Mass loss determination of wheat kernels infested by granary weevil from X-ray images

Mass losses in wheat kernels infested by the granary weevil were determined using soft X-ray imaging. The mass loss strongly depended on the life stage of the pest insect. Hence, determination of the correlation between developmental stage and mass loss may help to decide management strategies and can also be used to determine time and place of infestation. The mass losses were calculated from X-ray images, taken from 20 to 66 days after infestation, using the grey scale. To compare calculated mass loss (CML) with the actual mass loss, wheat kernels were weighed. Interdependence of the mean values of the CML and weighed mass (WM) on infestation time was determined and fitted by linear and polynomial curves. During these studies kernels from the infested sample were assigned to six categories based on the CML and morphological features obtained from the X-ray images. The categories were as follows: sound, small larva, medium larva, large larva, pupae and emerged. Comparison of kernels assigned to categories based on mass with kernels classified by area of grey scale revealed that mass was more reliable in assigning grain to particular classes. The mass index decreased the number of wrongly classified kernels. The polynomial curve for mass loss can be used to give an indication of the time and place of infestation. (C) 2011 Elsevier Ltd. All rights reserved.