Location: Invasive Species and Pollinator Health
Project Number: 2030-22000-033-039-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Jun 15, 2025
End Date: Jun 15, 2026
Objective:
Identify factors affecting establishment and persistence of the vine mealybug parasitoid Anagyrus vladimiri to improve biological control efforts for vine mealybug
Approach:
ARS researchers will survey A. vladimiri populations across California grape growing regions. ARS will target key areas including the North Coast (Napa, Sonoma), Northern Interior (Lodi), East San Francisco Bay (Contra Costa), Central Coast (San Luis Obispo, Santa Barbara), and Central Interior (Fresno, Tulare). In areas where vine mealybug is persistent and widely distributed, ARS researchers will work with local extension professionals and growers to identify a minimum of 30 unique vineyard blocks to sample per region, representing diversity in geography, microclimate, and farming practices. In areas where vine mealybug is more narrowly distributed, ARS will sample fewer blocks, due to anticipated lack of availability. Likewise, other areas, such as the North Coast and Central Interior, may be represented by more than 30 sampled blocks, as the research team has a long history working with vine mealybug in those regions. For each study site, ARS will collect pertinent descriptive vineyard information from the management team, including planting date, cultivar, rootstock, vine mealybug pest status (year when pest was first detected at the site, severity of economic damage), and stacked management practices (insecticides, mating disruption, biological control, ant bait). ARS will collect relevant climatic and environmental variables, including seasonal precipitation, growing degree days, and elevation to characterize each site. Additionally, in Napa County, researchers will coordinate with staff in the Agricultural Commissioner’s office to obtain records of frequency and geographic distribution of parasitoid releases that are part of a program funded by the Wine Grape Pest and Disease Control District.
Due to the clumped distribution of mealybugs, and their prevalence in hidden locations under the bark (Geiger and Daane 2001), ARS will sample grapevine clusters rather than performing timed searches of individual vines. Targeting clusters will improve sampling efficiency and allow us to increase the number of samples that can be collected from each block. If vine mealybug has not colonized clusters at a site, ARS will substitute leaf samples, or those collected under the bark. Timing of sample collection will reflect seasonal phenology of the mealybug, which commonly colonizes clusters from veraison through harvest. In each block, researchers will haphazardly select vines for sampling, based on spatial information of vine mealybug distribution acquired from the vineyard management team. ARS will collect 50 total grapevine clusters per block, representative of the distribution of vine mealybug within the block. Whole clusters will be harvested, placed individually in plastic zipper bags, and transported to the USDA-ARS facility in Albany, where researchers will monitor parasitoid emergence. Sample date and geolocation of each sample will be collected in the vineyard, using Survey123.