[Disturbances in the digestive tract of Ips sexdentatus (Insecta: Scolitidae) induced by Parasitorhabditis ipsophila (Nematoda: Rhabditidae)].

The histological study of the digestive tract in Ips sexdentatus parasitized by P. ipsophila showed major destruction of the microvillosities as well as vacuolization of the epithelial cells in the terminal part of the mesenteron. No damage could be observed in the hind gut nor during low contamination. Concurrently, the biochemical study indicated a lower amount of proteins in the alimentary bolus of parasitized insects along with a higher amount of proteins in the intestinal wall. Damage seemed chiefly mechanical and accounted for the disorders previously observed in populations. The apparent contradiction between the magnitude of damage to the intestinal epithelium and the mild effects of parasitism on host populations might be explained by the preferential location of nematodes in the terminal part of the mesenteron and the proximal part of the hind gut.