Farming Insects For Their Products And Byproducts

Not only living insects are marketed. Dead insects and products derived from them can also be of high commercial value. In fact, insect products and by-products probably account for the lion's share of insect commercialization.

Implements for Research

Insects provide critical basic tools for studying a great many aspects of biology. Because Drosophila melanogaster, a common fruit fly, is small, has a short life cycle, and is inexpensive and easy to rear, it is an extremely valuable organism for biological research, particularly in the fields of genetics and developmental biology. Drosophila has been used extensively and intensively as a model organism for research for almost a century, primarily to uncover the relatedness of genes to proteins and to study and map the underlying mechanisms of genetic inheritance and gene expression. More recently, the field of developmental biology, especially embryology, has relied on Drosophila in explorations of how a complex organism arises from a relatively simple fertilized egg. The genome of Drosophila, recently sequenced, maps the gene structure of that seminal organismal model. Gene products such as Drosophila polypeptides and transcripts, and investigative tools such as the Drosophila Activity Monitor for circadian rhythm research, provide highly marketable products for the scientific supply industry. Moreover, specific, even mutant strains of Drosophila may be purchased, as well as supplies for rearing and maintaining cultures, and specialized equipment for conducting experiments.

Insect products are also marketed for other research functions. For instance, they are used for genetic and molecular markers. The enzyme luciferase, derived from fireflies, is an excellent marker for assaying gene expression. These markers are produced and sold commercially. Indeed, specialized equipment for detecting the expressed bioluminescence is also marketed. Cell lines derived from insects is another powerful research tool. For example, protein-based human and veterinary vaccines and therapeutic proteins are produced by using baculovirus expression vector systems in insect cell lines. Human and animal protein products derived from insect cell lines are marketed for a number of purposes, including drug screening and clinical trials.

Food Products

Insects are an extremely rich source of high-quality proteins, fats, essential vitamins, and minerals. It is therefore not surprising that dead insects and products derived from them are marketed for their nutritional value. These products can take the form of human food, pet food, and livestock feed.

honey One can hardly think of insects as a source of human food without envisioning honey, diligently produced by worker bees. Honey was used as a sweetener in ancient Egypt and continues to be popular today, both in cooking and for sweetening foods to be consumed immediately. Entire industries are built around honey bees both as crop pollinators and as master producers of honey. The latter industry ends with the sale of honey products on the supermarket shelf, but the intermediaries are varied and include, beyond those involved in rearing honey bees, equipment for extracting honey from combs, devices for straining and clarifying honey, and beekeeping books and magazines that keep the honey producer up to date on the latest developments in the industry.

human food One often thinks of insects as human food in a novelty context, like being dared to eat fried mealworms, crickets, or chocolate-covered ants at the county fair. But insects have been a serious source of human nutrition for a very long time. This association substantially waned as urbanization and "westernization" spread, but in the less developed corners of the globe it continues unabated. Accordingly, about 500 species in some 260 genera and 70 families of insects are used for human food somewhere in the world, especially in central and southern Africa, Asia, Australia, and Latin America. Even in the West, insect foods need not be a novelty. Where they are consumed, insects provide 5.10% of the annual animal protein of indigenous peoples. Some Native American peoples consumed saturniid moth larvae as a main part of their diets. Currently, more than 100 species of insects are sold as human food at local markets in rural Mexico, where they constitute a regular part of the local diets. In Thailand, the specialized sex pheromone gland from giant water bugs provides a flavoring to shrimp paste. Thus, marketing insect-derived foodstuffs in selected regions of the globe contributes to local economies, but repugnancy of insect foods in western cultures continues to thwart economic opportunity for mass-producing and marketing these products in the West.

pet food Birds, lizards, fish, caiman, crocodiles, turtles, and a host of other insectivorous pets survive and breed much better if supplied with protein and nutrients that are available from live or dead insects. Rearing and selling these insects to the public is a thriving business (Fig. 2) Madagascar hissing roaches are sold as reptile food, whereas crickets are marketed for consumption by a variety of pets.

livestock feed Beyond pet food, insects can provide a highly nutritious food source for domestic animals and livestock. Although low in such amino acids as methionine-cysteine, arginine, and tryptophan, when supplemented by

FIGURE 2 Superworms (Zophobus morio) are popular large mealworms originating from South America available in pet stores for reptile and amphibian food. (Photograph by Gail Kampmeier.)

these, insect protein forms an excellent feed. Under clinical trials, white rats (the universal experimental animal for testing new medical and pharmaceutical findings) fed Mormon cricket meal demonstrated the great potential of insects as a major source of protein for rats. China recognizes the potential nutritive value of insects as feed for fish, poultry, pig, and farm-grown mink. There, experiments have demonstrated that insect-derived diets are cost-effective alternatives to more conventional fish meal diets. House fly larvae and pupae, silkworm pupae, and mealworm larvae are the major source of these insect-based diets. Fly larvae fed on poultry manure have been experimentally incorporated back into poultry feed. When this system is in place, it will take the concept of recycling to a whole new level.

Secretions and Dyes

A number of insects have the ability to secrete substances such as waxes and resins through specialized glands. Dyes too can be extracted from insect tissues. Many of these products are of high commercial value.

sericulture Among fine fabrics made of natural products such as wool, cotton, linen, and leather, silk is almost always the most highly prized. Silk cloth is woven from a secretion of the silkworm, Bombyx mori. In the Orient, sericulture, a 4700-year-old industry, has built up around this insect and its precious secretion. The silk is a continuous-filament fiber consisting of fibroin protein, secreted from two larval salivary glands in the insect's head, and a gum called sericin, which cements the two filaments together. Silkworm larvae secrete this substance to weave cocoons within which they pupate. To obtain the fibroin protein filaments, cocoons are softened in hot water to remove the sericin. Single filaments are drawn from cocoons in water bowls and combined to form yarn, which is drawn under tension and wound onto reels, dried, packed according to quality, and sold as raw silk. It was once believed that silklike synthetic fibers would replace silk, thus decimating the silk industry, but that has not occurred. In fact, world silk production nearly doubled over the last 30 years. Together, China and Japan manufacture more than half of the world production. Other countries, like Nepal, are intensifying their silk production. The sericulture industry is complex, and many suppliers commercially produce and sell products to culture silkworms, obtain the raw silk, refine the silk, weave it, produce clothing from it, and sell the products on the market. Wild sericulture also exists: that is, fibers from cocoons other than the silkworm are used, often by native peoples, in a similar manner. This industry is less relevant to the modern world of commerce, but it fuels local industry and provides clothing and other needs of native peoples, especially in India.

spider silk Spider silk, like that of silkworms, is composed of fibroin. However, unlike silkworms, which secrete silk from salivary glands in the head, spiders secrete silk from glands at the tip of the abdomen. Depending of the type of silk that is to be made, the spider mixes the fluid from up to six different glands and regulates the speed and volume of release. Spider silk is an extraordinarily strong and elastic material. On a weight basis, it is stronger than steel; a pencil-thick strand of silk is strong enough to snare a Boeing 747 airplane in midair. DuPont advertises that the company's researchers are studying biopolymer structures of the spiderwebs. They have used recombinant DNA technology to produce analogues of spider silk in yeast and bacteria and are planning to promote this synthesized material for all manner of construction purposes.

royal jelly Royal jelly, a substance secreted by the salivary glands of worker honey bees, stimulates the growth and development of queen honey bees. It is one of the most difficult of all foods to harvest, commanding astronomical prices because of its scarcity and high demand, fueled by belief in its healing properties. What royal jelly can do for humans is controversial, but it purportedly reinvigorates the body and extends the life span. Pantothenic acid, a major ingredient, is useful in treating some bone and joint disorders. Rheumatoid arthritis symptoms may subside with the injection of this acid. When pantothenic acid is combined with royal jelly, even better results are reported. This product is sold by many health food companies.

beeswax Glands on the underside of young worker honey bee abdomens secrete small wax platelets, which are masticated and molded inside the hive into a comb of hexagonal cells that are then filled with honey. Additional wax is used to cap the cells for honey storage. Of all the primary products of the honey bee, wax has been, and remains, the most versatile and most widely used material. For centuries, beeswax has been regarded as the best material for making candles. An excellent wax for polishing woods and floors, it is also an ingredient in general-purpose varnishes. It has uses in packaging, processing, and preserving foods, and as a separation agent in the confectionery industry and in cigarette filters. Textiles and papers are waterproofed with products containing beeswax. Emulsions containing beeswax clean and soften leather goods.

Batik, an Asian method of coloring cloth, is based on the principle that wax (traditionally beeswax) protects areas that are not to be stained when the cloth is immersed in the dye solution. This protection feature is used for waterproofing and as an anticorrosion rust inhibitor to prevent dissolution of the metal in steel drums used to store and ship honey. Materials for embedding or electrically insulating circuits of high and ultrahigh frequency include beeswax. Beeswax is used as a binder when lubricant characteristics are desired or if mixtures are to be ingested. It is an ingredient in slow-release pellets of pyrethrum pesticides. Glass can be etched with hydrofluoric acid when areas that are not to be etched have been protected with beeswax. Various inks, pens, markers, and even carbon paper often contain small amounts of beeswax. Ancient jewelers and artisans formed delicate objects from wax and cast them later in precious metals. Colors of 2000-year-old wall paintings, as well as wrappings of Egyptian mummies, contain beeswax. Beeswax has long found use in medicines and body lotions. As a coating for pills, beeswax facilitates ingestion. Other products in which beeswax is a traditional ingredient are grafting wax, crayons, sealing wax, protective car polishes, and thread for sewing sails and shoes.

resins Shellac has been in use for 3200 years and is made from an insect native to India and Myanmar, the lac scale, Laccifer lacca. Lac females infest branches of fig trees and cover their bodies with a resinous secretion that hardens into a shield. Between 17,000 and 90,000 insects are needed to produce a pound of lac. The resins are ground to free the lac granules, which are then crushed and boiled in water. The floating lac is skimmed off, dried, and placed in burlap bags, which are stretched over a fire. As it is heated, the bags are twisted and the melted lac drips out. Before hardening, the lac is stretched like toffee. After hardening, the lac is broken into pieces and sold. Lac is the basic ingredient of a vast list of products besides shellac, including stiffening agents in the toes and soles of shoes and felt hats, shoe polishes, artificial fruits, lithographic ink, glazes in confections, phonographic records, playing card finishes, and hair dyes.

inks Iron gall ink is arguably the most important ink in the history of the Western civilization. It is made of vitriol, gum, water, and, most notably, tannin extracted from Aleppo galls. Oaks produce Aleppo galls in response to a chemical substance secreted by larvae of the cynipid wasp, Cynips gallae-tinctoriae. The gall provides both food and protection for the larva. Tannin content of the gall is highest before the wasp exits. Iron gall ink is still sold and used for many purposes. Because iron gall ink is indelible, it was the ink of choice for documentation from the late Middle Ages to the middle of the twentieth century. It was very popular with artists as a drawing ink, used with quill, reed pen, or brush. It is now used by the U.S. Treasury in the ink for printing money. The range of objects that contain iron gall ink is enormous. It was used for most manuscripts, music scores, drawings, letters, maps, and official documents such as wills, bookkeeping records, logs, and real estate transactions.

dyes Historically, adult female Mediterranean scales (Kermes iticies and K. vermilio), Oriental lac insects (Kerria lacca), central European scales (Porphyrophora polonica), and New World cochineal scales (Dactylopius coccus) were used in the preparation of red dye by a number of indigenous populations. Today, cochineal dye is the most important. It is obtained from an extract of the bodies of scale females found feeding on a cactus native to Mexico and Central America. The insects' bodies contain the pigment called carminic acid, which is effective in repelling potential predators such as ants. This substance is obtained by subjecting a mass of the crushed insects to steam or dry heat. Because 70,000 scale bodies are needed to produce a pound of cochineal, the dye is extremely expensive. Once commonly used as a scarlet-red mordant dye for wool and as a food coloring, cochineal has been largely replaced by synthetic products. It continues to be used as a coloring agent in cosmetics and beverages. Furthermore, the art of cochineal dying is practiced by natives in southern Mexico. The cochineal scale is still widely cultivated as a source of commercial dye in the Canary Islands and in parts of Central and South America. It is sold and chiefly used now as a biological stain.

Pharmacology

Even 3600 years ago, insects, their parts, and toxins derived from them were used to alleviate a number of human ills. Some of the remedies were less than effective (e.g., notably hirsute flies and bees used to treat baldness). Other insect-derived remedies were more credible because they have at their core a chemical property that today confirms their efficacy. For example, the hemolymph of cicadas has a high sodium ion concentration and was recommended in preparations to treat bladder and kidney dysfunction. Hemolymph is known to possess antibacterial properties and has thus been recommended in prescriptions to treat bacterial infections and sepsis. Traditional Chinese medicine includes a wealth of insects and other arthropods in its pharmacopoeia. Dried cockroaches, blister beetles, maggots, silkworm larvae, cicada exuviae, cicada nymphs and adults, and recipes using mole crickets, mantid oothecae, and silkworm frass can be purchased at traditional Chinese drugstores.

Aside from bee venom therapy described earlier, products from honey bees have long been used to promote health and as a food source (Fig. 3). Honey, royal jelly, bee pollen, and propolis are all sold to treat a variety of ailments from anorexia to insomnia to cardiovascular diseases, and to promote wound healing. More information can be obtained from the American Apitherapy Society.

Blister beetles are the major source of cantharidin, the active ingredient of "Spanish fly." This chemical has been used to topically treat warts and can be ingested for its aphrodisiac properties. Acute renal failure and death can arise from overdosing on cantharidin. These findings have prompted the removal of cantharidin from use in the United States, but Chinese researchers have discovered that beetles (e.g., Mylabris phalerata and M. cichorii), long used in traditional medicines, contain antitumor properties. Researchers are attempting to balance the potential cancer-fighting properties with undesirable side effects by testing less toxic analogues of cantharidin.

Adornments and Displays

Certain insects lend themselves or their products to the making of spectacular jewelry. Beetles are probably the most notable because of their durable, often iridescent, hardened forewings, called elytra, and interesting body shapes. They can be made into brooches or encased in plastic for key chains and paperweights; many tropical species are reared specifically for this purpose. Beetle elytra have also been woven into textiles. Insect galls and morpho butterfly and dragonfly wings have been incorporated into jewelry designs. Caddisfly larvae glue together tiny stones, grains of sand, and bits of litter to form cases that protect them in their aquatic environment. Furnished specific materials such as gold nuggets, shells, or semiprecious stones, they will incorporate these materials into their protective cases, which can then be harvested and made into earrings, necklaces, tie tacks, and pins. Insects trapped in

FIGURE 3 Honey, skin care products, and cough lozenges all make use of products from honey bees. (Photograph by Ann Coddington Rast.)

fossil amber also are sold for jewelry and displays. Although butterflies and beetles are commonly encountered in displays, a wide variety of insects are sold for those purposes, as well whether as decoration or for educational uses.

Party Favors and Pranks

For the prankster, live Madagascar hissing cockroaches are sold as party favors and "stocking stuffers" for the holidays. Honey bees embedded in plastic cubes shaped like ice can be purchased to be placed in a guest's drink. Mexican jumping beans, which are bean seeds containing larvae of a small moth Carpocapsa saltitans, have been popular as novelties for decades.

Homemade Pet Food Secrets

Homemade Pet Food Secrets

It is a well known fact that homemade food is always a healthier option for pets when compared to the market packed food. The increasing hazards to the health of the pets have made pet owners stick to containment of commercial pet food. The basic fundamentals of health for human beings are applicable for pets also.

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