doi:10.1094/CPLEX-2012-0316-01R | VIEW ARTICLE

Research

Detection of Lesser Grain Borer Larvae in Internally Infested Kernels of Brown Rice and Wheat Using an Electrically Conductive Roller Mill1,2

D.Brabec,^3,4T.Pearson,³ and P. W.Flinn<sup>3

1</sup>This paper was originally published in CFW Plexus. It is reprinted here with permission from the authors. Citation of the paper should reference the original publication and DOI number.²This paper reports the results of research only. Any mention of a proprietary product or trade name does not constitute a recommendation or endorsement by the U.S. Department of Agriculture. The USDA is an equal opportunity provider and employer.³USDA-ARS Center for Grain and Animal Health Research, Manhattan, KS, U.S.A.⁴Corresponding author. E-mail: Daniel.Brabec@ars.usda.gov. Cereal Foods World 61(2):65-70.

Modifications were made to a small laboratory mill to enable the detection of rice kernels internally infested by immature grain insects. The mill, which was originally designed for wheat, monitors electrical conductance through the grain and detects kernels that are infested with live insects based on abrupt changes in electrical conductance as the insects inside the kernels are crushed between the mill rolls. The mill was adapted to detect rice infested by immature lesser grain borers (LGB) by altering the gearing and reducing the gap between the two mill rolls to produce shear between the rolls. Samples of LGB infested long, medium, and short grain (dehulled) brown rice and hard red winter wheat were tested in both the modified and original mills. The detection rates for long grain brown rice kernels infested with large, medium, and small LGB larvae were 97, 83, and 42], respectively, with the modified mill and 61, 22, and 4], respectively, with the original mill. Similar detection rates were observed for medium and short grain brown rice with the modified mill. The detection rates for hard red winter wheat kernels infested by large, medium, and small LGB larvae were 98, 94, and 78], respectively, with the modified mill and 78, 67, and 38], respectively, with the original mill. More time was required to process a sample through the modified mill than through the original mill. For rice, a 500 g sample could be processed in ≈150 sec, making the instrument useful for quality control checks of incoming and outgoing product and for monitoring grain during storage to determine whether fumigation is necessary. However, for drier wheat kernels, the flattened teeth in the modified mill allowed kernel slippage; as a result, the benefit of increased accuracy might not outweigh potential feeding issues.