Impact of seeding rates on whitehead incidence and yield loss caused by the Mexican rice borer in rice

The Mexican rice borer, Eoreuma loftini, is a major pest in Southern U.S. rice, causing yield losses up to 50% in Texas. Larval feeding leads to panicle damage, causing white and empty panicles, reducing yield. Current management relies on seed treatments with Dermacor X-100 (A.I.: Chlorantraniliprole), raising concerns of insecticide resistance. Seeding rates influence pest dynamics and yield by promoting a strong and uniform rice stand. Incorporating optimal seeding rates into current management may offer an effective and sustainable alternative. This study evaluated the influence of seeding rates on whitehead numbers and yield loss against rice stem borers. We hypothesized that higher seeding rates would lead to fewer whiteheads as increased plant density may restrict oviposition and consequently larval establishment, therefore decreasing yield loss. Two field experiments were conducted in 2024 and 2025 at Texas A&M AgriLife Research and Extension Center in Beaumont-TX. Treatments followed a 5x2 factorial design with five seeding rates (35, 70, 105, 140 and 175 lbs/acre) and two insecticide treatments (Dermacor-treated and Dermacor-untreated), and 5 replications per treatment. Seeding rates and insecticide treatments were the independent variables, while whiteheads, yield, and percent yield loss were the dependent variables. ANOVA was used to evaluate the main effects, followed by Tukey’s test for treatment comparisons, using RStudio. The results of this study will be discussed later and will provide a better understanding of the relationship between whiteheads and yield loss at different panicle densities. Optimizing seeding rates can reduce the unnecessary insecticide use and minimize yield loss.