What's wrong with aphids? They feed on and stress leafy plants like tomatoes, spinach, and zucchini. Their feeding weakens the plants and makes it difficult for the plants to produce well all season long.
Last August we presented a blog post about the UVM Entomology Research Lab's on-farm investigation into whether “habitat plants” can sustain predatory insect populations to assist in keeping the aphid population low in our hoophouses. We planted habitat plants at intervals among the tomato plants in one of our heated hoophouses. Each type of habitat plant had a purpose of either providing food, shelter, or reproductive sites for beneficial predatory insects.
Read the full blog for fascinating detail about the types of pests and predatory insects we catalogued last year.
We establish habitat plants consisting of beans, alyssum, borage, marigolds and dill. Last year we found that borage, alyssum and dill attracted the highest diversity of insects, including pests. These pests in turn attracted beneficial insects which preyed on the pests and relied on the habitat plants to host a consistent food source for the season. Once in the hoophouse the predatory insects move throughout the plants, finding and preying on aphids throughout the hoophouse crops, thus helping to keep pests such as aphids at tolerable levels for the plants. Already this season Hannah has seen a good volume and diversity of predatory insects present to help control the aphids.
Juliette, our Greenhouse Manager, with a newly seeded "banker plant" before it was transplanted into hoophouse
In a second hoophouse we are trying another method of aphid control. We transplant a succession of “banker plants”, which are bunches of winter wheat grass purposefully "infected" with a type of aphid that is tasty to predatory insects but that does not feed on tomatoes or other vegetable crops (it feeds specifically on wheat grass and a few related plants). The purpose of the banker plant is to sustain the "good aphids" so they can be a consistent food source for predatory insects that feed on all types of aphids. This way when the bad aphids show up in the hoophouse to feed on the tomato leaves, there is an established predatory insect population that preys on and controls the aphids.
Why go through the trouble? We want to grow vigorous, healthy tomato plants and other crops in our hoophouses all season long without having to rely on chemical controls that can be unhealthy for us, for you, and for the many good insects and small animals that inhabit our farm. Plus it's simply amazing to learn about and watch all the different insects!
