Migratory locust | |
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Female migratory locust | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Orthoptera |
Suborder: | Caelifera |
Family: | Acrididae |
Subfamily: | Oedipodinae |
Tribe: | Locustini |
Genus: | Locusta Linnaeus, 1758 |
Species: | L. migratoria |
Binomial name | |
Locusta migratoria | |
Synonyms | |
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The migratory locust (Locusta migratoria) is the most widespread locust species, and the only species in the genus Locusta. It occurs throughout Africa, Europe, Asia, Australia and New Zealand. Because of the vast geographic area it occupies, which comprises many different ecological zones, numerous subspecies have been described. However, not all experts agree on the validity of some of these subspecies.
Many other species of grasshopper with gregarious and possibly migratory behaviour are referred to as 'locusts' in the vernacular, including the widely distributed desert locust.
At 6.5 Gbp, [1] the migratory locust possesses one of the largest known insect genomes. [2]
The migratory locust is polyphenic. It transitions between two main phenotypes in response to population density; the solitary phase and the gregarious phase. As the density of the population increases the locust transforms progressively from the solitary phase towards the gregarious phase with intermediate phases:
Pigmentation and size of the migratory locust vary according to its phase (gregarious or solitary form) and its age. Gregarious nymphs have a yellow to orange covering with black spots; solitary nymphs are green or brown. The gregarious adult is brownish with yellow, the latter colour becoming more intense and extensive on maturation. The solitary adult is brown with varying extent of green colour depending on the colour of the vegetation. Gregarious adults vary in size between 40 and 60 mm according to the sex; they are smaller than the solitary adults.
The phase transition may be mediated by DNA methylation in the brain. Expression of the DNA methyltrasferase gene Dnmt3 is high in the brain of the gregarious form, decreases in gregarious locusts when they are isolated, and increases in solitary locusts when they are crowded. Knock-down reduces phase-related locomotor activity. [3] Transcriptionally, Dnmt3 is linked with phase-core transcriptional factor, hormone receptor HR3. [3]
Increased extracellular K+ was found to cause membrane depolarization in muscle activating nerves by Hoyle 1953. This then in turn reduces the nerve potential, with the final result of reducing the force output of said muscle. He also found chronic cold temperatures to increase K+ in the haemolymph. These changes affect L. migratoria's nerve states because – as with insects and animals in general – nerve cells have a high K permeability, which allows K+'s transmembrane distribution to determine most cellular diffusion potential. This is shaping and will continue to shape the distribution of L. migratoria's range under climate change. [4]
Locusts are highly mobile, and usually fly with the wind at a speed of about 15 to 20 kilometres per hour (9.3 to 12.4 mph). Swarms can travel 5 to 130 km or more in a day. Locust swarms can vary from less than one square kilometre to several hundred square kilometres with 40 to 80 million individuals per square kilometre. An adult locust can consume its own weight (several grams) in fresh food per day. For every million locusts, one ton of food is eaten.
In Africa, the last serious widespread plague of L. m. migratorioides occurred from 1928 to 1942. Since then, environmental transformations have made the development of swarms from the African migratory locust unlikely. Nevertheless, potential outbreaks are constantly monitored as plagues can be devastating. The Malagasy migratory locust (L. m. capito) still regularly swarms (roughly twice every ten years). The desert locust, which is very similar to the African migratory locust, remains a major threat too.
Locust survey and control are primarily the responsibility of the Ministry of Agriculture in locust-affected countries and are operations undertaken by national locust units. The Food and Agriculture Organization (FAO) of the United Nations provides information on the general locust situation to all interested countries and gives warnings and forecasts to those countries in danger of invasion.
The migratory locust is an edible insect. [5] [6] In Europe, the migratory locust is officially approved for the use in food in Switzerland (since May 2017). [7] On 2 July 2021, the European Food Safety Agency published a scientific opinion stating that the consumption of migratory locust in frozen, dried or ground state is safe for humans. [8] On 12 November 2021, the EU member states gave their green light for the EU Commission to authorize the placing on the market of migratory locust as a food. This is one of the final steps in the novel food authorization procedure. As a next step, the Commission will now adopt a legal act. [9]
L. migratoria is found over a vast geographic area, and its range covers many different ecological zones. Because of this, numerous subspecies have been described; however, not all experts agree on the validity of some of these subspecies. [10]
Other species of Orthoptera that display gregarious and migratory behaviour are called locusts. This includes:
The Senegalese grasshopper (Oedaleus senegalensis) also often displays locust-like behaviour in the Sahel region.
Locusts are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstances they become more abundant and change their behaviour and habits, becoming gregarious. No taxonomic distinction is made between locust and grasshopper species; the basis for the definition is whether a species forms swarms under intermittently suitable conditions; this has evolved independently in multiple lineages, comprising at least 18 genera in 5 different subfamilies.
Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago.
The desert locust is a species of locust, a periodically swarming, short-horned grasshopper in the family Acrididae. They are found primarily in the deserts and dry areas of northern and eastern Africa, Arabia, and southwest Asia. During population surge years, they may extend north into parts of Southern Europe, south into Eastern Africa, and east in northern India. The desert locust shows periodic changes in its body form and can change in response to environmental conditions, over several generations, from a solitary, shorter-winged, highly fecund, non-migratory form to a gregarious, long-winged, and migratory phase in which they may travel long distances into new areas. In some years, they may thus form locust plagues, invading new areas, where they may consume all vegetation including crops, and at other times, they may live unnoticed in small numbers.
The red locust is a large grasshopper species found in sub-Saharan Africa. Its name refers to the colour of its hind wings. It is sometimes called the criquet nomade in French, due to its nomadic movements in the dry season. When it forms swarms, it is described as a locust.
Crustacean cardioactive peptide (CCAP) is a highly conserved, amidated cyclic nonapeptide with the primary structure PFCNAFTGC-NH2 (ProPheCysAsnAlaPheTyrGlyCys-NH2) and a disulfide bridge between Cys3 and Cys9. It is found in crustaceans and insects where it behaves as a cardioaccelerator, neuropeptide transmitter for other areas of the nervous system and a hormone. CCAP was first isolated from the pericardial organs of the shore crab Carcinus maenas, where it has a role in regulating heartbeat. It was assumed that this was the peptide's main function and its name reflects this.
Corazonin is a highly conserved neuropeptide found in many insects, in particular locusts and cockroaches.
The Australian plague locust is a species of locust in the family Acrididae native to Australia, where it is a significant agricultural pest.
Insects as food or edible insects are insect species used for human consumption. Over 2 billion people are estimated to eat insects on a daily basis. Globally, more than 2,000 insect species are considered edible, though far fewer are discussed for industrialized mass production and regionally authorized for use in food. Many insects are highly nutritious, though nutritional content depends on species and other factors such as diet and age. Insects offer a wide variety of flavors and are commonly consumed whole or pulverized for use in dishes and processed food products such as burger patties, pasta, or snacks. Like other foods, there can be risks associated with consuming insects, such as allergic reactions. As commercial interest in insects as food grows, countries are introducing new regulatory frameworks to oversee their production, processing, marketing, and consumption.
Dociostaurus maroccanus, commonly known as the Moroccan locust, is a grasshopper in the insect family Acrididae. It is found in northern Africa, southern and eastern Europe and western Asia. It lives a solitary existence but in some years its numbers increase sharply, and it becomes gregarious and congregates to form swarms which can cause devastation in agricultural areas. The species was first described by Carl Peter Thunberg in 1815.
Calliptamus italicus, the Italian locust, is a species of 'short-horned grasshopper' belonging to the family Acrididae, subfamily Calliptaminae.
In 2012, Madagascar had an upsurge in the size of its Malagasy migratory locust populations. In November of that year, the government issued a locust alert, saying that conditions were right for swarming of the pest insects. In February 2013, Cyclone Haruna struck the country, creating optimal conditions for locust breeding. By late March 2013, approximately 50% of the country was infested by swarms of locusts, with each swarm consisting of more than one billion insects. The authorities changed the situation to plague status. According to one eyewitness: "You don't see anything except locusts. You turn around, there are locusts everywhere".
Pacifastin is a family of serine proteinase inhibitors found in arthropods. Pacifastin inhibits the serine peptidases trypsin and chymotrypsin.
Locusta migratoria manilensis, commonly known as the Oriental migratory locust, is a subspecies of the migratory locust in the family Acrididae. It is sufficiently different in size and structure from the African migratory locust to be considered a distinct subspecies of the migratory locust. It is found in southeastern Asia and is an important agricultural pest in the region. It is normally a solitary insect but when conditions are suitable, it enters into a gregarious phase when the young form into bands which move together and the adults into swarms. Although outbreaks may have recently been fewer in number and size because of changes in agricultural practices and better locust detection, the insects remain active as crop pests and the potential for outbreaks is still present.
Locusta migratoria migratorioides, commonly known as the African migratory locust, is a subspecies of the migratory locust family Acrididae.
Locusta migratoria cinerascens is a subspecies of the migratory locust in the family Acrididae.
CYP305M2 is a cytochrome P450 enzyme found in migratory locust that catalyzes the key step of biosynthesis of phenylacetonitrile (PAN). PAN in turn is used as an aposematic chemical defense against predators.
Schistocerca piceifrons is a large locust in the subfamily Cyrtacanthacridinae: Acrididae. There are two subspecies. S. p. piceifrons is sometimes called the Central American locust and S. p. peruviana is sometimes known as the Peruvian locust.
Schistocerca cancellata is a species of locust in the subfamily Cyrtacanthacridinae. It is the major swarming species in subtropical South America. This species shows typical locust phase polymorphism. Solitarious nymphs are green, but gregarious ones are yellow with a black pattern. There are morphological differences between solitarious and gregarious adults. For many years the two phases were believed to be different species and the gregarious form was mistakenly identified as S. paranensis. The solitary phase is found in South America between 18°S and 35°S. Plagues originate in a desert and semi-desert zona permanente in NW Argentina, SE Bolivia and W Paraguay, when good rains allow successful breeding, followed by gregarisation. Swarms of gregarious adults may then migrate into crop growing regions.
CYP303A1 is an insect gene belongs to the cytochrome P450 family, first found in Drosophila melanogaster, highly expressed in pupal stage. Its ortholog also found in Locusta migratoria.