Script 72.7

Notes to broadcasters

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Farmers worldwide experience significant crop losses from damage to stored grains by the bruchid beetle. Sometimes over half of the stored cowpeas are damaged. The following program looks at a few control methods to protect stored pulses, especially cowpeas, from beetle/bruchid damage. You may wish to air script number 1 in this package, “Is an insect always a pest?” together with this program, to give farmers a sense of how much time and income they will save by protecting their grain from pests.


Today’s program is about how you can protect stored pulses or grain legumes from damage by bruchid beetles.

Bruchids love beans – especially cowpeas. They usually attack pods in the field before harvest. The larvae develop in the stored seeds, which they eat. Bruchid beetles can destroy your food supply and damage the seed for the next crop

What can you do about these beetle pests? You are about to hear the stories of two women farmers who found ways to protect their stored grain without using chemical pesticides.


Aisha farms a small plot of land to support her three children. Her husband died a few years ago and she depends on her crop of cowpeas and a small vegetable garden to feed her family.

Each season, almost all of Aisha’s cowpea crop was damaged by bruchids and a lot of it was ruined. As I said, she depended on those cowpeas to feed her family. She knew she had to do something.

Aisha remembered how her parents used wood ash to protect stored cowpeas from beetles. So she decided to try it for herself. And it worked.

This is how Aisha protects her stored crop.

For a few months before the harvest, she collects wood ash from the cooking fire in a large bowl. She sieves the ash to take out any big lumps of charcoal.

After the harvest, she mixes wood ash and cowpea in a bowl. She pours one cup of wood ash and one cup of cowpea into the bowl and sifts them together. She keeps mixing the wood ash and cowpea this way until the bowl is full. Then she pours the mixture into a large clay jar and presses down firmly.

When the jar is full, she covers the top with a thin layer of ash – about half the length of your middle finger.

Each time Aisha removes some cowpeas she adds a fresh layer of ash to the top of the clay jar. She always washes her cowpeas thoroughly before cooking.

Aisha’s stored cowpeas are now free of weevil damage.


You’ve just heard how Aisha, a woman farmer, protects her cowpea from beetle damage. But of course each farmer has her own method. Now let’s hear how Dafina keeps beetles out of her stored grain.

Dafina grows cowpeas and soybeans and sells most of her grain at the market.

Like Aisha, Dafina was losing a lot of her stored cowpea because of damage from bruchid beetles. She decided to sell most of her crop soon after harvest… so the beetles wouldn’t have time to do so much damage. But prices are lower at that time of year. And Dafina was losing money.

Dafina talked to other farmers and learned that high temperatures kill beetles and their eggs, larvae and pupae. They told her that she could heat the grains to high temperatures in a simple solar heater. Dafina made the heater herself using a grass mat, a jute or hessian sack, plastic sheeting and some stones. She bought the plastic sheets at the village market.

This is how Dafina heats her cowpeas to kill the beetles.

On the first sunny day after threshing, Dafina lays a sack on top of a grass mat. She pours a thin layer of cowpeas – no more than two to three deep – onto the sack. Then she puts a sheet of clear plastic on top. She tucks the clear plastic under the sack, and uses small stones to hold the edges in place.

Dafina leaves the seeds like this for at least two hours in the middle of the day. The grain gets so hot that the bruchid beetles are killed. Then she removes the cowpeas and stores them in sacks.

Dafina does this every day until she has treated all of her crop.

For extra protection, Dafina and her son turn the sacks upside down each morning and evening for the first few weeks. This helps to kill any beetles that are in the sacks.


There are many ways to protect your stored grains from bruchid beetle damage without using pesticides. Today we’ve heard about mixing wood ash with your grain and drying grains in a homemade solar heater. There are other methods too. Talk to other farmers. Experiment with techniques and ideas. Find a method of protecting your grain that works for you


  • Contributed by Belinda Bruce, researcher/writer, Vancouver, Canada.
  • Reviewed by Peter Golob, Post-Harvest Consultant, and Dr. Georges Ntoukam, Grain Legumes Entomologist, IRAD Cameroon/Montana State University.

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