Aphid Biological Control in Greenhouses with a Novel Banker Plant System

View the project final report

Commodities

• Additional Plants: ornamentals

Practices

• Crop Production: greenhouses, nurseries
• Pest Management: biological control

Banker plants provide resources for arthropod natural enemies when target pests are scarce, enabling in-greenhouse reproduction of the natural enemies for continuous production and reducing or eliminating the costs of otherwise-required weekly natural enemy shipments. There are banker plant systems for small aphid pest species and for large aphid pest species. But they are not compatible and cannot be used in the same greenhouse simultaneously because they both use aphid species that only infest barley as the host plant. This common host plant allows the aphid species from one system to eventually displace the aphid species of the other system. This project will evaluate the use of a novel banker plant system, using pea aphids (a large aphid) on potted fava bean plants as hosts for the parasitoid Aphidius ervi. Because this novel system uses fava bean rather than barley, it would be compatible with the other barley-based banker plant system for small aphids. Experiments will be done in research greenhouses to determine optimal timing and production of the fava beans, the pea aphids, and the parasitoids. The resulting banker plant system will be evaluated in a commercial greenhouse during Spring ornamental crop production. Thus, this new banker plant system should make it possible for both A. colemani and A. ervi to co-exist, reproduce, and provide successful cost-effective biocontrol of nearly all greenhouse aphid pests. If successful, a fact sheet for growers will be prepared and used in grower presentations that will outline the details of the system.

This project seeks to develop and test a cost-effective, relatively simple system for in-greenhouse production of a parasitoid species, Aphidius ervi, that attacks larger pest aphids such as foxglove or potato aphid, using non-pest pea aphids on fava bean plants.  The project will combine research to develop the system with a commercial trial to test the system. Three research objectives will be done. The first will determine the best growth stage of fava bean plant to infest with pea aphids to balance maximum aphid production with minimal plant decline. The second will check that Aphidius colemani parasitoids, commonly used for small aphid biocontrol, do not outcompete A. ervi on the fava bean banker plants with pea aphids. The third will evaluate the pattern of parasitoid production, both in numbers and over time, when aphid-infested fava beans are exposed to the parasitoids at various growth stages. Using research results, we will trial the system in a commercial greenhouse on Spring crops. A fact sheet about the system will be prepared for growers. The successful system will give growers a way to simultaneously produce two parasitoid species, one for large aphids and another for small aphids, providing complete biocontrol of aphids.