Controlling pests without pesticides


Notes to broadcasters

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Farmers who use only chemicals for pest management run the risk of starting a cycle of new problems. For example, pesticides become less effective with time, as insects develop resistance. In addition, pesticides kill “good” insects. To avoid these problems, advise farmers to use alternatives to pesticides and to implement more than one practice at a time. Methods such as crop rotation, intercropping, and hand-picking insects, are all effective techniques in crop protection. If one method fails, others will keep working. The following spots highlight some of the problems of using chemical pesticides, and offer possible alternatives


Spot #1: Problems with pesticides

Many farmers will tell you that pesticides are their first choice for pest control. At first, pesticides appear to get the job done. There are fewer pests and higher crop yields. But after a while, you’ll notice that pesticides don’t only kill pests. They also kill many of the good insects – those friendly insects that help you by eating insect pests. Before you spend money on pesticides, be aware that pesticides kill beneficial insects too.

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Spot #2: Insects develop resistance to pesticides

Do you use chemicals to control pests? If you use only pesticides for pest management, here’s something to consider… Over time, pests can become resistant to pesticides. This means that the pests are no longer killed by the chemicals. What happens is that the chemicals kill the weakest insects. This leaves the strongest insects to breed a new and stronger generation of pests that are not affected by the pesticide. So the pesticides don’t work any more.

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Spot #3: Use a combination of pest control methods

Many farmers ask themselves how they can possibly protect their crops without pesticides. The best way to control pests is to use several methods at the same time. Rotating crops, fertilizing the soil, hand-picking insects, and intercropping are all good strategies for crop protection. And a combination of three or four of these methods is best. If one method fails for some reason, the other methods will still protect your crop.

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Spot #4: Learn about the life cycle and behaviour of crop pests

If you’re planning a pest control strategy for your next crop, start with learning about the pest. Learn as much as possible. Learn about its life cycle, where it lives, how it behaves, and when it does the most damage to your crop. Find out about its natural enemies, and the relationship between the pest and your crop. You can do this by watching the pest carefully in the field. You may be surprised to know that some insects have three different stages of development, while others have four stages. And some insects have mouths that suck and others have mouths that bite. An agricultural extension agent can help you learn more about the pests in your region.

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Spot #5: When should you control a pest?

Why is it so important to learn about the pests in your field or garden? If you know what a pest looks like at each stage of its development, you can decide when it’s easiest to control. Some pests are easier to control as eggs, some as larvae, and some once they become adults. You also need to know when exactly the insect feeds on the crop. Does it feed in the day or at night? In what season is it a problem? You don’t want to waste time or money trying to control a pest when it’s not even bothering the plant.

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Spot #6: Prevent insects from becoming pests

Good crop management is one of the best ways to reduce the pest population. For example, if you fertilize the soil well, the plants will get all the nutrients they need. If they get all the nutrients they need, they will stay healthy and suffer less damage from pests. Selecting good seeds is another way to make sure crops can resist pests. And rotating crops makes it difficult for pests to survive in the same location year after year. All these practices help prevent insects from becoming a problem in the first place.

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Spot #7: Diversify crops to reduce pest damage

If you plant many different crops and crop varieties together in your garden or field, insects will do less damage to your crops. If you plant a large area with one crop, it’s easy for pests to find the crop. But if you plant many different crops in small areas, or in rows beside other crops, it’s harder for the pests to find the crops they like to eat.

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Spot #8: Experiment with different pest management strategies

When you decide what combination of pest control methods to use, you can always experiment with a few different methods. Find out what combination works best. When you are choosing your methods, you need to be creative and consider the problems carefully. Remember! Insects are not just enemies that will destroy your crops. They are part of the natural environment. In a balanced environment, both insects and people have enough to eat. Using only chemical pesticides changes the balance in nature. But by using several different control methods at one time, you can find a way to work with nature, instead of against it.

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  • Contributed by Jennifer Pittet, researcher/writer, Thornbury, Canada.
  • Adapted from Developing Countries Farm Radio Network Package 28, number 3, What is integrated pest management?, and Package 38, number 10, Integrated pest management: radio spots.
  • Reviewed by Hélène Chiasson, PhD, Codena inc., Saint-Charles-sur-Richelieu, Québec, Canada.

Information sources

  • Interview with Hermogenes Castillo, P.Agr., Guatemala City, Guatemala, 1992.
  • Manejo integrado de plagas insectiles. Guatemala City: ALTERTEC, 1992.