Cyclical development of Trypanosoma (nannomonas) Congolense broden in Glossina Morsitans centralis machado, glossina fuscipes fuscipes newstead and glossina brevipalpis newstead

Abstract

Developmental cycle of Trypanosoma (Nannomonas) congolense Broden in Glossina morsitans centralis Machado, ~. fuscipes fuscipes Newstead and~. brevipalpis Newstead was investigated with a view to better understand this subject and, to compare cyclical development of two different I. (N.) congolense serodemes in the three different tsetse species belonging to morsitans, palpalis and fusca groups. Results showed that both these I. (N.) congolense serodemes completed cyclical development in the three tsetse species by day 25 after the infected feed. However, variation in susceptibility to the infection between the three tsetse species, was evident. The cycle of development was confined ,to the midgut and proboscis. No haemocoelic infection was observed. Survival of I. (N.) congolense (IL 1180 and IL 2281) was best in ~. ffi. centralis (44.2%; 45.0%), intermediate in §. brevipalpis (9.7%; 7.5%) and poor in §. f. fuscipes (0%; 2.5%). Differences in the gut. environments of different laboratory-bred cultures of Glossina Westwood species and subspecies have been suggested such that I. (N.) congolense parasites can survive better in the guts of some than others and undergo cyclical development to metacyclics in the hypopharynx. The transmission frequency of infection to mice by §. ffi. centralis and §. brevipalpis infected with I. (N.) congolense IL 1180 and the number of trypanosomes discharged by infected §. ffi. centralis at a single feed were also studied. Results showed that . centralis transmitted the infection more efficiently (94.0%) than ~. brevipalpis (23.5%). The mean number of trypanosomes discharged at a single feed by~. m.centralis was 93.04±10.0. There was no significant difference between the male and female tsetse in this respect. The survival and reproductive performance of the three different tsetse given infected feed as tenerals were compared. Results suggested that development of I. Uf. ) congolense IL 1180 in the three tsetse species had no deleterious effect on their survival and on the reproductive performance of the female tsetse. The weights of the puparia, their emergence rate and sex ratios of the emergent flies were not affected by the

infection. Effect of higher than optimum incubation temperature of puparia and maintenance temperature of infected adults of ~. m. central is, ~. f. fuscipes and ~. brevipalpis on I. (N.) congolense IL 1180 infection rates were also investigated. Results showed that, tsetse produced by puparia of ~. m. centralis incubated at 290±1 oC, and the pupar ia of three speci es incubated at 280±10C during the day and 250±loC at night were more susceptible to I. (N.) congolense IL 1180 infection than tsetse produced by puparia incubated at 250±10C. The maintenance temperature of the infected adults did not appear to affect the infection rates.