Evaluation of larval growth process and bamboo consumption of the bamboo powder-post beetle Dinoderus minutus using X-ray computed tomography

Abstract

The bamboo powder-post beetle Dinoderus minutus is a major pest of felled bamboo in Japan. In this study, X-ray computed tomography (CT) was utilized to non-destructively trace the movement of the larvae of D. minutus inside infested bamboo specimens and to evaluate the bamboo consumption of the larvae. The infested specimens, which had been enclosed with adult D. minutus beetles, were scanned using a microfocus X-ray CT system every 2 to 5 days. Larvae and other stages of the beetles were clearly recognizable in the CT images with a voxel size of 61.9 μm, and they were distinguishable from the bamboo, insect tunnels, and frass. The larvae were traced until pupation, and the length and volume of their tunnels were measured to evaluate their bamboo consumption. The tunnel length and volume bored by one larva was estimated to be 0.98 mm and 1.06 mm3 (0.70 mg of oven-dry mass) per day within the average observation period of 22 days, respectively, and the active larval period was estimated to be 39 days in our experimental conditions.