-laden cacti Napalea cochinillifera were introduced into Australia for this dye with disastrous consequences. By 1925, 250000 km² of valuable range land was covered by prickly pear cactus. To control the spread of prickly pear cactus in Australia, the cactus moth (Cactoblastis cactorum) was introduced, and by 1930, vast areas of cactus scrub have been denuded by cactus moth larvae. Side effects have caused a havoc: the moth has attacked other species of cacti, some of which are rare and endangered ^[4].

Farming

The cochineal is farmed by planting already infected pads and protecting the predators, cold and rains. Several natural enemies can reduce the whole populations of this insect on its cacti hosts. Of all the depredators, insects seem to be the most important group. Insects and their larvae as weaver worm, pyralid moth (order Lepidoptera), lady bug (Coleoptera), fly, drum worm (Diptera), needle worm (Neuroptera) and ant (Hymenoptera) have been identified. Many birds, including domestic, rodents, especially rats, and reptiles also are predators of cochineal population.

In regions, dependant on cochineal production, pest control measures have to be taken seriously. For small cultivations most effective and safe manual method of control has proved. For large cultivation farms advanced methods have to be developed: alternative bioinsecticides or traps with pheromones ^[5].

The Dye

A deep crimson dye is extracted from the Cochineal insect females. Cochineal is used to produce scarlet, orange and other tints of red colour dyes, too.

Dye Production

The insects are collected at approximately age of ninety days. The insects are knocked, brushed or picked from the cacti into bags; it is a highly labor-intensive activity. The insects are gathered by small groups of collectors who sell them to local processors or exporters ^[6].

The insects are killed by either immersion in hot water (after which they are dried) or by exposure to sunlight, steam, or the heat of an oven. The variety in the appearance of commercial cochineal is caused by these differing methods. The immersion technique produces grey grains known as grey cochineal ^[7]. Heating technique produces almost black grains known as black cochineal. The insects must be dried to about 30 per cent of their original body weight before they can be stored without decaying^[8]. It takes around 70,000 insects to make one pound of cochineal.

There are two main forms of cochineal dye: cochineal extract is a colouring made from the raw dried and pulverised bodies of insects, carmine is a more purified colouring made from cochineal. The dried insects and extracts must conform to the buyer’s specification for very low maximum levels of bacteria^[9]. The colouring comes from carminic (kermesic) acid. Cochineal extract natural carminic acid content is usually 19-22% ^[10].

To prepare carmine, the powdered insect bodies are boiled in ammonia or 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 the shades of purple, lime is added to the alum ^[11].

Now Cochineal is produced commercially only in Peru, which produces about 200 tonnes per year ^[12], and the Canary Islands, which produce only about 20 tonnes per year^[13]. France is believed to be the world’s largest importer of cochineal, but Japan and Italy are also important direct importers. A high proportion of these imports are reexported in processed form, mainly to other developed economies^[14].

History

The cochineal was used by the Aztecs and Mayans. 11 cities conquered by Montezuma in 15th century paid a yearly tribute of 2000 decorated cotton blankets and 40 bags of Cochineal dye each ^[15]. Spanish conquistadors introduced the dye from Mexico to Europe during the 17th century. The Mexican city of Oaxaca, Oaxaca, and its hinterland owed much of its prosperity in the 17th and 18th centuries to the cochineal trade. It has since been imported to and cultivated in other locations, such as Peru and the Canary Islands, where it became a lucrative export ^[16]. The dye industry was so economically important, that it was third highest source of income for Spanish colonies after gold and silver exports. Once Mexico has been the first dye producer during the colonial period ^[17].

Recipes for artists' use of carmine appear in many early painting and alchemical handbooks throughout the Middle Ages. Carmine lakes appear frequently in European oil paintings from François Boucher to Raoul Dufy ^[18].

In the course of the 20th century, trade in cochineal diminished, as it was replaced by synthetic compounds, like alizarin crimson and many other substitute dyes. In recent years it has become commercially valuable again ^[19], because, unlike many commercial synthetic red dyes, it is non-toxic and not carcerogenic (however, some people are allergic to carmine - see a section below).

Usage

Wool dyed with cochineal

Traditionally cochineal was used for colouring fabrics. Now it is used as a fabric and cosmetics dye and as a natural food colouring, as well as for oil paints, lake, pigments and watercolours. Cochineal dye coloured wool and cotton is still important material for Mexican folk art and crafts. Because it can cause severe allergies, when used as a food additive, the dye must be labelled on packaging labels ^[20]. Sometimes Carmine is labelled as E120.

The water soluble form is used in alcoholic drinks with calcium carmine, the insoluble form, being used in a wider variety of products. Together with ammonium carmine they can be found in alcoholic drinks, bakery products and toppings, biscuits, desserts, drinks, icings, pie fillings, variety of cheddar cheese, sauces and sweets. It gives Campari and other Italian aperitifs their colour, too^[21].

Carmine is one of the very few pigments considered safe enough for use in eye cosmetics ^[22]. A bright red dye and the biological stain carmine used in microbiology is often made from the carmine extract, too ^[23]. The pharmaceutical industry uses cochineal to colour pills and ointments ^[24].

Controversy

An unknown percentage of people have been found to have allergies to carmine, ranging from mild cases of hives, to anaphylactic shock. Carmine has been found to cause asthma in some people ^[25]. Cochineal is one of the colours that the Hyperactive Children's Support Group recommends be eliminated from the diet of hyperactive children.

Natural carmine dye used in foods can render them rather unattractive to vegetarian consumers, and Muslims consider carmine containing food forbidden (haraam), because insects are used in dye production (see above).

References

1. ^ Template:Web reference author
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3. ^ Canary Islands cochineal producers homepage
4. ^ Template:Web reference author
5. ^ Template:Web reference author
6. ^ Template:Web reference author
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See also

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de:Koschenille es:Cochinilla nl:Karmijn pt:Cochonilha vi:Bọ yên chi