Feasibility of Automatic Aeration for Insect Pest Management for Rice Stored in East Texas

Aeration using automatic controllers was compared with manually-activated aeration (manual aeration) in bins of farm-stored rice in Nome, Texas, from 17 September 2002 through the end of the year. Manual aeration was defined as the farm owner manually activating the fans in mid-October, while automatic aeration employed activation temperatures of 23.9°C, 15.6°C, and 7.2°C for three discreet cooling cycles. Population development of Rhyzopertha dominica (F.), the lesser grain borer, and Sitophilus oryzae (L.), the rice weevil, was assessed by confining 20 adults of each species with 150 g of rough rice in separate cages placed at 6 different locations in the top of the rice mass. Total heat units at temperatures above 15°C were 150 to 300 degree days (DD) lower in bins with automatic aeration compared to manual aeration. Temperatures from 17 September through mid-October were 8°C to 10°C less in bins with automatic aeration than in with manual aeration, and 3°C to 6°C less during the remainder of the year. The number of adult R. dominica in the cages from bins with manual aeration were 45.4 +/-13.1, 114.5 +/- 17.7, and 223.0 +/- 24.8 after 5, 10, and 15 weeks, respectively, while populations in cages from bins with automatic aeration were significantly less (P < 0 .05); 0.8 +/- 0.3, 24.5 +/- 4.5, and 21.7 +/- 2.7 after 5, 10, and 15 weeks, respectively. There was no statistical difference (P = 0.05) in the number of adult S. oryzae collected in cages from bins with manual versus controlled aeration after 5 weeks (11.7 +/- 8.1 and 0.3 +/- 0.3, respectively), 10 weeks (14.7+/-7.1 and 18.0 +/- 9.6, respectively), and 15 weeks (39.0 +/- 21.2 and 10.5 +/- 5.6, respectively). However, the variation in the data set could have masked the apparent differences in the two aeration strategies.