Without pausing to wipe the sweat from their brows, workers in northern Ivory Coast picked cotton by the handful - a crop saved by the use of extra insecticides after a new pest wreaked record damage across West and Central Africa last season. The crisis highlighted the region's vulnerability to invasive species and a reliance on chemical solutions that research shows will not in the long term protect a crop that supports millions and is a prized foreign currency earner for cash-strapped governm