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No taxonomic distinction is made between locust and grasshopper species; the basis for the definition is whether a species forms swarms under intermittently suitable conditions. In English, the term "locust" is used for grasshopper species that change morphologically and behaviourally on crowding, forming swarms that develop from bands of immature stages called hoppers. The change is referred to in the technical literature as "density-dependent phenotypic plasticity".
Normally, these grasshoppers are innocuous, their numbers are low, and they do not pose a major economic threat to agriculture. However, under suitable conditions of drought followed by rapid vegetation growth, serotonin in their brains triggers dramatic changes: they start to breed abundantly, becoming gregarious and nomadic (loosely described as migratory) when their populations become dense enough. They form bands of wingless nymphs that later become swarms of winged adults. Both the bands and the swarms move around, rapidly strip fields, and damage crops. The adults are powerful fliers; they can travel great distances, consuming most of the green vegetation wherever the swarm settles. [3] Swarming behaviour decreased in the 20th century, but despite modern surveillance and control methods, swarms can still form; when suitable weather conditions occur and vigilance lapses, plagues can occur. [5] [6]The Fiqh of Halal and Haram Animals". Shariahprogram.ca. Archived from the original on 24 September 2015 . Retrieved 12 April 2015. Distinctive changes in behavior before and after migration - Insects preparing to migrate may suspend reproductive activities and change their feeding habits. Some will climb to the top of a tree to assess and make use of the wind currents when they depart. Locusts, which are normally solitary insects, become gregarious. Reid, Chris; Carlesso, Daniele (April 19, 2021). "Bridges, highways, scaffolds: how the amazing engineering of army ants can make us smarter creators". The Conversation . Retrieved 2021-04-20. The migratory system in the east is further complicated, and undergoing rapid change, by a recent trend for alternative wintering destinations and loss of migration, and it is becoming clear that a substantial number of eastern monarchs no longer reach Mexico (Fig. 1). A significant proportion of eastern monarchs now migrate via Florida in the autumn, where they break reproductive diapause and become subsumed within the resident, continuously breeding, populations in south Florida [ 11] and Cuba [ 42]. Additionally, an increasing proportion of autumn migrants break reproductive diapause and abandon migration in the Gulf Coast region of Texas, to join the small, but increasing, resident breeding population in this region [ 43]. This change is induced by recent widespread planting of tropical milkweed ( Asclepias curassavica) in gardens, an exotic larval food-plant which has enabled winter-breeding to take place, and it appears that migration is easily lost in monarchs [ 36]. Thus, the switch of many migrants to winter breeding in southern Florida and Texas leads to the loss of individuals from the eastern migratory population and a consequent reduction in migratory connectivity, and may also be one of the drivers of the long-term decline in the size of the Mexican winter population [ 10, 12, 37]. Martin TG, Chadè’s I, Arcese P, Marra PP, Possingham HP, Norris DR. Optimal conservation of migratory species. PLoS One. 2007;2:e751.
a b c Harmon, Katherine (30 January 2009). "When Grasshoppers Go Biblical: Serotonin Causes Locusts to Swarm". Scientific American . Retrieved 7 April 2015. A biological pesticide to control locusts was tested across Africa by a multinational team in 1997. [54] Dried fungal spores of a Metarhizium acridum sprayed in breeding areas pierce the locust exoskeleton on germination and invade the body cavity, causing death. [55] The fungus is passed from insect to insect and persists in the area, making repeated treatments unnecessary. [56] This approach to locust control was used in Tanzania in 2009 to treat around 10,000 hectares in the Iku-Katavi National Park infested with adult locusts. The outbreak was contained without harm to the local elephants, hippopotamuses, and giraffes. [46] Fromme, Alison (2005). "Edible Insects". Smithsonian Zoogoer. Smithsonian Institution. 34 (4). Archived from the original on 11 November 2005 . Retrieved 26 April 2015.von Beeren, Christoph; Tishechkin, Alexey K. (2017-02-10). "Nymphister kronaueri von Beeren & Tishechkin sp. nov., an army ant-associated beetle species (Coleoptera: Histeridae: Haeteriinae) with an exceptional mechanism of phoresy". BMC Zoology. 2 (1): 3. doi: 10.1186/s40850-016-0010-x. ISSN 2056-3132. During the last two millennia, desert locust plagues have appeared sporadically in Africa, the Middle East, and Europe. Other species of locusts caused havoc in North and South America, Asia, and Australasia; in China, 173 outbreaks over 1924 years. [36] The Bombay locust ( Nomadacris succincta) was a major pest in India and southeastern Asia in the 18th and 19th centuries, but has seldom swarmed since the last plague in 1908. [38] Rogers, S. M.; Matheson, T.; Despland, E.; Dodgson, T.; Burrows, M.; Simpson, S. J. (2003). "Mechanosensory-induced behavioral gregarization in the desert locust Schistocerca gregaria". Journal of Experimental Biology. 206 (22): 3991–4002. doi: 10.1242/jeb.00648. PMID 14555739. S2CID 10665260.
Monitoring [ edit ] Eugenio Morales Agacino on expedition monitoring locusts in the desert of Spanish Sahara, 1942 a b Kronauer, Daniel J. C.; Johnson, Robert A.; Boomsma, Jacobus J. (2007). "The Evolution of multiple mating in army ants". Evolution. 61 (2): 413–422. doi: 10.1111/j.1558-5646.2007.00040.x. PMID 17348950. S2CID 36371272. Interaction with humans and animals [ edit ] Ancient times [ edit ] Locust detail from a hunt mural in the grave-chamber of Horemhab, Ancient Egypt, circa 1422–1411 BC Kellogg, Elizabeth A.; Shaffer, H. Bradley (1993). "Model Organisms in Evolutionary Studies". Systematic Biology. 42 (4): 409–414. doi: 10.2307/2992481. JSTOR 2992481. The workers of army ants are usually blind or can have compound eyes that are reduced to a single lens. There are species of army ants where the worker caste may show polymorphism based on physical differences and job allocations; however, there are also species that show no polymorphism at all. [5] The worker caste is usually composed of sterile female worker ants. [6] Soldiers [ edit ]Army ants make their nests (known as bivouacs) at night with their own bodies. They organize themselves into a sort of huge ball in a tree trunk or a burrow that they dig for this purpose. Brower LP, Pyle RM. The interchange of migratory monarchs between Mexico and the western United States, and the importance of floral corridors to the fall and spr Brady, Seán G; Fisher, Brian L; Schultz, Ted R; Ward, Philip S (2014). "The rise of army ants and their relatives: diversification of specialized predatory doryline ants". BMC Evolutionary Biology. 14: 2–14. doi: 10.1186/1471-2148-14-93. PMC 4021219. PMID 24886136. Wrege, Peter H.; Wikelski, M.; Mandel, J. T.; Rassweiler, T.; Couzin, I. D. (2005). "Antbirds parasitize foraging army ants". Ecology. 8 (3): 555–559. doi: 10.1890/04-1133. S2CID 1704704. Taylor LR. Insect migration, flight periodicity and the boundary layer. J Anim Ecol. 1974;43:225–38.
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