Tuesday, March 16, 2010


Researchers at IITA are intensifying efforts to find a sustainable and natural solution to control populations of the whitefly - Bemisia tabaci.

These tiny insects transmit the viruses that cause Cassava Mosaic Disease and Cassava Brown Streak Disease. Together these diseases are wreaking havoc with Africa’s cassava production, causing an estimated US$ 1 billion worth of damage annually.

In addition to transmitting viruses, whitefly also cause physical damage to the cassava plants. Studies conducted in Uganda showed that yield losses from whitefly damage alone can be as much as 50%.

IITA is investing in a two year project that will identify the most effective natural enemies of the whitefly so they can be deployed to reduce their populations. It will also explore cassava varieties, including wild relatives, with resistance to the pest. The project will be carried out in collaboration with the International Centre for Tropical Agriculture and the University of Tel Aviv in Israel and will target Nigeria, Cameroon, and Tanzania.

The whitefly has several parasitoid (parasitic wasps) enemies that develop within young whitefly larvae, eventually killing them. Although local parasitoids already take out up to half of all whitefly young, the new project aims to make this control even stronger by introducing exotic varieties.

Dr James Legg, an IITA entomologist who has been working on cassava diseases for over 10 years, said: “We have been studying the biological characteristics and genetics of this ‘super-abundant’ Bemisia whitefly and assessing its local natural enemies. With the new project, we will intensify our efforts to search for and test the effectiveness of these natural enemies as part of an integrated disease management strategy.”

In the past IITA has successfully implemented classical biocontrol programmes. With this new project it is hoped that by combining biocontrols in novel ways with host plant resistance greater strides can be made in tackling one of Africa’s most destructive pests.

Adult whitefly.

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