Three Dimensional Temporal and Spatial Distribution of Adults of Tribolium castaneum (Coleoptera: Tenebrionidae) in Stored Wheat Under Different Temperatures and Adult Densities

Three dimensional temporal and spatial distributions of adults of Tribolium castaneum (Herbst) at insect densities of 0.1 (low), 1.0 (medium), and 5.0 (high) adults/kg wheat (A/kg) were determined in a 1.5 t bin of wheat with 11 +/- 0.8%, 13 +/- 0.6% and 15 +/- 0.3% moisture contents (wet basis) at 20 +/- 1, 25 +/- 1 and 30 +/- 1 degrees C. The 1.5 t of wheat was sampled at five locations. At each location, grain was separated into three 15 kg vertical layers and adult numbers in each layer were counted. Adults did not prefer any location in the horizontal direction, while fewer adults were recovered from the bottom layers than that from the top and middle layers. Number of adults at a location with any temperature or insect density did not correlate with its adjacent locations in either vertical or horizontal direction. The temporal continuous property existed at all insect densities. These results were consistent with the tendency of the aggregation of the adults at the low and medium densities. Adults had highly clump distributions at low and medium densities and this aggregation behavior decreased with the increase of insect densities. Temperature tested did not influence their aggregation behavior.