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The most infamous of the various types of whitefly is the "B" biotype of Bemisia tabaci, also known as the silverleaf whitefly, Bemisia argentifolii. This "super bug" was first identified in the Middle East, but introduced into Florida in the 1980s, and is spreading throughout Latin America. The UK's Department for International Development has funded several projects on whitefly-borne viruses of major food crops in Africa and India, mainly through the DFID Crop Protection Programme. Several of the current CPP projects, or their precursors, have had links with the Tropical Whitefly Integrated Pest Management Project and share similar characteristics: 1. Crops involved have a clear poverty focus. 2. Projects work with farmers developing controls appropriate to their circumstances. 3. Resistant varieties have a key role in control with the use of cultural measures such as mixtures and phytosanitation. 4. Key epidemiological information is sought on the whitefly vector and sources of the virus.
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Integrated est management
As a global pest, whiteflies affect a wide range of agricultural and horticultural crops including cotton, tobacco, beans, cassava, tomato and sweet potato. Its spread is causing immense damage and tackling the pest requires concerted international action. Elizabeth Warham of the UK's Department for International Development (DFID) reports how the war is being waged.
Whitefly on cassava leaves - they are responsible for transmitting diseases such as cassava mosaic virus.
The most infamous of the various types of whitefly is the 'B' biotype of Bemisia tabaci, also known as the silverleaf whitefly, Bemisia argentifolii. This `super bug' was first identified in the Middle East, but introduced into Florida, USA in the 1980s, and is spreading throughout Latin America.
In Africa, it has moved south into Sudan, and was recently identified for the first time in India where it attacks a wider range of crops, reproduces more rapidly, inflicts more damage, and is more resistant to insecticides than indigenous Indian biotypes.
Whilst the B biotype phenomenon has been widely publicised, other biotypes of B. tabaci are currently responsible for damage of similar if not greater magnitude in other cropping systems and locations.
Addressing the problem
DFID has funded several projects on whitefly-borne viruses of major food crops in Africa and India, mainly through the DFID Crop Protection Programme (CPP). DFID also supports the Tropical Whitefly Integrated Pest Management Project under the umbrella of the Systemwide Programme of Integrated Pest Management (SP-IPM) of the Consultative Group for International Agricultural Research (CGIAR).
The Project is co-ordinated by the International Centre of Tropical Agriculture (CIAT), in Colombia, working with four other international agricultural research centres: the International Institute for Tropical Agriculture; Centro Internacional de la Papa, Peru; Asian Vegetable Research and Development Centre (AVDRC), Taiwan; and the International Centre for Insect Physiology and Ecology, Kenya. This international work is carried on through six sub-projects in Asia, Africa and Latin America.
Several of the current CPP projects, or their precursors, have had links with the Tropical Whitefly Integrated Pest Management Project and share similar characteristics:
crops involved have a clear poverty focus;
projects work with farmers developing controls appropriate to their circumstances;
resistant varieties have a key role in control with the use of cultural measures such as mixtures and phytosanitation; and
key epidemiological information is sought on the whitefly vector and sources of the virus.
New multi-donor collaborative project DFID recently approved funds for a project managed by CIAT as part of the Tropical Whitefly Integrated Pest Management Project which is supported by a multi-donor consortium of DFID, the Australian Centre for International Agricultural Research, Danish International Development Assistance, the United States Agency for International Development, and the New Zealand Ministry of Foreign Affairs and Trade.
The DFID-funded project focuses on whitefly-borne viruses of major food crops in Africa and Latin America, and is specifically linked to and complementary to the DFID-funded CPP whitefly project, with collaborators from the Natural Resources Institute (UK), Tel Aviv University (Israel), the University of Arizona and the Danforth Centre (USA) as well as the national programme partners in Uganda, Tanzania, El Salvador, Mexico, Colombia and Ecuador.
Components of Research
This five year project seeks to develop various management programmes for the devastating whitefly-borne virus diseases of cassava, sweet potato, beans and vegetables, which if not contained will threaten food security and create an obstacle to improved livelihoods for small farmers in Africa, Latin America and Asia. Specifically this project is expected to contribute to crisis mitigation of the Cassava Mosaic Disease (CMD) pandemic in Tanzania, with post-crisis management and stabilization of cassava in Uganda.
Further, the Project will develop integrated pest management (IPM) packages, for whitefly pests and whitefly-transmitted diseases, which will be highly effective, safe, affordable and easy to deliver to poor farmers in the Tropics. The main components will be: strengthening the Tropical Whitefly Integrated Pest Management Project Network; characterizing target hot spots; basic research on whitefly pest and disease dynamics; validating IPM components; and developing training materials.
Potential policy outcomes
In East Africa, it is anticipated that guidelines will be developed on the best ways in which to combine host plant resistance, phytosanitation and natural enemy based approaches to controlling whitefly transmitted viruses of cassava and sweet potato. By working through governmental research partners, it is anticipated that guidelines developed will inform national policy on IPM implementation.
In Latin America, the new project is expected to develop policy recommendations on the impact of insecticide subsidies, the establishment of well-defined cropping dates and crop rotation systems in target areas, and the movement of vegetable seedlings across national borders. These recommendations would be distributed at the government level with the Ministries of Agriculture (El Salvador and Mexico) and with the producers associations in the hope of influencing both policy and practice.
The potential of whiteflies to inflict crop damage, with catastrophic consequences for poor communities, cannot be underestimated. The challenge for this unique publicly funded international research partnership is to find imaginative solutions to control this pervasive pest and prevent it spreading further.
Copyright Research Information Ltd. Sep 2002