Introduction

Africa is endowed with enough land to undertake small- and large-scale activities to strengthen household security, national development, transboundary cooperation and regional integration to transform trade, and create new opportunities for sustainable development which is sensitive to the environment and social and economic issues. There are, however, many threats and challenges which continue to undermine such progress, limiting its potential. These include pandemics such as HIV/AIDS, climate variability and change, extreme weather events such as drought and floods, ineffective land-use planning, land degradation and desertification, invasive alien species (IAS), limited or weak governance systems, corruption and greed, armed conflict and the attendant overexploitation of natural resources, and limited foreign direct investment (FDI). Limited domestic investment and wasted opportunities and loss of revenue due to leakage in sectors such as tourism are also important factors.

Pests

Locust invasions, 2004. More than ten countries were affected by the locust invastion in 2004-the worst since 1986-1989. (Source: FAO)

In addition to extreme weather events, such as drought and floods, pests pose a serious threat to food security. For example, in 2004, more than ten countries in Western and Northern Africa were invaded by swarms of locusts, destroying vegetation and crops.

Desert locusts periodically invade Northern Africa and the Sahel – the 1986-1989 plague cost more than US$300 million to control. In 2004, locusts started invading the Sahel from the end of June, with Mauritania, Mali, Senegal and Niger the worst affected. More than 2.5 million rural households were at risk of food shortages as over four million hectares (ha) of crops and farmland were invaded by the swarms. In Mauritania, about 1.6 million ha were invaded and an estimated 80 percent of crops were destroyed. The invasion also affected national economies. For example, Morocco spent about US$30 million in defense of an agricultural sector worth US$7,000 million in 2002, of which US$1,000 million were in export earnings.

Ironically, good rains, which would normally boost agricultural production, also provided ideal weather conditions for the locusts to multiply. The desert locust has been described as a pest of unusually destructive powers. A tonne of locusts – just a small part of an average swarm – eats the same amount of food in a day as 2,500 people. Each swarm is composed of millions of insects, sometimes covering several hectares. Adult locusts can fly over 200 km per day, easily crossing borders.

Invasive Alien Species

Invasive alien species (IAS) are a major factor in environmental change in Africa, contributing to or exacerbating human vulnerability and foreclosing some livelihood and development options. Invasive species impact on economic sectors such as agriculture, forestry, fisheries, tourism, water management and hydropower production.

The region is now home to hundreds of IAS – both plant and animal – but the magnitude of the problem varies from country to country, with some such as South Africa facing serious challenges to control different types of IAS. On Marion Island, for example, the numbers of the island’s only land bird – the lesser sheathbill – have dropped, and the introduced house mouse is suspected of out-competing the bird species for food.

Plant and animal invasive alien species cost millions of US dollars annually in terms of lost revenue and expenditure on control measures. The World Conservation Union (IUCN) estimates that worldwide the economic costs of invasive alien species are about US$400,000 million annually. If control measures can be used as an indicator of the magnitude of the problem, the proposals by the African Ministerial Conference on the Environment (AMCEN) to raise more than US$265 million to fund various projects in Africa over 3-5 years show that IAS are as significant an environmental issue in the region as land degradation, drought and biodiversity loss.

Further Reading

• Howard, G.W. and Matindi, S.W., 2003. Alien Invasive Species in Africa’s Wetlands – Some threats and solutions. IUCN – The World Conservation Union, Nairobi.
• Joubert, L., 2005. Sub-Antarctic Warming. Africa Geographic. February 2005, 64-69.
• NEPAD, 2003. Action Plan for the Environment Initiative. New Partnership for Africa’s Development, Midrand.
• UNEP, 2004. Invasive aliens threaten biodiversity and increase vulnerability in Africa. Call to Action. United Nations Environment Programme, Nairobi.
• UNEP, 2006. Africa Environment Outlook 2