Friends and Enemies of Aphids

In this program, two hard-working farmers discuss a problem they share aphids. As we follow their conversation, we discover that Farmer 1 seems to have no easy solution to the aphid problem while for Farmer 2 aphids are a problem of the past and he tries to pass on some tips to his friend. The conversation takes place at the farm of Farmer 1.

My, my! You’ve a fantastic crop this year.

Uh, you’ve got to see the other side of the field before you say that. Let’s go over and see. I’m going to show you how big this insect problem is.

What is the secret?

None at all. In fact, I am devastated. These things are multiplying very fast. I don’t know whether I’ll have any crop left by harvest time. I don’t even know the name of these small devils!

Aha! I know the chaps! These are aphids. Naughty, tiny things!

Say that again?

Aphids…A P H I D S.

Uhmm…

Yes, they are as tiny as a seed and sometimes even smaller.

Right, I’ve seen that they feed on young shoots or stalks of plants, and on this side of the field look they have invaded the underside of the tender young leaves.

That’s right. They feed by sucking the juice from the tender parts of your plants. This makes the plants weak and less productive. Ants are friends to aphids. Ants like to eat the honey dew that aphids release from their back ends and so ants protect aphids and their eggs. Naturally, aphids have many enemies as well.

How do I control the multiplication of the aphids?

How you work your field counts. For example, aphids like to eat plants that have been given too much nitrogen,so be careful when you fertilize. Don’t use too much nitrogen fertilizer. It’s better to use composted manure or other organic fertilizers that have a good balance of nutrients. Also, aphids prefer to attack plants that are under stress, for example, during extended dry periods.

You said that aphids have many natural enemies. What are these? Why don’t they kill the aphids in my field?

It could be that you don’t have enough different kinds of plants growing on your land to attract these natural enemies. If you have a good mix of plants, then you will attract friendly insects, birds, and spiders which eat aphids and other insects. For example, you can attract these helpers by planting trees, shrubs, and flowers around your fields. These plants provide food and shelter for friendly insects and birds.

Examples of insect friends that will eat aphids are lacewings (Chrysopa spp.) and ladybug beetles (Hippodamia convergens). They will eat lots of aphids and other insects too. In fact, many farmers around the world are making a real effort to encourage these insects to stay near their farms.

So it is not wise to clear the bushes surrounding the field then?

No. With the trees and shrubs you can also encourage parasitic wasps to stay near your farm. These wasps are tiny, about the same size as the aphids. They lay their eggs in the bodies of aphids. The baby wasps eat the insides of the aphids, which kills most of them. When the tiny wasps come out of the bodies of the dead aphids, they lay their eggs in some more aphids. Since these wasps eat the nectar of flowers you must try growing different flowering plants around or in your field to help these tiny helpers control pests.

On their way back to the homestead the farmers continue their discussion about aphids. Farmer 2 talks about plants with strong smells which repel aphids and other insect pests. He says by interplanting with plants such as garlic, mint, chives, marigold, chili peppers, neem, false indigo and others you may be able to discourage the aphids from infecting your crops.

Many of these plants can also be used to make effective pesticides. Some farmers have found that neem spray works against aphids. Other farmers use garlic spray.

Ooh, yes?

Sure, just by observing which plants the insect pests avoid, you can discover all sorts of new natural pesticides.

Are there no other means of killing these insect pests…such as traps?

Oh, sure! Many aphids are also attracted to yellow surfaces, perhaps because this is the colour of a weak plant. So one way to trap the aphids is to use bright yellow boards, cloth or anything else.

And how do they get trapped?

You cover the yellow material with something sticky, for example a glue mixture or oil. You can make the glue mixture by dissolving a quarter pound of glue in 1 gallon of warm water overnight. You can also use a yellow bowl with a little soapy water. Put the trap near the infected plants and watch the aphids get trapped.

That sounds interesting indeed! I must thank you very much for your time and advice. I shall certainly use some of the methods you’ve given me today.

Yes, there are many ways to control aphids. Some of them might work better for you than others. Here are the important rules to remember when controlling aphids. Encourage natural enemies by growing many different crops and by keeping trees, shrubs, and flowers growing around the fields. Apply organic manures instead of nitrogen fertilizers. Experiment with different sprays and repellent crops.

The important thing is that you try different techniques, so that you can find the best ones for you. The best part is that some of these techniques will control other pests besides aphids. So, in the end, you will discover an integrated pest management program which will help control all your pests. And this strategy will be something that you can pass on to your children and grandchildren and so on.

Goodbye!

Goodbye, and once again, thank you very much.