Author
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Martin, Phyllis |
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Schroder, Robert |
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Li, Betty |
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Submitted to: American Society for Microbiology
Publication Type: Abstract Only Publication Acceptance Date: 8/4/2001 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: We found elaterinide(cucurbitacin E-glycoside), a feeding stimulant for the corn rootworm pest complex in a bitter mutant of Hawkesbury watermelon. The juice of this melon can be combined with insecticidal compounds to kill adult corn rootworm beetles. The feeding stimulant can be applied at a rate of 1 gallon per acre, even though the active ingredient is only 0.05% of the total weight. For transportation and handling, the juice needs to be concentrated. Both spray drying and freeze drying, processes that would be amenable to scale up, led to an unacceptable, sticky, hygroscopic product with a high sugar content. The concentrations of glucose and fructose in the original juice were 2% and 4%, respectively. We sought to eliminate these sugars through fermentation. The juice ferments naturally, but slowly, upon storage at room temperature, and we are identifying the microbe(s) responsible for this process. One of the predominant yeasts isolated from this fermentation has been identified as Rhodotorula rubra. The sugar content of the juice was not reduced during a 7-day period when inoculated with this yeast. However, we were able to use commercially available Saccharomyces strains that reduced both sugars to below the level of detection within two days in 5 gallons. We concentrated the fermented juice to a powder by spray drying. These fermented products had the same level of elaterinide as the fresh juice, and had the same level of feeding stimulation for corn rootworm beetles in laboratory choice tests. In field tests, the activity against corn rootworm beetles was the same for fermented or fresh juice component. Fermentation appears to be an inexpensive first step in the concentration of this compound. |
