Research consultancy
Desert Locust, Schistocerca gregaria (Forskal) is a major threat to agricultural production in countries in the arid and semi-arid regions of Africa mainly north of the equator, in the Near East and in Southwest Asia. In these regions, rural populations are already farming under very harsh conditions and encounter major difficulties in meeting their subsistence requirements.
The Desert Locust is a very opportunistic insect, once it has changed under favourable environmental conditions from the solitary into the gregarious phase, i.e. the phase when locusts group together in hopper bands and swarms. It can travel long distances and ravage whatever crop and pasture it encounters. The 2003–05 upsurge offers a classic example of this characteristic, which makes it so difficult to forecast accurately the development and spread of the Desert Locust, and subsequently undertake survey and control actions in a timely and effective manner.
In the past, according to available records, swarms originating from the Central Region preceded Desert Locust population explosions in the Western Region.[1] However, the 2003–05 upsurge was the first in the Western Region in which swarms from the Central Region played no part. Within 12 months the situation changed from solitary locusts, scattered over the northern part of the Sahel region, where they caused no damage, into one where swarms were spreading into pasture and crop land over an area extending from Chad to Mauritania, and from Morocco to the Libyan Arab Jamahiriya. Thus, within a very short period of time, an extremely wide area was threatened by Desert Locust populations that were larger and denser than those encountered during the 1986–89 campaign. During the 1986–89 campaign, over a three-year period, 16.9 million ha were treated in the Central and Western Regions, compared to 12.9 million ha over some 15 months during the 2003–05 upsurge in the Western Region.
Thus, notwithstanding these very positive developments, effective monitoring of locust populations and action preparedness remain key elements in Desert Locust control. At a workshop on contingency planning for Desert Locust control held at Nouakchott in May 2004, it was concluded that advance warning of outbreaks was still rather problematic and was probably only possible at one-month’s notice with low reliability. Upsurges could only be forecast up to three months in advance with relatively low reliability, while the forecast period for the development of a plague was around six months, but reliability was higher. The short time available for advanced warning of the onset of locust outbreaks and upsurges reinforces the importance of having realistic contingency plans in place to enable countries to respond rapidly and adequately (FAO, 2004).
