Location: Crop Improvement and Protection Research
Project Number: 2038-22000-020-033-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Jun 10, 2026
End Date: Dec 31, 2028
Objective:
Objective 1 – Create cyclic bioactive peptides and identify those that have the greatest disruption of their target G Protein Coupled Receptors (GPCRs) in western flower thrips.
Objective 2 – Formulate the cyclic peptides with nanoparticles.
Objective 3 – Determine the efficacy of bioactive peptides in managing western flower thrips and diamondback moth.
Approach:
Objective 1: 5-10 previously identified peptides will be structurally modified (i.e., cyclized) to increase their stability and hydrophobic properties. Peptides will be tested for their binding potential against the CAPA receptors (CAPA-Rs) using previously established protocols. Each CAPA-R gene from western flower thrips and diamondback moth will be expressed in Sf9 insect cells to test the binding of the cyclic peptides in concentration-response experiments to measure EC50 values for each CAPA peptide to their CAPA-R. The top 1-2 cyclic peptides for each insect’s CAPA-Rs will be used for nanoparticle formulation in Objective 2.
Objective 2: Three nanoparticles will be used to formulate the top 1-2 cyclic peptides selected from Objective 1. To identify which nanoparticle provides the greatest feasibility andefficacy, each peptide mixture will be screened against western flower thrips using an in vitro feeding assay in a microcentrifuge tube. For each treatment, a single 2–4-day old WFT will be placed in a 1.7 mL microcentrifuge tube containing a 1 µL droplet of 10 nmol peptide in 1% sucrose solution. The droplet will be replenished as needed and mortality will be recorded for 14 days. A minimum of three replicates will be performed for all treatments.
Objective 3: The final selected cyclic peptide and nanoparticles will be topically applied to soybean cotyledons fed on by western flower thrips and broccoli leaf discs fed on by diamondback moth to evaluate the efficacy of the peptides. The nanoparticle-formulated peptides will be diluted to a
concentration of 200 nmol in 10 µL water and then applied to the plant tissue. For each treatment, ten 2–4-day old thrips and 2nd instar diamondback moth larvae will be tested in at least three replicates.