n minneapolis — Bachman’s, a century-old floral and garden center here, is testing a new pest-control technique — using bugs to control other bugs. In an effort to eliminate its reliance on chemical pesticides, Bachman’s began using beneficial insects on two of its floral crops at its growing range in Lakeville, MN.
“We expanded the use of beneficials in our crop of poinsettias and our mum crop as well,” company chief executive officer Dale Bachman told The Produce News. “It’s working well. The predatory mites are going after spider mites and thrips, the parasitic wasps are going after white fly, and the nematodes are going after thrips in the soil and they are good against fungus gnat larva when they are in the soil. They have to be in a confined greenhouse to be effective.”
Tiny cards containing wasp larvae were distributed amongst the poinsettias, and were replaced weekly for many months, instead of spraying the plants with insecticides.
“As they evolve, the parasitic wasps come out and are very difficult to see, very small,” Bachman said in a news release. “They move into the crop and then they consume the pests that we’re trying to control.”
On the fall mum crop, microscopic spiders were used and growers sprayed a coating of the insects on the plants every week.
“I think after a year, I think we’ve seen a lot of progress,” said Bachman’s grower Louis Rutten in a news release. “The resistance with pests toward chemicals is getting higher and higher, so we saw at one point we were losing the battle.”
If you’re wondering if the insects will still be on the plants and will make it into your business or your consumers’ homes, Bachman says you don’t have to be concerned about that.
“The beneficials that we use in the program are very short lived. That’s why we have to keep replacing those cards and allowing them to emerge when we are trying to protect the crop from pests,” Bachman told The Produce News. “They are very specialized feeders, and as their food source decreases, so does the population of the beneficials.
“As we continue with the program and there’s less food for them, then they naturally go away. We can also anticipate when we will be shipping and we can trail off the use of beneficials as we approach the shipping point,” Bachman said.
The use of beneficial insects and mites instead of pesticides began in Europe in the 1960s, but it is a relatively new practice in the United States.
“Our resource for the beneficials is based in Wisconsin,” said Bachman. “Even though they come from Koppert Biological Systems in Europe. And the organisms themselves are very nearly microscopic and indiscernible to the naked eye — you wouldn’t recognize them.”
Bachman estimates that growers reduced chemical usage by more than 90 percent in the two test floral crops. If the beneficial insects continue to be effective and do not negatively affect the plants they are being used on, the company plans to use the technique with more crops in the future.