|Wilson, L. Ted|
|Arthur, Franklin - Frank|
Submitted to: Ecological Modelling
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2017
Publication Date: N/A
Citation: N/A Interpretive Summary: The use of low volume airflow rates to cool stored grains, commonly referred to as aeration, is an important component of management plans for stored wheat. However, there is comparatively less research on using aeration to cool rough rice stored in the south central USA. Scientists at Texas A&M University developed a comprehensive model that integrates aeration with historical weather data to predict population growth of two major pests of stored rice, the lesser grain borer and the rice weevil. Results show that increasing the airflow rates to more quickly cool a storage bin provided more benefit that decreasing the target temperature, especially in the southern rice-growing regions of eastern Texas and western Louisiana compared to eastern Arkansas and southeastern Missouri. Cooler temperatures in the northern region allowed for usage of lower initial aeration temperatures compared to the southern region. Variations in weather data between years also affected predicted population levels. Results show that specific strategies must be developed for regions or even individual states, but regardless of location aeration greatly reduced predicted population growth compared to bins that were not managed with aeration.
Technical Abstract: The objective of this study is to determine the potential effectiveness of aeration in controlling rice weevil, Sitophilus oryzae (L.), and lesser grain borer, Rhyzopertha dominica (Fabricius), as an alternative to the use of insecticides. Grain temperature, moisture, and pest population dynamics were simulated at each layer and radial position within a storage bin using a two-dimensional aeration model linked to an age-structured distributed-maturation insect population model. The models were parameterized using data from the literature. Regional analysis across major U.S. rice producing states suggests adult populations of both species decrease progressively towards higher latitudes mainly due to lower fall and winter temperatures. Increasing the storage bin aeration target temperature from 7.2°C to 15.6°C more than doubled the adult populations in the southern states, but the effect in the more northerly rice producing states was much less due to ambient air temperatures seldom reaching the target temperature. An increase in aeration airflow rate from 0.69 to 1.38 m3/min/MT (metric ton) had a greater impact in reducing adult populations than a decrease in the aeration target temperature. Weather variation between years within a county greatly impacted pest populations. Even in the southern states, predicted rice weevil populations under aeration exceeded 1000 adults/MT in less than half of the years. These results highlight the site-specific impact of aeration on S. oryzae and R. dominica and the need to develop cost-effective site-specific aeration and insect pest management strategies.