BLOOMINGTON, Ill.— Growing high tunnel crops presents a unique set of problems including defense against insect pressure. The latest research on introducing natural biological enemies proven to help control high tunnel crop pests will be revealed by a University of Illinois entomologist and an Extension educator at 6 p.m. on Thursday, June 23 at the Dixon Springs Agricultural Center in Simpson. 

The two-year research project was conducted to help Illinois growers protect their investment, according to Kacie Athey, specialty crops entomologist. During the trial, insect predators were released into high tunnels with tomatoes, peppers and other crops to gauge their effectiveness in reducing common pest populations of spider mites, aphids and other insects capable of debilitating specialty crop yields and quality. 

Raghela Scavuzzo, associate director of food systems for the Illinois Farm Bureau and executive director of the Illinois Specialty Growers Association, who is not associated with the field day presentation, encouraged members who utilize high tunnel growing systems to follow the recommendations of the researchers. 

“This research will identify what specific types of insects are useful to reduce pests in high tunnels,” Scavuzzo said. “We’ve always talked about what types of insects to utilize for pollination and protection, and you see companies that bring insects into greenhouses such as bees that can help with pollination inside greenhouses and hydroponic equipment. This continued research is very important for us to understand what kinds of animals and insects can really help increase production.”

Along with Blonwyn Aly, U of I Extension educator, Athey conducted research that could extend the benefits of high tunnel gardening, which include a longer growing season, increased crop diversity, higher yields and improved quality. “Anyone interested in learning more about biological control options and high tunnel vegetable production is welcome to join us and capitalize on this on-farm learning and networking opportunity,” said Aly.

Spider mites are among the most problematic insect predators affecting high tunnel production of tomatoes and peppers, according to Scavuzzo. 

“The researchers will talk about various ways to control them. The catch is that a lot of insecticides cannot be used inside high tunnels, and so they will come with some really great information on the best practices for that,” she said. “Aly previewed their research during the 2022 Illinois Specialty Crops Conference, but I am looking forward to a much more in depth presentation on this.”

According to the researchers, using common pesticides to control insects in high tunnels can be counterproductive. Because not many insecticides are labeled for use within high tunnels and some insecticides can remove natural predators, pest outbreaks are more likely.

The researchers hope their work can help strike a population balance between insects categorized as pests and their natural enemies, minimizing damage from the insect pests. The answer may be biological control, or intentionally introducing natural predators to control insect pests and reduce crop damage, according to Aly and Athey.

A 2017 study by Purdue University entomologists identified weaknesses in pest protection in high tunnel production of tomatoes and other specialty crops. Purdue professor of entomology Ricky Foster tested the theory that the enclosed nature of high tunnels kept insects from getting into the structure and causing severe damage to plants inside. “Our data clearly show that is not true,” said Foster, who published the study results in the journal Pest Management Science.

Foster’s research team tested plants from three different plant families and the pests that are most often associated with those crops. These crops and pests were tomatoes and hornworms, broccoli and the cabbage looper, imported cabbageworm and diamondback moth, and cucumber and the cucumber beetle. The two-year study found increased presence of the pests in high tunnels when compared with adjacent open field plots.

Also in 2017, Purdue postgraduate researcher Laura Ingwell tested the benefits of adding flowers to the rows of produce under high tunnels. Ingwell reported increases in beneficial natural enemies when zinnia and gomphrena were introduced into tomato and cucumber production systems.

There is no cost to attend the Dixon Springs (354 State Highway 145 N; Simpson) field day. Pre register at go.illinois.edu/BiologicalControl or call (618) 695-2441. For more information, contact Bronwyn Aly at (618) 695-2441 or baly@illinois.edu.