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Laboratory Bioassays At the end of the 36-week storage period, approximately 100 grams of grain from trier samples were placed in each of 3 jars (0.24 liter) for each bin (3 reps per treatment per species) A total of 50 R. dominica, T. castaneum, or S. oryzae adults that were 2-3 weeks old was added to each jar for a specific species Bioassays for adult beetle mortality (7 day exposure) and F1 progeny production (after 7 weeks) were conducted at 28.0 °C and ~65% relative humidity (Fig. 4) P. interpunctella were evaluated at 36 weeks by placing 20 eggs on sticky black paper strips placed on 40 grams of half-crushed wheat in 0.12 liter jars and emerged adults were counted (Fig. 5) Field Evaluation of Three Diatomaceous Earth Application Treatments for Controlling Stored Wheat Insects Edmond L. Bonjour1, Siwei Liu1, Thomas W. Phillips1, and Frank H. Arthur2 1Oklahoma State University, Department of Entomology and Plant Pathology, 127 Noble Research Center, Stillwater, OK 74078 2USDA-ARS Grain Marketing and Production Research Center, 1515 College Avenue, Manhattan, KS 66502 E-mail addresses: ELB4119@okstate.edu; lsiwei@okstate.edu; tomp@okstate.edu; arthur@gmprc.ksu.edu Experimental Protocol Three DE applications of Dryacide® and an untreated control were applied to wheat at bin filling in July 2004 (3 bins per treatment) in bins containing 170 bushels of hard red winter wheat (Fig. 1) DE applications were as follows: 1) top-layer application to the top 50 cm of grain (500 ppm) 2) layered application – top and bottom 50 cm of grain (500 ppm) in combination with an empty bin application 3) total grain mass application (300 ppm) All bins were challenged with insect infestations by the addition of 100 adults each of R. dominica, T. castaneum, and C. ferrugineus into the tops of each bin at the time of bin filling and for the next three consecutive weeks Field Sampling Grain samples were collected from the bins by combining two grain trier samples per bin at 4, 8, 12, 16, 20, and 36 weeks post-treatment and insects were sifted from the samples and counted (Fig. 2) One probe trap sample per bin was collected for a duration of one week at each of the above post-treatment periods and the insects trapped were identified and counted (Fig. 3)