The migratory locust (''Locusta migratoria'') is the most widespread

locust Locusts (derived from the Latin ''locusta'', locust or lobster) 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 b ...

species, and the only species in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''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 In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

have been described. However, not all experts agree on the validity of some of these subspecies. While it reaches plague proportions in drier areas, it is solitary in northern Australia savannas. Many other

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

grasshopper 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. Grassh ...

with

gregarious Sociality is the degree to which individuals in an animal population tend to associate in social groups (gregariousness) and form cooperative societies. Sociality is a survival response to evolutionary pressures. For example, when a mother was ...

and possibly migratory behaviour are referred to as 'locusts' in the vernacular, including the widely distributed

desert locust The desert locust (''Schistocerca gregaria'') 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 ...

. At 6.5

Gbp Sterling (symbol: £; currency code: GBP) is the currency of the United Kingdom and nine of its associated territories. The pound is the main unit of sterling, and the word '' pound'' is also used to refer to the British currency general ...

, the migratory locust possesses one of the largest known insect

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

s. This article contains quotations from this source, which is available under th
Creative Commons Attribution 4.0 International (CC BY 4.0)
license

Polyphenism

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 In physics, chemistry, and other related fields like biology, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic Sta ...

may be mediated by

DNA methylation DNA methylation is a biological process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter (genetics), promoter, DNA methylati ...

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. Transcriptionally, ''Dnmt3'' is linked with phase-core transcriptional factor,

hormone receptor A hormone receptor is a receptor molecule that binds to a specific hormone. Hormone receptors are a wide family of proteins made up of receptors for thyroid and steroid hormones, retinoids and Vitamin D, and a variety of other receptors for various ...

HR3.

Neurochemistry

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 Hemolymph, or haemolymph, is a fluid, similar to the blood in invertebrates, that circulates in the inside of the arthropod's body, remaining in direct contact with the animal's tissues. It is composed of a fluid plasma in which hemolymph ce ...

. 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.

Relationship with humans

Economic impact

Locusts are highly mobile, and usually fly with the wind at a speed of about . 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

, 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 The Food and Agriculture Organization of the United Nations; . (FAO) is a specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition and food security. Its Latin motto, , translates ...

(FAO) of the

United Nations The United Nations (UN) is the Earth, global intergovernmental organization established by the signing of the Charter of the United Nations, UN Charter on 26 June 1945 with the stated purpose of maintaining international peace and internationa ...

provides information on the general locust situation to all interested countries and gives warnings and forecasts to those countries in danger of invasion.

As food

The migratory locust is an edible insect. In Europe, the migratory locust is officially approved for the use in food in

Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...

(since May 2017). 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. 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 A novel food is a type of food that does not have a significant history of consumption or is produced by a method that has not previously been used for food. Designer food Designer food is a type of novel food that has not existed on any regional ...

authorization procedure. As a next step, the Commission will now adopt a legal act.European Commission (2 November 2021):
Approval of second insect as a Novel Food
'.

Subspecies of ''Locusta migratoria''

''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. * '' L. m. burmana'' Ramme, 1951 * '' L. m. capito'' Saussure, 1884 (Malagasy migratory locust: Madagascar) * '' L. m. cinerascens'' Fabricius, 1781 (Italy, Spain) * '' L. m. migratoria'' (Linnaeus, 1758) (europe) * '' Locusta migratoria manilensis'' (Meyen, 1875) * '' L. m. migratorioides'' (Fairmaire & L.J. Reiche, 1849) (African migratory locust: Africa and Atlantic islands) * '' L. m. tibetensis'' Chen, Yonglin, 1963 * ''L. m. danica'' (Linnaeus, 1767) = ''L. m. migratoria'' (Linnaeus, 1758) * ''L. m. gallica'' Remaudičre, 1947 = ''L. m. migratoria'' (Linnaeus, 1758) * ''L. m. solitaria'' Carthy, 1955 = ''L. m. migratoria'' (Linnaeus, 1758)

Other species called 'locusts'

Other species of Orthoptera that display gregarious and migratory behaviour are called ''locusts''. This includes: * American locust, '' Schistocerca americana'' * Australian plague locust, ''Chortoicetes terminifera'' * Bombay locust, '' Nomadacris succincta'' * Brown locust, ''Locustana pardalina'' *

Desert locust The desert locust (''Schistocerca gregaria'') 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 ...

, ''Schistocerca gregaria'' * Egyptian locust, '' Anacridium aegyptium'' * Italian locust, '' Calliptamus italicus'' * Moroccan locust, '' Dociostaurus maroccanus'' *

Red locust The red locust (''Nomadacris septemfasciata'') 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 language, French, due to its noma ...

, ''Nomadacris septemfasciata'' * Rocky Mountain locust, ''Melanoplus spretus'' – extinct * Sahelian tree locusts, '' Anacridium melanorhodon'' * Spur-throated locust, '' Austracris guttulosa'' (note: "spur-throated grasshoppers/locusts" may also refer to spp. in other genera) * Sudan plague locust, '' Aiolopus simulatrix'' The Senegalese grasshopper (''Oedaleus senegalensis'') also often displays locust-like behaviour in the Sahel region.

Photos

Locusta migratoria L1.jpg, First instar nymph (gregarious) Locusta migratoria L2 and L4.jpg, Second and fourth instar nymphs (gregarious) Locusta migratoria L3.jpg, Third instar nymphs (gregarious) Locusta migratoria L4.jpg, Fourth instar nymph (gregarious) Locusta migratoria part of hopper band.jpg, Part of a hopper band in Kazakhstan Locusta migratoria hopper band4.jpg, Hopper band in Kazakhstan

Footnotes

References

* *

External links

Food and Agriculture Organization (FAO)

Biolib

Fauna Europaea
* Genus ''Locusta'' a
Orthoptera Species File on Line

Sound recordings of Migratory Locust at BioAcoustica
{{Taxonbar, from1=Q1059580, from2=Q15122569 Oedipodinae Orthoptera of Africa Orthoptera of Asia Orthoptera of Europe Orthoptera of Oceania Insects of Australia Acrididae of New Zealand Insects described in 1758 Edible insects Animal migration Taxa named by Carl Linnaeus Insect pests of millets