Comparative anatomical and histological study of the alimentary canal of Dendroctonus parallelocollis, D. rhizophagus, and D. valens (Coleoptera: Scolytidae)

A comparative study of the anatomy and histology of the alimentary canal of Dendroctonus parallelocollis Chapuis, D. rhizophagus Thomas & Bright, and D. valens LeConte shows similar characteristics among the 3 species. Important differences, however, are observed in the position of the gastric caeca and the cytology of the midgut. These species have characteristics not found in other scolytids, such as the division of the crop into 2 regions, the presence of chitinous plates that divide the proventriculus into 3 regions, diverse cellular aspects located from the ventricular valve to the midgut, and a close relationship of the Malpighian tubules with the posterior foregut, anterior midgut, and distal hindgut.