Growers may be able to combat whiteflies and other greenhouse pests by using "banker" plants that act as storehouses of predatory insects.
Cindy McKenzie, an entomologist with the Agricultural Research Service in Fort Pierce, Fla., has conducted extensive studies showing how papaya, corn and ornamental peppers can serve as banker plants for insect parasitoids and predators, according to a news release.
Banker plants act as a kind of homebase for predators.
They eat what they find on the banker plants, then disperse to seek out pests on greenhouse crops.
Before they leave the banker plants, most of the predators will lay eggs on them, providing another generation of pest control.
But using banker plants is an art.
You need to select not only the right insect predator, but also the alternative prey that will keep them alive but won't damage the crop.
The plants and predators also can't be a source of disease.
McKenzie worked with Lance Osborne, a University of Florida entomologist at the Mid-Florida Research and Education Center in Apopka, and post-doctoral researcher Yingfang Xiao.
They chose papaya as a banker plant and the minute Encarsia sophia wasp as the predator.
Encarsia larvae feed on silverleaf whiteflies.
The system is now being tested in commercial greenhouses.
The researchers also have shown that corn can serve as a banker plant for gall midge that controls two-spotted spider mites.
In addition, they're looking at whether ornamental peppers can bank the predatory Amblyseius swirskii mite, which controls whiteflies and thrips.
Results are promising, and the technique is catching on among growers.