Non-chemical Insecticides Aid Farmers | Germany| News and in-depth reporting from Berlin and beyond | DW | 26.09.2004
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Non-chemical Insecticides Aid Farmers

Locust plagues destroy crops and threaten the lives of people dependent on farming in the world's poorest regions. A new method of fighting the insect infestation promises relief without relying on chemical pesticides.


A flying plague for farmers in Africa

When black clouds of locusts descend on a field of ripe grain in Africa, there is no hope of harvesting even a single kernel. The insects consume everything in their path. Like a plague, they wipe out the crops and destroy the main source of income for poor subsistence farmers.

Up until now the only means of fighting the insect infestations has been through heavy douses of chemical pesticides. But this combatant is both costly and damaging to the environment, not to mention hazardous to humans working with the crops. That is why scientists at the geographical institute at the Technical University in Berlin have developed a safer and cheaper alternative using electricity.

Chemical free insect-killer

A team of German researchers working with Professor Frithjof Voss have devised an electrical grid powered by a portable generator run by a 12-volt battery to frighten off locusts and other enemy insects. The battery is constantly recharged through solar cells, making the device environmentally friendly.

At the heart of the grid is a four-meter long by half-a-meter high net which is dragged manually across the field. Vibrations created by the wire net frighten off the insects, and those which come too close are immediately shocked and killed. Compared to chemical pesticides, the technology is not only safe for the environment, but offers clear economic advantages, said Professor Hans-Jörg Ferenz from the department of zoology at the University of Halle.

"This apparatus works with the need for pesticides. All you need to kill insects is high voltage. This, in comparison to other methods, is cost efficient because there is only a one-time cost with the initial purchase of the equipment. The grid can be used by individual farmers who can install it across their fields whenever necessary."

Field tests successful

Heuschrecken in Nigeria

A farmer shows locusts that have descended on crops at Shinkafi, in the northern Nigerian state of Zamfara, in August.

Although the electric grid has primarily been tested in China, researchers believe that it is suited for use in developing countries in the sub-tropical and tropical regions as well. These are the regions most in need of technology to fight off grass hoppers and locusts which frequently destroy crops near harvest time.

"These regions are aware of the Voss Electrical Grid. It has already been suggested that the grid be used to kill insects before they reach the adult stage, before they develop wings and while they still move around on foot," said Ferenz.

Such an application could work well, the zoologist explained, because grasshoppers and locusts move around in groups close together. The grid would be able to eliminate a particularly large number of insects in a small area.

Developing effective killing methods

Currently, scientists in Halle are investigating the use of special insect attractants combined with the electric grid. Pheromone, for instance, could be applied to the center of the net to lure and kill specific species of insects. Such a double method would be especially effective in eliminating insects in the larva stage, before a wide-spread locust or grasshopper plague breaks out, said Ferenz.

The professor and other scientists concerned with insect infestations have stressed early detection as the key to eliminating and ultimately preventing wide-spread plagues. "Recognizing at an early stage where the swarms tend to develop and killing them before they begin to migrate is the best method," Ferenz said."Close monitoring of known breeding sites helps determine where a possible outbreak will emerge," he said.

Heuschreckenplage in Afghanistan

Afghan men use sheets of plastic, scarves and blankets in northern Afghanistan to sweep swarms of hopping locusts into trenches.

And all this can be done without the use of insecticides. A fungus, for example, can be introduced to attract insects to a certain location, or a farmer can apply growth inhibitors to slow down the development of insects and reduce the size of the population. There are also certain natural products that have a poisonous effect on the insects but do not harm the rest of the environment.

Limits to success

Despite its seeming success, there are limits to the German invention. The Voss electric grid does not work well in long grass or among trees. In order to be really effective, vegetation must be kept short, and the field should not be too big.

Of course, the grid itself is not enough to sufficiently combat and prevent giant insect infestations, such as those which frequently plague North Africa. Satellite photographs, detailed weather forecasts and local observations are crucial to fighting the pests.