Location: Crop Improvement and Protection Research
Project Number: 2038-22000-020-027-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Apr 1, 2025
End Date: Mar 31, 2026
Objective:
Objective 1: Advance the development of new thrips traps.
Objective 2: Characterize Impatiens necrotic spot orthotospovirus (INSV) infections in weedy species.
Objective 3: Conduct thrips surveys in lettuce crops.
Approach:
Objective 1: To selectively improve the capture rate of thrips using newly developed traps, several chemical attractant lures will be combined to test the performance. Traps with different chemical lure treatments will be randomized and deployed at the Spence Research Farm at USDA-ARS in Salinas, CA with 50 feet of separation between them. Every 2-3 days, collection vials containing thrips and other captured insects will be retrieved and the process will be repeated for up to 2 weeks. Two replicates (6 traps total) will be conducted in parallel and repeated a total of four times. The placement of the chemical lure treatments will be re-randomized for each replicate. The capture efficiency of the different chemical lure treatments will be assessed by counting the number thrips and bycatch for each treatment.
Objective 2: Several key weed species have been previously identified as reservoirs for INSV. Weed species will be propagated at the USDA-ARS in Salinas, CA and western flower thrips reared in a colony will be used to setup INSV transmission assays. For each plant species, a single plant will be exposed to 10 viruliferous adult western flower thrips (5 male + 5 female) and allowed to feed for a 5 day inoculation access period (IAP). Thrips will be killed off and the plants will be placed in a thrips-proof cage inside a greenhouse for 3 weeks. A minimum of three plants for each species will be inoculated, along with an equal number of uninoculated plants. Lettuce will also be included as positive controls. At 7, 14, and 21 days, plants will be recorded for any symptoms of INSV infection. At the end of the experiment, leaf tissue and root tissue will be collected and tested for INSV using DAS-ELISA. A summary of disease symptoms (if present) and infection type (systemic or local) will be summarized and presented.
Objective 3: To gain a better understanding of the major thrips species that are associated with lettuce, surveys will be conducted in commercial lettuce fields in six locations on the Central Coast, including in San Benito County (Hollister/San Juan Bautista), Santa Cruz County (Watsonville), and Monterey County (Castroville, Salinas/Chualar, Gonzales/Soledad, Greenfield/King City). At each location, three fields will be selected, and 5 lettuce plants will be collected per field. Sampling will be conducted once in the Spring, Summer, and Fall to account for differences in thrips species present in the crops. Lettuce plants will be collectively washed to recover thrips from each field and season and stored in ethanol. Thrips will be initially sorted at the genus level using a stereoscope and depending on the composition that is present within a sample, up to 10 thrips will be slide mounted for species identification at the USDA-ARS. A summary of the thrips species composition across seasons and region will be summarized and presented.