Live Thrips Traps: Using Inexpensive Marigolds to Draw Thrips Away from Greenhouse Crops
IPM Laboratories, Inc. collaborated with one New York farmer, one Niagara County Cooperative Extension agent, two professional scouts, and one Environmental consulting firm to evaluate marigolds as a Guardian Plant for thrips in sweet pepper fields and snapbeans as Guardian plants for eggplant fields. The 2011 season data has been collected and is now being analyzed. During the 2011 season, inspections of the experimental field and other nearby fields were also organized informally by local growers and a pesticide representative to see the predators in action. The project cooperators will be sharing the project results at grower meetings, including a Western NY Vegetable Growers Meeting in Lockport in late February and the Mid-Atlantic Fruit and Vegetable Conference in Hershey in February. Our project, when completed, will be the first outdoor documentation of Guardian Plants that pull pests out of crops and support natural enemy reproduction in vegetables fields.
In 2010, the Zittel farm in Eden, New York, experienced extremely high numbers of thrips and significant damage on pepper plants that had been transplanted from the greenhouse to the field despite 5 insecticide treatments. Beneficial insects are extremely successful at controlling thrips in greenhouse peppers because pepper flowers support continuous reproduction of the thrips predator, Orius insidiosus. In 2011, we proposed to test adding marigold Guardian Plants to pepper fields to pull thrips from the peppers and to support Orius reproduction until the peppers begin to flower and support Orius reproduction on their own.
In another area of the farm, imidicloprid pesticide used in June to control Colorado potato beetle on eggplants devastates the spider mite predator population, resulting in spider mite outbreaks that bronze the fields and require 2 summer sprays. In 2010, snapbeans were planted in the pesticide-free tractor lanes as trap plants for spider mites and reproduction sites for predatory mites. The predator mites spread at least four rows into the eggplants and suppressed the spider mites to a level similar to miticides in the rest of the field. In 2011, we proposed to repeat this planting scheme for a second year, under more controlled conditions, to document the success and usefulness of this IPM method.
Weekly scouting of pests and predators was planned to track the establishment and production of the released natural enemies (the single most important indicator of the predator’s continued ability to perform in the field). The in depth scouting was also designed to provide information on how far the predators will spread into the field from the Guardian Plants, so that we could plan how far apart to space the Guardian Plants in the field during future efficacy tests.
Success in the pepper/marigold Guardian Plant System would be demonstrated by the following:
• There will be evidence of Orius establishment and reproduction as indicated by the presence of Orius nymphs in the marigold beat samples.
• The marigolds will draw thrips away from the pepper plants, resulting in few thrips on the peppers and obvious thrips on the marigolds.
• The Orius will keep the thrips numbers from exploding on the marigolds.
• As the peppers begin to flower, the Orius will transfer over to the pepper plants and reproduce on them as well.
• Thrips numbers will subside with the expanding natural enemy population.
Success in the eggplant/snapbean Guardian Plant System would be demonstrated if the following questions can be answered by the weekly scouting data:
• Will the predators establish on the bean release rows as evidenced by increasing numbers over the season? And, if so, how far will the predators spread from the bean release row?
• If there are no beans, will the predators establish on the eggplant rows onto which they were released? And, if so, how far do they spread from the release rows?
• What are the spider mite and predator levels on the bean rows, the eggplants in rows adjacent to the release sites, eggplants 2 rows away, and 4 rows away?
• What are the spider mite and predator levels on the eggplants that had predators released onto them directly and control eggplants that received no predators?