For further information contact: Anthony Bellotti

Visit the Web sites of the Tropical Whitefly IPM Project, and of the Cassava Improvement Project (in Spanish)

Colombian agricultural researchers have just released a cassava variety resistant to one species of whitefly—apparently the first variety of any food crop with resistance to this pest, which poses a global threat to many food and cash crops.

The new variety, which is resistant to the species Aleurotrachelus socialis Bondar, was released early this year as ‘Nataima-31’ by the Colombian Corporation for Agricultural Research (CORPOICA). It resulted from a cross between two cassava clones, one collected in Ecuador (MECU 72) and the other in Brazil (MBRA 12). The cross was made at the International Center for Tropical Agriculture (CIAT), based in Palmira, Colombia

‘Nataima-31’ will provide farmers with a valuable option, not only because it gives high yields (averaging 33 tons of fresh roots per hectare) but also because it does not need pesticides for whitefly control.  The variety is thus friendly to the environment and economical for farmers, unlike current commercial varieties, which require as many as six applications of highly toxic insecticides per cropping cycle.

‘Nataima-31’ also has low hydrocyanic acid content and good culinary qualities. In addition, it is less vulnerable to physiological deterioration (that is, it is not as perishable as other varieties) and can serve both as human food and for agroindustrial use.

The whitefly is a tiny insect with white wings that is associated with numerous food and cash crops. While this pest is mostly found on cassava, sweet potato, beans, tomato, pepper, potato, eggplant, squash, and melon, it also attacks some 50 other species of cultivated plants.

In the tropics 43 important species of whitefly have been reported. Some are both a pest and disease vector. That is, the insect not only feeds on the plant but also carries disease-causing viruses, which potentially can result in total crop loss.

Farmers, in desperation, intensify their use of insecticides. But the whitefly has a high capacity to either develop resistance to these chemicals or adapt to new host crops. Thus, production costs and risks to both the environment and human health increase significantly.

Hence, the development of ‘Nataima-31’ is an important advance for world agriculture. “We traveled a long road to get this cassava with resistance to a species of whitefly,” says Anthony Bellotti, leader of CIAT’s Integrated Pest and Disease Management Project.

The research that led to the new variety involved the evaluation of more than 5,000 cassava clones for whitefly resistance. It was a collaborative effort, begun in 1980 by CIAT and CORPOICA and supported by Colombia’s Ministry of Agriculture and New Zealand’s Ministry of Foreign Affairs and Trade. The work now forms part of a global effort, begun in 1997, when scientists throughout the world came together to combat whiteflies.

This initiative, known as the Tropical Whitefly IPM Project is part of the Integrated Pest Management Program of the Consultative Group on International Agricultural Research (CGIAR).

Coordinated by CIAT, the project involves experts from the national programs of 30 countries; advanced research laboratories in Australia, Germany, New Zealand, the UK, and USA; and five international agricultural research centers.