title: Population dynamics of Glossina palpalis gambiensis symbionts, Sodalis glossinidius, and Wigglesworthia glossinidia, throughout host-fly development.
abstract: The tsetse fly (Diptera: Glossinidae), the vector of trypanosomes causing human and animal trypanosomiasis, harbors symbiotic microorganisms including the primary symbiont Wigglesworthia glossinidia, involved in the fly's nutrition and fertility, and the secondary symbiont Sodalis glossinidius, involved in the trypanosome establishment in the fly's midgut. Both symbionts are maternally transmitted to the intrauterine progeny through the fly's milk gland secretions. In this study, we investigated the population dynamics of these symbionts during fly development. Wigglesworthia and Sodalis densities were estimated using quantitative PCR performed on Glossina palpalis gambiensis at different developmental stages. The results showed that the density of the primary Wigglesworthia symbiont was higher than that of Sodalis for all host developmental stages. Sodalis densities remained constant in pupae, but increased significantly in adult flies. The opposite situation was observed for Wigglesworthia, whose density increased in pupae and remained constant during the female adult stage. Moreover, Wigglesworthia density increased significantly during the transition from the pupal to the teneral stage, while mating had a contradictory effect depending on the age of the fly. Finally, tsetse fly colonization by both symbionts appears as a continuous and adaptive process throughout the insect's development. Last, the study demonstrated both symbionts of G. p. gambiensis, the vector of the chronic form of human African trypanosomiasis, to be permanent inhabitants of the colony flies throughout their life span. This was expected for the primary symbiont, Wigglesworthia, but not necessarily for the secondary symbiont, S. glossinidius, whose permanent presence is not required for the fly's survival. This result is of importance as Sodalis could be involved in the tsetse fly vector competence and may constitute a target in the frame of sleeping sickness fighting strategies.
authors.affiliation: UMR 177, IRD-CIRAD, CIRAD TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
authors.forename: Illiassou
authors.initials: I
authors.lastname: Hamidou Soumana
authors.forename: David
authors.initials: D
authors.lastname: Berthier
authors.forename: Bernadette
authors.initials: B
authors.lastname: Tchicaya
authors.forename: Sophie
authors.initials: S
authors.lastname: Thevenon
authors.forename: Flobert
authors.initials: F
authors.lastname: Njiokou
authors.forename: Gérard
authors.initials: G
authors.lastname: Cuny
authors.forename: Anne
authors.initials: A
authors.lastname: Geiger
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D004755:Enterobacteriaceae / Q000235:genetics* / Q000302:isolation & purification; D005260:Female; D006801:Humans; D008297:Male; D012098:Reproduction; D013559:Symbiosis; D013997:Time Factors; D014353:Trypanosomiasis, African; D014370:Tsetse Flies / Q000254:growth & development* / Q000382:microbiology*; D044106:Wigglesworthia / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins