European migratory locust

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European migratory locust
European migratory locust (Locusta migratoria), green form

European migratory locust ( Locusta migratoria ), green form

Systematics
Order : Grasshoppers (Orthoptera)
Subordination : Short-antennae terrors (Caelifera)
Family : Field locusts (Acrididae)
Subfamily : Wasteland Horror (Oedipodinae)
Genre : Locusta
Type : European migratory locust
Scientific name of the  genus
Locusta
Linnaeus , 1758
Scientific name of the  species
Locusta migratoria
( Linnaeus , 1758)

The European migratory locust ( Locusta migratoria ) is a grasshopper from the family of field locusts (Acrididae). Like the other migratory locusts , it has been a feared agricultural pest from ancient times until today , causing damage in the millions in Africa, the Middle East and East Asia. The species occurs in southern Mediterranean Europe, but is economically insignificant here today. Apart from rare individual flying in, the species no longer occurs in Central Europe today; their earlier, permanent occurrence (away from incoming swarms) is controversial.

features

Brown shape
When mating

It is a large field locust, males reach about 33 to 51 millimeters, the slightly larger females 39 to 55 millimeters of body length. The front wings ( tegmina ) are very long, they protrude far beyond the tip of the abdomen, they are roughly twice as long as the hind legs, in the male a maximum of about 56 millimeters long in the female. The head has an approximately rectangular shape in profile, so the front is vertical. The forehead dimples are indistinct, roughly triangular and border directly on the eyes. The mandibles are bluish in color. The pronotum has a clear central keel, which is notched in the middle by a transverse furrow, side kills are missing. When viewed from above, its rear edge is triangularly drawn backwards. The thorax is covered by fine hair on the ventral side. On the upper side of the hind legs ( femora ) there is a row of small, pointed thorns. The hind wings are clear (hyaline) with no coloration or banding.

The species occurs in two phases, a solitary phase, which remains in the habitat and lives individually, and a gregarious phase, which combines to form large, migrating swarms. These are mostly distinguishable by their color, otherwise by some morphological features. However, there are transitional forms between the phases (so-called transiens phase) that cannot be clearly assigned. The individuals of the solitary phase are mostly green in color with dark spots, but brown individuals also occur. The rear rails are usually red or reddish. The pronotum is hardly constricted when viewed from the side, its central keel is high, arched in side view, the rear edge is rectangular. The individuals in the gregarious phase are brown or brown-gray in color, often with two black longitudinal stripes on the pronotum. The rear rails are more yellowish. The pronotum is clearly constricted when viewed from the side, the central keel is low and straight or even slightly recessed, the rear edge is obtuse-angled. The hind wings are a little longer compared to the solitary phase.

The European migratory locust can be distinguished from the (closely related) genus Oedaleus by the lack of a cross mark on the pronotum (which it has given the name "cross horror"); it also has high-contrast transverse banding of the forewings. It can be distinguished from the desert locust Schistocerca gregaria by the lack of a cone-shaped protrusion between the front hips. Anacridium aegypticum, which is quite common in southern Europe , can be easily distinguished by its striped complex eyes.

Life cycle

In the more northern parts of its range, the species reaches one generation per year; in the tropics, however, up to five generations can develop per year ; here it develops without an obligatory diapause ; Adults then appear all year round. In North Africa, three generations are reached a year. In winter cold climates the species overwinters in the ice stage. The eggs are covered by a foam-like substance oothecae stored in the ground, each ootheca contains 50 to 70 eggs. To develop successfully, they have to absorb water from the surrounding soil, which takes about 10 to 20 days. The first larvae hatch in the northern parts of the range around mid to late May, in North Africa (Algeria) as early as March. The species has five larval stages which, under favorable conditions, can each pass through in five to six days, resulting in a total development time of 35 to 40 days. The larvae (actually nymphs , called "hopper" in the English-speaking world) of the gregarious phase combine to form large swarms immediately after hatching.

Stridulation and hearing

In contrast to numerous other grasshopper species, the males of the European migratory locust do not attract the females by means of stridulation . The males can produce sounds in the usual way with field locusts (friction of the hind legs over the wings), but only use these when they are disturbed by competitors during mating. Both sexes have functional tympanic organs and hearing, which they use to avoid enemies, for example they are able to hear the ultrasound locating sounds of flying bats and to avoid them. The hearing ability of the species and its neural basis has been extensively tested, it serves as a model organism for the physiology of hearing in insects.

habitat

It is quite a Eurocean species, as can be seen from the huge distribution area spanning several continents. However, the species needs moisture in its egg and larval phase and only occurs in habitats that are moist to the ground. Preferred habitats are open, unforested, often sandy floodplains and bank zones of bodies of water, in particular the broad, only occasionally water-bearing valleys of unregulated wild river landscapes and river deltas offer optimal conditions. In the humid tropics it also develops in secondary grasslands (after deforestation). It also goes to a certain extent on corresponding cultivated land, so it was only established in the Algerian Sahara with irrigation cultures; as a rule, however, it disappears with more intensive land management. The species is quite frost-tolerant, especially in the egg stage, but adults are not viable for long when exposed to temperatures below freezing. The northern limit of distribution in Asia correlates roughly with the southern limit of the taiga zone, with populations spreading north and south showing greatly different cold tolerance.

The species prefers to feed on grasses, but takes on a variety of other plants when there is a lack of food. They then feed on other monocotyledons , on dicotyledonous plants, only as emergency food if nothing else is available. A common food plant of the solitary form is in particular reed ( Phragmites australis ).

Morph

Corazonin

The solitary (single living) and gregar (swarm-forming) form of the European migratory locust differ not only as adults and nymphs in body shape and color, but also in physiology and behavioral characteristics. The solitary form lives longer and produces more eggs, it is predominantly nocturnal. The gregarious shape forms large swarms that also fly during the day. Although slightly smaller and lighter than the solitary form, their brains are larger.

The gregary form is induced by environmental stimuli in the nymph stage. If numerous nymphs live together in a small space, because many females have laid numerous eggs here next to each other, it is inevitable that they will constantly bump into each other. Touch receptors on the body surface, especially in the antennae and the large femora of the ankle bone, cause the transition to the wandering form if they are frequently stimulated. Two hours of crowding are sufficient for this under laboratory conditions. In the wild, however, the transition usually takes place gradually, spread over several generations.

The release of the gregary form is a dimorphism that is controlled and released by epigenetic mechanisms (there are no differences in the genetic material). For decades, research on triggering has focused on hormonal factors. There are differences, for example, in the level of juvenile hormone and in the level of serotonin ; Corazonin , a neuropeptide involved in the stress reaction , was identified as being largely responsible for the change in color. However, none of these substances alone initiate complete conversion. More recent research is now concentrating on a possible route via genomic imprinting through (possibly epigenetically hereditary) DNA methylation . However, the details of the phase change have not yet been clarified.

Even the swarms of nymphs of the wandering form can reach enormous densities. Sometimes it was reported that the bottom was covered 15 centimeters deep by locust larvae. The older stages form marching columns that maintain their direction over a long period of time, with the swarm traveling distances of 24 kilometers. Imaginal locusts of the migratory form fly during the day (with the wind), usually they take a rest at noon, they mainly eat at dusk. If available, they prefer grasses as food, including the cereal species belonging to the grasses. Flying swarms cover hundreds of kilometers. Often secondary swarms are formed in the approach areas due to eggs being laid. Descendants of a swarm from a primary outbreak area in Mali in 1929 reached South Africa in 1932, a distance of about 7,000 kilometers.

distribution

The European migratory locust colonizes all of Africa including the island of Madagascar , southern and southeastern Europe and almost all of Asia south of the boreal coniferous forest zone . In the east it reaches the island of Kunashir ( Kuril Islands ). It occurs over the Southeast Asian island chains to Australia and New Zealand.

In Europe, the species occurs in all countries on the Mediterranean. The northern limit of the distribution is on the southern Alps, it reaches Switzerland in the canton of Ticino . Previously existing populations on the Vorderrhein and in the Rhone Valley (Valais) have now died out with the river regulation and the associated destruction of the floodplain landscape. In Central and Northern Europe, the species has hardly been observed since around 1950, although individual animals are occasionally reported.

In Germany, incoming swarms have been reported in the chronicles since the Middle Ages; the species received special attention from chroniclers because it was one of the biblical plagues . In the Xanten annals from the 9th century AD, it says, for example: “In the year of the divine Incarnation, 873, an immeasurable multitude of locusts, which appeared from the east in August, devastated almost all of Gaul. They were larger than other grasshoppers and had six pairs of wings. ”At least the number of pairs of wings is definitely to be regarded as a false observation. The swarms observed mainly moved along the river valleys of the Danube, Elbe and Oder, the area of ​​origin is assumed to be the Danube Delta and the steppe region between the Danube and Dnepr estuaries on the Black Sea. The last find of an individual animal on German soil dates back to 1949. It is no longer possible to determine whether the species was ever able to reproduce in Germany. There is also no evidence of populations in Baden-Württemberg, which borders on known populations in France and Switzerland.

Taxonomy

The species was by Carl Linnaeus in 1758 as gryllus (Locusta) migratorius first described . This description referred to the gregarious form, Linnaeus also had the solitary form, described a second time under the name Gryllus (Locusta) danica . The species was declared a type species of the genus Locusta by a subsequent decision of the ICZN in 1944 in order to take into account its traditional use. The conception of species and genus was confused for centuries. At times eleven subspecies were recognized, most of which were raised to species rank by various editors at some point. There are therefore numerous synonyms (for synonymy cf.).

In a study from 2012, the genetic structure of the species was then fully elucidated for the first time. In agreement with numerous previous studies, most of the traditional subspecies could not be differentiated. A two-part genetic structure resulted from a northern and a southern line. The southern includes populations from Africa (including Madagascar), Mediterranean Europe, Asia Minor, tropical South Asia including southern China, and Australia. The northern line includes animals from France, Russia, Central Asia, northeast China, and Japan. This confirmed the existence of several taxa side by side in France, which had long been recognized morphologically. Based on older names, the northern line was taken as the type subspecies Locusta migratoria migratoria , the southern line as the subspecies Locusta migratoria migratorioides . Although an internal genetic structure can also be seen in these lines, whereby the animals of Madagascar differed most genetically, they are too similar to each other to be able to establish further subtaxa. In Eurasia, the northern and southern subspecies are mostly separated by the Palearctic desert belt, but they also come into direct contact with one another at the western (France) and eastern (China) ends. Despite the huge inhabited area, the swarm formation would otherwise prevent a genetic differentiation within the species. The genetic population structure ( phylogeography ) suggests an origin of the species in Africa, where numerous very closely related and similar species live.

European migratory locust and man

Importance as a pest and control

Like all migratory locust species, Locusta migratoria can cause very high damage in agriculture, especially when it occurs in mass in the migratory form. There are large numbers of damage reports. The historical reports of "swarms of locusts" in Central Europe are usually related to this species, even if the chroniclers say that they belong to the species is usually not really recognizable. The entomologist Herbert Weidner reconstructed the arrival of a swarm in 1693 using historical sources. The animals obviously came from the Black Sea region and migrated up the Danube, whereby there must have been secondary centers of dispersion in the steppe regions in the central Danube valley. From here there was a mass immigration to the area of ​​Vienna: partial swarms penetrated into the Inn valley, to Bohemia and Silesia, north to Thuringia, individual animals even reached England.

More recent damage reports are available e.g. B. from northern China since 2003. At times, more than 20,000 hectares of grassland were affected there, and the nymphs reached densities of up to 1,000 individuals per square meter. Further damage is reported, for example, from northeast India and especially from Africa. In Central Asia, the importance of the species compared to more drought-loving species such as Calliptamus italicus has decreased due to the death of the wetlands on the Aral Sea . In Australia the economic importance of the species is low compared to other migratory locusts.

The most common method of control is spraying insecticides , especially the active substance class of phosphoric acid esters , such as malathion . However, after decades of use of the funds, as expected, some local populations have developed resistance to them. Azadirachtin , a substance with a hormonal effect, obtained from the neem tree , is also used against grasshoppers. In Australia there are also field trials with the insect pathogenic fungus Metarhizium anisopliae .

Importance as a food

Dried locusts as food or ingredient for meals
Whole, prepared grasshoppers and mealworms on a street food market in Germany

The European grasshopper is used as an edible insect . In Switzerland , it has been approved as a food since May 1, 2017. European locusts may, under certain conditions, be given to consumers as whole animals, shredded or ground. In the EU , in which edible insects are considered a novel food and require approval, the European migratory locust has not yet been approved as a food. In 2018, however, two authorization applications were submitted, on which a decision by the European Commission is still pending.

Importance as feed

L. migratoria is often used as a food animal for z. B. bred some types of lizards .

attitude

Warmth, occasional UV radiation and sufficient food are important when rearing or keeping L. migratoria . If this is not available in sufficient quantities, it is advisable to grow fast-growing wheat . An approx. 15 centimeter high ground area is required in the terrarium to lay eggs. The development from egg to larva takes about a month.

Web links

Commons : Locusta migratoria  - album with pictures, videos and audio files

Individual evidence

  1. ^ Kurt Harz: Geradflügler or Orthoptera. In: Friedrich Dahl (founder): The animal world of Germany and the adjacent parts of the sea. 44th part. Gustav Fischer Verlag, Jena, 1960.
  2. ↑ a b c I. Ya. Grichanov: Locusta migratoria L. - Migratory Locust, Asiatic Locust. Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries. Economic Plants and their Diseases, Weeds and Pests. 2003-2009 online
  3. ↑ a b Leila Benfekih, Daniel Petit (2010): The annual cycle of Saharan populations of Locusta migratoria cinerascens (Orthoptera: Acrididae: Oedipodinae) in Algeria. Annales de la Société Entomologique de France (ns) 46 (3-4): 351-358.
  4. ↑ George Basil Popov, My Hanh Launois-Luong, Jaap van der Weel (1990): Les Ootheques des Criquets du Sahel. Collection Acridologie Opérationnelle no.7. Permanent Inter-États de Lutte contre la Sécheresse dans le Sahel. [locust.cirad.fr/ouvrages_pratiques/pdf/DFPV7.pdf PDF]. Fig. On page 70.
  5. ↑ AR Bar-Ilan, A. Shulov, MP Pener (1969): The Stridulation of Sexually Mature Males of Locusta migratoria migratorioides (R. and F.) in Relation to Temperature and Some Other Factors. Physiological Zoology Vol. 42, No. 4: 417-428.
  6. ^ Daniel Robert (1989): The auditory behavior of flying locusts. Journal of Experimental Biology 147: 279-301.
  7. ↑ JW Dawson, W. Kutsch, RM Robertson (2004): Auditory-evoked evasive maneuvers in free-flying locusts and moths. Journal of Comparative Physiology A 190: 69-84. doi : 10.1007 / s00359-003-0474-3
  8. ↑ Leila Benfekih, Antoine Foucart, Daniel Petit (2011): Central Saharan populations of Locusta migratoria cinerascens (Orthoptera: Acrididae) in irrigated perimeters: is it a recent colonization event? Annales de la Société Entomologique de France (ns) 47 (1-2): 147-153.
  9. ↑ Xiao-Hong Jing & Le Kang (2003): Geographical variation in egg cold hardiness: a study on the adaptation strategies of the migratory locust Locusta migratoria L. Ecological Entomology 28: 151-158.
  10. ^ EA Bernays, RF Chapman, J. MacDonald JER Salter (1976): The degree of oligophagy in Locusta migratoria (L.). Ecological Entomology 1: 223-230. doi : 10.1111 / j.1365-2311.1976.tb01227.x
  11. ↑ Section afterBart början, Filip Sas, Ulrich R. Ernst, Julie Tobback, Filip LEMIERE, Michiel Vandegehuchte, Collin R. Janssen, Liesbeth Badisco, Elisabeth Marchal, Heleen Verlinden, Liliane Schoofs, Arnold De Loof (2011): Locust phase polyphenism : Does epigenetic precede endocrine regulation? General and Comparative Endocrinology 173 (1): 120-128. doi : 10.1016 / j.ygcen.2011.05.003
  12. ^ A b Distribution map in: A. Steedman (Editor) (1990): Locust handbook. (3rd edition) Chatham: Natural Resources Institute, vi + 204pp. digitized: The New Zealand Digital Library
  13. ↑ African migratory locust Locusta cinerascens at Orthoptera.ch
  14. ↑ T. Usaitis T., Bumbulyte L. (2011): New record of Locusta migratoria (Linnaeus, 1758) (Orthoptera: Acrididae) from Lithuania. New and Rare for Lithuania Insect Species 23: 112-113.
  15. ↑ Quotation from Jana Sprenger: "The Plague of Caterpillars" Perception, damage and control of insects in the forestry and agriculture of the Prussian Brandenburg (1700-1850). Diss. Georg-August-Universität Göttingen, 2011. ISBN 978-3-930037-76-6
  16. ↑ ZV Waloff (1940): The Distribution and Migration of Locusta Europe. Bulletin of Entomological Research, Volume 31, Issue 3: 211-246.
  17. ↑ Peter Detzel: The locusts of Baden-Württemberg. Eugen Ulmer Verlag, 1998. ISBN 3-8001-3507-8 .
  18. ^ C. Linnæus (1758): Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. - pp. [1-4], 1-824. Holmiæ. (Salvius). digitized by GDZ Göttingen digitization center
  19. ↑ Locusta migratoria in Orthoptera Species File online (Version 5.0 / 5.0)
  20. ↑ Chuan Ma, Pengcheng Yang, Feng Jiang, Marie-Pierre Chapuis, Yasen Shali, Gregory A Sword, Le Kang (2012): Mitochondrial genomes reveal the global phylogeography and dispersal routes of the migratory locust. Molecular Ecology 21: 4344-4358 doi : 10.1111 / j.1365-294X.2012.05684.x
  21. ↑ Bernard Defaut (2006): Eléments pour la Faune de France of Caelifères: 5. A propos de Locusta migratoria cinerascens (Fabricius, 1781) (Caelifera, Acrididae, Oedipodinae). Matériaux Orthoptériques et Entomocénotiques, 11: 59-61.
  22. ↑ Herbert Weidner (1986): The trails of the European migratory locust, Locusta migratoria migratoria Linnaeus, 1758 in Europe in 1693 (Saltatoria, Acridiidae, Oedipodinae). Scoreboard for Pest Management, Plant Protection, Environmental Protection 59: 41-51.
  23. ↑ Seiji Tanaka & Dao-Hong Zhu (2005): Outbreaks of the migratory locust Locusta migratoria (Orthoptera: Acrididae) and control in China. Applied Entomology and Zoology Vol. 40 No. 2: 257-263. free download
  24. ↑ FA Gapparov & AV Latchininsky (2000): What are the Consequences of Ecosystem Disruption on Acridid ​​Diversity and Abundance? In: Jeffrey A. Lockwood, Alexandre V. Latchininsky, Michael G. Sergeev (editors): Grasshoppers and Grassland Health. Managing Grasshopper Outbreaks without Risking Environmental Disaster. NATO Science Series 2. Environmental Security.
  25. ↑ History of locust and grasshopper outbreaks in Australia ( Memento of the original from December 10, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . Australian Government, Department of Agriculture. last reviewed June 8, 2012. @1@ 2Template: Webachiv / IABot / www.daff.gov.au
  26. ↑ Galina Benkovskaya, Konstantin Kitaev, Elena Surina, Maxim Udalov (2011): Research Progress in Understanding Insecticide Resistance in Oriental Migratory Locust, Locusta migratoria manilensis. Resistant Pest Management Newsletter Vol. 20, No. 2: 257-263.
  27. ↑ JC Scanlan, WE Grant, DM Hunter, RJ Milner (2001): Habitat and environmental factors influencing the control of migratory locusts (Locusta migratoria) with an entomopathogenic fungus (Metarhizium anisopliae). Ecological Modeling, Volume 136, Issues 2-3: 223-236. doi : 10.1016 / S0304-3800 (00) 00424-5
  28. ^ FSVO (April 28, 2017): Insects as food .
  29. ↑ European Commission (2018): Summary of the dossier: Migratory locust (Locusta migratoria) . Dossier of the application for authorization for European migratory locusts as food (novel food).
  30. ↑ European Commission (2018): Whole and ground Grasshopper (Locusta migratoria) . Dossier of the authorization application for whole and ground European migratory locusts as food (novel food).
  31. ↑ Insektenwirtschaft.de: Locusts as food .
  32. ↑ The Guardian / Daniel Boffey (April 3, 2020): Edible insects set to be approved by EU in 'breakthrough moment' .
  33. ↑ Forbes / Alex Ledsom (April 4, 2020): Edible Insects Most Likely Coming To European Supermarkets Soon .