Washington State University research is pursuing natural alternatives to pesticides for managing agricultural pests.

The research explores the option of attracting natural predators of pests to orchards by planting specific flower species.

Doctoral student Lessando Gontijo conducted experiments alongside WSU entomologist Betsy Beers and WSU biological control expert Bill Snyder for the research project.

Gontijo, who came from Brazil to study in Pullman, said he has been working on the project for the past four years.

The group has conducted multiple experiments. In one, they screened flowers and selected sweet alyssum as the species with the highest attraction for a fly species called syrphids. They also compared the behavior of woolly apple aphids in plots with and without the flowers and studied movement of the syrphids between the flowers and the canopy of the apple trees, Gontijo said.

“We wanted to make sure that the flies would not just visit the flowers and leave the orchard; we wanted them to visit the canopy where the aphids are,” he said.

Gontijo said the group used a technique called ELISA while conducting these experiments. In the technique the flowers are sprayed with egg whites and have traps to capture the flies in the tree canopy, he said.

Beers said researching pesticides is important for growers, communities and families for multiple reasons.

“Encouraging biological control of pests helps stabilize our artificial agro-ecosystems and allows growers to use pesticides only when necessary to prevent crop loss, which saves money,” Beers said. “Today’s pesticides are far safer for humans, but sometimes have a negative impact on natural enemies.”

Beers said she and Snyder have been working on the research project as an advisers to Gontijo. Limiting pesticides only to the amount necessary leads to a better environment for biological control, which in turn means fewer pesticides are needed, Beers said.

After several years of testing, the researchers developed recommendations for growers to control pests.