Natural enemies are often released in large numbers (inundative releases) in the hopes that they will take the insect pests by storm. With inoculative releases, only a few natural enemies are released early in the season with the hope that they will reproduce and spread out on their own in search of the insect pests. As part of ongoing investigations into the ability of Trichogramma ostriniae to control European corn borer (ECB), Mike Hoffman of Cornell University tried early-season inoculative releases to see how well this technique would work.
At each of four farms in central New York, about 200,000 T. ostriniae females were put into six half-pint cartons fitted with screening for protection from predators, and the cartons were attached to corn plants. This method is simpler and less expensive than weekly inundative releases, making it more likely to be one that growers will adopt.
The wasps were still parasitizing ECB egg masses up to 80 days after their release, indicating successful establishment and reproduction in the fields. The wasps moved around quite well. They were observed traveling over distances of at least 300 feet within and between corn fields, and it is believed they will travel further where conditions make it worth their while.
This method has considerable promise in not only sweet corn in New York, but in other crops in other areas as well. However, additional trials are needed to determine the optimal times and densities for wasp releases.
New York State Integrated Pest Management Program Annual Report, 1998
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