he main active chemical in neem oil called ‘azadirachtin’, (with it’s highest concentration in seeds) is very effective in increasing mortality, by disturbing metamorphosis, and in reducing general activity of locusts and grasshoppers. But neem oil can also be applied as a repellent. When neem oil is applied to crops and grassland, locusts will not eat on them as they develop a ‚dislike’ taste during evolution. Even under the extreme climatic situation of the Sahara, research has shown that the desert locust is repelled from feeding for up to 10 days after the crop has been treated with neem oil.
How to make neem insecticide
The seeds are the primary source of insecticide. Pick them off the tree when they are greenish/ yellow. During this stage they contain the highest concentration of azadirachtin). They can be used in the form of simple aqueous extracts or as a basic raw material for formulated pesticides. The leaves are also used as simple aqueous (water) extracts. After picking the seeds, dry them in airy conditions (in sacks or baskets) to avoid formation of mould. Remove the flesh from the seeds and wash away any remaining shreds. Grind 500 grams (g) of neem seed kernels in a mill or pound in a mortar. Mix the crushed neem seed with 10 litres of water.
It is necessary to use a lot of water because the active ingredients do not dissolve easily. Stir the mixture well. Leave to stand for at least 5 hours in a shady area. Spray the neem water directly onto crops using a sprayer or straw brush. Neem water can be stored and will remain effective for 3 to 6 days if it is kept in the dark. Kenya needs a sustainable solution to control the locusts and to protect crops and grassland hence the need to invest in research and trials for alternative control methods. Neem oil is one possible option and farmers should be supplied with neem oil products to protect their resources during locust invasion.
There are locally produced neem based biopesticides retailing in the market, which farmers who cannot access neem trees can buy for use in their farms. Examples include: Neemros® and Neemroc®.