The push and pull of greenhouse pest control

The idea is to breed crops that are more attractive to pests, grow them in a specific area and spray mostly there

LONDON, Ont. — An Agriculture Canada researcher is taking what might be described as a “sucker punch” approach to greenhouse pest control.

First draw target insect pests to desired areas within your greenhouse, and then knock them down.

The research involves developing transgenic crop plants, including tomatoes, which can either be more attractive to insect pests or less attractive with changes in the volatile gaseous chemical compounds they emit.

“We actually found the insects were spending more time on the transgenic tomatoes, feeding and reproducing. What we soon realized (was) that we had more of a pull effect then a push,” Ian Scott said.

“Our idea is to place these plants into a greenhouse setting so there could be a general movement of insects toward these plants and away from the main crop.”

Scott said the strategy could reduce pesticide use by targeting specific sections of a greenhouse where insects congregate.

The technology might also be used with other biological controls, such as essential oils and farmer-friendly predatory insects that feed on pests.

There is still interest in plant chemicals that repel insects, but Scott said his team has had more success with attractant volatiles, for which marigolds are well known.

Additional transgenic lines are being tested to see if this “pull effect” can be increased.

Researchers are also evaluating placement strategies.

“I believe a 10-to-one ratio of regular plants to trap plants would be a viable option. Otherwise, the trap plants would take up too much space,” Scott said.

“We hope in about year we can have small scale trials here in our greenhouse at the London Research and Development Centre.”

Researchers are collecting and evaluating volatile plant gases by placing plants inside glass domes where the gases are collected.

Using their findings, synthetic compounds could be developed that might be used as a spray.

Beneficial impacts in the greenhouse will also be examined.

Scott feels neither the pull or push effect will discourage predatory insects that are attracted to other insects. Insect pollinators on which greenhouse operators rely are more likely to be affected.

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