Understanding the spatiotemporal distribution of Frankliniella occidentalis (Thysanoptera: Thripidae) in a certified sweetpotato seed greenhouse

Western flower thrips (Frankliniella occidentalis Pergande) are a common pest of sweetpotato in greenhouse production. Sweetpotato certified clean foundation seed (CCFS) programs begin with virus-tested plant material that is grown from tissue culture for distribution to certified growers that propagate disease-free plants in the greenhouse. Certified sweetpotato seed growers must adhere to strict phytosanitary standards that include insect free plant material. Frankliniella occidentalis is a chronic pest in these production systems that can lead to phytosanitary rejections under high densities. As a result, growers rely on prophylactic insecticide applications rather than IPM programs to ensure thrips-free plants in these greenhouses. To better understand the establishment and population dynamics of F. occidentalis, a 10 week study was conducted in 2025 in a North Carolina certified clean seed greenhouse facility. We collected adult thrips using a regular grid of yellow sticky cards distributed throughout the ~640 m2 facility. Time series data was analyzed using Spatial Analysis by Distance IndicEs (SADIE) procedure in R. Results document the population dynamics of western flower thrips within the greenhouse over space and time. This research will provide insight to growers on the establishment of thrips during the greenhouse season, which will help inform a more targeted approach to sampling efforts and insecticide applications. The resulting reduction of insecticide applications will help slow the development of resistance and provide safer working conditions for greenhouse employees.