Farmers who grow beans (Phaseolus vulgaris L.) know the damage the larvae of the common bean weevil (Acanthoscelides obtectus) can do. The larvae can quickly reduce a bag of beans to nothing. But the problem is easy to solve according to Dr. Martha Quentin from Michigan State University. Just turn the bags of beans upside down twice a day. Or, if the beans are not in a bag, somehow move the beans twice a day.
Dr. Quentin discovered that bean weevil larvae have to wedge themselves up against one bean surface so that they can get enough leverage to bore into another bean. After that, it takes the larvae about 24 hours to actually get into a bean.
So, if the beans are moved around twice a day, then the larvae are disturbed and have to position themselves all over again. If that happens enough times, the larvae can never bore into a bean and they eventually die from hunger. There is also the chance that they might get squashed as the beans are moved around. Dr. Quentin found that over 96 per cent of the larvae were killed by moving the bag of beans twice a day.
Common lamb’s-quarters (Chenopodium album) is a plant that grows wild in many regions of Latin America. Farmers in San Francisco la Paz de Santa Maria Chimalapa in southern Mexico use the leaves of this plant to control weevils in stored beans.
The farmers cut the leaves and dry them in the sun. Then they grind the leaves to a powder with a hand mill. They mix the beans with the powder until the beans are completely covered with powder, and store them in sacks. It is not necessary to remove the powder even if using the beans for cooking. In fact, many people say that the flavor is better with the lamb’s-quarters leaves in the cooking pot.
To control weevils in stored corn, the farmers mix the grain with whole dry leaves of the common lamb’s-quarters plant. Then they cover each sack of grain in storage with 2 centimetres of the leaves.
The traditional crops of Zambia which used to help farmers get through hungry times are gradually disappearing because farmers prefer to grow export crops. But these traditional crops are still valuable. They can be grown using locally available resources and they provide a balanced diet.
The Adaptive Research Planning Team (ARPT) at the Misamfu Regional Research Station in Kasama, Zambia, is collecting some of these traditional crops. They plan to:
1) make a permanent collection of all crop varieties grown in their province.
2) identify local crop varieties that are tolerant to acid soil conditions.
3) identify plant characteristics which make some crops tolerant to acid conditions.
4) observe variations in maturity periods, pest and disease resistance, drought tolerance and seed characteristics.
5) make a source of germplasm available for breeding purposes.
The main crops being collected are millet, sorghum, rice, cassava, sweet potatoes, groundnuts, beans, cowpeas, and pigeon peas. The researchers hope to encourage local people to reconsider the importance and value of these traditional food crops.
‘From the United States’:
- Department of Entomology,Michigan State University, East Lansing, Michigan 48824, U.S.A.
- Adapted from “The Farming World” Transcript No. 1689, British Broadcasting Corporation, Bush House, The Strand, P.O. Box 76, London, U.K.
- Interview with Isaac Matus, Maderas del Pueblo del Sureste, Justo Sierro No. 407, Matias Romero, Mexico.
- “Indigenous crops”, pages 56 and 57 of Sustainable agriculture (1990, 60 pages), Report of the Workshop on Sustainable Agriculture held from March 25-April 5, 1990, at the Musa Farm Institute, Kasama, Zambia. Available from Youth Promoter, Mbala Diocese, P.O. Box 450014, Mpika, Zambia.
- Further information available from: Adaptive Research Planning Team, Misamfu Regional Research Station, Box 410055 Kasama, Zambia.