Julie:
The following may help your students -
http://www.usaid.gov/regions/afr/succes ... alawi.html
Flossie Paliani in Kanyimbo Village is another smallholder farmer who has adopted new land management practices. "Until recently, I had a chronic problem of soil erosion and could not afford chemical fertilizer, so crop yields were low," she explained. "I never thought I could change the situation." With assistance from government extension agents partnered with USAID/Malawi, she made several changes. She learned to reduce erosion and runoff by planting vetiver hedgerows and realigning planting ridges on the contour. She planted Tephrosia with maize to restore soil fertility and now gets bumper crops. She also gets firewood from Tephrosia and uses extracts from pounded leaves soaked in water as an insecticide in her vegetable garden. Around her homestead, she has planted other trees for shade, firewood and aesthetics.
Cassava self-help
It works! An extract made from cassava flour can be used to kill off the white cassava cochineal Aonidomytilus albus, according to experiments at the Lake Alaotra station of FOFIFA, the Agricultural Research Centre of Madagascar. The technique comes from Brazil, and could bring considerable benefits to Malagasy farmers. Cassava is principally a staple food grown for local consumption, and the cost of pesticides is prohibitive for these farmers.
-Charlotte Razafindrakato, FOFIFA
Based on what I found so far I would suggest making a water extract of cassava leaves. Four parts cassava leaves (by weight) and one part water. You may need to add more water. Grind in a mortar and pessel or use a wooden bowl and a stick to pound to leaf/water mix into a paste. Please do this outside with the wind blowing away from the workers. Filter trough cheese cloth or course weave cloth.
To test the insecticidal properties use the following protocol - Apply the extract with a dropper on a cotton ball in a plastic bottle and place one or more of the test insects in the bottle and close the bottle with cloth and a rubber band. If the insects die you will then need to make dilutions of the concentrated extract (1 drop extract + 9 drops water, 2 drops extract + 8 drops water, 5 drops extract + 5 drops water) to determine an effective dose. Always use water as the control to test the extract and dilution against. Make sure the wind blows away from the workers.
Matt Mulanax, Ph.D.
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julie