Abstract:
Purpose of review: This review focuses on the current state of the use of botanical pesticides by resource-poor farmers in Africa and Asia for protection of durable stored produce against pest infestation, with the view of identifying critical challenges and information gaps that need further research. Findings: The use of plant materials may be a safe, cost-effective method of grain preservation against pest infestation among lowresource poor farmers who store small amounts of grains. There is a dearth of information on the use of plant materials by rural farmers in Asia and Africa for stored product protection and several plants being used in different countries are yet to be identified. The most promising candidate plant materials for future use as grain protectants are Azadirachta, Acorus, Chenopodium, Eucalyptus, Mentha, Ocimum, Piper and Tetradenia, together with vegetable oils from various sources. Neem is the only traditional plant from which several commercial products have been developed worldwide, especially in India. Several secondary compounds are responsible for the insecticidal action of botanicals. Active research is ongoing in several countries to determine the efficacy and use of locally available plants for controlling insect pests. However, the bulk of the trials are laboratory-based and of short duration. Little or no information is available on how farmers actually apply botanicals to protect their stored produce against pest infestation. It should be possible to use the existing farmer knowledge about botanical pesticides as a framework to develop more cost-effective and sustainable storage-pest control strategies for small-scale farmers in sub-Saharan Africa. Directions for future research: For the use of botanicals for stored product protection to be validated, further information is required on: the exact application procedures and formulations used by farmers; their residual effects against key pests over a longer duration; toxicity of the materials to non-target organisms; and local availability of appropriate extraction and application techniques. A major research priority is a well designed on-farm trial to validate the efficacy of botanicals for stored product protection using standard procedures and formulations that can be transferred to other communities. Donor agencies and entrepreneurs must support and give priority to research projects and initiatives that pursue optimal methods of using plant protectants on durable products at the farm level with the focus on the development of the most cost-effective procedures for application, as well as identifying the active components, safety standards and the development of commercial products at a reasonable cost. © 2007 Stewart Postharvest Solutions (UK) Ltd.