Tackling the invasive rice delphacid (Tagosodes orizicolus Muir), evaluating insecticide efficacy and varietal response

Since its detection in 2015, the invasive rice delphacid (RD) (Tagosodes orizicolus) has become a major threat to rice production in Texas. This phloem-feeding pest can reduce yields by 30–40% through direct feeding and up to 75% when transmitting Rice hoja blanca virus (RHBV). Limited insecticide options and the lack of host resistance in Texas rice varieties make effective management challenging. This study evaluated potential control strategies through host preference and insecticide efficacy experiments conducted under greenhouse and field conditions. In the varietal preference experiment, nine rice varieties were infested with adult RDs, allowing mating and oviposition. Female adults selected plants for egg laying, and the number of first instar nymphs was recorded on 3-, 5-, and 8-week-old plants. One-way ANOVA (SAS) indicated no significant differences among varieties at any growth stage. For greenhouse insecticide efficacy, three-week old plants were infested with RDs for five days before application of five insecticide treatments. Courier SC and Endigo ZCX significantly reduced nymph emergence per plant, whereas Dimilin 2L and Flonicamid performed similarly to the control. A field efficacy trial was conducted in a farmer’s field (25 × 200 ft strips) using nine insecticide treatments. RD numbers were recorded at 3, 7, and 14 days after treatment (DAT) using a sweep net. Overall, Courier, acephate, and courier+portal showed the lowest mean RD counts. These results provide preliminary insights into potential chemistries and varietal tools for managing RD and will inform the development of integrated pest management strategies for Texas rice.