Biological development of Trypanosoma (Nannomonas) congolense IL 1180 in Glossina morsitans morsitans Westwood 1851 (Diptera : Glossinidae)

Abstract

Teneral Glossina morsitans morsitans (Mall) infected with Trypanosoma congolense IL 1180 were parasitologically examined from days 3 to 15 (D3-D5) at 72 h intervals. Microscopic examination of the digestive tract showed that on D3 75% of the flies were infected in the midgut only. On D6, procyclic, mesocyclic and metacyclic forms were observed in 82, 74 and 26% of the flies, respectively. Metacyclic forms found on D6 revealed the precocity of the parasite biological cycle. From D9 on, all midgut infected flies also developed trypomastigotes in the proventriculus and esophagus. Occasionally, mesocyclic forms were observed in the proboscis of flies with mature infections. In addition, epimastigote and metacyclic forms were clustered in several groups fixed to the labial walls. With no sex distinction, the procyclic index changed between various cycle periods. The metacyclic infection rate showed a progressive increase between D6-D15. This increase also concerned the vectorial competence, except for the period D9-D12. Global values of vectorial competence calculated from D6 on were 0.5381 for males and 0.5194 for females. They did not show significant differences between sexes.