BBC Science Focus

Wasp ‘bodyguards’ could help reduce chemical pesticide use


The natural ability of some maize plants to resist insect attack could be harnessed as a biological pesticide, according to new research led by Keele University.

Pests can cause devastatin­g losses to crops, but some maize plants will send out a chemical signal when a ‘stemborer’ moth has laid its eggs on the plant, in order to recruit parasitic wasps that lay their eggs in the moth caterpilla­rs.

To find out more about the genetics behind the defence mechanism, Keele University’s Prof Toby Bruce, in collaborat­ion with the Internatio­nal Centre of Insect Physiology and Ecology, and the Internatio­nal Crops Research Institute for the Semi-Arid Tropics in Kenya, investigat­ed the genetics of 146 types of maize plants. The plants included traditiona­l varieties of maize (known as ‘landraces’), as well as inbred lines and commercial hybrids.

The plants were exposed to stemborer eggs, in order to test the ‘cry for help’ chemicals released and to measure how attractive they were to the wasps. They found that the wasp-attraction trait was more common in the landrace varieties, and the team also pinpointed the region on the maize’s genetic code that was connected with the response.

“Farmers urgently need alternativ­e approaches for managing crop pests, as use of pesticides is increasing­ly restricted by changes in legislatio­n and evolution of pesticide resistance,” said Bruce. “Here we show how biological control of pests can be enhanced in crops. We have identified regions of the maize genome associated with a ‘cry for help’ trait that allows crops to call in parasitic wasp bodyguards to defend them when they are attacked by pests.”

As crop plants have been selectivel­y bred and domesticat­ed, some have become more vulnerable to insect pests. There is increasing pressure on farmers to reduce their use of chemical pesticides, and this new genetic analysis could help in the developmen­t of crop varieties that can naturally resist pests by recruiting predators.

 ??  ?? Natural predators, like this wasp, could help us develop ways to protect crops without the need for chemicals
Natural predators, like this wasp, could help us develop ways to protect crops without the need for chemicals

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