|To help keep thrips at bay, Hoffman Nursery turned to North Carolina State University to study the minute pirate bug (Orius insidiosus). Orius is a natural predator of thrips, and the nursery tried to attract and keep Orius with ‘Black Pearl’ ornamental pepper banker plants. Banker plants support the survival and the reproduction of predators.
Hoffman Nursery grows ornamental and native grass liners under cover and outdoors. Wendy Trueblood, a growing supervisor at the nursery, began researching the use of beneficial insects to reduce the need for chemical sprays.
“I had a hard time finding information on how to sustain the beneficial populations, especially in our environment of open greenhouses,” Trueblood said. “And we were having difficulties with biological controls being effective.”
She asked Steven Frank from North Carolina State’s entomology department for help.
His graduate student, Sarah Wong, set up experiments at the nursery. Wong set up three treatments in 12 greenhouses: control houses with no pesticide, no Orius and no banker plants; augmentation with no insecticide, release of O. insidiosus and no banker plants); and banker plants with no insecticide, release of O. insidiosus and banker plants. Each release of Orius consisted of one 500-count bottle. Each banker plant house had 24 ‘Black Pearl’ plants.
Orius feed on the pollen of ‘Black Pearl’ plants, keeping the predators around greenhouses and nurseries, even if pests aren’t present, Wong said. But growers must pick the peppers to get them to flower, which may present a labor and time issue.
“The pepper plants were a bit difficult for us to manage since it’s not something we produce, plus the labor involved of harvesting the peppers,” Trueblood said.
One issue with Orius is they like to disperse quickly, which created a problem at Hoffman’s open greenhouses.
“We did see Orius doing their job against thrips, but they were free to escape and other predators could get in such as spiders and eat the Orius,” Wong said.
There wasn’t a significant difference between the augmentation treatments and the banker plant treatments. But this summer Wong is experimenting with Orius and ‘Black Pearl’ in a closed environment to find out how to best use the two in tandem.
“We want Hoffman and other growers using this treatment to get the most bang for their buck in the banker plant houses,” Wong said. “We’re trying to understand how ‘Black Pearl’ pepper pollen benefits Orius so it eats more thrips.”
However, Orius are native and great against small-bodied arthropods, Wong said.
“They’re really good beneficial insects to have around. They hang out in flowers and benefit from pollen in their diet,” Wong said. “So the more flowers in and around the greenhouses and fields the better.”
The timing of releases of Orius is crucial.
“Don’t release them at noon when it’s 120°F in the greenhouse,” Wong said. “Release them in morning and when you’ll have a low level of disturbance.”
It’s also important to understand Orius are an early-season predator and work best as a preventive measure for thrips, Wong said.
“Growers need to have realistic expectations with open greenhouses, because both predators and pests will come and go,” Wong said.
For more: Wendy Trueblood, firstname.lastname@example.org. Sarah Wong, email@example.com.