UT Research Increasing Organic Options to Control Cucumber Beetles

KNOXVILLE, Tennessee – Organic crop producers may have another tool to add to the toolbox of options to manage cucumber beetles in cucurbits.

Mary Rogers, University of Tennessee organic research associate with Extension’s Organic and Sustainable Crop Production Lab, has received an $8,154 Southern Sustainable Agriculture Research and Education (SARE) Graduate Student Grant to explore the effects of naturally occurring fungi on spotted and striped cucumber beetles.

“Cucumber beetles are significant pests of cucurbits like pumpkins and melons because they have multiple generations and can build up over time,” said Rogers. “In addition they are vectors for bacterial wilt, which can kill the vines. Organic growers are limited in what they can use for cucumber beetle management and need alternatives.”

In the two-year study, Rogers is applying biopesticides made from naturally occurring microorganisms to determine how well they control cucumber beetle. Research has shown that three fungi species (Beauveria bassiana, Metarhizium anisopliae and Isaria fumosorosea) may be effective in killing the pests.

“The fungal spores land on the insect’s cuticle, germinate, enter the beetle and digest the insect from the inside,” said Rogers.

In preliminary laboratory settings, Rogers has found some positive results from Isaria fumosorosea, with 20 percent to 25 percent of the beetles sprayed with the biopesticide showing mycosis.

“I’m measuring how much of the plant leaves the beetles eat as a standard for infection,” said Rogers. “Symptoms are not visible immediately, but infected beetles will act sick, become sluggish and slow down their feeding.”

Later this summer, Rogers plans to take her study to the field and compare the biopesticide control to carbaryl applications (a conventional standard) and row covers (a cultural control method).

“A good Integrated Pest Management plan is sustainable and focuses on a variety of tactics using cultural, physical and biological controls,” said Rogers.

For now, organic growers are limited to such management options as row covers, clay-based crop protectants, and trap cropping. And each has its own challenges, said Rogers.

Cucurbits under row covers require pollination, which adds to the management costs. Non-toxic clay-based products, while effective as a barrier against insect feeding, need to be reapplied after a rain. Trap cropping requires its own specific management techniques to make sure that the varieties attract the pest and lure them away from the cash crop. In addition, beetles need to be managed in the trap crops.

“I’m hoping that these biopesticides can be just one more tool to a grower’s IPM toolbox,” said Rogers.

More about the study (GS10-095), “Efficacy of Entomopathogenic Fungi in an Integrated Pest Management Plan for Cucumber Beetles in Melons and Pumpkins,” can be found on SARE’s national project database.

Graduate Student Grants, one of Southern SARE’s seven grant opportunities, are for Master’s and PhD students leading sustainable ag efforts throughout the Southern region. Calls for Proposals for the 2011 Graduate Student Grants program is now open. Application deadline is June 1, 2011.

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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.