Scanning microscopical observations on the foregut structures o mosquitoes and their role for the ingestion of microfilariae (author's transl)

Experiments on the transmission of Brugia malayi by various mosquitoes had shown that microfilariae ingested by some species were badly damaged when they reached the stomach, but were much less hurt in others. The structures of the foregut likely to cause these injuries, were investigated and documented by scanning microscope techniques. In Anopheles albimanus, A. arabiensis, A. stephensi and A. pharoensis which have well developed armatures the microfilariae showed a high rate of destruction. In A. stroparvus as well as in Aedes aegypti, Ae. togoi and Culex fatigans in which these structures are missing or poorly developed the larvae were much less affected. From the size, shape and position of the different papillae, spines, rods and cones observed it can be concluded and confirmed that the pharyngeal armature (buccopharyngeal bar) will be by far the most important structure responsible for the injuries of the microfilariae. However, it appears that the characteristics of different filaria species can play an important role in preventing such damages.