Locusts: no time to lower the guard
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CTA. 2006. Locusts: no time to lower the guard. Spore 121. CTA, Wageningen, The Netherlands.
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Constant vigilance is needed, now as in the past, to avoid locust invasions, which are by nature, erratic.
Constant vigilance is needed, now as in the past, to avoid locust invasions, which are by nature, erratic. Even after a lull of several decades, there can be no let up and research efforts will have little impact if national and regional surveillance and warning systems are not up and running. Arelentless prevention strategy is needed in the fight against locusts, especially in Sahelian countries, where swarms of these formidable crop pests tend to concentrate. In its first issue in 1986, Spore warned, the fact that there have been no mass invasions .does not mean that the threat is over , stressing that, we clearly cannot afford to relax our guard. These proved to be prescient words. For it was a weakening of anti-locust systems, at both national and regional level, which contributed to two major desert locust invasions, in 1987-89, and in 2002-04, in Sahelian and Maghreb countries, as well as to an invasion of the migratory locust in Madagascar between 1997 and 2000. On each occasion, a delayed response resulted in soaring costs for donors: US$300 million in 1987-88 and $100 million in 2004. Added to those sums were expenses incurred by the affected countries, losses to farmers whose fields were ravaged, and the suffering of those no longer able to feed themselves. However, the past 20 years have seen significant developments in the tools available for locust prevention. The areas known as gregarisation zones , where locusts swarm, have been more accurately identified and techniques for collecting information about insect populations have been simplified. In Mauritania, amongst other countries, inspection units use palm-held computers linked to global positioning systems (GPS) and transmit their data via radio to the headquarters at FAO in Rome. There have also been rapid strides in improving the accuracy of aerial spraying. The new generation of organophosphate pesticides is less damaging to the environment than organochloride chemicals such as dieldrin and DDT that were previously used and which are now banned by the Stockholm Convention on Persistent Organic Pollutants signed in 2001 by 91 countries (see Spore 107, pages 4 and 5). Eliminating stockpiles of these obsolete pesticides, estimated to total 50,000 t in Africa alone, is an extremely costly procedure and much still remains to be done. The most recently developed products offer a barrier treatment which halts the progress of the locusts, an approach which saves time and allows a more targeted use of the product, which would formerly have been sprayed over entire regions. But more still needs to be done to improve prevention techniques. New avenues of research must be explored if there is to be a fuller understanding of how and why these formidable swarms of locusts form, so that early detection mechanisms can be set in place, based on the ecological conditions likely to favour an outbreak. Greener pesticides Studies on pheromones and biopesticides have come a long way in the past 20 years. Less damaging to the environment, these could soon represent a viable alternative to conventional products. Mycopesticides undoubtedly offer the greatest hope. After 10 years of research, the international Lubilosa consortium (Biological Control of Locusts and Grasshoppers), which brings together scientists from several continents, has developed Green Muscle, based on a pathogenic fungus. This green pesticide has proved itself in a series of field trials, and in 1997, it attracted the interest of FAO. The involvement of private companies in the programme has now led to production on an industrial scale. In 2000, Niger became the first country to use the product in its anti-locust operations. But questions linger over aspects related to the use of this living organism. Green Muscle takes between 4 to 10 days to kill the insects time enough for the swarms to move on before dying. At present, there is no way of telling if locusts have been treated or not, so blanket, rather than barrier treatment is necessary. Another limiting factor is the as yet imperfect understanding of how long the product lasts and how long it remains effective after manufacture. And doubts remain over existing capacities for large-scale production. Currently undergoing trials, the application of pheromones, which interfere with the communication signals between the insects to prevent them from swarming, could prove a useful addition to the present array of tools. Prompt action costs money But, however effective they may be, weapons used to fight locusts can only work if they are used in tandem with well functioning surveillance and prevention systems. Some organisations simply do not have the necessary clout. A case in point is the Joint Anti-Locust and Anti-Aviarian Organization (OCLALAV), launched in Dakar in 1965 by a dozen countries, and which, since the 1980s, has received no contributions from member countries and is now widely discredited on the international scene. The locust invasion that swept West Africa in 1987 was only brought under control after a long delay, the response mounted with hurried and inadequate resources. Faced with the plague of 1997, Madagascar also reacted 6 months too late, the delay caused by a lack of materials and the authorities reluctance to use pesticides, which could damage the island s precious natural heritage. Since then, the new national locust control centre, the Centre national antiacridien, has been working with the French Agricultural Research Centre for International Development (CIRAD) to set up a GPS surveillance system. In the meantime, African countries are also trying to draw lessons from past failures. In 1994, the Emergency Prevention System for Transboundary Animal and Plant Pests and Diseases (EMPRES) launched a Desert Locust programme, hosted by FAO. In 1997, it received the funds needed to cover the nine countries of the Horn of Africa and the Near East. A reserve fund is crucial It was not until 2000 that the Commission for Controlling Desert Locusts in the Western Region, better known by its French acronym CLCPRO, was set up in Algiers. This system, on a smaller-scale and less costly than that of OCLALAV, relies on cooperation between the Maghreb and Sahelian countries. The former offer logistical support (vehicles, planes, etc.) and the latter intensify local surveillance in areas where locusts swarm. The principle is based on the sharing of any information collected as well as tools for prevention. Intelligence gathering is supplemented by satellite monitoring. NOAA and Meteosat supply data about weather conditions while SPOT-Vegetation offers information about rainfall and vegetation. But, in 2003, CLCPRO had still not received any funding, so was not ready to handle a new invasion. Yet again, urgent appeals went out to the international community. By the time the funds that were pledged finally materialised, a major operation was needed: in the end, 13 million ha had to be sprayed. Today, the mechanism is working. Responsibility for maintaining it rests with the African countries , stresses Michel Lecoq of the Locust Ecology and Control (PRIFAS) at CIRAD, who strongly urges the setting up of a reserve fund . He claims this is a crucial step if funding and resources are to be mobilised quickly in case of an emergency. This locust expert believes that FAO should also set up its own reserve fund. Another pressing need exists for a system which can define varying degrees of alert and intervention. At present, EMPRES outlines what is needed for each country to carry out routine monitoring. But it is up to each country to establish its own emergency plan. A delicate task, given that the technical and legal mechanisms vary from one country to another. In the wake of the 2002-2004 crisis, EMPRES finally received funding in 2005. If there is too much money, the various anti-locust units may be tempted to increase staff numbers or the quantity of vehicles, unnecessarily. But afterwards, they have to pay for their upkeep , warned Lecoq. For that reason, he believes it would be better that the donors be joint managers of CLCPRO rather than having to devise last minute strategies when disaster strikes. See Links page 10 and Publications page 13 OCLALAV: Benin, Burkina Faso, Cameroon, Chad, Côte d Ivoire, Gambia, Mali, Mauritania, Niger and Senegal. CLCPRO: Algeria, Chad, Libya, Mali, Mauritania, Morocco, Niger, Senegal and Tunisia. Légende : A swarm of desert locusts in Madagascar Photos: M Lecoq © CIRAD
SubjectsCROP PRODUCTION AND PROTECTION;
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