   #copyright

Desert locust

2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and
Fish

                iDesert locust
   Desert locust in solitary phase
   Desert locust in solitary phase
           Scientific classification

   Kingdom:  Animalia
   Phylum:   Arthropoda
   Class:    Insecta
   Order:    Orthoptera
   Suborder: Caelifera
   Family:   Acrididae
   Genus:    Schistocerca
   Species:  S. gregaria

                                Binomial name

   Schistocerca gregaria
   Forsskål, 1775

   Plagues of the desert locust (Schistocerca gregaria) have threatened
   agricultural production in Africa, the Middle East and Asia for
   centuries. The livelihood of at least one-tenth of the world’s human
   population can be affected by this hungry insect. The Desert Locust is
   potentially the most dangerous of the locust pests because of the
   ability of swarms to fly rapidly across great distances. It has two to
   five generations per year. The northern highlands of Ethiopia (Tigray)
   and Eritrea slow the movements of desert locusts to the breeding areas
   of the Red Sea coast. Potential desert locust plagues originating in
   east Africa can be prevented if action is taken during or before
   localized outbreaks in Eritrea and Sudan (Jahn 1993 ). The 2004 desert
   locust outbreak has caused significant crop losses in West Africa and
   had a negative impact on food security in the region. It was one of the
   main factors contributing to the famine in Niger.

Desert locust ecology

   The desert locust lives a solitary life, until it rains. Rain causes
   vegetation growth and spurs the development of eggs that have been laid
   in the sandy soil. The new vegetation provides food for the newly
   hatched locusts and provides them with shelter as they develop into
   winged adults.
   Solitary (top) and gregarious (bottom) desert locust nymphs
   Enlarge
   Solitary (top) and gregarious (bottom) desert locust nymphs

   When vegetation is distributed in such a way that the nymphs, usually
   called hoppers, have to congregate to feed, and there has been
   sufficient rain for a lot of eggs to hatch, forced physical contact
   causes the insects' hind legs to bump up against one another. This
   triggers a cascade of metabolic and behavioural changes that signal the
   insects' transformation from solitary behaviour to gregarious
   behaviour. When the locusts become gregarious they change from green
   coloured to yellow and black, their bodies become shorter, and they
   give off a pheromone that causes them to be attracted to each other,
   enhancing hopper band and subsequently swarm formation. Interestingly,
   the nymphal pheromone is different from the adult one. When exposed to
   the adult pheromone, hoppers become confused and disoriented, because
   they can apparently no longer "smell" each other, though the visual and
   tactile stimuli remain. After a few days, the hopper bands disintegrate
   and those that escape predation become solitary again. It's possible
   that this effect could aid locust control in the future.

   During quiet periods, called recessions, locusts are confined to a
   16-million-square-kilometer belt that extends through the Sahara Desert
   in northern Africa, across the Arabian Peninsula, and into northwest
   India. When conditions are right swarms invade countries on all sides
   of the recession area, as far north as Spain and Russia and as far east
   as India and southwest Asia. As many as 60 countries can be affected.

   Swarms regularly cross the Red Sea between Africa and the Arabian
   Peninsula and are even reported to have crossed the Atlantic Ocean from
   Africa to the Caribbean. A single swarm can cover 1200 square
   kilometers and can contain between 40 and 80 million locusts per square
   kilometer. The locust can live between three to six months, and there
   is a tenfold increase in locust numbers from one generation to the
   next.

Crop loss

   Desert locusts can consume the approximate equivalent of their body
   mass each day (2 g) in green vegetation: leaves, flowers, bark, stems,
   fruit, and seeds. Nearly all crops, and non crop plants, are at risk,
   including millet, rice, maize, sorghum, sugarcane, barley, cotton,
   fruit trees, date palm, vegetables, rangeland grasses, acacia, pines,
   and banana. What is more, locust droppings are toxic, and spoil any
   stored food that is left uneaten.
   Locusts feeding
   Enlarge
   Locusts feeding

   Crop loss from locusts was noted in the Bible and Qur'an; these insects
   have been documented as contributing to the severity of a number of
   Ethiopian famines. During the twentieth century, Desert Locust plagues
   occurred in 1926-1934, 1940-1948, 1949-1963, 1967-1969 and 1986-1989.
   The significant crop losses caused by swarming desert locusts,
   exacerbate problems of food shortage, and are a threat to food
   security.

Control

   NASA has developed methods for detecting conditions and regions likely
   to give rise to swarms by satellite. Satellite data, combined with
   weather information and ground surveys, are used by the FAOs Desert
   Locust Information Service to produce forecasts published on the Web
   and in regular locust bulletins. They also provide information and
   training to affected countries and arrange for funding from donor
   agencies in case of major upsurges and plagues.

   The desert locust is a difficult pest to control, and control measures
   are made more difficult by the large and often remote areas (16-30
   million sq. km) where locusts can be found. Undeveloped basic
   infrastructure in some affected countries, limited resources for locust
   monitoring and control and political turmoil within and between
   affected countries further reduce the capacity of a country to prevent
   swarms.
   Desert Locust Schistocerca gregaria
   Enlarge
   Desert Locust Schistocerca gregaria

   An ecological method to control desert locust is with natural enemies.
   These include predatory and parasitic wasps and flies, predatory beetle
   larvae, birds, and reptiles. The downside is that they are easily
   overwhelmed by the sheer magnitude of most swarms and bands if these
   were to be the only defense used in a serious outbreak. However, they
   can help poor farmers since they might change the direction the swarm
   is heading. Another old African method is by putting poisonous or
   aromatic plants next to the crop they are trying to protect.

   At present the primary method of controlling desert locust swarms is
   with organophosphate insecticides applied in small concentrated doses
   by vehicle-mounted and aerial sprayers. The insecticide must be applied
   directly to the insect. Control is undertaken by government agencies in
   locust affected countries or by specialised organisations like the
   Desert Locust Control Organisation for East Africa (DLCO-EA).

Biopesticides

   Biopesticides include fungi, bacteria, neem extract and pheromones. The
   effectiveness of many biopesticides equals that of conventional
   chemical pesticides, but there are two distinct differences.
   Biopesticides take longer to kill the insect, plant diseases or weeds,
   between 2 and 10 days. More importantly, while there are approximately
   25 million cases of severe work-related pesticide poisoning in
   developing countries each year, biopesticides are harmless to other
   creatures and the environment.

   There are two types of biopesticides - biochemical and microbial.
   Biochemical pesticides are similar to naturally occurring chemicals and
   are non-toxic, such as insect pheromones use to locate mates, while
   microbial insecticides like Green Muscle® come from bacteria, fungi,
   algae or viruses that either occur naturally or are genetically
   altered. They generally suppress pests by producing a toxin specific to
   the pest or by causing a disease.

   A biological control product, Green Muscle®, has been available since
   the late nineties. It is based on a naturally occurring
   entomopathogenic fungus (i.e. insects-infecting fungus) , Metarhizium
   anisopliae var. acridum. The species M. anisopliae is widespread
   throughout the world infecting many groups of insects, but it is
   harmless to humans and other mammals and birds. The variety acridum has
   specialised on short-horned grasshoppers, to which group locusts
   belong, and has therefore been chosen as the active ingredient of the
   product.

   The product is available under different names in Africa and Australia.
   It is applied in the same way as chemical insecticides but does not
   kill as quickly. At recommended doses, the fungus typically takes two
   to three weeks to kill up to 90% of the locusts. For that reason, it is
   recommended for use mainly against hoppers, the wingless early stages
   of locusts. These are mostly found in the desert, far from cropping
   areas, where the delay in death does not result in damage. The
   advantage of the product is that it affects only grasshoppers, which
   makes it much safer than chemical insecticides. Specifically, it allows
   the natural enemies of locusts and grasshoppers to continue their
   beneficial work. These include birds, parasitoid and predatory wasps,
   parasitoid flies and certain species of beetles. Though they cannot
   always prevent plagues, they can limit the frequency of outbreaks and
   contribute to their control.

New Control Methods

   The LUBILOSA project was initiated in 1989 in response to environmental
   concerns over the heavy use of chemical insecticides to control locusts
   and grasshoppers during the 1986-89 plagues. The project focuses on the
   use of beneficial disease-causing micro-organisms (pathogens) as a
   biological control agent for grasshoppers and locusts. These insects
   were considered to be too mobile and to reproduce too fast to be
   readily controlled by a classical biological control.

   Pathogens have the advantage that they can be produced in artificial
   culture in large quantities and be used with ordinary spraying
   equipment. The entomopathogenic fungus is traditionally seen as needing
   humid conditions to work well. The LUBILOSA project has found a way to
   avoid this by spraying fungal spores in oil. Even under desert
   conditions the biopesticide developed by LUBILOSA, called Green
   Muscle®, can be used to kill locusts.

2004 Desert locust outbreak

   In 2004, West Africa faced the largest desert locust outbreak in 15
   years. The costs of fighting this outbreak have been estimated by the
   FAO to have exceeded US$60 million and harvest losses were valued at up
   to US$2.5 billion which had disastrous effects on the food security
   situation in West Africa. Lack of rain and cold temperatures in the
   winter breeding area of Northwest Africa slowed down the development of
   the locusts and allowed the locust control agencies to stop the cycle.
   In 2005, only a couple of swarms invaded the Sahel countries. Though
   significant breeding occurred in the summer in the border area of Chad
   and Sudan, the situation appears to be under control for the time
   being.

   The countries affected by the 2004 outbreak were Algeria; Burkina Faso;
   the Canary Islands, Cape Verde; Chad; Egypt; The Gambia; Guinea; Libyan
   Arab Jamahiriya; Mali; Mauritania; Morocco; Niger; Saudi Arabia;
   Senegal; Sudan; Tunisia; Yemen.

   Retrieved from " http://en.wikipedia.org/wiki/Desert_locust"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
