Project Overview

Reports

Commodities

Target Pests

Practices

Grass seed production is an essential component of Wyoming agriculture, supporting both forage and seed markets across the region. However, producers face growing challenges from variable weather, limited pest management tools, and stringent seed quality standards. In recent years, thrips have become a major concern, feeding on seed heads and reducing seed yield and viability. Producers in the Bighorn Basin have reported extensive “silver top” symptoms floret whitening, sterility, and seed scarring consistent with thrips injury (Dreves et al., 2021; Schell and White, 2024). While Anaphothrips obscurus (Müller) (Thysanoptera: Thripidae) is recognized as the dominant species, field observations suggest other thrips species, including Chirothrips sp. and Rhipidothrips sp., may also contribute to damage (Kamm, 1972; Rao et al., 2010; PD and co-PD observation). Despite growers in the Bighorn Basin reporting symptoms consistent with thrips injury, no systematic effort has been made to identify the complete species complex or to develop management strategies suitable for Wyoming’s unique grass seed systems. Current management relies on broad-spectrum insecticides, which provide only short-term control and increase the risk of resistance and secondary pest outbreaks (e.g., mites). Given their rapid reproduction, sustainable management of thrips will require integrated approaches beyond chemical control.

This Project Initiation proposal will generate proof-of-concept data to advance an IPM framework for thrips in Wyoming’s perennial grass seed systems. The effort combines field monitoring, biological control evaluation, and targeted Extension effort to establish the foundation for a future multi-state IPM program. Year-round monitoring in grass seed production areas will document the composition and seasonal patterns of the thrips species complex. Greenhouse trials will test the effectiveness of entomopathogenic fungi; Beauveria bassiana and Metarhizium anisopliae as sustainable biological control options. Findings from these studies will inform grower-specific recommendations and help reduce reliance on broad-spectrum insecticides. Extension activities of this proposal will include the development and distribution of fact sheets, leaflets, and real-time pest alerts, along with field day demonstrations and a Western IPM webinar to share results and best practices.

The project will deliver short-term outcomes such as species identification, preliminary biocontrol data, and improved stakeholder awareness. Over time, the adoption of microbial control and monitoring practices will promote reduced pesticide use and enhanced thrips management. In the long-term, this project seeks to build regionally coordinated IPM strategies across major grass seed growing states such as O, ID, and WA, where thrips pose significant risks to seed certification and export value. By addressing an urgent and under-researched pest problem through a sustainable, knowledge-based framework, this project directly supports Western IPM Center priorities for reducing pesticide risks and advancing biological control in pest management innovation.

Objective 1: Conduct year-round monitoring and identification of thrips species complex in grass seed production systems of WY.

Understanding the diversity and phenology of thrips species is critical for developing targeted and effective management strategies. Limited information currently exists on the species complex affecting grass seed crops in WY, particularly in the Bighorn Basin. Continuous monitoring will reveal which species are most prevalent, their population trends, and period of peak activity and may also reveal potential differences in thrips susceptibility among grass varieties. While establishing precise regional economic thresholds is a long-term goal, this monitoring effort will generate the essential information needed to support that future work. This information will serve as a foundation for effective timing of control measures tailored to local production systems.

Obj.2. Evaluate the efficacy of entomopathogenic fungi for the management of the thrips complex under controlled greenhouse conditions.

Thrips management in perennial grasses is challenging because conventional insecticides cannot effectively reach all life stages; eggs are embedded within plant tissues, and pupae develop in the soil, where they remain protected. Additionally, insecticide applications can disrupt natural predator populations, potentially leading to secondary pest outbreaks such as mites. Evaluating EMF provides a sustainable alternative. In perennial grasses, EMF can establish and offer long-term thrips suppression, particularly against soil-dwelling prepupa and pupa stages. Greenhouse bioassays will assess two EMFs for virulence, and compatibility, identifying candidates for future field research to reduce pesticide reliance.

Obj 3: Develop and deliver educational materials to disseminate project findings and enhance awareness of thrips management among grass seed producers.

Translating research findings into practical and accessible communication is essential for the successful adoption of IPM strategies. By developing a fact sheet, leaflet, conducting field day presentations, and hosting a webinar through the Western IPM Center, this objective ensures that research results reach growers, consultants, and extension professionals. Enhanced awareness will empower grass producers to identify thrips damage, understand their seasonal biology, and apply appropriate management tactics. These outreach efforts will strengthen relationships between stakeholders and foster collaboration between researchers, extension specialists, and the grass seed growers in WY and beyond.