NCSU Study of Parasitic Wasp Could Help Control Common Pest of Vegetable Crops

RALEIGH, North Carolina – Figuring out where a tiny parasitic wasp lives and eats could prove beneficial for growers trying to control a common pest of vegetable crops.

North Carolina State University graduate student Sriyanka Lahiri, with the assistance of NCSU entomologist and professor David Orr, has received a $9,735 Southern Sustainable Agriculture Research & Education Graduate Student Grant to study the habitat and nutritional requirements of Telenomus podisi – a wasp the size of a grain of pepper that is parasitic to the brown stink bug (Euschistus servus), a common pest of a host of crops from cotton to tomatoes to grapes.

“If we can understand the key factors that affect the life history of these wasps -- where they live, where they overwinter, what their nutritional requirements are – we can implement landscape conservation practices that support their habitat and provide a food source,” said Orr. “Very little, if any research literature exists, that tells us anything about these fascinating organisms.”

The Scelionidae family of parasitic wasps is largely an open book, but what little researchers do know about the insects leaves them awestruck.

“They are really incredible creatures,” said Orr. “They can live for nearly a year in a lab setting which makes them easy to study, and they have the capacity to overwinter as adults.”

The tiny parasitic wasp Telenomus podisi is being studied as a potential biological control of the brown stink bug, a pest of vegetable crops. Here in the lab researchers introduce the wasp to a stink bug egg mass. Photo courtesy of NCSU entomology

The wasp attacks the brown stink bug by targeting its eggs. The female wasp injects venom into the stink bug eggs killing them, then lays her own eggs inside the stink bug eggs. The larvae hatch out and feed on the egg remains, pupate inside the eggs, then emerge to start the process over again.

“The wasps will go through as many generations as their hosts,” said Orr. “Wherever you find the pests, you’ll find the wasps. They are very common in the landscape.”

The NCSU work is targeting field edges and tree lines where the brown stink bug has been found attacking crops over the summer in the hopes of identifying overwintering spots of the parasitic wasp.

“Are they in the furrows of tree bark? Can they be found in younger trees or older trees? Or maybe they are hiding inside vacant cocoons and old egg cases of other insects,” said Orr. “We basically want to know what non-crop hosts and structures support parasitic wasp habitats.”

In addition, the researchers are exploring the importance of amino acids in the wasp’s diet, and what overwintering food sources are available to them that provide those nutrients.

“Amino acids aid in rebuilding egg stores come spring, so if we can identify food sources or provide food sources to the parasitic wasps that give them the nutrients they need, we are extending their life span and helping the female generate more eggs, having a greater impact on brown stink bug populations,” said Orr.

Learn more about the project, “Potential for Conservation Biological Control of Stink Bugs in North Carolina,” by visiting the national SARE projects database and search by project number GS11-104.

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Published by the Southern Region of the Sustainable Agriculture Research and Education (SARE) program. Funded by the USDA National Institute of Food and Agriculture (NIFA), Southern SARE operates under cooperative agreements with the University of Georgia, Fort Valley State University, and the Kerr Center for Sustainable Agriculture to offer competitive grants to advance sustainable agriculture in America's Southern region.