Methyl Bromide Alternatives for Maize Grain Storage in Kenya

Among the maize pest complex that occur in both farms and bulk storage systems in Kenya, the weevil (Sitophilus zeamais Motsch. ), grain moth (Sitotroga cerealella Olivier) and the larger grain borer (Prostephanus truncatus Horn) are major primary pests compared to the red flour beetle (Tribolium casteneum Herbst) which is a secondary pest of stored produce. Of the methods used to control the above pests, chemical fumigants and grain dusts are the choice options. Methyl bromide, a broad spectrum fumigant will be phased-out in Kenya in 2015 in accordance with the 1985 Vienna Convention and 1987 Montreal's Protocol for article 5 (developing) countries. Apart from phosphine gas, no other alternative is available for use in bulk storage. Though carbon dioxide fumigation is feasible it requires longer exposure period of 15 days. While fumigation ensures 99.9% pest control, there is need to invest in new grain protectants and non-chemical alternatives to compliment phosphine use and to ensure it remains effective. . The available grain dusts address pest problems at small farmer level, but the way farmers use them is of concern. The prospect of insects developing resistance to phosphine and grain dusts is real and poses great danger to the grain storage sector. The strategies that can mitigate against pest resistance need to be identified and demonstrated to all stakeholders. Adoption of hermetic grain storage by smallholder farmers and grain traders would contribute to reduced use of phosphine and grain protectants thus provide untreated 'refuge' from selection as part of resistance management strategies. Kenya needs more capacity building to identify and evaluate new and credible alternatives.