How Farmers use Biological Pest Control

Backgrounder

Part I: Chickens control ticks In nature, small birds keep wild buffaloes free of pests by eating ticks and other insects that attack them. These small birds are natural predators of ticks. Veterinarians in Kenya use a method of tick control for cows that copies this behaviour. Here is the method, which you might want to try yourself.

Build a row of cow pens, each one being about three meters by four meters in size. Give each cow enough room to lie down in its own pen. Along the back side of the cow pens, build a runway or corridor for chickens, with small doors into each cow pen.

Take the cows to the pens every morning. Then release the chickens into the cow pens. The chickens will feed on the insects that live on the animals. The cows allow the chickens to look for ticks inside their ears and on their back. It is a good idea to give the chickens a 10 to 15 minute break by taking them out of the pen every now and then to help their digestion and maintain their appetite. One chicken can swallow two hundred ticks in three hours! Continue to give the chickens their regular diet. By the way, this method can also work for goats.

This is an example of biological pest control where the predator is a chicken, which controls the pesky ticks.

Part II: Virus controls cassava hornworm Farmers in Brazil are using a virus to save their cassava crops from the cassava hornworm (Erinnyis ello). They have been able to protect 60 to 100% of their cassava. Farmers use the virus in a homemade pesticide.

Here is how it works. Hornworm caterpillars are a major pest of cassava. When hornworms are attacked by a virus, called Baculovirus, they get sick and die. You will find the dead hornworms hanging from the cassava plants. To make the pesticide, choose hornworm larvae that are balloon shaped, burst easily, and release a white, smelly liquid. These are the larvae that have died most recently. Mash ten to twelve large larvae (7 9 centimetres long) or 22 medium size larvae (4 6 centimetres long) with enough water so that you can easily strain the solution through a clean cloth or fine filter. Mix this liquid with about 30 litres of water. Use this solution to spray one hectare of cassava. You may want to experiment with the quantity of water so you get just the right amount for your crop.

Spray the liquid directly on the cassava plants. This spreads the virus among the hornworms and kills them. The best time to spray is when each plant has 5 7 small larvae (2 centimetres long) on it. Check the plants for larvae at least once a week.

Because this homemade pesticide only attacks the hornworm, it does not harm the environment and does not disturb the friendly insects in your field.

Part III: Parasite combats the sugarcane top shoot borer The top shoot borer is an insect pest that eats sugarcane. It can eat 30% of a farmer’s crop. Chemical sprays have not been successful.

Some farmers control the top shoot borer by collecting and destroying its eggs. Unfortunately, this also destroys parasites which live inside the eggs of the borer. These parasites can be useful to the farmer.

The parasite is a small fly that lays its eggs inside the egg of the top shoot borer. The fly’s eggs develop into larvae inside the borer’s eggs. This kills the borer’s eggs before they can hatch. Adult flies emerge and look for more borer eggs to lay their eggs in.

Scientists have found a simple way to increase the population of the parasitic fly that kills the top shoot borer. First, collect pieces of bamboo that have two and a half internodes and three nodes. (The internode is one section of bamboo and the node is the solid point in between that joins the sections together.) The node at the top acts as a waterproof cap. Sharpen the other end of the bamboo to a point so it will stick in the ground. Cut a small, finger sized hole (3cm X 3cm) just below each of the two top nodes. Slightly above each of the two bottom nodes, drill a small hole just big enough to let water drain out.

Smear a sticky mixture of resin and castor oil around each hole. Then stick the bamboo stakes in the ground. Collect egg clusters of the top shoot borer from the sugarcane plants and push them through the bigger holes along with a small piece of leaf. You want the eggs to drop down to the bottom of each section of bamboo. Many of the eggs already infected by the fly will die. The ones that hatch and become larvae will try to get out but the sticky mixture around the holes will trap and kill them. Only the adult flies emerging from the infected eggs can fly straight out of the bigger holes, thanks to their small size, and fly into the crop field to find more egg clusters to parasitize. This small parasite can only fly a distance of about six meters. For this reason you need to have one bamboo stake placed every 6 and a half metres in the field.

You can start this when the top shoot borer activity is just beginning, and add fresh egg clusters to the bamboo stakes each week. This method helps to boost the numbers of parasitic flies in your field. It can reduce the numbers of top shoot borers by 20%. If the bamboo stakes are planted early in the season, more can be killed.

This is an example of biological pest control where a parasitic insect controls an insect pest.