The Use of Banker Plants in Integrated Pest Management
What is a banker plant? – A banker plant is a plant that has a population of reproducing natural enemies on it. These are plants that are different to the crop we are growing, and they attract a species of insect similar to the pest we want to control, which is called an alternate host. These alternate hosts will not feed on our crop, just the banker plants. Natural enemies are then introduced and they feed on these alternate hosts. If the pest come, the thriving natural enemy insect population will move from the banker plants and attack the pest on our crop. In the picture, greenhouse tomatoes growing, alongside papaya banker plants. This is done to produce natural enemies which control whitefly.
Banker plants are interspersed throughout the crop to establish a resident populations of natural enemies that will attack the crop pests if they should happen to try infesting the crop. In this picture, an army of ladybeetles devour aphids. The approach is considered an environmentally friendly alternative because it reduces insecticide use and offers growers a low-cost, self-perpetuating alternative
This is a schematic view of natural enemies moving between the crop and the banker plant. This is the aim of the system: the natural enemies (blue triangles) will move from the banker plant (light green) in search of food. If the crop (dark green) is infested with the pest (red squares) for which the system was designed (spidermites or whiteflies), they will be attached and killed.
Example of Banker plants 1 –Aphids – barley banker plant that produce parasites to manage aphids. Rhopalosiphum padi (Bird-cherry aphids) on winter barley (Hordeum vulgare L.) Schizaphis graminum on winter wheat or Rhopalosiphum maidis (Corn leaf aphid) on sorghum. All of these aphids can serve as prey for various predators and parasitoids that attack melon and green peach aphids.
Example of Banker plants 2 – Encarsia sophia populations grow on papaya banker plants. They attack and reproduce on the Papaya whitefly. They will move to another crop to control the whitefly pest (Bemisia tabaci). See the first picture of this blog to see the system.
Examples of Banker Plants 3: Ornamental Pepper have been used to establish Amblyseius swirskii for biological control of multiple pests in greenhouse vegetable production.
The use of banker plants has been successful among foliage growers. Research shows a lot of potential for greenhouse vegetable production as well. In the picture, Technician Katherine Houben (from the University of Florida) looks for beneficial insects on a papaya banker plant
How to start? Introduce the alternate host – You can’t just put the predator in and hope for the best. You need a food source for it—an alternative prey—and you need to be sure that the alternative prey doesn’t become a pest itself. In the picture, barley seed being planted (left) and at 1 week after planting (right). The plants must be covered with hairnet at all times to protect the alternate host population.
After there is a good population of the alternate host, you introduce the natural enemy species that will feed on them and also your target pest. In the picture, a parasitic wasp using aphid as host.
Does this work at the field level? A good example of a banker plant is the Crape Myrtle, a common landscape plant. At the Suwannee Valley Agricultural Extension Center in Live Oak, FL, they have planted Crape Myrtle in dry corner of pivot and other surrounding areas of the farm. The alternate host specie is the Crape Myrtle aphid. Populations of ladybeetles grow here and can help managing crop pests.