A look at new options for biocontrol

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Suzanne Wainwright-Evans

by Sonja Heyck-Merlin

Suzanne Wainwright-Evans is a horticultural entomologist and owner of Buglady Consulting. She specializes in using biological controls as part of an IPM program. In a webinar sponsored by UConn Extension, UConn IPM and USDA, Wainwright-Evans discussed new biocontrol products and practices for greenhouse ornamentals.

One new product is called BioBee BioSF, produced by the German company E-nema and distributed in the U.S. by BioBee. This product uses Steinernema feltiae nematodes to control western flower thrips, onion thrips and fungus gnats. This formulation is designed for pre-incorporation into the media.

What makes this nematode formulation unique is its slow-release over a period of 42 days. According to Wainwright-Evans, they are capsules that look and feel like wet, tapioca pearls. The nematodes are located inside a liquid core at the center of the capsule with a soft hydrogel on the outside. She said, “When you incorporate these into your media, they slowly release nematodes over time. Instead of just getting a shot of nematodes up front, you get a consistent slow release, and can have better control over time.”

Another benefit of these nematodes is that they’re compatible with most pesticides. Growers also don’t have to worry about thrips and fungus gnats developing resistance, so they can be used repeatedly through the growing season. Wainwright-Evans also thinks there is retail potential to market these nematodes at garden centers. “For example, people with houseplants can dibble a hole into their growing medium and drop some of these capsules in,” she said.

However, Wainwright-Evans has questions about how long they will remain viable in the soil. “I think there’s a lot of variables involved, the main one being temperature. I think trials need to be done in the United States at different soil temperatures and using different media to see how long they will last. I have concerns in the southern states where it gets really hot if these are going to be able to continue to release 42 days later in the soil.”

Another new BioBee product is called BioPersi+. This product contains Phytoseiulus persimilis, a control for spider mites. According to Wainwright-Evans, P. persimilis is traditionally reared on two-spotted spider mites, but the new product rears the P. persimilis on dust mite eggs.

“What’s interesting is that when the P. persimilis feeds on the dust mite eggs, they’re not red like the ones reared on the two-spotted spider mites,” she said. “When they are released and start to feed on two-spots, they get a reddish color. I think it will be interesting to see if growers can use this as a kind of scouting tool. If you release these white P. persimilis and then you start finding red ones, it means they found the two-spots in your crop.”

This product not only provides adult P. persimilis but also eggs, juveniles and food for them to eat during shipping. Because the product contains food, Wainwright-Evans has observed that the P. persimilis in this new product is not as aggressive when released. She recommended that if a two-spotted spider mite problem exists already, growers should opt for the traditionally reared P. persimilis. If it’s being used as a preventative, however, the new product may be advantageous because the younger population will help provide a longer control period.

The third product Wainwright-Evans discussed was a banker plant system, using fava beans, from IPM Labs. This system is used to control larger sized aphids, such as potato and foxglove aphids, and works well for controlling these pests in most spring bedding plants and mums. It utilizes the parasitic wasp Aphidius ervi to control these aphids.

Banker plants contain a population of reproducing natural enemies on it. Banker plants attract a species of insect similar to the pest that needs controlling, which is called an alternate host. These alternate hosts feed only on the banker plants. Natural enemies are then introduced, and they feed on the alternate hosts. If the pests come, this insect population will move from the banker plants and attack the pest on the crop.

Growers first need to raise the fava bean plants, purchase some pea aphids (Acyrthosiphon pisum) and release them onto the fava beans. Once the aphid population is established, the grower releases A. ervi, which begin to parasitize the aphids. The tiny wasp lays its eggs in the pea aphid as well as any potato and foxglove aphids. “You will need to continually plant more fava beans because the pea aphids will overtake your banker plants,” Wainwright-Evans said.

Wainwright-Evans also talked about Tricholine, a newer product from Bioline AgroSciences. This product contains different ages of Trichogramma sp., which are parasitoids for some species of caterpillar eggs. The Trichogramma sp. arrive on a stiff release card, containing different ages of Trichogramma sp. for a longer release period. “Caterpillars aren’t typically a major issue in indoor production,” she said, “but with more resistance happening with bt sprays, it’s another option to be aware of.”

Finally, Wainwright-Evans cautioned growers about the use of biocontrols that are not registered with the EPA. She shared a story of a grower who purchased what they believed to be Metarhizium fungi, used to control many species of insects. Wainwright-Evans had the product tested at a laboratory, and the product contained significant levels of other fungal, bacterial and yeast contamination. The Metarhizium spore viability was less than 25%.

“Please stick with the EPA registered products. These products are researched and tested,” Wainwright-Evans concluded.

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