THE Food and Agriculture Organisation of the United Nations report, "Edible insects – future prospects for food and feed security" is fascinating reading.

Edible insects have always been a part of human diets, but in some societies there is a degree of distaste, if not revulsion, for their consumption.

Contrary to popular belief, insects are not merely a famine food eaten in times of food scarcity, or when purchasing and harvesting conventional foods becomes difficult. Many people around the world eat insects out of choice, largely because of their palatability and their established place in food cultures.

From ants to beetle larvae –eaten by tribes in Africa and Australia as part of their subsistence diets – to the popular, crispy-fried locusts and beetles enjoyed in Thailand, it is estimated that insect eating is practised regularly by two billion people worldwide. More than 1900 insect species have been documented as edible, most of them in tropical countries.

Globally, the most commonly consumed insects are beetles (31%), caterpillars (18%), and bees, wasps and ants (14%). Following these are grasshoppers, locusts and crickets (13%), cicadas, leafhoppers, plant hoppers, scale insects and true bugs (10%), flies (2%) and other orders (5%).

Red maguay worms, a moth larvae – and white maguay worms – a butterfly larvae – are found throughout Mexico. When fully mature, these highly nutritious caterpillars are considered a delicacy by Mexican farmers. They are generally eaten deep fried or braised, seasoned with a spicy sauce and served in a tortilla.

Witchetty grubs refer to the large, white, wood-eating larvae of several moths and beetles found in Australia. However, the term applies mostly to the larvae of the cossid moth, which can be found 60cm below ground feeding on the roots of river red gums.

The grub is the most important insect food of the desert and was a staple in the diets of Aboriginal women and children. Edible either raw or lightly cooked in hot ashes, they are sought by Aborigines as a high-protein, high-fat food. The raw witchetty grub tastes like almonds – when cooked, the skin becomes crisp like roast chicken and the inside turns light yellow in colour.

Although the majority of edible insects are gathered from forests, research into developing mass-rearing systems has begun in many countries to provide a nutritious source of human protein.

Insects as food and feed has emerged as an especially relevant issue in the 21st century due to the rising cost of animal protein, food and feed insecurity, environmental pressures, population growth and increasing demand for protein among middle classes. Thus, alternative solutions to conventional livestock and feed sources are urgently needed. We will see a lot more consumption of insects, or entomophagy, in the future.

Insect farming is not such a novel idea. Some insect species, such as bees and silkworms, have a long history of domestication because of the value of their products. Insects are also reared in large numbers for the purposes of biological control (eg as predators and porasitoids), health (eg maggot therapy) and pollination. The concept of farming insects for food is, however, relatively new. An example of rearing insects for human consumption in the tropics is cricket farming in the Lao People's Democratic Republic, Thailand and Vietnam.

In temperate zones, insect farming is performed largely as family-run enterprises that rear insects such as mealworms, crickets and grasshoppers, mainly as pets or for zoos. A few industrial-scale enterprises are in various stages of start-up for rearing mass quantities of insects such as black soldier flies. They are mainly for consumption as whole insects or to be processed into meal for feed.

Recent high demand and consequent high prices for fishmeal and soy, together with increasing aquaculture production, is pushing new research into the development of insect protein for fish and poultry feed. Available evidence suggests that insect-based feeds are comparable with fishmeal and soy-based feed formulae.

A three-year, €3 million EU-funded project, PROteInsect, is investigating how flies can contribute to feed requirements of non-ruminants. The project is being led by scientists at the Food and Environment Research Agency near York, and comprises a global partnership that includes Stirling University. The main focus is on developing ways of mass-producing maggots from the house fly that will be fed potentially on pig and poultry manures and other waste such as draff (the mash left after brewing and distilling).

Eggs are produced from adult flies and then seeded into the waste matter to hatch into maggots or larvae. As the larvae leave the waste to pupate, they empty their guts, and it is at this stage they are ideal for harvesting. It's reckoned a tonne of waste will produce 100kg of larvae, and that the process will leave about half the original amount of waste.

Dr Elaine Fitches, co-ordinator of the PROteINSECT global consortium, said: "We are looking at developing a White Paper with a view to having a discussion at EU-level on how best to proceed with drafting legislation that will allow the use of larvae-based proteins in animal feed supplements. We are also looking at the quality of the product and safety aspects. So, we are carrying out animal feed trials on non-ruminants at different inclusion rates as well as looking at the environmental impact of a range of insect production systems."