The Cochineal

Jul 23, 2017 Features / Columnists, Interesting Creatures in Guyana

The cochineal is a scale insect in the suborder Sternorrhyncha, from which the natural dye carmine is derived. A primarily sessile parasite native to tropical and subtropical South America as well as Mexico and Arizona, this insect lives on cacti in the genus Opuntia, feeding on plant moisture and nutrients. These insects are found on the pads of prickly pear cacti, then are brushed off and dried.
The insect produces carminic acid that deters predation by other insects. Carminic acid, typically 17-24 percent 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. Today, carmine is primarily used as a colorant in food and in lipstick.
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. Some towns in the Mexican state of Oaxaca are still working in handmade textiles using this cochineal.
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 insects are soft-bodied, flat, oval-shaped scale insects. The females, wingless and about five 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.

The Cochineal

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.
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 Syrphidaeand 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. [Source Wikipedia]