Moroccan migratory locust

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Moroccan migratory locust
Dociostaurus maroccanus

Dociostaurus maroccanus

Systematics
Order : Grasshoppers (Orthoptera)
Subordination : Short-antennae terrors (Caelifera)
Family : Field locusts (Acrididae)
Subfamily : Grasshopper (Gomphocerinae)
Genre : Dociostaurus
Type : Moroccan migratory locust
Scientific name
Dociostaurus maroccanus
( Thunberg , 1815)

The Moroccan migratory grasshopper , scientific name Dociostaurus maroccanus, is a field grasshopper that lives in steppe-like habitats and semi-deserts. Like all migratory locusts , it is a feared agricultural pest in the region .

features

It is a medium-sized grasshopper, one of the largest species within the genus. Males are 17 to 30 millimeters long, females 20 to 33, exceptionally up to 38 millimeters, with considerable size differences between different individuals. The large, parallel-sided cover wings ( Tegmina ) protrude far beyond the tip of the abdomen and the hind knees. The animals are mostly yellowish-gray in their primary color and are drawn with a lot of contrast with dark spots and bands. On top of the pronotum there is always a high-contrast drawing made up of four yellow lines that form an "x" interrupted in the middle, in a dark field. The hind wings are hyaline without any coloration or banding, and the cover wings are almost transparent and translucent, with indistinct darker spots. The rear rails are mostly red with a basal yellow ring, but they can also be pink or yellowish in color. The head is rounded in profile at the front, the part of the forehead protruding over the antenna bases (called the fastigium) pentagonal when viewed from above. The vertex dimples on the forehead are transversely trapezoidal, the wider side next to the complex eyes.

The species occurs in two different morphs or phases. Usually the animals live individually (solitary). In these animals, the thigh (femur) of the ankle bone, which is quite slender in the species, has a striking pattern of three black spots. If a large number of animals appear together in a confined space, they develop the gregarious or migrating form. These animals are slightly larger, the wings are longer, the head is orange in color and the spots on the hind legs are faded or absent. These differences can already be seen in the nymphs .

distribution

The Moroccan migratory locust is widespread in arid North Africa, west of the Atlantic coast (including the Canary Islands and Madeira ), in southern Mediterranean Europe, across Asia Minor eastward, east to Tajikistan and northern Afghanistan . It usually does not occur south of 28 ° and north of 49 ° north latitude . In Africa, the atlas in Morocco and the Tell atlas in Algeria are mainly populated. In Europe, the northernmost deposits are in the Crau in southern France, in the Puszta von Hortobágy in Hungary, in the Romanian Moldau region and southwest Ukraine, the Crimea and the North Caucasus. It is common in southern Spain and the Balkans, but is largely absent in Catalonia .

Life cycle

The species forms in the entire distribution area only one generation per year ( monovoltin ). By far the longest phase of life is the egg phase, it lasts 9 to 10 months; during this time neither larvae nor adults can be found. The females lay the eggs , which are enclosed in an ootheca , in the ground at a depth of about one to three centimeters. As a rule, each female creates two ooths, occasionally three or four, each with 16 to 45 eggs, on average 30 eggs. The storage time is late spring or early summer. The young nymphs then hatch no earlier than in the spring of the following year. Two complementary mechanisms ensure the diapause . Embryonic development initially stops at temperatures above 25 ° C, which are almost always exceeded in the species' habitats in summer. The development only starts again at temperatures below 16 ° C, in autumn. However, it stops again when the temperature drops below 10.5 ° C. In addition, the egg must be able to absorb water from the soil for successful development, i.e. it needs a certain amount of soil moisture, which can only be present in the habitat in winter.

The hatched nymphs go through five larval stages, they require 36 to 38 days in the laboratory, the individual stages between 4 and 7 (up to 12) days. During this time, sufficient warmth is essential for successful development. About five days after the imaginal molt, the animals are ready to mate, the imagines live for a total of 30 to 40 days. The imaginal period is in spring (April to May), in northern regions it is shifted towards summer.

Stridulation

Both sexes of the species can produce a song through stridulation, a row of cones called a "file" is drawn on the hind femur over the edge of the wing. The males produce a song to attract females. Another is produced by both sexes as a disturbance sound when touched. A third was registered in the male during the attempt at mating.

Habitat and way of life

The Moroccan migratory locust lives in semi-arid steppes or semi-deserts with winter rain, so that in spring there is usually a somewhat lush vegetation made up of annual plants. It lives in regions with around 300 to 500 millimeters of annual precipitation . For them, however, only 100 millimeters of rain in spring is optimal; in wet years the ootheca fungi, which means that fewer animals survive. As a result, it reaches the highest settlement densities, especially in particularly dry years, especially when several occur in a row. If three or more dry years follow one another, in favorable habitats there is often a mass increase ( gradation ), the animals then change to the migration phase. In dry years the vegetation is often better developed only in patches, there is a lot of open ground between green islands, these conditions are particularly beneficial for the development of the species. Often in the habitat of the species Bulte the onion-panicle grass ( Poa bulbosa ) or the sedge Carex pachystilis remain as the last green, the species are eaten by the grasshopper.

In terms of human influence on the species, two opposing tendencies can be observed. It only lays eggs in undisturbed soil; no eggs are laid in plowed arable land. However, it reaches particularly high densities in regions devastated by humans and their grazing cattle , in which the vegetation cover has been destroyed by overgrazing . Mass reproductions are almost exclusively pronounced in overgrazed regions. In semi-deserts it therefore occurs particularly often in the vicinity of human settlements and is absent in undisturbed habitats, for example in Algeria. In some regions, such as Hungary, it may have become at home at all through a different type of devastation, the draining of the extensive wetlands. If grazing becomes too intense, so that the grass steppe is replaced by Artemisia populations, the species disappears again and is then replaced by other species such as Calliptamus barbarus .

The species prefers a medium (submontane) altitude range between 500 and 1,000 meters above sea level, it occurs exceptionally at higher (up to 2,200 meters) and lower (up to 100 meters). It prefers heavy, clayey soils for laying eggs. In the diet it is polyphagous and eats grass and herb species equally.

Mass increases, economic importance

The Moroccan migratory locust is one of the most important agricultural pests within its range. The older nymphs (called "hoppers" in the English-speaking world) of the wandering form form marching columns from overpopulated areas that can reach lengths of several kilometers with only a few meters width. The flighty adults fly into cultivated land and can cause great damage here, but the flocks hardly relocate their area of ​​residence, longer hikes are included in this species. The largest ever registered swarm of the species had an area of ​​18-25 square kilometers with a density of 50-300 animals per square meter. The main damage usually consists in the destruction of the pasture land with a lack of feed for the cattle. The regions affected can be considerable, more than 500,000 hectares in Afghanistan in 1989, 300,000 hectares in Syria in 1947, 400,000 hectares in Iraq in 1948, 1 million hectares in 1993 in Kazakhstan. Tragically, mass reproductions are particularly common in war and crisis areas when the population has no way of fighting the animals. The mass reproductions in Europe before 1920, in France and in the Balkans, are directly linked to the effects of the First World War, in which large previously cultivated areas fell fallow and these fallows of the species offered optimal conditions at times. The last mass increase in Hungary, 1983, is associated with the upheaval of the turning point. The species also benefited from the war in Afghanistan

Historical mass reproductions

Mass reproduction of the Moroccan migratory locust is not a modern phenomenon; it has probably been a part of mankind since it first settled down. The earliest evidence that reports about it are accidentally obtained Akkadian cuneiform texts from the Habur region in northern Mesopotamia. Around 1700 BC, the governor of Qattunan wrote to King Zimri-Lim of Mari that the crops in his province had been destroyed by locusts for two consecutive years. Based on the description in the letter, the infestation can be related to this species with relative certainty; it would be very atypical for other migratory locusts. About 500 years later, the official Sin-mudammiq described a second plague in the same area to his superior, the Grand Vizier in Dur Katlimmu , under the rule of Tukulti-Ninurta I , King of Assyria . The residents of Waššukanni could not pursue the king's enemies because the locusts had eaten their crops. Even then, grasshopper outbreaks can often be associated with war events. From further Assyrian texts it emerges that the animals were fought in peacetime in their breeding areas, when they left the ground; that was not possible in times of crisis. Even today, the rural population in Afghanistan fights the animals when there is a (crisis-related) lack of pesticides by digging trenches in front of the marching columns of the nymphs to pave their way to the cultivated land.

Taxonomy

The genus Dociostaurus comprises 21 species, 4 of which live in North Africa and 5 in Spain. Dociostaurus maroccanus was first described as Gryllus maroccanus by Carl Peter Thunberg , it is the type species of the genus Dociostaurus Fever , 1853. The type locality is the Moroccan Atlas. Some taxonomists call it Stauronotus maroccanus , but the generic name is a more recent synonym (it refers to the same type species). All other synonyms have been out of use for a long time.

Individual evidence

  1. ↑ a b Abdelhamid Moussi, Abderrahmane Abba, Abboud Harrat, Daniel Petit (2014): Description of Dociostaurus biskrensis sp. nov. and male allotypes of four species: Pamphagulus bodenheimeri dumonti, P. uvarovi, Sphingonotus ebneri and Notopleura pygmaea (Orthoptera: Acridoidea) in the region of Biskra, Algeria. Zootaxa 3755 (4): 379-390. doi: 10.11646 / zootaxa.3755.4.4
  2. ↑ a b I. Ya. Grichanov: Dociostaurus maroccanus (Thnb.) - Moroccan Locust. Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries. Economic Plants and their Diseases, Weeds and Pests. 2003–2009 online
  3. ↑ a b Dociostaurus maroccanus near Louveaux, Amédégnato, Poulain, Desutter-Grandcolas: Orthoptères Acridomorpha de l'Afrique du Nord-Ouest
  4. ↑ Hojun Song: Density-Dependent Phase Polyphenism in Nonmodel Locusts: A Minireview. In: Psyche. Volume 2011, Article ID 741769, doi: 10.1155 / 2011/741769 ( online )
  5. ↑ Ionuţ Ştefan Iorgu, Elena Iulia Iorgu, Nadejda Stahi (2013): The Orthoptera (Insecta) from Middle and Lower Prut River Basin. Travaux du Muséum National d'Histoire Naturelle "Grigore Antipa" 56 (2): 157-171. download
  6. ^ Josep Maria Olmo-Vidal (2006): Atlas of the Orthoptera of Catalonia (Atlas of Biodiversity No.1).
  7. ↑ a b Moroccan Locust at FAO Locust Watch
  8. ↑ C. Santiago-Alvarez, E. Quesada-Moraga, P. Hernandez-Crespo (2013): Diapause termination and post-diapause development in the Mediterranean locust Dociostaurus maroccanus (Orth., Acrididae) under field conditions. Journal of Applied Entomology 127: 369-373.
  9. ↑ E. Quesada-Moraga & C. Santiago-Alvarez (2001): Rearing and breeding of the Moroccan locust Dociostaurus maroccanus (Thunberg) (Orthop., Acrididae) under laboratory conditions. Journal of Applied Entomology 125, 121-124.
  10. ^ A b María Dolores García García, Esther Larrosa Pérez, Eulalia Clemente Espinosa, Juan José Presa Asensio (2005): Contribution to the knowledge of genus Dociostaurus Fieber, 1853 in the Iberian Peninsula, with special reference to its sound production (Orthoptera: Acridoidea ). Anales de biología, vol. 27: 155-189.
  11. ↑ Barnabás Nagy (1990): A hundred years of the Moroccan Locust, Dociostaurus maroccanus Thunberg, in the Carpathian Basin. Boletin de Sanidad Vegetal (Fuera de serie) 20: 67-74.
  12. ↑ a b c d Alexandre V. Latchininsky (19989): Moroccan locust Dociostaurus maroccanus (Thunberg, 1815): a faunistic rarity or an important economic pest? Journal of Insect Conservation 2: 167-178.
  13. ↑ Field crop protection in northern Afghanistan. Afghanistan Project findings and recommendations. Report prepared for the Government of Afghanistan by the Food and Agriculture Organization of the United Nations acting as executing agency for the United Nations Development Program. Rome, 1995.
  14. ↑ Barnabás Nagy (1994): Grasshopper Gradations in Hungary 1993. Articulata 9 (1): 65-72.
  15. ↑ a b B. Stride, A. Shah, Shah Mahmood Sadeed (2003): Recent history of Moroccan locust control and implementation of mechanical control methods in northern Afghanistan. International Journal of Pest Management Volume 49, Issue 4: 265-270. doi: 10.1080 / 0967087031000101098
  16. ^ Karen Radner (2004): Eat and be eaten. Locusts as a disaster and a delicacy in the ancient Near East. The World of the Orient 34: 7-22.

Web links

Commons : Moroccan Migratory Locust  - Album with pictures, videos and audio files