Dociostaurus maroccanus (Thunberg 1815)

Systematic position: Class Insecta, order Orthoptera, sub-order Caeliferae, super-family Acridoidea, family Acrididae, sub-family Gomphocerinae and genus Dociostaurus OR sub-family Acridinae, tribe Dociostaurini, genus Dociostaurus depending on the classification, usual or Russian

Synonyms: Gryllus maroccanus Thunberg 1815; G. cruciatus Charperntier 1825; Oedipoda vastator Fischer de Waldheim 1846; Epacromia oceanica Walker 1870

Identification: Average-sized acridid. Hind tibia red. Yellowish or whitish cruciform figure on the pronotum. Adults from solitary and gregarious phases show morphometric and chromatic differences, the first being smaller, with a higher ratio of the femur and elytra lengths, brighter general body colour and black spots on the hind femora and elytra more marked.

Biological group: Polyphagous insect pests

DISTRIBUTION

The distribution area of the Moroccan Locust extends from Atlantic islands (Canaries, Madeira) in the west to Kazakhstan and Afghanistan in the east. The northern limits of its distribution area are reached in Hungary and Rumania. In Africa the species occurs in Morocco, Algeria, Tunisia, Libya, and Egypt, with latitude 28N as the southern edge of its distribution area. It is present in west and central Europe, i.e. Portugal, Spain, France, Italy, Hungary, countries of ex-Yugoslavia, Greece, Bulgaria, Moldova and south-west Ukraine as well as in Caucasus, i.e. Armenia, Azerbaijan and Georgia. The species is also found in the Middle East and Minor Asia, i.e. in Turkey, Syria, Lebanon, Israel, Jordan, Iraq and Afghanistan. In the eastern part of its distribution area, the Moroccan Locust is present in all Central Asian countries, i.e. Tajikistan, Uzbekistan, Tajikistan, Kyrgyzstan and Kazakhstan, the latter hosting the extreme north-eastern point of its distribution area (60 km E of Almaty). The Moroccan Locust is not found north to 49N.

MORPHOLOGY

Imago (adult) has a medium-sized and slender body. Body length varies from 16.5 to 28.5 mm (male) and 20.5 to 38.0 mm (female). Individuals of solitary phase are finer than those of gregarious phase. Elytra are well developed, almost transparent, stretching considerably behind apex of hind femur, sometimes with sparse small-sized brownish or greyish spots. Length of elytra varies from 17.5 to 27 mm (male) and 23 to 36 mm (female). Wings are colourless. Hind femora are thin, 3.7-4.2 times longer than wide. Length of hind femur varies from 13.2 to 17.4 mm (male) and 15.5 to 21.6 mm (female). General body colour: greyish-yellowish with dark spots. Hind femora can have or not black bands, depending on the phase. Hind tibia is usually red, less often yellow, pinkish, or even whitish. On pronotum, there is yellowish or whitish cruciform figure, with narrow striae not extending behind transversal furrow.

BIOLOGY

Moroccan Locust is a univoltine species (one generation per year), with winter egg diapause. Females lay 2-3 (less often 4) egg pods containing an average of 30 eggs (min. 16 to max. 45) in bare patches of ground in mosaic vegetation (virgin, unploughed lands), which is a characteristic feature of the species (therefore, ploughing is detrimental for this locust). Group oviposition is observed and egg pod density is sometimes very high, up to several thousands per square meter. The egg pods may be in small earth pockets in rocky ground, just below the surface or up to 4 cm depth in firm soil; eggs can also be laid directly in plant clumps or in cracks of very dry soil. Egg laying occurs approximately one month after adult appearance, i.e. from May onwards. After winter diapause, hatching occurs from February to April, depending on latitude and altitude. There are 5 hopper instars. Whole hopper development takes from 25 to 40 days with duration of each nymphal instar from 5 to 10 days. From the second instar, hoppers can start marching together. The highest densities can reach several thousands per square meter. Fledging usually takes place during April and copulation starts from 2 to 10 days later. Adults dissapear in the middle of summer.

ECOLOGY AND BEHAVIOUR

Multivorous. Moroccan Locust is characteristically found in semi-arid steppe or semi-desert areas with abundant spring ephemeral vegetation, being favoured by a spring rainfall of 100 mm or more. The altitude of these areas usually varies from 500 to 1,000 m a.s.l., with exceptional observations at 100 m and up to 2,200 m. Poa bulbosa is a very regular constituent of ephemeral vegetation and other commonly associated plants are Stipa capensis, Cynodon dactylon, Hordeum murinum and small sedges and dicotyledons. These plants complete their development by early summer. High-density locust populations may be found into mosaic of bare ground and vegetation. Compact virgin soil is necessary to the species and can derive from sheep and goat activities.

Increase in locust numbers usually occurs when temperatures exceed average and rainfall is below normal; in the distribution area of the Moroccan Locust, spring rainfall (from March to May) is about 100 mm. Spring rainfalls under this amount for the second or third consecutive year usually lead to population increase. Hoppers show gregarious behaviour, marching in long lines up several kilometres long by several metres deep. During outbreaks, hoppers bands destroy almost completely sparse vegetation in hatching places; then, they start moving down from dry foothills towards cultivated plains and damage sowings on their route. Adults show swarm activity; flights last longer over the day when the temperature increases. The flight altitude is generally comprised between 20 and up to 100 m with a speed of 8-10 m/s. Flights are usually no longer than 50-75 km during the whole season; however, up to 250 km flights have been reported.

ECONOMIC IMPORTANCE

The Moroccan Locust is one of the most serious pests of many cultivated plants and threatens agriculture of steppes, foothills and arid areas in the climatic Mediterranean area. Human activities have important unsuitable and favourable impacts on its habitats: expansion of agriculture results in reduction of potential oviposition sites; on the contrary, over-grazing of dry pastures provide appropriate laying conditions as well abandoned cultivations becoming fallow lands with a mosaic of ephemeral vegetation and bare ground.

USEFUL PLANTS ATTACKED

Grain crops including wheat, barley, millet, rice and maize as well as fabaceous (peas, beans, lentil, alfalfa, clover); - leaves, stalk and grain can be attacked. Trees, especially young saplings, can be damaged: date palms, citrus, fruit trees, olives, figs. Forage crops incl. clover, are also affected. Other plants attacked include cotton, grape vines, tobacco, sunflower, vegetable (cabbage, carrot, onion, salad), which can be completely eaten.

NATURAL ENEMIES

There are a number of parasites and predators such as several species of beetles, flies, the wasp Sphex subfuscatus, mites, etc., including egg parasites (the beetle Trichodes laminatus and the fly Thyridanthrax sp.). Serious infestations of eggs by the fungus Fusarium acridiorum have also been reported.

SOME RELATED REFERENCES

Bei-Bienko, G.Ya. 1932. A manual of locust survey. Leningrad: Upravlenie Sluzhby ucheta Gos. OBV Narkozema SSSR, 159 pp.
Bei-Bienko, G.Ya. & Mishchenko, L.L. 1951. Locusts of the fauna of the USSR and adjacent countries. Opredeliteli po faune SSSR, N38, parts I & II. Moscow & Leningrad: AN SSSR, 668 pp.
Latchininsky, A.V., Sergeev, M.G., Childebaev, M.K. et al. 2002. Locusts of Kazakhstan, Central Asia and adjacent territories. Larami: Association for Applied Akridology International / University of Wyoming, 387 pp.
Sergeev, M.G. 1986. Regularities in distribution of orthopterous insects of Northern Asia. Novosibirsk: Nauka, 238 pp.
Uvarov, B.P. 1977.Grasshopers and Locusts. A Handbook of General Acridology. Vol. II. London: COPR.