The research has been running since February 2011 at Childs Farm in Cooling, Kent, where grower David Long grows 61ha of pears at a site where pear sucker had become a major problem.
The trial's coordinator, Farm Advisory Services Team fruit consultant Chris Levett, allowed the sucker's main predator, the flower bug Anthocoris nemoralis, and other predators - earwigs, hoverfly and lacewing larvae - to multiply enormously.
"We didn't mow until the end of October so the place looked a terrible mess," he said. "There were masses of nettles along the tree rows and windbreaks, but it was environmental heaven for predators.
"By mid June, we found they had built up to a level that was giving substantial control of the pest despite continued egg laying and by July, instead of having to fight off adult sucker, we were in danger of being eaten alive by anthocorids."
Levett added that insecticide treatments for the pest were largely counterproductive, with the exception of Envidor (spirodiclofen). This was applied on the trial site in mid May.