1.6.1. Insects as human food: entomophagy
In this section we review the increasingly popular study of insects as human food. Probably 1000 or more species of insects in more than 370 genera and 90 families are or have been used for food somewhere in the world, especially in central and southern Africa, Asia, Australia, and Latin America. Food insects generally feed on either living or dead plant matter, and chemically protected species are avoided. Termites, crickets, grasshoppers, locusts, beetles, ants, bee brood, and moth larvae are frequently consumed insects. Although insects are high in protein, energy, and various vitamins and minerals, and can form 5–10% of the annual animal protein consumed by certain indigenous peoples, western society essentially overlooks entomological cuisine.
Typical “western” repugnance of entomophagy is cultural rather than scientific or rational. After all, other invertebrates such as certain crustaceans and mollusks are favored culinary items. Objections to eating insects cannot be justified on the grounds of taste or food value. Many have a nutty flavor and studies report favorably on the nutritional content of insects, although their amino acid composition needs to be balanced with suitable plant protein. Nutritional values obtained from analyses conducted on samples of four species of insects cooked according to traditional methods in central Angola, Africa are shown in Table 1.2. The insects concerned are: reproductive individuals of a termite, Macrotermes subhyalinus (Isoptera: Termitidae), which are dewinged and fried in palm oil; the large caterpillars of two species of moth, Imbrasia ertli and Usta terpsichore (Lepidoptera: Saturniidae), which are degutted and either cooked in water, roasted, or sun-dried; and the larvae of the palm weevil, Rhynchophorus phoenicis (Coleoptera: Curculionidae), which are slit open and then fried whole in oil.
Mature larvae of Rhynchophorus species have been appreciated by people in tropical areas of Africa, Asia, and the Neotropics for centuries. These fat, legless grubs (Fig. 1.2), often called palmworms, provide one of the richest sources of animal fat, with substantial amounts of riboflavin, thiamine, zinc, and iron (Table 1.2). Primitive cultivation systems, involving the cutting down of palm trees to provide suitable food for the weevils, are known from Brazil, Colombia, Paraguay, and Venezuela. In plantations, however, palmworms are regarded as pests because of the damage they can inflict on coconut and oil palm trees.
In central Africa, the people of southern Zaire (presently Democratic Republic of Congo) eat caterpillars belonging to 20–30 species. The calorific value of these caterpillars is high, with their protein content ranging from 45 to 80%, and they are a rich source of iron. For instance, caterpillars are the most important source of animal protein in some areas of the Northern Province of Zambia. The edible caterpillars of species of Imbrasia (Saturniidae), an emperor moth, locally called mumpa, provide a valuable market. The caterpillars contain 60–70% protein on a dry-matter basis and offset malnutrition caused by protein deficiency. Mumpa are fried fresh or boiled and sun-dried prior to storage. Further south in Africa, Imbrasia belina moth (see Plate 1.4) caterpillars (see Plate 1.5), called mopane, mopanie, mophane, or phane, are utilized widely. Caterpillars usually are degutted, boiled, sometimes salted, and dried. After processing they contain about 50% protein and 15% fat — approximately twice the values for cooked beef. Concerns that harvest of mopane may be unsustainable and over-exploited are discussed under conservation in Box 1.3.
In the Philippines, June beetles (melolonthine scarabs), weaver ants (Oecophylla smaragdina), mole crickets, and locusts are eaten in some regions. Locusts form an important dietary supplement during outbreaks, which apparently have become less common since the widespread use of insecticides. Various species of grasshoppers and locusts were eaten commonly by native tribes in western North America prior to the arrival of Europeans. The number and identity of species used have been poorly documented, but species of Melanoplus were consumed. Harvesting involved driving grasshoppers into a pit in the ground by fire or advancing people, or herding them into a bed of coals. Today people in central America, especially Mexico, harvest, sell, cook, and consume grasshoppers.
Australian Aborigines use (or once used) a wide range of insect foods, especially moth larvae. The caterpillars of wood or ghost moths (Cossidae and Hepialidae) (Fig. 1.3) are called witchety grubs from an Aboriginal word “witjuti” for the Acacia species (wattles) on the roots and stems of which the grubs feed. Witchety grubs, which are regarded as a delicacy, contain 7–9% protein, 14–38% fat, 7–16% sugars as well as being good sources of iron and calcium. Adults of the bogong moth, Agrotis infusa (Noctuidae), formed another important Aboriginal food, once collected in their millions from estivating sites in narrow caves and crevices on mountain summits in south-eastern Australia. Moths cooked in hot ashes provided a rich source of dietary fat.
Aboriginal people living in central and northern Australia eat the contents of the applesized galls of Cystococcus pomiformis (Hemiptera: Eriococcidae), commonly called bush coconuts or bloodwood apples (see Plate 2.3). These galls occur only on bloodwood eucalypts (Corymbia species) and can be very abundant after a favorable growing season. Each mature gall contains a single adult female, up to 4 cm long, which is attached by her mouth area to the base of the inner gall and has her abdomen plugging a hole in the gall apex. The inner wall of the gall is lined with white edible flesh, about 1 cm thick, which serves as the feeding site for the male offspring of the female (see Plate 2.4). Aborigines relish the watery female insect and her nutty-flavored nymphs, then scrape out and consume the white coconut-like flesh of the inner gall.
A favorite source of sugar for Australian Aboriginals living in arid regions comes from species of Melophorus and Camponotus (Formicidae), popularly known as honeypot ants. Specialized workers (called repletes) store nectar, fed to them by other workers, in their huge distended crops (Fig. 2.4). Repletes serve as food reservoirs for the ant colony and regurgitate part of their crop contents when solicited by another ant. Aborigines dig repletes from their underground nests, an activity most frequently undertaken by women, who may excavate pits to a depth of a meter or more in search of these sweet rewards. Individual nests rarely supply more than 100 g of a honey that is essentially similar in composition to commercial honey. Honeypot ants in the western USA and Mexico belong to a different genus, Myrmecocystus. The repletes, a highly valued food, are collected by the rural people of Mexico, a difficult process in the hard soil of the stony ridges where the ants nest.
Perhaps the general western rejection of entomophagy is only an issue of marketing to counter a popular conception that insect food is for the poor and protein-deprived of the developing world. In reality, certain sub-Saharan Africans apparently prefer caterpillars to beef. Ant grubs (so called “ant eggs”) and eggs of water boatmen (Corixidae) and backswimmers (Notonectidae) are much sought after in Mexican gastronomy as “caviar”. In parts of Asia, a diverse range of insects can be purchased (see Plate 2.1). Traditionally desirable water beetles for human consumption are valuable enough to be farmed in Guangdong. The culinary culmination may be the meat of the giant water bug Lethocerus indicus (see Plate 1.6) or the Thai and Laotian mangda sauces made with the flavors extracted from the male abdominal glands, for which high prices are paid. Even in the urban USA some insects may yet become popular as a food novelty. The millions of 17-year cicadas that periodically plague cities like Chicago are edible. Newly hatched cicadas, called tenerals, are best for eating because their soft body cuticle means that they can be consumed without first removing the legs and wings. These tasty morsels can be marinated or dipped in batter and then deep-fried, boiled and spiced, roasted and ground, or stir-fried with favorite seasonings.
Large-scale harvest or mass production of insects for human consumption brings some practical and other problems. The small size of most insects presents difficulties in collection or rearing and in processing for sale. The unpredictability of many wild populations needs to be overcome by the development of culture techniques, especially as over-harvesting from the wild could threaten the viability of some insect populations. Another problem is that not all insect species are safe to eat. Warningly colored insects are often distasteful or toxic (Chapter 14) and some people can develop allergies to insect material (section 15.2.3). However, several advantages derive from eating insects. The encouragement of entomophagy in many rural societies, particularly those with a history of insect use, may help diversify peoples’ diets. By incorporating mass harvesting of pest insects into control programs, the use of pesticides can be reduced. Furthermore, if carefully regulated, cultivating insects for protein should be less environmentally damaging than cattle ranching, which devastates forests and native grasslands. Insect farming (the rearing of mini-livestock) is compatible with low input, sustainable agriculture and most insects have a high food conversion efficiency com- pared with conventional meat animals.
Table 1.2. Proximate, mineral, and vitamin analyses of four edible Angolan insects (percentages of daily human dietary requirements/100 g of insects consumed).
(After Santos Oliviera et al. 1976, as adapted by DeFoliart 1989.)
|Nutrient||Requirement per capita (reference person)||Macrotermes subhyalinus (Termitidae)||Imbrasia ertli (Saturniidae)||Usta terpsichore (Saturniidae)||Rhynchophorus phoenicus (Curculionidae)|
(Larva after Santos Oliveira et al. 1976)
(After Cherikoff & Isaacs 1989)
The arthrodial membrane between tergal plates is depicted to the right in its unfolded and folded conditions. (After Hadley 1986; Devitt 1989)