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Scientists control water hyacinth with weevils

Weevils are environmentally friendly and more economical than other control methods (G. Goergen/IITA)
Weevils are environmentally friendly and more economical than other control methods
G. Goergen/IITA

Weevils have been introduced by scientists into the Mono River, in Benin, to limit the spread of water hyacinth, the invasive plant now found in waterways across Africa. "These weevils feed only on water hyacinth and proved to be effective biocontrol agents of the water weed when used in the Oueme River eight years ago," says Obinna Ajuonu, a scientist with the International Institute of Tropical Agriculture (IITA), "So we are confident this approach will yield results."

Floating freely, mats of water hyacinth double in size every four to seven days, obstructing electricity generation, irrigation, navigation and fishing. The weed also increases diseases such as bilharzia and water loss resulting from evapotranspiration. In Sudan, it has been estimated that more than 400 hectares could be irrigated with the annual water loss from evapotranspiration (from water hyacinth) over 300 square kilometres of the Nile.

Mass-produced by the Department of Agriculture in Porto-Novo, the weevils - Neochetina eichhorniae and N. bruchi - were bred using a start-up colony supplied by IITA, which also provided technical assistance. Although it may take some years for the impact to be seen, Ajounu explains that the weevils are environmentally friendly and more economical than other control methods.

Written by: Oluyinka Alawode

Date published: October 2010

 

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