Temporal stability of Glossina fuscipes fuscipes populations in Uganda

Richard Echodu,Chaz Hyseni,Jon S Beadell,Loyce M Okedi,Adalgisa Caccone,Serap Aksoy

doi:10.1186/1756-3305-4-19

Abstract

BackgroundGlossina fuscipes, a riverine species of tsetse, is the major vector of human African trypanosomiasis (HAT) in sub-Saharan Africa. Understanding the population dynamics, and specifically the temporal stability, of G. fuscipes will be important for informing vector control activities. We evaluated genetic changes over time in seven populations of the subspecies G. f. fuscipes distributed across southeastern Uganda, including a zone of contact between two historically isolated lineages. A total of 667 tsetse flies were genotyped at 16 microsatellite loci and at one mitochondrial locus.ResultsResults of an AMOVA indicated that time of sampling did not explain a significant proportion of the variance in allele frequencies observed across all samples. Estimates of differentiation between samples from a single population ranged from approximately 0 to 0.019, using Jost's DEST. Effective population size estimates using momentum-based and likelihood methods were generally large. We observed significant change in mitochondrial haplotype frequencies in just one population, located along the zone of contact. The change in haplotypes was not accompanied by changes in microsatellite frequencies, raising the possibility of asymmetric mating compatibility in this zone.ConclusionOur results suggest that populations of G. f. fuscipes were stable over the 8-12 generations studied. Future studies should aim to reconcile these data with observed seasonal fluctuations in the apparent density of tsetse.

Highlights

Tsetse flies, Glossina spp (Diptera: Glossinidae) transmit several species of pathogenic trypanosomes causing Human African Trypanosomiasis (HAT) and African Animal Trypanosomiasis (AAT)
In order to investigate the impact of seasonal climate changes on population size and to gain further insight into the population dynamics of G. f. fuscipes, we evaluated temporal changes in gene frequencies at one mitochondrial locus and 16 microsatellite loci in multiple Ugandan populations
Following sequential Bonferroni correction, only one locus pair exhibited significant linkage, and only in one population, confirming previous work showing that these loci were unlinked [10,14]

Summary

Introduction

Glossina spp (Diptera: Glossinidae) transmit several species of pathogenic trypanosomes causing Human African Trypanosomiasis (HAT) and African Animal Trypanosomiasis (AAT). HAT affects human welfare directly through the chronic and acute forms of the disease caused by Trypanosoma brucei gambiense and T. b. AAT, on the other hand, stands as a major obstacle to the development of more efficient and sustainable livestock production systems in tsetse-infested areas [1]. A major challenge to controlling HAT is lack of suitable prophylactic drugs and vaccines against trypanosomiasis. A riverine species of tsetse, is the major vector of human African trypanosomiasis (HAT) in sub-Saharan Africa. Understanding the population dynamics, and the temporal stability, of G. fuscipes will be important for informing vector control activities. A total of 667 tsetse flies were genotyped at 16 microsatellite loci and at one mitochondrial locus

Methods

Results

Conclusion