Automated monitoring using acoustical sensors for insects in farm-stored wheat

An automated method using cables with acoustical sensors was compared with the conventional grain sampling method for monitoring insect populations in wheat stored in 1 or 2 bins on each of 6 farms in Kansas. Seven flexible cables, each with 20 sensors 15 cm apart, were installed vertically in the grain mass along a transect across the diameter of the bin. A computer collected and stored the data. The automated system detected insects in all of the bins in which insects were found in grain samples and provided a good estimate of infestation level. Lesser grain beetle, Rhyzopertha dominica (F.) was the dominant species, and red flour beetle, Tribolium castaneum (Herbst), and rice weevil, Sitophilus oryzae (L.) were also detected. The number of times that insect sounds were detected was correlated with insect density in grain samples over a density range of 0-17 insects per kilogram. Insects were most abundant in the top center of the wheat stored in bins, and only a few sensors in this area were needed for early detection. Insects were found in grain samples at 5-37 sensor locations in any bin, but locations differed between bins. Insects were found in grain samples at a total of 50 sensor locations in 10 bins. Sensors will need to be distributed over a representative portion of a bin to determine insect infestation levels accurately.