D3106: Impact of seeding rates on whitehead incidence and yield loss caused by the Mexican rice borer in rice

The Mexican rice borer (MRB, Eoreuma loftini) is a major pest of rice in the Southern U.S., capable of causing up to 50% yield loss in Texas. Larval feeding within stems damages developing panicles, resulting in whiteheads (sterile or empty panicles) that reduce grain yield. Current management relies heavily on prophylactic use of the seed treatment Dermacor X-100 (chlorantraniliprole), raising concerns about sustainability and potential resistance. Seeding rate may influence pest pressure and crop resilience by affecting plant density, canopy structure, and stand uniformity.
This study investigated the effects of seeding rate on whitehead incidence and yield loss associated with MRB. We hypothesized that higher seeding rates would reduce whitehead numbers and yield loss by limiting oviposition sites and larval establishment. A field experiment was conducted in 2025 at the Texas A&M AgriLife Research Center in Beaumont, TX, using a 5x2 factorial design with five seeding rates (35, 70, 105, 140 and 175 lbs/acre) and two insecticide treatments (Dermacor-treated and untreated), with five replications per treatment. Independent variables were seeding rate and insecticide treatment; dependent variables included whitehead incidence, grain yield, and percent yield loss. Data were analyzed using ANOVA followed by Tukey’s test in RStudio.
The combination of 105 lbs/acre with Dermacor X-100 resulted in the lowest whitehead density and highest yield, showing the greatest reduction in yield loss compared to other treatments. Although not statistically significant, this trend suggests that optimizing seeding rates could enhance integrated pest management by reducing reliance on insecticides while maintaining high yields.