Use of a Web-Based Model for Aeration Management in Stored Rough Rice

Abstract

A web-based model was used to simulate the impact of aeration on population growth of the lesser grain borer, Rhyzopertha dominica (F.), and the rice weevil, Sitophilus oryzae (L.), in stored rough rice, Oryza sativa L., at Beaumont, TX. Simulations were run for each of 10 yr with 1 August as the start date; 31 December as the end date; beginning populations of 2.5 adults per metric ton (1000 kg); starting grain temperatures of 29.4, 32.2, and 35.0 degrees C; and aeration airflow rates of 0.27, 0.79, and 1.40 m3/min/metric ton of rice. In the absence of aeration, populations of both species increased exponentially, with maximum production of R. dominica and S. oryzae at starting grain temperatures of 35.0 and 32.2 degrees C, respectively. Final predicted populations of R. dominica on 31 December from grain starting temperatures of 29.4, 32.2, and 35.0 degrees C were 5465, 6848, and 11,855 per ton, respectively; final predicted populations of S. oryzae were 13,288, 21,252 and 4355, respectively. Aeration led to a reduction in grain temperature and a decrease in pest populations, regardless of starting grain temperature or aeration airflow rates. Predicted populations of R. dominica on 31 December ranged from 12 to 63 adults per ton at all grain starting temperatures and airflow rates; populations of S. oryzae on 31 December ranged from 108 to 193 adults per ton at all grain starting temperatures and airflow rates. The predicted population levels in aerated rice represented at least a 98% reduction compared with unaerated rice. Results show the utility of the web-based model and how the various model inputs can help define broader patterns of insect control in rice stored in the south central United States.