The massification of an atypical field symptom: damaged oilseed rape caused by Aulacobaris coerulescens (Col.: Curculionidae) using computed tomography approaches

Abstract The green rutabaga beetle, Aulacobaris coerulescens Scopoli, 1763 (Col.: Curculionidae) is an essential and decisive pest of European oilseed rape. Its damage is caused by its larvae developing in the stem. We performed non-destructive computer tomography-based imaging on characteristically damaged plant samples from open fields to expand this knowledge. We examined the size and location of the larva and the cavitation formed in the stem, its position relative to the formed hypertrophy and the density values of the damaged tissue structures. Our experimental results confirmed that the larva of A. coerulescens causes hypertrophy in the stem regions close to the attacked root nodules above the formed chamber. It has been confirmed that there is a positive correlation between the volume of the formed cavitation and the volume of the hypertrophy located above it ( r = 0.52), and between the distance between the cavitation and the hypertrophy and the length of the hypertrophy ( r = 0.95). The analysis of the tissue density values showed that the tissues located above the cavity, including the hypertrophy, are less dense than the tissue characteristics of the healthy stem. The tissue destruction caused by the larval activity prevents the translocation of nutrients and water in the acropetal direction of the plant, which will result in a drastic reduction in yield. Based on the achieved information, it can be stated that targeted protection against the species should become a necessary element of the oilseed rape cultivation technology in the areas affected by the pest.