Location: Crop Diseases, Pests and Genetics Research
Project Number: 2034-22000-015-026-N
Project Type: Non-Funded Cooperative Agreement
Start Date: Oct 1, 2025
End Date: Sep 30, 2026
Objective:
Objective 1: Examine whether metabolites produced by Californian vineyard-isolated biological control fungi could limit sharpshooter and mealybug development, feeding, reproduction, or survival.
Objective 2: Separate metabolites to characterize and test for individual effects on limiting sharpshooter and mealybug development, feeding, reproduction, or survival.
Approach:
Objective 1: Previous collected and examined Californian Trichoderma strains (including isolates from T. asperellum, T. harzianum, and T. reesei) and entomopathogenic fungi (including isolates from the order Sordiales) have shown potential to reduce pathogen growth or directly colonize insects. Observations of media led to evidence that numerous metabolites are produced by these strains, and these could be utilized as biorational products to reduce insect populations. To test this, four Trichoderma and four entomopathogenic fungal strains will be grown in potato dextrose broth amended with sterilized, pulverized insects (a mixture or sharpshooter and mealybug cadavers) to induce production of potential insecticidal metabolites. After two weeks of growth, the broth will be filter-sterilized and collected for testing. The filtered, spent broth will be added at a 1:10 ratio in sterile water, which will then be used in cut-leaf bioassays. These cut-leaf bioassays will involve putting young grapevine leaves, cut at the petiole, into small test tube arenas where the water with the spent broth can be drawn up. Either sharpshooters or mealybugs will be then allowed to feed on the leaf. A mix of instars and adults will be used. The rate of instars developing, number of eggs developed in adult females, time spent feeding, and overall survival rate will be observed over six weeks. A total of ten replicates per insect (mealybug or sharpshooter) at each growth stage will be used. Sterile water alone will be used as a negative control, and a solution of imidacloprid as a positive control.
For Objective 2, the spent media, following sterilization, will be extracted in methanol or dichloromethane, and injected into a high-performance liquid chromatography for separation by a reverse-phase column and fraction collection to collect individual or groups of metabolites. These will then be tested individually using similar methodology in Objective 1. Mass spectrometry and nuclear magnetic resonance will be attempted to further describe and characterize these metabolites, if possible.