Locusts, grasshoppers (mostly Acrididae and Pyrgomorphidae), crickets (Gryllidae) and katydids (Tettigoniidae) are insects of the order Orthoptera. Many are edible and more than 80 species of locusts, grasshoppers and crickets are consumed worldwide for human food in Africa, South America and Asia. They may be part of the normal diet, or delicacies sold by street vendors. They are eaten at home or in restaurants, both in rural and urban areas (DeFoliart, 1989; Ramos-Elorduy, 1997; van Huis et al., 2013).
Edible Orthoptera species
Locusts are a group of grasshopper species that become gregarious and migratory when their populations are sufficiently dense. During the swarming phase, locusts destroy or severely damage crops. They are a major pest of historical importance, notably in Africa (North, West, Sahelian, Madagascar), Australia and the Middle-East. A locust swarm can represent a considerable amount of biomass, containing up to 10 billion insects and weighing approximately 30,000 t (DeFoliart, 1989; Ramos-Elorduy, 1997; van Huis et al., 2013). The swarming behaviour makes locusts relatively easy to harvest for food. In Africa, the desert locust (Schistocerca gregaria), the migratory locust (Locusta migratoria), the red locust (Nomadacris septemfasciata) and the brown locust (Locustana pardalina) are commonly eaten. In Japan, China and Korea, rice field grasshoppers (including Oxya yezoensis, Oxya velox, Oxya sinuosa, and Acrida lata) are harvested for food (van Huis et al., 2013). In Mexico, chapulines, which are grasshoppers of the Sphenarium genus, and notably Sphenarium purpurascens, a pest of alfalfa, are popular edible insects (Cohen et al., 2009). The grasshopper Ruspolia differens, which is actually a katydid, is a common food source in many parts of eastern and southern Africa. Crickets are a common food in South East Asia, particularly in Thailand: the house cricket Acheta domestica, Gryllus bimaculatus, Teleogryllus occipitalis, Teleogryllus mitratus, the short-tail cricket Brachytrupes portentosus and Tarbinskiellus portentosus are edible cricket species (van Huis et al., 2013).
Harvesting and farming
Grasshoppers, locusts and crickets are usually collected in the wild, preferably at night (using artificial light) or in the morning when the temperature is cooler and the insects are less active and easier to catch. Due to the demand, commercial farming of locusts, grasshopper and crickets for the food and feed market is developing in South East Asia. As of 2012, there were about 20,000 cricket farmers in Thailand, raising the species Acheta domestica and Gryllus bimaculatus. Orthoptera, and particularly locusts, are commonly raised to feed pets and zoo animals (van Huis et al., 2013).
In India, the mass-rearing of grasshopper species Oxya fuscovittata, Oxya hyla and Spathosternum prasiniferum has been studied experimentally. The use of jars with a volume of 2500 cm3 was sufficient to give a density of 10,000 insects per m3 for Oxya fuscovittata, and 7100 insects per m3 for Spathosternum prasiniferum, and resulted in mortality rates of 12 and 15% respectively. The smaller size of Spathosternum prasiniferum meant that more could be kept per unit area compared with Oxya fuscovittata (Das et al., 2009). When comparing Oxya hyla and Spathosternum prasiniferum, Oxya hyla showed higher values for fecundity, fertility and body weight and lower values for nymphal mortality. Brachiaria mutica was found more suitable than Dactyloctenium aegyptium and Cynodon dactylon for annual biomass production of both acridids (Das et al., 2012a; Das et al., 2012b). Sorghum halepense has also been proposed as a potential forage plant for Oxya fuscovittata (Ganguly et al., 2010).
Cricket farming (Acheta domestica)
The house cricket, Acheta domestica, is easy to farm and can produce from 6 to 7 generations per year. It is omnivorous and can eat a large range of organic materials. Production is feasible at temperatures higher than 20°C, the ideal temperature being 28-30°C. 2000 insects can be bred on 1 m². The cricket population self-regulates by cannibalism (Hardouin et al., 2003).
Use for livestock feeding
Orthoptera, like other insects, are highly nutritious and contain large amounts of protein. Various grasshopper, katydid and cricket species are already used for pets and zoo animals and have been investigated for livestock feeding. Because of the availability of large quantities of dead locusts, resulting from locust outbreaks, they are a good potential feed for livestock, especially poultry, and locust meal has been proposed as a poultry feed since the 1930s. Poultry are also a means to control locust and grasshopper populations. Since the 2000s, the development of aquaculture in Africa and Asia and the search of alternative sources of protein have led to trials on the feeding value of locusts and grasshoppers for catfish and tilapia.