Unravelling landscape factors associated with outbreaks of thrips and thrips-transmitted viruses in lettuce in California

Lettuce is one of over 100 crops that are grown in the agriculturally rich region of the Salinas Valley of California. In recent years, the thrips-transmitted virus, Orthotospovirus impatiensnecromaculae, commonly known as Impatiens necrotic spot virus (INSV) has emerged as a primary concern for lettuce production in the region, resulting in hundreds of millions of dollars in losses. Both the vector, Frankliniella occidentalis, and virus have an extensive host range of plant species that are found in the region, which includes other crops and weeds. Understanding the driving factors that lead to thrips infestations and INSV outbreaks is crucial for improving existing management strategies. Here, we sought to identify landscape factors that may be associated with vector abundance and virus outbreak in lettuce crops and describe, 1) the development and application of molecular tools to detect vector populations that are associated with INSV, and 2) results from >60 field surveys conducted from 2023-2024 to understand the role of the landscape (adjacent crops, habitats, etc.) as drivers of thrips infestations and INSV incidence. Outcomes of the work and their implications for managing thrips and thrips-transmitted viruses will be discussed.