SLU news

Push-pull instead of chemical control

Published: 20 November 2012

On 13 November, “Vetandets Värld”, a popular science programme at the Swedish Radio, focused on biological control in the form of push-pull cultivation. EPOK 's expert Ulf Nilsson explains more about the method.

Push-pull is a pest management strategy against damaging insects, first described in 1987. The idea is to utilize chemical properties of plants to protect the cultivated crop against insect pests. How insects perceive the world is largely based on chemical information. They use scent molecules from plants to find the right host plant.

Confusing and alluring scents
In push-pull systems, the crops, such as maize, are cultivated together with other plants whose chemical signals confuse insects so that they cannot find their way to the corn plant. The idea is to intercrop a plant together with the crop that is repulsive so that the insects do not want to fly into the crop (this is the push- plant). On the outer edges of fields are however plants cultivated that are attractive to the insects (this is the pull-plants).

Plants that fool harmful organisms to lay eggs
An effective pull-plant, is not only attractive, but can also stimulate the insects to lay eggs even though the larvae can not develop on the plant and are dying before it becomes fully developed. The most well-studied and practically utilized push-pull system is used in East Africa (mainly Kenya) to protect maize against a moth whose larvae does great damage on corn plants.