Migratory locust

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Migratory locust
Wanderheuschrecke-03.jpg
Female migratory locust
Scientific classification OOjs UI icon edit-ltr.svg
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
  • Acridium migratorium
  • Acridium plorans
  • Pachytylus australis(Saussure, 1884)
  • Pachytylus migratorius(Linnaeus, 1758)
  • Pachytylus migratorioides(Fairmaire & L.J. Reiche, 1849)
Close-Up of a Locusta migratoria

The migratory locust (Locusta migratoria) is the most widespread locust species, and the only species in the genus Locusta. It occurs throughout Africa, Asia, Australia and New Zealand. It used to be common in Europe but has now become rare there. 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]

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:

Solitaire = solitary phase → transiens congregans (intermediate form) → gregarious phase → transiens dissocians (intermediate form) → solitaire = solitary phase.

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]

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. 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]

Relationship with humans

Economic impact

Adult female (top), adult male (bottom left), fifth instar nymph (bottom right) Die Gartenlaube (1875) b 585.jpg
Adult female (top), adult male (bottom left), fifth instar nymph (bottom right)

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.

As food

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]

Subspecies of Locusta migratoria

L. m. migratorioides female (solitary) Locusta m. migratorioides female.jpg
L. m. migratorioides female (solitary)
L. m. migratorioides male (solitary) Locusta migratoria migratorioides male.jpg
L. m. migratorioides male (solitary)

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 called 'locusts'

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.

Photos

See also

Footnotes

  1. Wang, Xianhui; Fang, Xiaodong; Yang, Pengcheng; Jiang, Xuanting; Jiang, Feng; Zhao, Dejian; Li, Bolei; Cui, Feng; Wei, Jianing; Ma, Chuan; Wang, Yundan; He, Jing; Luo, Yuan; Wang, Zhifeng; Guo, Xiaojiao; Guo, Wei; Wang, Xuesong; Zhang, Yi; Yang, Meiling; Hao, Shuguang; Chen, Bing; Ma, Zongyuan; Yu, Dan; Xiong, Zhiqiang; Zhu, Yabing; Fan, Dingding; Han, Lijuan; Wang, Bo; Chen, Yuanxin; Wang, Junwen; Yang, Lan; Zhao, Wei; Feng, Yue; Chen, Guanxing; Lian, Jinmin; Li, Qiye; Huang, Zhiyong; Yao, Xiaoming; Lv, Na; Zhang, Guojie; Li, Yingrui; Wang, Jian; Wang, Jun; Zhu, Baoli; Kang, Le (2014). "The locust genome provides insight into swarm formation and long-distance flight". Nature Communications. 5: 2957. Bibcode:2014NatCo...5.2957W. doi:10.1038/ncomms3957. ISSN   2041-1723. PMC   3896762 . PMID   24423660.
  2. Li, Sheng; Zhu, Shiming; Jia, Qiangqiang; Yuan, Dongwei; Ren, Chonghua; Li, Kang; Liu, Suning; Cui, Yingying; Zhao, Haigang; Cao, Yanghui; Fang, Gangqi; Li, Daqi; Zhao, Xiaoming; Zhang, Jianzhen; Yue, Qiaoyun; Fan, Yongliang; Yu, Xiaoqiang; Feng, Qili; Zhan, Shuai (2018). "The genomic and functional landscapes of developmental plasticity in the American cockroach". Nature Communications. 9 (1): 1008. Bibcode:2018NatCo...9.1008L. doi:10.1038/s41467-018-03281-1. ISSN   2041-1723. PMC   5861062 . PMID   29559629. CC-BY icon.svg This article contains quotations from this source, which is available under the Creative Commons Attribution 4.0 International (CC BY 4.0) license
  3. 1 2 Hou, Li; Wang, Xuesong; Yang, Pengcheng; Li, Beibei; Lin, Zhe; Kang, Le; Wang, Xianhui (2020). "DNA methyltransferase 3 participates in behavioral phase change in the migratory locust". Insect Biochemistry and Molecular Biology. 121: 103374. doi:10.1016/j.ibmb.2020.103374. PMID   32283278. S2CID   215758648.
  4. Overgaard, Johannes; MacMillan, Heath A. (2017-02-10). "The Integrative Physiology of Insect Chill Tolerance". Annual Review of Physiology . 79 (1). Annual Reviews: 187–208. doi: 10.1146/annurev-physiol-022516-034142 . ISSN   0066-4278. PMID   27860831.
  5. Oonincx, Dennis G. A. B.; van Itterbeeck, Joost; Heetkamp, Marcel J. W.; van den Brand, Henry; van Loon, Joop J. A.; van Huis, Arnold; Hansen, Immo A. (29 December 2010). "An Exploration on Greenhouse Gas and Ammonia Production by Insect Species Suitable for Animal or Human Consumption". PLOS ONE. 5 (12): e14445. Bibcode:2010PLoSO...514445O. doi: 10.1371/journal.pone.0014445 . PMC   3012052 . PMID   21206900.
  6. Barsics, F., 2010. L'alimentation des Populations locales de Madagascar productrices de Vers à Soie. - Univ. de Liège.: 1-84.
  7. Bundesamt für Lebensmittelsicherheit und Veterinärwesen (2017-04-28): "Insects as food" (German only)
  8. EFSA (2 July 2021): Safety of frozen and dried formulations from migratory locust (Locusta migratoria) as a Novel food pursuant to Regulation (EU) 2015/2283. In: EFSA Journal. Vol. 19, Issue 7. DOI: https://doi.org/10.2903/j.efsa.2021.6667.
  9. European Commission (2 November 2021): Approval of second insect as a Novel Food .
  10. Chapuis, M-P.; Lecoq, M.; Michalakis, Y.; Loiseau, A.; Sword, G. A.; Piry, S.; Estoup, A. (1 August 2008). "Do outbreaks affect genetic population structure? A worldwide survey in a pest plagued by microsatellite null alleles". Molecular Ecology. 17 (16): 3640–3653. doi:10.1111/j.1365-294X.2008.03869.x. PMID   18643881. S2CID   4185861.

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<span class="mw-page-title-main">Grasshopper</span> Common name for a group of insects

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<span class="mw-page-title-main">Desert locust</span> Species of grasshopper

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.

<span class="mw-page-title-main">Red locust</span> Species of grasshopper

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.

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References